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Poly Bushes...a mechanics viewpoint!


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So while I was down at Fensport on Thursday I was chatting to the mechanic, Dave, in the workshop while he was working on my car. Got off talking about poly bushing the suspension and he had a rather interesting viewpoint...

Now generally on this forum people have either done it already or are thinking about it/want to do it. (Until Thursday I fell into the later category myself). The impression I've been given by most up to now is that poly bushing your suspension is a good thing, helping to prolong the life of the major suspension components, but this may not entirely be the case. This is basically what Dave was saying:

'Poly bushes by nature are harder than standard rubber bushes. Therefor fully poly bushing the suspension makes everything slightly stiffer, giving better handling in the corners. The flip side however is that they also transmit a lot more vibrations through the major components and into the body of the vehicle. Now obviously in a track car you don't care about a few extra vibrations, but in a road car it could have a dramatic effect on the comfort level of the ride, especially on rough roads. Personally I would never fit poly bushes to a road vehicle'

He was also saying that if you do go poly bush you need to do everything or nothing, as only doing a few at a time may upset the overall balance of the suspension components with some being stiffer than others. And as for prolonging the life of the major components, well he thought not, possibly quite the opposite even. More vibrations=more wear. He did of course say though that a worn out bush is worst of all and the quickest route to ruining your suspension.

So all in all a very interesting viewpoint and should generate some good discussion. Enjoy :)

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I had a similar conversation a while back, hence no poly bushes on my rebuild. Basically identical feedback from a couple of local garages.

Although its not just poly bushes, It turns out there are lots of things that people sell as performance upgrades that are either not....or will even make your car worse than standard. It's a minefield out there.

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I keep saying it, but Toyota spend millions in r&d creating a good compromise between performance, comfort, reliability and ecconomy. Yet people seem to think they can do better after reading some sales spiel.

if you improve one aspect, you lose others. Polybushes remove the cushioning effect from road vibration so will inevitably cause more wear to spherical joints in the chain. Likewise lower profile tyres - these will also reduce the ease of controlling the car as they are less progressive and also have a greater tendancy to just let go when hitting a slippery bit.

Too many times I see modified cars being broken because the owner can't cope with running them.

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I had Poly bushed Front wishbones fitted to my 6, Why? you might ask.

To buy and fit a pair of secondhand Poly bush wish bones was cheaper than buying one genuine bush from Toyota and have that fitted.

Polybushes don't have to be stiffer than the original rubber ones that are OEM.

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Everything you hear, you have to take with a pinch of salt.

Some changes will make some areas better and make some others worse etc etc.

Its the owners choice.

I hear about Toyota spent x amount of research blah blah, but that was along time ago and some areas (not all) has moved on and and improved since then, so some areas/mods will improve the car than the original parts ever did.

It all depends what and how the owner wants the celica to perform.

I would be careful what some of these garages say also, as the mentioned garage at the start of this topic thought they knew all about the 7afe engine and they didn't.

Go with your instincts, weigh up the pros and cons and do what you want............its your car after all not theirs. :)

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I have full Polly bushes set up along with upgraded anti roll bars meister r suspension and 17inch rims, with strut braces front and rear, car handles well very well to Say, I do however feel every jolt more but since having seats rebuilt with uprated foam and better bolster, it has made a great improvement for comfort.

You do get increased wear on other parts steering rack and track rod ends etc but if checked and maintained no real issue.

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Iain, I have to agree with Dave from Fensport on that. Harder bushes will make the ride feel stiffer as will any 'Sports' upgrade to the suspension. Larger diameter wheels in their nature need lower profile tyres, this gives you less 'give' in the side walls meaning you have a harder ride. Lower springs will give a similar result. less movement in the suspension travel means higher rate springs (stiffer). Pilly bushes also will give you a harder ride. The Axial, radial, torsional & conical rates will more than likely be higher over a similar movement.

Major motor manufacturers spend millions on suspension design & analysis. I know this as that is one area I am involved with at work, mainly on the testing & measurement of suspension. A small change in rubber hardness can have a dramatic change in handling. Mind You 95% of the drivers on the road may not notice the difference. When, however you do notice a difference you have probably gone too far.

We are not test drivers, so wouldn't know where the limit is (even though we would like to think that we are all prospective Touring Car or GT car champs).

At the end of the day it's down to personal preference and cost. If you want to renew all the suspension bushes, and can afford it, I would go OEM. If you budget is small then go for what is practical.

Something that has big wheels and slammed low to the ground may look better than standard, but the consequences are in the ride feel.

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Simple point the mechanic is making is leave your car sstandard on standard rims and tyres or you will ruin it........but where is the fun in that

On the flip side as awesome as my gtiii was handling wise On run flats and trd shocks and springs, the comfort level was so bad even On motorways that I had to get another car for commuting

As for the argument that pollys make stuff wear out faster. I don't really buy that as the stuff that wears out on Celica suspension is the oem rubber bushes and Toyota will only sell you a new arm, factor in that if one side goes you should really buy the other and your into hundreds of poundage for rubber crap that will wear our again in a few years

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Everything on a car is a question of a design compromise, performance, economy, longevity, cost etc. My view point is that I own a car that is late in its life, components are worn and need replacing, ergo I replace them with parts better suited to my requirements. A stock car has to be so many things to so many people, my car has to what I want it to.

're the r&d stuff I don't agree. The technology that was current when for example a 165 was built and now is hugely different, from tyres to ecu. The single best mod I did to my 165 was replace its brain. It transformed the car. Technology moves at a frightening pace, why not take advantage of that?

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My opinion is that you have to take into account the purpose of the car in the first place,and like Rich etc has said,work out your compromises.If you have your car as your daily,and you are going over the usual crap roads,speed bumps and all that stuff then having a lowered car that's fully polybushed on large rims with low profile tyres,then you are going to compromise comfort AND longevity of a lot of your parts.Comes with the territory.Im lucky in that at the moment im running a cheapo Micra as a daily,therefore my Celica can have a fair bit of license to be modded.Springs,exhaust,all this stuff.Ive polybushed the uprated rear ARB as it is by design stiffer and is actually there for a purpose therefore it is supplied with polybushes anyway.Ive kept my wheels to a 16" and on a 45 profile.Trying to get the best package for me and what the car is used for;its not a track car so I haven't gone balls out polybushing the whole lot,thats not to say that I wont replace some of the bushes as I go but I still want to spice the car up but not make it so its a pain in the ass,even though its an odd week night blast and weekend car.I still want it to handle properly,go quickly and be a drivers car;its all about getting the balance right for your needs.

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I knew this would generate some good conversation :-) some really interesting stuff coming out.

Briano: I did not know that you can't buy standard replacement rubber bushes on their own. That alone is obviously a good reason for going polly if a bush needs replacing!

25th: True about their not so great handling of the ST, but keep in mind this is now the mechanic talking privately away from the ears of management, so as I said, his viewpoint, not the CO's.

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It's very rarely the rubber that wears out on the standard suspension. It's normally the rod ends or sperical bushings (many people mistake the latter for rubber and replace with poly making the suspension softer !! )

People replace the ECU with a mappable one and end up with better ecconomy and more power. Seems like a win/win, however it has NOTHING to do with newer technology and everything to do with the mapping - it has had nearly all the safety margin taken out. One duff batch of fuel, or a bit of drift with age or temperature (it takes man years of mapping to get corrections right, if anyone thinks £200 for a couple of hours on the dyno gets a perfect map they're seriously deluded by the sales patter). A recent case was a well known 165 owner who fitted an AFR gauge and found his previously mapped PFC was running 12.5 AFR + on boost - very lucky not to have killed his engine. I can also think of at least one person whose engine went pop soon after fitting a PFC running right on the edge to achieve a target power.

I'm not saying that people shouldn't tailor a car to their needs, but don't go into it blind thinking there is no downside to any modification.

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I am sure mr smith would love to here one of his grease monkeys have just talked you out 200 quids worthy of ploy bushes :D

I tend to agree with most , as soon as you upgrade , enevitably you could move a problem further up the line and cause ware , but not extreme ware , if fitting polys is gonna balls up your shocks then the shock were on there way out in the first place and were due replacing

I did 3/4 poly bush upgrade on my gen 4 , with added lowered springs and 16 inch rims , the car was a lot more hard core , or fun in my terms :)

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Chris, I know about that car, and the change in the settings, Two of my best mates who went to the RR session with him where at my house today. lets just say you only have half the info :-)

I would disagree re my ECU, The technology for the first gen GTE was out dated by the time the 205 came along, for example no AFM on the later car. The stock ECU just over fuels to hell, safe to a point, but also increasing wear in the engine though bore wash . Toyota themselves had to retro modify the cooling system expansion tank after launch, so they do not always get it 100% right even with their millions. What about the stock manifold?, it has an design flaw that leads to cracking, unless you re weld, a better option is replacing it with a different one.

The mapping can be as safe or as good as the mapper, just as a stock part fitted to a stock car can be compromised by poor fitting by a mechanic. New technology enables one to achieve more, but if it is fitted by an idiot the results will still be bad.

Any modification done badly and without research can damage a car, that's a given. but people should not be put off by that, as sure as eggs is eggs if you neglect a stock car you can kill it just as quick.

plus in some cases, Toyota will no longer make or stock the correct OEM parts for older cars, therefore forcing you at times to consider taking other action.

Edited by alwayzsidewayz
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I don't think it is black and white, some bushes perform different functions so some take better to changing than others. Sometimes the Oem bush performs a function like a certain amount of rear steer, different toe depending on height, ie raised rear braking vs squat under power adding to stability. Its a very subjective thing and therefore cant ever be pinned down in either direction but as a general rule the oem will be a good balance in terms of compliance and you have to be selective about what you polypush and consider the function and in some cases a rose joint could be better or just leaving it stock. Roll the dice really if you don't properly think about it you might make it better you might not.

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Im not bothered by the noise or slightly bumpy ride. I run a fully polybushed chassis, with uprathed camber arms, rear TRD Xbrace and front strut tower brace along with heavey duty anti roll bars. She handles like it on rails.

and i like it that way. its persoanl preference. my Evo is a nice stock comfortable and relativly quiet ride, and my celica is my road legal track bit of fun.

Being an engineer i figured it kind of obviouse putting hard bushes in will indeed put more strain the the other components, but thats just how it is. take the good with the bad. brand new coilovers, see how long they last! :lol:

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An example of where Toyota got it horribly wrong is the exhaust system on the V6 3VZFE Camry, the Y-connector where the 2 banks comes together is more of a T-joint and is no good for the flow. There have been good gains all round demonstrated by replacement of this part of the system alone.

My V6 Surf (3VZE) was the same and if I had of kept it I would have changed that joint for summat better.

Re-polybushes they will always be a compromise, but as mentioned if bushes need replacing then it's often the cheapest solution.

My MR2 is fully polybushed with coilovers but it won't be used everyday. Celica may be in the future but I'm undecided at the moment.

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