How Shocks Work - Introduction to Rally Car setups, v2.3

[@antonskuzenko1444]

Just what I needed. Nowhere else on KZbin do they explain THIS. It makes a lot of sense wrt to the 'floating' ride. Going to revalve and try this in my rally car.

[@SuspensionTruth]

Good stuff - do let us know how your changes work out.

[@antonskuzenko1444]

@@SuspensionTruth so the reason i was searching for exactly this sort of explanation is because last year I launched the rear end of the car off the bump stops sky high after a series of averagely large consecutive bumps, i.e. my rear end 'packed up' over the bumps and by 4th or so bump there was no shock travel left to absorb it. As I suspected it, most likely due to too stiff rebound which is normally a multiplier magnitude of the bump damping stiffness, and indeed such was the then shock valving. So as promised, I've got a new set of all 4 shocks with this philosophy in mind. So far on the tarmac/broken concrete it works great. You can feel how driving slow it actually feels harsh, but once at speed is good and compliant, even a little soft, if I may say so, for my liking, but I've only driven on the softest setting on tarmac/broken concrete so far and didn't get much chance to stiffen the settings, as was still re-adjusting myself to the now improved car. I was on roughly 0.25 high speed damping coefficient in compression and 0.15 in rebound front and rear. I'm sure even stiffer compression and proportionately stiffer rebound to the tune of 0.45 comp / 0.35 rebound would work even better. On to the gravel at the end of the month, so will hopefully keep you posted how it feels there

[@antonskuzenko1444]

@@SuspensionTruth One other thing - At the time of writing these comments I worked at the Ford Motor Company and did rallying for fun but have since made the move to Bentley Motors in a Chassis Engineer capacity and when I checked with the guy responsible for the dampers, what do you think I found? Perhaps not much of a surprise to you but exactly THIS! Their dampers are heavily compression damping biased for this exact reason - floating ride in a fairly heavy vehicle. Anyway, I thought you'd like to know you were bang on the money with the ride physics all those years ago!

[@SuspensionTruth]

Good to hear independent confirmation. Appreciate your feedback!

[@racingmaniacgt1]

Interesting point, working with some ride engineers tuning off-highway vehicles, they noted the same need for the dampers to need more compression damping....

[@mas921]

Fantastic video! Makes perfect sense !

[@SuspensionTruth]

Thank you! It's a video from quite a while ago but I'd say the principles hold as I learned from my mentors and continued to test and refine on my own. Driving a car with a neutral or slight 'rally-style' damper bias is an amazing experience! Have you?

[@mas921]

@@SuspensionTruth honestly not yet! I hope so though ^___^

[@SuspensionTruth]

Excellent!

[@SuspensionTruth]

If you want more help, you can contact us to do a consultation on getting your setup better dialed in. Right now I've got a Mazdaspeed 3 to build some tarmac "rally-style" shocks for!

[@adrianrodriguez6046]

Your videos are very educational, thank you!

[@SuspensionTruth]

You're welcome!

[@Psychedelicbananas]

I searched for Bilstein valve sets, and there are about 20 variations, half linear half digressive. How to know which set has compression exceeding rebound? none of the vendors specify info on that. Maybe you have a link to some bilstein manual or this?

[@SuspensionTruth]

You'll need to refer to the Bilstein valving manuals - generally they list rebound first and compression second, force in Newtons. Bilstein Valving Manual here: www.bilsteinus.com/fileadmin/user_upload/user_upload_us/pdfs/motorsport/en/Motorsport_valving_manual.pdf and main download page here: www.bilsteinus.com/downloads/product-information/

[@htpzt]

I have Bilstein B8's in my Miata, with the stock valving. Would just flipping around the piston give me some type of "ghetto" rally valving, as a flipped around B8 curve looks pretty similar to what you've drawn here?

[@SuspensionTruth]

+htpzt Assuming you mean the 90-97 Miata, then it would be more 'rally' style but the rebound would be almost non-existent and the compression forces might be dangerously high. If you flip the piston you may as well change out the valving to something that works better. Bilstein has useful valving guides in their tech manual, you can hunt around or contact their tech support for that info. I can design valving for you as well via paid consultation.

[@SuspensionTruth]

Hi Scott, your second comment didn't get saved so please restate it. In my experience/analysis, yes to your first sentence though it depends on how your dampers produce bump and rebound forces, as you can have TOO much bump or rebound. Rebound (extension resistance) SLOWS the rate at which the wheel extends. It's crucial to understand the physical effect of each adjustment. If you have 'too much rebound', the wheel will NOT get back out and track the road, which is jacking down.

[@Lindholmer5k]

So after seeing this 3 part series, iv concluded that what i want for my little toyota yaris/vitz/echo is a damper that is set up a bit more like a rally damper, paired with a set of stiffer springs as i live in 'no mans land'? looking for best possible grip, and the least amount of bodyroll i can get from a set of dampers/springs

[@SuspensionTruth]

If by no-man's land you mean off-road driving then I would be most concerned with maximizing suspension travel first, then perhaps mildly increasing spring rates. Often OE springs with well-tuned dampers (especially rally-style tuning) and sensible bump stop choice will do well on very rough roads. If you're really dealing with rally then custom length, long-travel 2.5" or 3.0" ID springs are what you'd be aiming for. If you're not driving off-road and just want a fast yet compliant b-road car, you can stiffen springs more at the expense of ride quality. Improving front negative camber gain (via crash bolts or an adjustable camber plate) is usually the most important step in optimizing suspension on an road-driven front-strut equipped economy car. You always want Flat Ride in your spring rates, which most OE springs usually provide but not all aftermarket springs do. Then a damper which isn't jacking down, which is very difficult to find (nearly impossible I'd argue) in an off-the-shelf set of aftermarket dampers.

[@Lindholmer5k]

Im on b-roads, the northern european kind, with insane patch work, lots of U- shaped tracks from heavy vehicles and sharp turns over crests all over. about half an hour of driving from my home, the roads get better tho, probably what you would expect a b-road to be ;) Anyway, after watching some of your videos yesterday I was trying to feel how the suspension was behaving, and in all actuality, I think its fairly OK, apart from what I think is underdampening at the front when going over ridges at 45/50mph, like a bridge joint. Tire bounces rapidly probably like 3/4 times before im not feeling the vibrations in the car. and the generaly non responsive steering with huge amounts of bodyroll in most situations... feels like it takes literaly 0.5 or more sec for the energy in the car to re-settle in to a turn and let the tires do their thing. Im glad i found your videos, i was about to pull the trigger on coilovers, but glad i didnt do it, as i dont want a lowered car anyway, i just want preformance

[@SuspensionTruth]

I hear you. Compared to a set of unknown aftermarket coilovers, probably designed for low cost and lowered height vs. real-world operation, the factory suspension is going to be your best bet. Especially from what you describe it doesn't sound that bad. If you can work with someone who can test your factory front and rear damper, then build an actual rally-style damper (doesn't need to be multi-adjustable, just better tuned) you'll have the best overall result. I'd say just enjoy yourself and perhaps down the road look for a used Miata or Mazda 3 which you can get Bilstein dampers for.

[@Lindholmer5k]

I've entertained the idea of a Miata before, seems like a fun car! I've got a thing for small 'gokart' like cars. But im highly sceptical of a convertable, seeing that we got a fairly wet and cold climate year around up here. If i could get my hands on a good chassis, that for whatever reason aint road worthy and sells for next to nothing, id build it up! Seeing all your videos on the subject, and your work with the Miatas, i wouldnt hesitate to buy a set from you, un-tested befor purchase ^^

[@hillclimber11]

Very nice video. I have a question. In my race car i have two bilstein rears with 230/110 bound/rebound and i am thinking to change them with some other bilsteins which are 175/90 bound-rebound. When cornering my rear inside wheel tends to lift as i have an axle. Will it be reduced with the new set up? is it going to be softer? Thanks in advance

[@SuspensionTruth]

Your question would require more information for me to answer it and I only answer setup questions after consultation form and fee payment. If you're interested in consultation you can visit fatcatmotorsports.com and look for Elite consult (individual). Thanks in advance!

[@antonskuzenko1444]

your rear wheel lifting has nothing to do with shock damping, it's roll stiffness distribution and ride height. if the rear wheel is lifting, it means rear axle has already offered all weight transfer it could possibly provide towards reducing your understeer. Mind, lifting rear wheel is a standard sight on FWD, especially French and Japanese, and isn't actually all that bad at all. To reduce this, try lowering your ride height or centre of gravity height and stiffening rear anti roll bar, but watch out for bump steer behaviour when lowering the front, and too much oversteer if rear ARB too stiff. Also, bilsteins normally specify their rebound first. so your quoted values of 230/110 are most likely 230 rebound and 110 bump setting, which is what the majority of bilsteins, including 40mm Escort inserts, are like. 200/100 is their most common valve setting unit

[@fastslapterence5904]

And the spring rates are quite soft, some examples, the Ohlins for Gr. N Tarmac: Impreza '08-'14 7f/6r kg and EVO VII-IX 7f/9r

[@SuspensionTruth]

Yes. Thanks for the info. I just watch a documentary on Group B from the 80s, 'Riding Balls of Fire'. Inspiring!

[@fastslapterence5904]

There's an article online WRC related about spring rates (rallybehindthestages springs&co) and I'm quoting the most interesting part: "In the mid to late 90's, the works Toyotas were running very hard springs, in the range of 50-80N/mm on the front for gravel and as much as 90-100N/mm on tarmac, if I remember correctly. Things changed drastically with the involvement of top Nordic drivers and Toyota Team Sweden (TTS) who went, together with some evolutions of the Öhlins dampers, way down to values around 45N/mm on the front. In those days, this was a revolution."

[@fastslapterence5904]

@@SuspensionTruth Thank you for your work and very educational videos, these are well explained and I think you would be an awesome teacher, I've learned a lot from your channel and i'm using this knowledge to help other enthusiasts. I'm a NB1 miata owner and member of the italian mx5/miata forum, I have a thread there about your findings/research on the OEM NA/NB suspension wich has over 18,000 views (title: Confronto tra Assetti Oem e Rally: Showa/Bilstein/B6-B8 di Fat Cat Motorsport) sorry but youtube won't let me put any links here. So you're well known and regarded to the italian miata community too 😊

[@fastslapterence5904]

Sorry, I had to make a correction to the specs, the site where i found them was incorrect reporting as Tarmac instead of Gravel, but still quite soft for a GR. N weight

[@SCOTTFREEDEN]

so then, would it "better" for me to set compression as stiff as possible for bumpy roads and rebound to be as soft as possible in order for me to get max grip? I was under the impression that rebound is usually set stiffer than bump for the wheel to get back out and track the road asap after compressing? ive been playing ard with my 3 way and im getting confused as to which set up gets me the most grip, compliant ride. if harshness is the way then by all means but im learning its not.. pls help

[@SuspensionTruth]

Harshness is definitely NOT the way... at least at low speed you always want rebound softer than compression to allow the tire to track the ground. Control over larger bumps *might* require more rebound than bump, but this can be overdone. Hope you haven't adjusted yourself into utter confusion with those 3 ways!

[@drtone]

U r my God!

[@SuspensionTruth]

That's a bit much, pardner, but I appreciate the thought! =p

[@charispsilopoulos407]

Hi. I own a suzuki swift sport and I installed h&r springs in order to lower the car 35-40mm and koni sport dumpers, rebound adjustable. I use the car as a daily drive in our really bad and patchy, full of pot holes roads but I also like some fast corner driving. I see that on full soft rebound, the car in city feels pretty smooth but on highway at 70mph I can feel the car going up and down. On a firmer setting, a little less than 1 turn out of 2 in the front and 1+ on the rear, the car feels to handle great and bodyroll seems way less than the soft setting but it hurts so much on potholes . So, I watched your videos and you said that it might feel gripier with higher rebound, but it is not. How would recommend me to tune rebound? Thank you very much for your awesome videos.

[@SuspensionTruth]

I've never said that adding rebound will make the car 'grippier'. Turning a koni sport to a higher damper setting will increase rebound, which slows down the rate at which the shaft extends, which keeps the suspension from following the road, which REDUCES grip. I'm always a fan of using the least possible rebound you can. That may mean the car feels 'less sporty' but the benefit is you have a less painful ride. Turn the adjuster toward a more soft setting. What you use is up to you. Lowering your car wasn't a very good idea if you're in an area with bad roads, unless the H&R springs also increased the spring rates significantly. You're probably bouncing off the bump stops because of the lowered height. The spring rates might also NOT be giving you Flat Ride which causes the suspension to oscillate more. I have no idea what the damping curves look like on those koni sports. You're trying to get the best ride and best handling on a damper that almost certainly is biased toward producing much more rebound than compression damping. That means, for the best ride quality you'll need to SOFTEN the dampers probably as much as possible for broken roads. Because the koni doesn't have enough compression, it won't give you good handling without turning up the rebound, which hurts ride quality. It's a very frustrating damper and it seems no matter which vehicle someone is using it, they can never find the right balance between handling and comfort. In summary: for best ride quality, you need to soften the (rebound) damping on a rebound-only adjustable damper like the koni sport. Also, be aware that having lowered the car significantly from stock and changing the spring creates other behaviors that can be decreasing your ride quality. Sometimes the least-bad combination is the factory suspension, or going to a coilover to adjust height and with damping curves you know and understand. That may not be available on your model, so unless you want to deal with the punishment go back to the factory suspension - or buy a Miata / similar vehicle where you can get some Bilsteins revalved and get better ride quality plus good handling. Good luck.

[@antonskuzenko1444]

​@@SuspensionTruth your word is gospel. everything - spot on.