Poly-Urathane VS' Rubber

[Smokey228]

okay, i been trying to do research, and im having very little luck...

i gotta fit new bushes to my ra23 but i dont know if i should use rubber or polyurethane...
ive heard a few different opinions, and ive read some old threads from the old forums... but basically wat i wanted to know is wat would be best for jus general road application. i may take my car to the track, but i dont want to build it for that as that will make up about 1.7% of the cars use...

so far ive been told that i should use poly on the front and rubber on the rear.
ive been told i shouldnt worry bout rubber on the rear and i shud use poly all round.

ive been told that the advantages of rubber in the rear means that id have more grip during body roll.
the negative to that would be that id create 'lag' wen launching. that wif poly the car would be more responsive...

wat are ppl here using in their 23's and wat do they use the car for. maybe its best to jus follow suit

[TurboRA28]

Howdy, I replaced pretty much every bush in my RA28 with Poly-Urathane. All the old rubber bushes were totally shagged. At the time I didn't give it a lot of thought, and just got Noltec to supply all new Poly bushes.

But i've also heard some rumors that rubber can be superiour, mainly in regards to how long it lasts and needs less servicing.

The car felt much better with the new poly-urathane bushes though.

Cheers
Joel

[Toobs]

Polyurethane will outlast your regular rubber components under pretty much all circumstances, however, you need to keep them lubricated otherwise they squeak creak and groan badly!

I have poly bushes all round and the only servicing I have ever done is to regrease the rear swaybar D bushes... no creaks or groans anymore!

[Norbie]

I also have poly all round on my Supra and it works great - however, for a live axle rear I would definitely use rubber. Poly bushes are too hard and can cause binding problems.

[Enchanter]

My experience is with a Mitsubishi Scorpion ( front engine rear drive live axel ), I have put poly troughout the whole car and I love it. The back end is quite taily on the gravel, though I have heard that this is the norm with these cars and the lowered kingspring would also be adding to this.
If I were to do it again I would go for poly, the ride is firm but very responsive.

Oh yes and on a Toyota note I will definately be putting poly in the Supra

Cheers

[Rodger]

My experiences and from reading.

When I built my TA-22, twenty odd years ago now, I replaced all the rear bushes with OEM rubber. The 22s use the same setup as the 23s.

I also used rubber in the front lower arm.

Now admitedly, I very rarely drive the 22, but when I recently have taken it to Wakefield Park for Track days I am very pleased at how well it handles. It feels better on the track than my race car did, full of poly bushes (probably due to me not servicing them regularly enough).

I have also driven several one owner, very low km, 15-20 year old, TA-22s and it is amazing how tight the original suspension really is.

Advantages of rubber:
They have the neccessary rotational properties without lubrication.
They are quieter and give an initial soft feel to the small bumps.

Disadvantages of rubber:
They can move longitudinally which changes the rear axle alignment under acceleration one way and braking the other way, so the rear tends to steer the car.

Advantages of Poly:
Almost completly stops the longitudinal movement.

Disadvantages of Poly:
Must be lubricated otherwise binding occurs which stops the arms from rotating as they are designed to do and regularly (once a year) must be checked/lubricated.
A bit hasher on the road over the small bumps such as "cats eyes".

I personally would recommend using the OEM rubber bushes. They will be good for longer than Smokey will probably own the car and several owners beyond that.

But use Poly for the swaybar mounts and ends and keep the body mounts lubricated to rotate. The ends tend to cop a lot of loading that distorts and breaks the rubber version fairly quickly.

My preference though for the new Race TA-22 I am building, is to use rose joints where possible and no rubber. Being a race car things will now get serviced and checked more regularly.

Regards

Rodger

[The Witzl]

**** edit: just asked what was answered


OK... so the benefit of rose jointing is a 110% eliminiation of lontitudinal movement, whilst giving a forever free rotation.... correct?

My guess is also that this would make the small bumps quite harsh??



The reason im interested is im going to be putting a boot full of power and loading behind my RA28, and it WILL be regularly 1/4mile track driven.... with the occasional wakefield day...... and will be road driven regularly.

The geometries and physics behind panhard rod 5 link live axle setups is not something i understand very well yet - but i wish to

[Andrew162]

My experience is with a Mitsubishi Scorpion ( front engine rear drive live axel ), I have put poly troughout the whole car and I love it. The back end is quite taily on the gravel, though I have heard that this is the norm with these cars and the lowered kingspring would also be adding to this.

Sentiments shared... I had an '84 GL Scorpion as my last ride, and it used to creak and groan like a bitch all the time. I didn't know what caused it, but the only thing I hadn't replaced was the bushes in the suspension. Swapped out the standard rubber for a polyurethane kit and it was bye-bye creaks and groans.

Yes, these cars are very tail-happy in the gravel, and even moreso in the wet. I do miss my old Scorpion, it was a fun car. Go the Weber's...
It was lowered on Jumboz Springs by about 45mm and that also attributed to a very tough ride.

Regarding the polyurethane on the RAV, I've got it mounted in the rear swaybar (4 points) and I don't hear a thing from it. I tried getting the stock 25mm front swaybar rubber bushes replaced for poly's, but I don't know anyone that makes them.. it's either 24mm or 27mm.

[Rodger]

Witzl,

I'll dig out the book I have been reading and without breaching copyright I'll quote some of the contents regarding bushing materials. It explains a lot of pros and cons to do with the performance of each product and the effects on handling.

The book also mentions making bushes from Nylon. This is a better material again than Poly as it is a true engineering plastic with very good lubricating properties. Anyone good with a lathe can machine them up easily and as a result is a good option to replace the OEM bushes and not have to cut and fabricate rose jointed ends.

Regards

Rodger

[Smokey228]

well i jus went up and got a quote for polyurethane ones as that seems to suite my application pretty well. but wat i wanted to jus quickly double check is, i plan on doing a 1ggte conversion sumtime in the next 2-3months. i jus wanted to ask if all round poly is gonna be suited to that aswell.

this is my quote anyway which ill hopefully get tomorrow and put in on sat for the puddy road run:

*Front*
Radius Rod Bushes : 30$
Drop Link Bushes: 25$
: 20$

*Rear*
Upper trailing arm: 79$
Lower trailing arm: 79$

and i gotta get the rear sway bar matched up cause noltec dont have a specific one for that...

does that seem alright?

[nb86]

one thing to look out for with poly is that although its very long wearing, if there is any fault or too much stress/not enough lube the can shear and tear to peices. rubber would just flare or distort in similar situations whereas poly tends to fail completely. ive seen a lot of poly bushes fail this way so it's definitely something to keep in mind. also with the 5 link rear a poly bush on the top LH control arm mount can put undue strain on the mounting points when accelerating, especially out of turns.

[Rodger]

Looks like a couple of good threads going here.

Combine this with the Adjustable control arms thread and some good ideas and views floating around.

Possibly a good FAQ topic.

Regards

Rodger

[Rodger]

Ignore this one.

Regards

Rodger

[The Last Streetfighter]

Does anyone know what Durometer Rubber and Poly the suppliers are using. I imagine the rubber would be in the area of 60 Shore A and the Poly to be about 80 Shore A.

[Rodger]

Cannot quote the durometer or either, but can say that the engineers designing rubber bushes can very the properties of the rubber to give a wide range of hardness to suit each application.

From what I am reading this control is not as easy for Poly bushes and there is not a fixed standard for this material so there are bad and good ones out there.

Regards

Rodger