How hitch height affects towball mass and trailer stability - it's not obvious

[@L2SFBC]

Support blog post for this video which addresses common questions including "but that's a load-share system and you said it wasn't". l2sfbc.com/my-error-on-the-hitch-height-video/

[@karlpokorny7130]

Robert the suspension at 4.10 is load sharing . It's called a roller rocker set. Former trailer builder

[@jxb178]

I’ve watched 4 or 5 of your towing videos now and they’re all extremely good. Thank you for making these!

[@L2SFBC]

You're welcome

[@anvilsvs]

Another effect related to leaf springs which is almost never addressed. Leaf springs have a roll steer effect. They act as a trialing arm suspension in that regard. If the front mounting point for the spring is higher than the axle mounting point you have an unstable condition. When the vehicle (car, trailer, whatever) rolls to one side the front portion of the spring on that side become effectively longer as it flattens and the other side becomes shorter. This steers the axle toward the side of the roll (outside on a curve causing the roll), a unstable condition (learned this from the Chrysler guru for ride and handling in the 1960s. "When all else fails to make the car stable, just lower the front spring eye (rear axle) one inch. Done, problem solved.") Raising the tongue also raises the front mount of the spring relative to the axle. Many small trailer springs have too much arch which already raises the front mount above the axle. Raising the tongue aggravates the problem. Here in the SE U.S. we often see trailers hitched to tall pick ups without a drop hitch. Tongue very high. "Well that's how you're supposed to hitch it. That makes it easier to load my lawn mower on the trailer because the ramp is lower." And then they wonder why their trailer is weaving all over the road. "Must be a bad trailer. I need to get a better trailer." Related stability issue: Tongue length. Increased distance from hitch ball to axle both smooths the ride of the trailer (reduced pitch over bumps) and reduces the trailer load effect on the hitch both side to side and vertical. Longer tongue also makes backing easier. How many times have I heard from people who now nothing about towing, "I can't handle a long trailer, it would be to hard for me to back it up." Precisely the opposite of reality. Semis (short truck, long trailer) are very easy to back. Crew cab pickup with 8' trailer nearly impossible to back because the trailer steers much more quickly than the truck. This wisdom coming to you from someone who at the age of 14 could back a four wheel trailer hitched behind a forage harvester hitched behind a John Deere with a hand clutch. Not easy, but it can be done. And at 77 I have a class E (non commercial class A) and still tow frequently up to 40,000 GCW using a 1T truck.

[@L2SFBC]

Thank you, very good points! Trailer dynamics is a sadly ignored field for trailer makers.

[@raymondclark1785]

A few days ago I saw a lifted box trailer. Both axles had been installed below the leafs which seemed to have too much curve. Not sure what he was trying to accomplish because with those axles it wasn't more ground clearance 😢 My boat trailers tounge is too short and is a PIA to back up 😢

[@johnwebster5983]

trailing arm suspension

[@blackbandit1290]

Well explained, thank you. I've been telling people about this for years and get laughed at sometimes. I've built a few trailers and designed methods to mitigate the roll-steer effects and they've all worked well. Flipping the link from rear to front also worked although the trailer was written off following being hit from behind by a person who failed to notice I had a trailer (with canopy) attached to my 4x4!

[@OttoMatieque]

Good info! I can attest to how much the level of the trailer can effects your towing experience. On one vacation I rented a single axle camper. My tow bar / hitch was too low for that trailer making it ride nose down. The trailer was well within the capacity of my truck. The handling felt like I was towing a large trailer and every bump in the road was transmitted through the hitch magnifying the felt impact on the truck. I purchased a new tow bar that raised the ball several inches and got the trailer leveled. The towing experience with the leveled trailer was much better (smoother, better control...)

[@L2SFBC]

Brilliant post, thank you!

[@Agent.K.]

I'm coming back to your videos because of a trailer a towed few days ago. It was very light (can be pushed easily by hand) but I was surprised by the amount of bounce it created when accelerating.

[@L2SFBC]

Bounce?

[@Agent.K.]

@L2SFBC Jerk might be the correct word 🤔

[@gregbrady2835]

that would have to be the most entertaining AD ive seen in a long time , keep her ,luv your products

[@twillford27]

Great video, this is the info I really needed. I have been towing unlevel and had three tire blow outs. Now I know why. Thanks very much.

[@craigclarke1628]

Another great piece of towing information that's not well known and a great reason to require towing license restrictions.

[@Malc664]

Yes. Even a semi-licensed driver like myself is not aware of Robert's knowledge. Thank goodness for his videos

[@danlux4954]

I didn’t know most of this but did know to get it as close to level as possible.

[@jimsnow8004]

Very Well Done! I am a retired Canadian Coast Guard Auxillary rescue boat guy. We trained safety procedures for towing disabled vessels, and I wish I'd had your video to show crew back in the day. This is the first of your vids I've seen, so forgive me if I suggest something you might well have already done, which is do a video on a systematic approach to analyzing a situation, personal ego, and planning the recovery. What are the no-go exit points?

[@L2SFBC]

Thank you, really appreciate that comment from someone with your background. What you describe is what I call the "psychology of recovery" and it is on my list as an unexplored topic. I will cover factors such as Groupthink, PressOnItis and PlanPersistence. I think that for safety the correct approach and mindset is more important than the gear. I did explore this topic a little in the video about whether you should back off a shackle or not, arguing that focus on quantifiable minutiae which makes 0.001% difference is a problem because it distracts from bigger, less unquantifiable risks such as fatigue and recovery load.

[@jimsnow8004]

@L2SFBC Yes, how does one zoom into tight focus and out to big picture at the right time? It's an art. And...a commander who righteously insists on a specific course of action, based on his subbornly preferred set of facts, is a commander who gets the "wrong" people killed.

[@brownmansadventures9374]

Love your work Rob. Very thorough as always. I've towed with inverted hitches and never knew some aren't supposed to be inverted. Perhaps do a clip on that topic alone as I'm sure people don't know about it.

[@L2SFBC]

So much to do...

[@brianwalker1933]

Same here. 😕

[@steveallen1340]

I guess this highlights that caravans have quite a lot of mass high above the axle line. The effect would be less pronounced for a trailer loaded with dirt.

[@BuckJoFiden]

Thanks mate. Your vids are really helping us get things sorted. Good onya 👍

[@L2SFBC]

Glad to help

[@johndobbyns8651]

Good video Robert. Just to add another factor to the discussion, because of the height of the centre of gravity, which may change with load, the centre of gravity moves forward, closer to the towball, when the towball is lowered, and rearward when the towball is raised, thus changing the distribution of load between the trailer axle group and the towball.

[@L2SFBC]

Indeed, I didn't want to make it too complex. I have another video using a model where I demonstrate the effect of height on stability - in fact two videos. Low CoG is good!

[@thebubaloomonkey]

If the link between the front and rear leaf springs can pivot, which it looks like yours can, then the axles are load sharing. Load on one axle will push up on the link, forcing the other axle down with an equal force.

[@L2SFBC]

True, but you can see that the TBM changes according to a non-load-share, the rear wheel comes off the ground, and load changes from front to rear axles on the trailer. So the load-share effect is tiny, and a nice contrast to the single axle which behaves in the opposite manner.

[@davidhogg3231]

I was confused by this as well. A rocker roller suspension type as shown in your video is a load sharing suspension.

[@alansailing1387]

@@L2SFBC The load sharing is not working because there is no weight on the trailer.

[@wanajday]

Tandem axles with slipper springs is non-load sharing suspension. Rocker suspension as in this tandem trailer is load sharing. The difference is probably due partly to the geometry relative to the suspension but more likely due to component friction which diminishes perfect load sharing.

[@L2SFBC]

@@wanajday l2sfbc.com/my-error-on-the-hitch-height-video/

[@Michael_Mears]

I went through this same process with our tandem trailer with non-load sharing suspension. I had the springs altered by the trailer manufacturer to suit our use (they often install 3.5T leaf packs which we did not need), then worked on getting the load distribution right, change the standard trailer hitch to an Ark XO 2T over-ride for articulation, then installed a Hayman Reese adjustable tow mount 3.5T (we tow 1.7T gross) on the ute, positioned it to tow level on flat concrete with the ute loaded. Also, the ute has had suspension upgrade for the higher constant load and towing. Before doing all this the tow rig and trailer handled like a bag of wet laundry and it was a rough ride. It wasn't fun. Now, it's so much better, though I still have four shocks to get installed on the trailer. Well worth doing.

[@ScottDLR]

At least you guys have parking brakes. Here in the US, we've got nothing and it would be fantastic to have such a feature. Thanks for an informative vid.

[@L2SFBC]

What! Didn't know that! Not that'd I'd rely on ours anyway...

[@Sabumnim666]

Once again a very informative video. Further to the points explained everyone pretty much, only adjust the tow ball height on their car well what if the van / trailer has a hitch height that is outside of the ADR limits of 360mm to 460mm "not sure if this is measured hitched to a vehicle or not". People have sometimes on leaf sprung vans flipped the axle for more clearance so that is a near 100mm height adjustment. Also I have seen off road vans where the hitch height is way more than the 460mm. I understand this is a point not in the focus of this video but it did raise some questions and i have not have any definitive answer on the subject.

[@applesbighatranch6906]

Great to see more of your always-excellent content, Robert! I wished to comment on (at least in the USA) the recommended TBM of 10-15% trailer weight... When towing recreationally (retired, now), I deliberately tow smaller and lighter trailers than what my tow vehicle is rated for. This has it's obvious benefits. I also use less than 10% TBM ("trailer tongue weight", here) because I work hard to load my trailer with it's heaviest cargo as centered over the trailer axle as is possible, with an eye for keeping weight away from aft of the axle. Your earlier vids on this topic (trailer loading for stability) are spot on. I suspect one reason for the recommended as high as 15% TBM could be due to the tow vehicle being a pickup truck or ute with an empty bed... we would want a heavier TBM to add weight to the lightly-loaded rear axle of the empty-bed tow vehicle. I think you get what I'm trying to say... I use an F150 but keep tools and equipment in the bed 24/7/365 and already have, before I add any trailer TBM nearly 50/50 F/R weight distribution. I therefore strive to achieve 5-7% TBM using my F150 as it is already loaded. My little combination tows like a dream. Thanks again as always for your great content.

[@L2SFBC]

Thank you for the educational comment, really adds to the video, appreciated!

[@midnight121190]

This makes so much common sense - thank you. I was so fixed on that 10-15%, but on a single axle trailer (what I have) it makes more sense to me to just focus on leveling the car and trailer.

[@midnight121190]

Are there any concerns going over bumps/inclines/declines/turns etc with it being only 5-7%?

[@applesbighatranch6906]

@@midnight121190 Only if your tow vehicle's rear axle is lightly loaded. See the second half of my original reply? I use less than 10% tongue weight/tow ball mass because my tow vehicle's rear axle is already sufficiently loaded even before I hang a trailer on it. Look for Robert's videos on the topic of trailer weight distribution. Safe travels!

[@midnight121190]

@@applesbighatranch6906 I did see that part just wanted to double check 👍 thanks for replying!

[@LeeKime-g9p]

Great informative videos. I learn something new with every one. Thank you. Lee

[@Rob-fx2dw]

Great information that everyone towinga caravan or boat or other should be aware of for the sake of safety as a priority and other reasons such as the effect on the comfort of the towingvehicle..

[@JazzbLu]

Excellent video! You should see some of the things I have with people in the U.S. and how they tow their trailers! The hitch is only 16-18 cm above the ground because it is so overloaded!

[@aussie-all-the-way]

Excellent video. One thing i will point out is when using the spring tow ball scale on a DO35 hitch use extreme care. With the rotational ability of these hitches I have seen a bloke get a fractured eye socket when the hitch rotated & was shot by the scale itself. Tyre chocks while excellent won't prevent the tow hitch rotating.

[@MichaelRobinson-fm6yi]

That's exactly what leapt out for me - very scary seeing the scale up on blocks while into the DO35. I've got a cheap tool that is basically a sleeve with a pin on the end - an adaptor which makes this situation safe.

[@davidrobinson990]

Another excellent and informative video Robert. Well done and thanks.

[@L2SFBC]

Very welcome please share

[@smitajky]

At 4:09 the photo appears to be of a compensated link suspension. If the rear wheel rises it puts pressure on the left hand end of the spring. Forcing the lever up. Which forces the font part of the lever down increasing the spring tension on the front wheel. A standard method used on railway engines for at least 150 years. Note that because the attachment points for the springs are above the pivot point of the lever this has the equivalent effect of an anti-rollbar. As the suspension moves away from the level one side increases its leverage and the other reduces its leverage. This creates a controlled amount of self levelling function. ( controlled by the design of the link but not adjustable).

[@L2SFBC]

l2sfbc.com/my-error-on-the-hitch-height-video/

[@aussiebaz5363]

Bloody excellent old mate, well presented and very concise. Thank you.

[@beansmalone1305]

That truck your towing with is pretty sweet.

[@barts1286]

The tandem axle trailer you used has roller/rocker suspension which is load sharing according to every thing I have read. Not that this changes any of your findings, in fact may suggest that roller/rocker only partially load shares. Thanks for an interesting and informative article.

[@L2SFBC]

Correct it is designed for load sharing, but doesn't really otherwise I wouldn't have got the results I did.

[@iffykidmn8170]

@@L2SFBC Perhaps more aptly named partial load sharing?

[@madbird1373]

If the tandem trailer had a significant load on it, ie. a car, that put the suspension into its working load region then the results would be negligible as the roller rocker suspension would do more load sharing than it does when not loaded enough as in this demonstration. Still a good demo of how non load sharing suspension works though.

[@JohnBlackborrow]

John, I am going to have to apologise. You have made me think further, and I have learnt something. I was thinking in terms of simple levers. The effect you have identified comes from the height of the van. As it leans down at the front the centre of mass moves forward minutely, putting more load on the ball, and when the ball height is increased the centre of mass moves rearward. But these are very small amounts. If the centre of mass is below the ball height (unlikely) the effect will be reversed. The closer the centre of mass is to the ball height the less the effect will be. But if you are that close to the limit of your towball capacity I think you need to review your rig.

[@jonedwards2107]

I live in Utah. My camper is standard with a flipped axle, so is quite high at the axle, and tilts forward under tow. I started with a fixed four inch lift, but just purchased an adjustable hitch which will give me almost nine inches of lift. That should make the trailer close to level under tow.

[@brsnorthernhorsejourney3579]

One additional reason for having trailer level is carrying livestock, horses in our case. This is because they travel standing and if trailer is nose high or nose low the animals will compensate by carrying more weight on their front or back legs as required making the whole trailering experience more uncomfortable for them. Perhaps not as large a concern on short trips but it can become an issue when hauling several hours +. Good points regarding the effects of trailer being out of level. Many of our North American horse trailers use rubber torsion axles which are non load-sharing similar to the tandem trailer from your demonstration.

[@L2SFBC]

Interesting, I want to do something on horse towing. I've never done it and didn't realise until recently how much care had to be taken with horses.

[@brsnorthernhorsejourney3579]

@@L2SFBC I think much of what you have already covered regarding proper set up, safe driving etc. is equally relevant. Equipment specifics and applicable regulations would likely be the major differences, and of course these would also vary depending on country. Don't know about other countries but here in North America there is very little in the way of required driver education for trailering.

[@markfryer9880]

​@@brsnorthernhorsejourney3579 Thirty years ago I asked the same question of Vic Roads as I was planning on towing a mobile billboard. No extra lessons required and the only time things started to get tricky was to do with P Platers and Learners. I was understandably flabbergasted.

[@andrewahern3730]

I’ve noticed that only smaller horse trailers are bumper tow. Anything more than 4 or so becomes 5th wheel/gooseneck. My guess is that the load is dynamic and if a larger livestock trailer were bumper towed, the truck’s squat would be all over the place

[@brsnorthernhorsejourney3579]

@@andrewahern3730 You're correct for the typical pickups commonly used as tow vehicles here in North America and their GVWR/GAWR ratings, I personally wouldn't go any larger than 2 horse on a 1500 ("1/2 ton") pickup for that reason. The "bumper tow" (a misleading term with today's vehicles, it has been a long time since you could tow anything of substance with a hitch ball mounted directly to bumper!) configuration can be used on trailers with fairly high GVWR's providing tow vehicle is of sufficient size and weight, an example being dump trucks that pull triaxle trailers carrying backhoes, rollers etc. In this application a gooseneck or fifth wheel hitch is not feasible due to dump box, and these trailers get pretty heavy loaded with equipment.

[@camtron0]

Great video! Very clear and concise! Thank

[@JimmyDevere]

I have been watching all the videos in this series on towing. First off, very informative, so thank you. Secondly, I have a suggestion for another video, and that is a step by step video/check list that covers all the points made in the series in a particular order. In other words, I am getting a lot of great information from the video series, but it's still not easy to apply this in actual tow scenario especially since it is easy to forget something,

[@L2SFBC]

On the way..

[@JimmyDevere]

@@L2SFBC Great! Thank you.

[@johnwebster5983]

Excellent video. Picking up my new caravan in a couple of weeks. I hope it sits level.

[@L2SFBC]

I hope so too!

[@TurboHappyCar]

Great video. I appreciate the through yet succinct explanation and the visual aids. 👍

[@L2SFBC]

Thank you

[@NeannMedical]

Great video, just confirmed a whole lot of things for me.

[@L2SFBC]

Glad to hear it!

[@derekheuring2984]

Very informative video Robert, thank you for sharing it with us. I'd be interested in seeing how the mass of the towing vehicle affects stability for any given towing load. The GVW of my Ram Power Wagon is 8565 lbs. and the GVW of the average Australian Ute is around 4,300 lbs. The PW has twice the weight of a Ute towing vehicle which should make it much more difficult for the "tail" to wag the "dog" so to speak. Everytime I watch a video of a Ute towing a travel trailer of any size it appears to me that they are on the thin edge of disaster. I tow a 5,500 lb. travel trailer with my truck and I don't even notice it's there, even when passing the bow wave of an 18 wheeler. Cross winds are no problem either unless they're extreme. The ratio of Towing vehicle weight/trailer weight of my set-up is 1.55, it would be inetresting with all things being equal how stability decreases with a lower ratio. Keep up the good work Robert, I thoroughly enjoy your videos!

[@L2SFBC]

Here's your answer on relative weights kzbin.info/www/bejne/gJaodnZrmruBec0

[@nicholasalexandrides4363]

I thought those roller rocker tandem setups were load sharing. From the Alko webpage: "Rocker Roller springs are used in a multi axle configuration. Linking the springs through a “rocker” assembly, a transfer of load is achieved when one axle is carrying a large percentage of the weight (crossing kerbs etc.) so that the loads are more evenly spread throughout the system."

[@L2SFBC]

Sort-of load sharing. Have a look at the Bruder video for true load sharing. You see the rear wheel of the trailer lift off the ground, and the hitch weight changed in accordance with non-load-share. kzbin.info/www/bejne/nqi4Zndrq9yFp8U

[@PJ-rf4uw]

I have to agree with Nicholas ..The rocker in between the leaf springs makes this suspension "true" load sharing within the limits where the rocker is able to rotate, usually the tow ball height has a height range of some 250mm(depending on distance from wheel centerline and tow ball) where both axles have the same weight.

[@servicetrucker5564]

@@PJ-rf4uw I came to say this but you beat me to it. Thanks for saving me some typing

[@johnsullivan6709]

​@@PJ-rf4uw Also agree. When the front axle is pushed up the rocker arm pushes down on the rear transfering load.

[@troycarnall7609]

It is a load sharing suspension set up. The reason it lifts an axle is due to limited wheel travel with that suspension. The other video he refers to is for an off road set up so it has more wheel travel and keeps the tyres in contact with the ground.

I don't know aboout you but that hitch flex is crazy!

[@saudk9261]

Great info Robert.. nice to educate all of us. I dont usually to a trailer but its good to know this info regardless cause it may save your "rear" end literally.

[@L2SFBC]

Thanks 👍

[@aussietrekker]

brilliant video, very professional and informative. i believe that with more novices towing larger caravans that we should have a licence endorsement where this valuable information could be included.

[@L2SFBC]

Glad you enjoyed it!

[@ianmac2963]

Thanks Robert

[@79series]

Another smashing video thanks.👍

[@johnh5215]

Hi Robert, excellent info, thanks. Have you considered doing a similar investigation into tow ball extensions and their benefit vs weights changes?

[@L2SFBC]

Maybe in future yes

[@Xstream65]

Great explanation and examples Rob 👍🏼👍🏼👍🏼

[@pwpaulwest]

That was a really informative video. Thanks a lot.

[@L2SFBC]

You're welcome please share 😊

[@GetCampingOz]

Great vid Robert! Really educational for those that don’t understand. Have you done a vid on breakaway cables on trailers and where they attach on to the vehicle ? This is always a debatable topic on social media and forums and I reckon would be great content for your channel! Cheers Adam

[@L2SFBC]

Maybe in future

[@joshc4519]

It appears in the single axle, by raising the hitch, the high center of gravity shifts the weight backwards, which reduces the weight on the hitch. On the unloaded tandem axle (with low center of gravity), raising the hitch shifts only a negligible amount of weight backwards. The dominant effect here is that the rear axle becomes the primary pivot point, which means the hitch has to take more weight. To visualize this, think about the rear axles as the wheelbarrow tire and the hitch where you pick it up. In the case where the front axle is the primary pivot point, think a teeter-totter with the load in the center. Less force is needed to balance the teeter-totter than the wheelbarrow.

[@geofflines60]

I wonder if the change is consistent as a percentage the more pitch is raised or lowered. Great video Dr Pepper.

[@L2SFBC]

Non-linear

[@jackdawg4579]

Interesting video thank you. Your tandem looked like it had walking gear or rocker arm type suspension, it if it does, it would be doing a little load sharing, but still a significant change.

[@L2SFBC]

Yes, it was doing a little load sharing, but not much!

[@andriekruger]

Be careful when using drop- or extended hitches. The towball position directly influences the results of the certification testing that all towbars must meet (in Australia anyway). That is why the hitch part number must be shown on the towbar compliance plate, if the hitch is removable. By using a different hitch to the one specified on the towbar compliance plate, you invalidate the certification testing making the towbar non-compliant.

[@Mick_4591]

So would that mean that i moving from a HR hitch to a E2 hitch would mean non compliance?

[@rossatkinson3160]

Please show us where in the adr, legislation or traffic rules that this is so. What you are saying is we can never use a hitch other than factory, and the part number is most definitely not displayed on any plate attached to the car.

[@andriekruger]

@@Mick_4591 Not sure what a HR hitch is (Hayman Reese...?) but yes, unless the towbar is certified for the E2 hitch, you will be non-compliant. Most manufacturers in Australia do not recommend using Weight Distribution Hitches anyway.

[@andriekruger]

@@rossatkinson3160 Not sure a KZbin comment is the best way to discuss this but I'll try my best. ADR 62/02 says "For vehicles with a maximum rated towing capacity of up to 3.5 tonnes ‘ATM’, the ‘Towbar’ towing bracket, towbar attachment and vehicle structure must comply with the requirements of AS 4177.1 - 2004 Towbars and towing brackets." AS4177.1 describe the static and dynamic test requirements for towbars, as well as the labeling requirements. (You can purchase a copy from SAI Global's website) It says: "Towbars shall be legibly and permanently marked or shall carry a permanently attached identification plate, made from a durable material, in a conspicuous location with at least the following information in characters in English not less than 2.5 mm high: (a) Factory mark, trade name or manufacturer’s name (if appropriate). (b) The vehicle make and model or Towbar Part Number. (c) The rated towball down load, in kilograms. (d) The rated towbar capacity, in kilograms. (e) Towing lug part number (if different from Towbar Part Number). (f) The words ‘FOR TRAILER TOWING ONLY’." Under the old Motor Vehicle Standards Act (MVSA), towbar manufacturers had to apply for a Component Register Number (CRN). The CRN has been replaced by a Component Type Approval (CTA) under the new Road Vehicles Standards Act (RVSA) that came into affect on 1 July 2021. To be able to receive either a CRN or CTA, you have to prove compliance with ADR 62/02, which means you had to meet all the requirements of AS4177.1, including submitting your test results. The reason why the "towing lug" (hitch) part number is required on the identification plate, is so that (amongst other things) the towball position used during the testing is defined. Some manufacturers would have more than one towing lug part number listed, or different orientations for the same lug (e.g. flipping the hitch upside down). All of these different positions if applicable would have been tested and results submitted as part of their CRN/CTA application. If you were to use a hitch that places the towball in a different position to what has been tested and certified, the test results are no longer valid, which means the CRN/CTA is invalid and the towbar manufacturer can no longer guarantee that their towbar would perform as per their design intent. I don't think you can post photos in a KZbin comment, else I would've posted some of the towbar labels on my Nissan Patrol. Have a look on your towbar itself. There must be a plate/label with the information required as per AS4177.1 on there. If not, your towbar is non-compliant. For those outside Australia, UNECE R55 have a similar requirement for Europe. So does SAE J684 for the US.

[@brucesutherland293]

Thanks @@andriekruger . That was much appreciated. And, it worked just fine as a KZbin comment :)

[@benmitchell8796]

Important matter. Thank you!

[@shafmahar4974]

Awesome videos… very informative. Thank you

[@L2SFBC]

Glad you like them!

[@MatDockerty]

Another good bit of info. I've always tried to keep a trailer level but hadn't thought much about why. Interestingly, I saw an ad today for a curt rockerball. Would love to see an analysis of that. It looks like a gimmick to me but I've been wrong before.

[@darrylpaulhus3069]

I have one and they do work very well. Takes a lot of the jerkiness out of the towball connection.

[@rossatkinson3160]

Rocker ball, or air shock hitches or GenY torsion hitch assembles, all are designed to take the shock out of trailer hitch connections. A must for longer and heavier trucks and US puckups. Isuzu advise it is a must, kedron will not warrant their vans without an air shocker hitch, stops the porpoising of trucks and vans.

[@Bennyboy-dog]

Great explanation and demonstration. My single axle camper hitch point is low by around 20-30mm, even after I've installed an high rise 50mm rated towball and that is at the limit of being able to open the barn door on the 4x4, and that result in less, but still substantial tilting of the trailer tow hitch downwards. I think my only choices are to a/ increase the tyre size of the 4x4 from (245x70 R16) 70's to 75's or b/ decrease the tyre size on the trailer from (265x75 R16) 75's to 70's or c/ both increase the 4x4 tyre size and decrease the trailer tyre size. Unfortunately the offsets and weight range of the wheels on the trailer are incompatible with the 4x4, so I can't just swap them.

[@jeffwuzhere]

There's the more extreme option D of having the attachment point of the trailer frame modified to sit lower. An adjustable height coupler would be a good choice if you decided to go that route.

[@Bennyboy-dog]

@@jeffwuzhere Thanks Ziduli. I have a adjustable tow hitch and could under mount the tow hitch on the trailer, but both options stop the vehicles barn door opening.

[@jeffwuzhere]

@@Bennyboy-dog Ah right. I realize now you'd have to modify and lower the trailer tongue a good ways back to gain the needed clearance through the full swing of a door. Didn't quite consider all the details I guess.

[@Bennyboy-dog]

@@jeffwuzhere I even considered cutting the bottom of the barn door off by 100mm to get the clearance, but oh, so much panel work! Nonetheless, thanks for the suggestion!

[@simonr23]

Does your suspension droop much when the van is attached? If yes, perhaps airbags, or a wdh would help?

[@stuartthorn696]

You might like to edit your segment on the tandem box trailer. The arrangement is full load sharing. A non load sharing tandem comprises two totally independent axles.

[@L2SFBC]

True, it's designed as a load share but doesn't really load share.

[@gordonflash8976]

Maybe an extention to this subject to cover load distribution adjustment methods, eg load inside the van, load adjuster / sway bars and agjustable suspension. Great video thanks.

[@L2SFBC]

Some of that on the way 👍

[@overlandready]

Here in the UK the hitch weight is set to about 75kg for most vehicles but up to 200kg or there abouts for 4x4's, Land Rover has a max 150kg towball weight. Tow ball weight is less critical than a lot of people think, correct weighting of the trailer is much more important as well as all single axle trailers should be nose down as that is a stability factor, nose up is inherently unstable as it forces weight back past the axle. I don't know if you can do a video on dynamic hitch heights and the effects on the trailer, but it would be interesting .

[@L2SFBC]

Yes, in Australia we have European vehicles with what to us are very low towball weights (which we call masses, wrongly). I prefer to European approach and agree with your comments thank you, Land Rovers over here go to 350kg TBM.

[@jonasstahl9826]

Single axles trailers a very easy to correct load, you can simply check the towball weight by lifting it up by hand to see if you are ok

[@lelenbates3367]

The problem with this scale is that the height should be adjustable to match the tow ball height.

[@L2SFBC]

Yes - you need to use blocks as I did.

[@stevetitcombe939]

Yes, that's exactly what I concluded. I've decided to measure the height of my 'nose weight' gauge when it's measuring my target nose weight of 90Kg and then comparing that height to the top of my tow ball (with my tow vehicle loaded with all my regular camping equiment). If the tow ball is the higher measurement then I'll make a standing block for that difference in height for my nose weight gauge to stand on.

[@bimble7240]

Very good video Robert, but 4:05 That looks like a load share setup to me. Am I wrong? How common are load share suspensions on caravans?

[@L2SFBC]

It's meant to load share but doesn't work effectively.

[@servicetrucker5564]

Your camp trailer has parking brakes? That’s cool. I wish my camper had them like my army trailer

[@jaywaight4561]

Thanks for another informative video

[@garyhancock1091]

I like to, and was always told, set my trailer at about 20mm down at the front from level, or 0.5 degree.

[@danlux4954]

What is the reasoning? Tandem or single axle?

[@bigpapaporsche1]

Very informative!

[@L2SFBC]

Glad it was helpful!

[@jimbobxcityguy5338]

Thanks this has helped me.

[@L2SFBC]

Glad it helped please share!

[@kululv]

the axle you showed at 4.07 min is for sure a load share suspension as the middle boogie acts as the load share device.

[@L2SFBC]

see pinned post

[@kululv]

@@L2SFBC thank you very much! The trailer with Elise loaded is actually the same system as your trailer only loaded.

[@cuepusher2504]

No matter how hard you push down on a towball it mass will not change. You are confusing Mass, Force, and Wight, as well as the unit of measurement to describe them. Good job using the concept of lode.

[@L2SFBC]

I agree with you. However, the parlance is TBM, Towball Mass. That is what people understand. The people who know the difference between mass, load and weight, and force being in newton as opposed to kilograms generally understand the simplication I'm making and why.

[@waynejill]

Is this correct? Load single axle van & towing vehicle fully as if you are going on a trip, including fuel, water and all the stuff your wife puts in at the last minute.😃 Nick off and go to the weighbridge. Van weight is 2500kg, tow ball weight 200kg. (Vehicle is say 3400 or whatever.) All your GVM's & GCM's are ok. Nick off to some flat ground. Unhitch van. Set up van level using spirit level on the A frame or perhaps a few degrees lower at the front. Set/adjust vehicle towball height the same as the van hitch. Hookup van to vehicle. If the vehicle sags in the rear, head off and spend some money on helper springs, air bags etc..(don't even think about asking her to remove anything from the van) and then start all over again.

[@L2SFBC]

Basically yes, welcome to the life of towing, and could you remove anything from the van, not her?

[@waynejill]

@@L2SFBC Actually her indoors weights 60kg, about the same as 3 jerry's full of diesel. Now that could be a swap. 🤣

[@christianrenteria2792]

great explanation

[@DIYCarRepairs]

Very informative, thanks.

[@L2SFBC]

You're welcome!

[@tpv59]

AWESOME. FANTASTIC. THANK YOU Rob. A LOT of work/research/knowledge/experience has gone in making this video. THANK YOU. Off topic, I have been trying to work out the, 'L2S-FBC' for 'years'. I assume, Love to ?????????? something something something. May I ask please, what does, L2SFBC mean? (I can't sleep!!! hahahahaha) Regards.

[@L2SFBC]

Life's too short for boring cars :-)

[@tpv59]

@@L2SFBC Hahahahahahahahahahahahahahahahahahahaha. THANK YOU Rob. WHAT a Classic!!! You made my day! Thanks again.

[@charlesclayton4644]

I my experience most problems are caused by the cars rear suspension being too soft however a possible argument towing drawbar down is it push's the cars rear axle down when you hit the cars brakes which naturally causes the cars nose down and the rear up. I don't have any experience towing a braked trailer which would probably help prevent this hinging effect if towing level.

[@L2SFBC]

The effect of load transfer under braking from rear to front is true, but you ALSO get the same effect on the trailer which has the effect of increasing TBM when you're braking. Often the trailer effect cancels the car effect.

[@Thyme2sea]

Thank you so much!

[@L2SFBC]

You're welcome!

[@slowboat6021]

glad my Touareg has air suspension, any load and it's level automatically. btw pretty sure that car trailer with the bell crank between the leaf springs has a form of load sharing? unlike vans with fully independent suspension.

[@michellebayly100]

Good vid thanks Robert. One thing though, at 1:50 you state that the van is level due to it having 70mm blocks under the tyres and 70mm blocks under the tow ball scale. Did you actually level the van using a spirit level because unless that scale is, coincidentally, exactly the right length when loaded, you can't assume 70mm under all three ground contact points results in the van being level? Or have I missed something?

[@L2SFBC]

Yes checked level I have a spirit in the caravan and I have used that area before. However what's important is that the change is consistent and it was at 70mm.

[@louhess6355]

Great video

[@L2SFBC]

Glad you enjoyed it

[@bstaplet]

Love these videos. Probably too late for a reply but what to do if van is level but weight distribution between van front/rear axles is about 60/40? Hard to get around this with front toolboxes, etc.

[@L2SFBC]

Never too late. Continue to centralise best as you can!

[@albelcher19]

I'm still confused about our setup. We have a 100 series Landcruiser, and a tandem 23' triple bunk Windsor. Weights all seem within range except the TBM (used your comprehensive calculator - thank you). Vehicle is 3500 tow, 350 ball. Van is 2474 ATM with 249 TBM. We recently took it over a 3 deck weighbridge (mostly loaded, except food, bikes and camp chairs), and it told us our TBM was 320kg (13%). Car rear noticeably sagging. There are 3 water tanks underneath (one in front, 2 behind axles), I don't believe we need all 3 full all the time. I believe our Cruiser has original suspension (soft) and that this can be upgraded, rather than doing a full GVM upgrade? I'm mostly confused being a tandem, nose down (soft suspension) so should lower TBM? But it doesn't seem that way? And should our TBM be sitting at 249 instead of 320? I don't know how to lower it?? Compliance plate didn't specify if TBM was at TARE or Max Rating. Any insight is greatly appreciated, I've seen a few of your videos and used your calculator, but still lost.

[@L2SFBC]

Yes you can upgrade suspension without GVM. If it's original, you should, the LC100 is not a new vehicle. 320 seems high for a 2474 ATM van yes, would suggest 10% or less. Tow level, not nose-down, LC100 suspension should help there.

[@MarkVoisey]

Very informative, thanks Rob. I know aftermarket airbag suspension does nothing to share load on the tow car's axles but I presume (and I know I shouldn't!) by using airbags to level the rig it would provide optimum towing and, in the case of my single axle trailer, relieve some weight on the towball and hence the rear axle? Great work, cheers

[@L2SFBC]

Absolutely right Mark, if the towcar can go level chances are the trailer will be level and life will be good!

[@ralan350]

If possible with a tandem car hauler like you used I will have the hitch a little high when empty so when I load the car it levels out

[@FMTOZ]

Thanks for this well thought out video. In either this video or another I couldn't help noticing that you have removed one of your spare tires from the van. Is this to save weight? I have a very similar van (a Mars Saturn 12.6) and I was considering doing just this for 'local trips', my concern was that there may be a balance issue.

[@L2SFBC]

Yes, just don't need the weight. No balance problems.

[@angeloudy]

I am always curious why there are not 4 wheel caravan trailers with front steering wheels. Trucks all use that kind of trailers with super heavy load and no trailer sway issue at all. There's no towball weight either since the trailer is free standing. The only downside I can think of is reversing, which is not a big deal.

[@L2SFBC]

Cost and weight. Might do something on this later.

[@racekar80]

I am interested in the open trailer if you had a load on it, like my car trailer which is exactly like this trailer. Depending where the load is on the trailer, makes a huge difference on your hitch weight.

[@L2SFBC]

Yes, that's different though - this is same load placement, varying hitch height.

[@maxg4958]

Great video... where do I find a link for the NZ company that has the adjustable trailer hitch; seen at 09:03. Thanks. Also, are there tow ball scales starting at 50 kg? They all seem to start at 100 kg.

[@Mick_4591]

As you mentioned anout using a WDH. There are others out there who say if you have to use a WDH then either you havnt packed the van correctly or you shouldnt be towing anyway . Thats because those the say this dont use a WDH and belive no one else shoud be using one

[@kadmow]

I am sure that you should be aware by now - at 4:07 (and onwards) the photo is of a load sharing suspension on the car trailer... (stated to be non load sharing) -that cast link is a load sharing equaliser link (between leaf springs) - "pretty sure" - a quick google shows your exact setup, those geometries simply don't have mich "sharing travel...

[@L2SFBC]

Yes, it is meant to load share but it doesn't really. I should have been clearer on that sorry.

[@samday6621]

Robert, I have air bags over the back axil of my Hilux, to help level the trailer. I’ve heard negative opinions on this however I’d like your thoughts. I’ve recently upgraded my trailer to a non load share tandem, and the front is low. If I invert the towball, the tailgate hits the hitch. I have added air to the bags however I’m not comfortable adding air to the full hight and not sure it would reach anyway.

[@L2SFBC]

Follow maker instructions for the airbags and they just reduce sag, not lift. Consider stiffer springs.

[@gregmillen4712]

No mention of the ADR for tow ball heights? IIRC they must be between 350 and 460mm from the ground to the centre of the ball. Assuming you started in the middle (405) then by raising or lowering 70mm puts the test outside of the legal height requirement. Or am I missing something here?

[@L2SFBC]

Yes there are limits and I could have mentioned them but the point is to show effects of hitch height. And the video is international.

[@SSRacing66]

Nice job on the demonstration with the two trailers, I didn't see that reverse effect coming on the tandem. But I'm left wondering if the tandem results would be different with a significant load (500-1000kg) on the trailer vs empty.

[@L2SFBC]

The suspension would load-share a little better, but even at max load the effect would still be there.

[@operation4wheelz]

Here’s a question, is TBM really the correct term? Being that mass remains a constant… shouldn’t tow ball “weight” or “download” be the correct term?

[@L2SFBC]

Yes but I just go with common usage.

[@operation4wheelz]

@ during my run, (albeit slow and short due to a high body mass). I realised that they are all measured in mass. It’s the only constant measure.

[@alexwood5425]

What effect does the wind load at say 80 kph on the front have on the tow ball weight?

[@L2SFBC]

Can you elaborate?

[@andrewpepper1038]

I guess you are talking about a caravan that is higher than the towcar. If so there will be a force at the top of the caravan that is trying to rotate the caravan about its axle, and this will inevitably reduce the towball mass to some degree.

[@benjaminweslake4174]

Any idea where the 10% TBM 'rule' comes from? I can't for the life of me figure out the rationale for it aside from being an easy number to calculate based on the ATM of the trailer 🤷🏻‍♂

[@markward38]

Robert, a hitch at the wrong height would it also compromise stability by swaying?

[@L2SFBC]

Yes

[@vmura]

i had a a 150kg motorbike hitched and upgraded with pedders shocks + springs on a rav4 2012 !

[@gregwilson2135]

Robert, how is an air suspension describes, load sharing or not? thanks

[@L2SFBC]

It can be load sharing or not.

[@Shontishar]

I have a ford raptor and a Cheval liberty touring xl horse trailer, I think it’s a tandem equal distribution weight and therefore would it be best to have towbar higher than trailer? There’re not level the trailer is 30cm but the raptor is 40 cm high on towbar. Thanks

[@L2SFBC]

No, tow level.

[@Physics072]

Its best to err on the slightly too low side. Too high causes sway on the highway too low = increased tongue weight and can squat the rear end of the tow vehicle.

[@L2SFBC]

no, tow level.

[@Physics072]

@@L2SFBC Its impossible to be perfectly level, the bars on the trailers are often not true. All im saying is if you have to err a little bit on the hitch height 1/2" low is probably more highway stable than 1/2" high. Sure perfectly level is the goal. Then you have to worry about tongue weight suspension squat and load the trailer in a way not to be too tongue light or heavy.

[@Physics072]

@@L2SFBC That is what I am talking about. A level trailer when hooking to the ball is important. But getting it perfect is not always possible due to ball height limitations on height adjustment. Then you have to load it up and some cars will squat, mine does not due to automatic airbags to level it. The higher the hitch from level = more sway on the highway. So err on the low side if given a choice. Is the clear enough?

[@davidshepack2484]

I have single axle trailer....is it better to tow with trailer pointed up or pointed down.

[@L2SFBC]

Level

[@daviddowney4290]

Great video thank you for that. My question is I have a long caravan 25 footer. I have an adjustable Hayman Reese towbar hitch when I connect to the car. How does one make the caravan level and the car level with the weight on it? Do you raise the hitch before you connect And keep going backwards and forwards. I have 350 kg 10% on my toe ball mess and my problem is I have airbags and new suspension. Caravan is at its weight max. Car is at its weight max at the rear of the car is sitting squad headlights up in the air.

[@L2SFBC]

Don't fixate on 10%, there's no science behind it. With 350kg TBM you're probably 500kg+ on the rear axle so stiffer suspension is your first job, and I'd also look to reduce the TBM a bit. Hard to say more without details.

[@iffykidmn8170]

How much does a say 12" drop hitch induce a leverage arm on the receiver it self? and how does it effect the capacity of the receiver?

[@L2SFBC]

A lot...don't recover off them, use with caution for towing

[@TedHarrold]

Hi Robert, I appreciate all your good advise on towing etc, but in this video where you measure the tow hitch weights of your big tandem trailer, you state that it is a non load sharing suspension. I can clearly see that it has a load sharing Rocker/Roller leaf spring system which means that the tow hitch weights will be wrong. Sorry Robert, regards, Ted.

[@L2SFBC]

Yes thanks see pinned post