Why Do FAST Drivers HATE Factory Suspension Bushes?

[@hpa101]

Building a fast car? Get $400 OFF the all-inclusive VIP package deal: hpcdmy.co/vipy50 Get 50% off your first Suspension Tuning Fundamentals course: hpcdmy.co/offery50 TIME STAMPS: 0:00 - The Last Thing Many Think Of 0:26 - Rubber OEM Bushings 1:15 - Why OEM Use Rubber 1:58 - NVH Considerations 2:51 - Compliance (Movement) & Solid Bushes 4:10 - Polyurethane Performance 5:02 - Powerflex Bush vs OEM/Factory Bush 5:59 - Deflection Testing Comparisons 6:35 - Less Compliance = More NVH 6:44 - 'Insert' Bushings 7:51 - Inserts Assume Bushes Are Serviceable 8:03 - Wear Over Time 9:07 - Driver Feedback 9:24 - Thank You, James! 10:00 - The More You Know, The Faster You Go!

[@patx35]

I find it amazing that a polyurethane bushing upgrade actually improves ride quality on some vehicles. It makes sense if you think about it. The inner sleeve in a poly bushing can freely rotate, almost like a ball joint. In contrast, rubber in an OE bushing is attached to the inner sleeve, which acts as an additional spring that can send road harshness directly to the chassis. As long as the vehicle doesn't use those weird off-axis bushings, a poly bushing upgrade would allow the suspension to move more freely, and send more road harshness directly to the shock and spring, which are the parts that are supposed to be absorbing road harshness.

[@HellaNorCal916]

I've always be a big fan of poly bushings. Even in daily driven cars. You can't beat the road feel and predictable driving dynamics of a solid bushing.

[@adri1leusha]

I've done nothing but bushings, suspension and sway bars and my car (also new wheels and tyres). The result is amazing, drivability is out of this world. I don't have reference laptimes or anything, buy I'm pretty sure I would gain more time on a technical circuit than a stock chassis with a turbo...

[@newagetemplar6100]

These bushes do have their uses especially with different hardnesses plus they are easier to install and maintain. Just be aware that there are cheap nasty ones out there too . I did have a customer once that purchased a cheap 5 link kit for a MK1 escort against my recommendation. Less than a year later the ‘so called ‘ polyurethane bushes had gone hard and broke up literally leaving 10mm of play . Power flex have been going for decades and although i generally have no need for their products , they do use high grade polyurethane for their bushes therefore it would make sense to buy theirs / quality ones . Ideal for suspension, gearbox and diff mounts etc but polyurethane does melt if close to an exhaust manifold and is not sometimes suitable. I have seen several e36’s melt aftermarket engine mounts on the exhaust side. Any race car I build I personally go for natural rubber engine mounts and the same chassis mount setup as a proper gp4 escort / World Cup x member , a far better way . If you do go aftermarket engine mounts make sure they will stand the temperature. Fitted a few powerflex suspension bushes in the past and never had any issues so thumbs up from me 👍

[@someguy4576]

Funny how you guys uploaded this, I was just looking into upgrading to poly bushings. Thanks for these videos, all info and not the usual youtube fluff, loving them!

[@hpa101]

Our pleasure! Pros and cons for everything but it's nice to have a bit of a middle ground option before you go for solid mounts etc which are great in the right application, but that is not in a vehicle that sees road use for decent lengths of time (as in driving for hours on the open road, not to a local 'hard park' on a Friday night) 😎 - Taz.

[@derekcable]

Years ago fitted poly bushes all round on a Mk2 16v Golf,drove like a go kart afterwards with no extra noise or vibration. On my present car I have poly inserts on the dog bone and gearbox mount with a bit of vibration on idle but not once the revs rise a bit.

[@spooler7828]

Just yanked mine out and install SPL spherical bearings in everything. I drove a car with them first and was quite impressed. Very little noise/vibration. Transmission or Diff bushing poly bushing 100%.

[@gordowg1wg145]

Old school trick was to tape the voids off and fill them with RTV or, for firmer results, a 2-part polymer mix. Of course, that was before the aftermarket started opening up one's options.

[@videomaniac108]

Thanks for the great content that is both interesting as well as informative. Your questions are very well focused on the questions and concerns that I usually have about these aftermarket performance parts.

[@marc9283]

Good point with the inserts! I own a Fiesta ST and i see many people throw on Powerflex inserts on their engine mounts which are just broken. Many people dont understand how these work.

[@guilhermeg345]

I've had powerflex bushes and still do, the dogbone mount for my car although they claimed no increased vibration, the engine vibrated at idle which was annoying, felt like a 20 year old car, everyone complained that my car was vibrating so it wasn't just me. I still use top strut mounts as they lower the car 10mm more and the rubber ones don't last 6 months due to it being lowered but yeah there's no miracles regarding nvh, you can feel everything even the crossing stripes. It also wear out the headlight projectors supports so now they vibrate at every road imperfection.

[@hpa101]

Cheers for sharing your experience! Shame about the NVH expectations not being met with that particular application. What series did you go for? I think most people are happy to accept a bit more in the name of performance but it all depends on the expectations that are set right, noting how many different options there are too 😎 - Taz.

[@guilhermeg345]

@@hpa101 I went for the normal purple series. On the dogbone mount was 70A (red) and the strut mounts 80A (purple).

[@daneprostamo-brown6552]

Hey mate, decreasing the compliance with a stiffer poly bush will always increase the resonant frequency of a system assuming other variables are kept the same. If you increase your idle rpm slightly you may find the issue is resolved. An engine is always best operated above the resonant frequency of the combined system. This can often be observed by looking at a washing machine spin up. Usually it resonates at lower spin speed but stabilises above such resonant frequency. Also misfires can cause similar vibration problems because the car fires at lower frequency which approaches the engine mount and motor resonant frequency. 👍🏽

[@guilhermeg345]

@@daneprostamo-brown6552 you're right but I didn't know better at the time and got carried by people's feedback. Powerflex themselves claimed no increased nvh, they don't mention that on their website anymore. I even checked the dogbone mount again and they changed the design a bit but I wouldn't risk again. I only remember the absolute nightmare it was to remove, one of the two pieces rotated due to the vibrations and I couldn't pull it out since it was bolted inside the subframe there was no space to fit more than a screwdriver. I had to melt it to take it out.

[@overdrive39]

The issue I have with Poly bushings are the life span is not liftime they degrade down to crumbs after a while.

[@ryanmalin]

i used to have poly bushings and engine mounts made from hockey pucks. NVH was a bit much but it handled great

[@slfrules1]

I've only used Energy Suspension poly bushings but i was surprised at how quickly they degrade. After 25k they were packed enough to fall out of their homes when i took the arms down. Second set pack in a little quicker and caught debris between the bushes and arms clearancing the aluminium. IMO Delrend

[@PANTYEATR1]

Great video. I've always been a fan of polyurethane bushings. They sharpen a dull suspension💪

[@jackweta]

When your pushing on track having the rear toeing out unpredictably is a pucka

[@gothicpagan.666]

Years gone by bushings for race cars were made from a phosphorous bronze type material with a grease point. This type of bushing or a spherical joint has a tendency to crack the chassis locally to the mounting points, it's the main cause of chassis failure, after driver error.🙂

[@byloyuripka9624]

that seems like a hard dance, you can make an unbreakable car by attaching four wheels to a solid block of iron, but that weighs a bit id imagine. so you have to pare as much away as possible, soft bushings seems like a good solution

[@gothicpagan.666]

@@byloyuripka9624 Yes in reality with a production based chassis, their are so many compromises that a tiny amount of suspension deflection isn't going to affect your lap times. With a single seater it's more critical, but then the average single seater driver is at a different level to a club level saloon pilot.

[@roadracing3]

Some production cars come with sealed rose joints/sphericals and it's a big step down to replace them with poly. Rose joints/sphericals are going to be a much better choice everywhere else if you want zero deflection and bind. I run away from poly except for anti roll bar mounts.

[@sexyfacenation]

What cars are you talking about?

[@roadracing3]

@@sexyfacenation Some suspension points on Gen5 and Gen6 Camaros use sealed rose joints. Using poly here is a step down when it comes to cornering perfection.

[@daanyl]

one of the best mods 👍especially if you got an older car. just changed all the balljoints and bushes on my type r and its amazing

[@BjornFSE]

Interesting..... RE to Spherical bushings, Is there a way to Extend the Lifespan of them ? I've had Poly Bushings in the past that have worn down over time (no not Powerfex but other brand), Our Caribbean roads do tend to be aggressive on vehicles... this has left me to wonder if the stiffer poly bushes would be best for the rougher roads... but I will say steering response and handling definitely gets a huge improvement by going Poly.

[@Takeitlightly6]

Ok ok ok stop because of these free sessions i am learning so much i hvent logged into class for many years.

[@hpa101]

hahaha great problems to have right! 😂 An interview like this is a long way off a course, but we're glad to be in a position where we can do them and don't plan to stop any time soon (WTAC is a month away 😎) - Taz.

[@richardclarke207]

I think the one thing people forget poly bushes vs oem rubber, is the rubber needs zero maintenance whatsoever, however poly defo needs maintenance, cleaning and lubricants are so important to how long the poly bush will last. Amount of customers that come with copper grease all over the bushes and moan about how rubbish they are…😅

[@injecttuning]

Great information

[@baribari600]

With some cars like the FD RX-7, you can't just go willy-nilly and replace everything with urethane or plastic, since some of the OEM bushings aren't really bushings at all. Powerflex makes a few bushings for the FD that shouldn't be replaced with anything but spherical bushings or OEM / Mazdaspeed parts. Superflex doesn't make this mistake.

[@TotoGeenen]

Can you elaborate further on this?

[@baribari600]

@@TotoGeenen Some OEM bushings are actually spherical bearings covered in rubber. Changing these to urethane would cause the suspension to bind.

[@bb1ben]

I have been warned that polyurathane does not deflect enough for some bushing locations and will tear and wear out extremely quickly, such as a lower inner control arm bushing on a double wishbone suspension since it deflects in 2 axis. Wonder if there is any truth to that. Havent had an issue with mine in that location yet

[@guilhermeg345]

It depends on the durometer but yeah I've seen cracked control arms as the bushing doesn't deflect enough.

[@bajkerjohnvolta]

Did someone have squeaking problems with Powerflex bushings. I really want to upgrade to poly, cause i am drive who notices every chage in suspension and it makes me mad. So please share ure experiences Thank you.

[@ghostwrench2292]

I recently went full poly (Powerflex and SuperPro) on my suspension - control arms front and rear, swaybar bushings, steering rack bushing and rear upper shock mounts are all poly. To be fair, I also installed coilovers at the same time so I cannot completely credit the poly bushings for the transformation in how my car handles. My car, a Mini Cooper (R53) is known for go cart handling and I can say my car is extremely responsive in steering inputs and is an absolute pleasure to throw into corners. With regards to NVH, I do have some squeaks to track down but I suspect the rear upper shock mounts are the culprit because although I did grease them, I was a bit light on applying grease there compared to everywhere else. Other than that, I am very happy with my suspension now and I do think polyurethane bushings are a worthwhile modification.

[@bajkerjohnvolta]

@@ghostwrench2292 wow. Thank you for repply :D

[@alundrasrt]

What is the maintenance of poly bushing, seems grease not tend to stick on those surface. Can I use lithium grease, wish is more viscous, please?

[@hpa101]

They are supplied with PTFE/Silicone bush assembly grease otherwise Powerflex state their bushes are maintenance-free. We didn't have a chance to get into that in the interview, so might be worth asking them for some more information and feedback from others using them in the same manner you plan to on that front. Note the lifetime warranty doesn't apply to the motorsport-targeted products sadly, but there isn't much on a race car you expect to last forever either to be fair so not really a deal breaker for those with reason to look into poly bushes in the first place - Taz.

[@alundrasrt]

@@hpa101 Thanks.

[@frankpeutz9106]

I missed the maintenance topic in the presentation. my experience is that pu buses need regular maintenance (at least every 2 years for street use and every year for track use). I also have bad experience with the use of PU at engine and gearbox mounting points.

[@Remenschneider]

If you are talking bushings, you need to be talking elastokinematics! It's a huge part of the suspension setup of a stock vehicle.

[@mmusic142]

Do this bushings add stress to the chassis?

[@petereacmen716]

“Poly bushes are great” -Poly bush manufacturer. Poly has its place in some applications but most times it ends up being a downgrade IMO

[@treeplusplus]

this channel is called high performance academy. Because poly bushes offer greater performance

[@flyonbyya]

Likely below is true… If I’m an enthusiast…poly yes If not….no

[@user-nh8rr7oi6l]

Зачетное видео

[@woocash2139]

What about pu creep deformation?

[@hpa101]

Not something we discussed sadly. Not sure if there is a study directly comparing PU creep to natural and synthetic rubber specifically. Maybe throw a link up if you find one otherwise that would be a great topic to bring up next time we visit any kind of bushing material comparisons for sure 😎 - Taz.

[@mm6705]

just an FYI do NOT use polyurethane for your bushings. They are not self lubricating, and will very shortly, if not immediately begin binding. They will still bind even with regular greasing via correctly installed grease fittings. You are supposed to use DELRIN or similar oil impregnated plastic that is self lubricating, and iirc stainless inner sleeves for a permanent solution. This will make all your car's joints very low resistance, as the delrin acts as a bearing. This is actually something that you will need to respring your car for, as the oem (or maybe you are replacing seized poly bushings) have quite a lot of built in resistance with reduce the spring rates needed on the corners. There are many ways to fuck this installation up, so be patient. Oh, and most cars don't have someone making the bushings as a kit, so you'll need to get them custom made. If you are driving a Miata...you are in luck! Someone makes kits!

[@dreednlb]

"The Last Thing Many Thing Of"

[@hpa101]

#allofthethings I don't know why, but that is a typo I make very often along with 'don't' instead of 'done'. In my defence, even Grammarly (which I often don't use but did this time) also missed that 😂 Thanks for pointing it out so I could fix it, appreciate it - Taz.

[@jesvans]

bushes ? =

[@hpa101]

Yep! Aka bushings 🌳 We draw the line at calling them shrubs, just FYI - Taz.

[@gordowg1wg145]

Small trees for the bigger ones.

[@cannaroe1213]

There's something going on with my suspension's shrubbery

[@jesvans]

@@hpa101 well, the Brit's often call things different names than Americans*. so i didn't know if this was one of them. and, i was joking with you 🙂 *and they drive on the wrong side of the road, lol

[@DavidLagendijk]

polyurethane is crap. It is just plain stupid to create friction in the mountingpoints of your suspension. Go spherical or leave Rubber in. The whole power flex hype is just marketing. It is cheap ass crap.

[@ghostwrench2292]

My experience in installing polyurethane bushings is that friction is significantly reduced. Control arm bushings articulate on a steel sleeve within the polyurethane bushing. It allows the component to move easier in the direction it is supposed to move and at the same time it resists component movement in directions the component is not supposed to move which allows the suspension to do its job more effectively.

[@DavidLagendijk]

@@ghostwrench2292 back to school.

[@cannaroe1213]

The hardest part about getting poly bushes is finding all the right bush sizes AND the right durometer. You should always buy your new poly bushes all at once, from someone who knows what car they're going on. With all the model years its often harder than it sounds. Obviously you can go stiffer or softer from there peicemeal, but i've seen some friends DIY their bushes from day 1, as they transitioned from rubber, and their cars always sound like that autistic pinball piano machine video. EDIT: kzbin.info/www/bejne/f6e4hmugpKeVZ7M

[@hpa101]

Still, has to be easier than building whatever the hell you call that machine you linked to. That's pretty wild, and super intriguing 😂 All at once is a great tip though, and yes sizing can be tricky until you have the part in your hand/can measure. Whenever there is any uncertainness between an A and B of something I haven't actually pulled off the car yet I just get both and return the one/s I don't need rather than pulling it off and then ordering while you're vehicle is immobile. Most part suppliers are 100% OK with you doing this unless something is an indent order, which is fair. Bit of a tangent sorry, happy Tuesday! - Taz.

[@cannaroe1213]

​@@hpa101 Not a tangent at all, that's absolutely spot on. Size-anxiety was an issue for me, VW T4 changed bush sizings the year my model was built from 35mm to 40mm, and best I could do was guesstimate the ID from the OD. If I'd just bought both i'd have finished the project a year earlier :D All the best mate