14 replies to this topic

[Gillybobs]

Just starting to renovate the subframes on my mini and and wondering what people opinions on rubber and poly bushes are. Im keeping the suspension standard as I want to use the mini to take my young son to car shows and I also want to try and keep the car a civilised as possible. I've heard that poly bushes transmit more road noise in to the car, Is this true?? but on the other hand I've heard the quality of rubber components is poor now and they perish easily? Is this true???

Im not looking to make the best handling car , Im looking to make the car not be to harsh be able to drive a few mile without  it doing my head in!!

 

What do people think is the best option for me??

  

[Carlos W]

On the front, go rubber or solid. 

 

If you go solid it's a good idea to reinforce the toe board.

[Guess-Works.com]

Personally I don't use Poly at all... I've seen too many poly bushes split, break and generally be of very poor construction..

 

New rubber bushes will be a lot better than the ones you have on the car, the alternative is to go solid mounted or rose joints for suspension arms.

[CityEPete]

Whatever you do dont fit the poly rear of front subframe ones, they are junk! They are actually far too soft compared to OEM ones, mine bent and pulled the metal insert tubes out of shape within a week so I fitted genuine rover ones.

Other than that the debate is endless I think, lol.

[Gillybobs]

Wouldn't solid mounting the subframe make the car a bit harsher and noisier??  

So there is not issue with the new rubber degrading quikly?? Is this just a myth Ive heard? 

[Cooperman]

Wouldn't solid mounting the subframe make the car a bit harsher and noisier??  

So there is not issue with the new rubber degrading quikly?? Is this just a myth Ive heard? 

In a word, no. The original Mini was designed to have the front sub-frame bolted in solidly and thus be a part of the load carrying structure.

Solid mounting of the front sub-frame on the later cars, to make them as close to the early cars as possible, is about the best thing you can do to improve the steering 'feel' and accuracy in addition to making the car stronger.

But as above, poly bushes are about the worst of all options.

[Gillybobs]

As a matter of interest why did they rubber mount the subframes then? 

[Harrison541]

To reduce road noise probably.

[Cooperman]

As a matter of interest why did they rubber mount the subframes then? 

As has been explained on other threads, in the mid-'70's the target market for the Mini changed from mainly younger drivers to middle-aged women, so Austin-Rover (or whatever they were calling themselves that week) thought NHV could be reduced by rubber mounting the sub-frame.

In fact it made little difference, but it certainly did reduce the super-accurate steering for which the Mini was famous, especially when the nasty cheap rubber s**t failed, as it often did/does.

Issigonis designed the Mini to have the front sub-frame solidly mounted so as to form part of the basic structure taking primary suspension and steering loads into the monocoque bodyshell. Rubber mounting changes that completely.

There are no other cars I can think of which have the front sub-frames attached to the body with rubber bits. My BMW certainly doesn't, nor does any other car I've owned. As an engineering design, rubber mounted sub-frame is poor. The HNV is normally controlled by the suspension bushes and the rubber engine mountings, as is the case with the pre-'76 Mini.

[jaydee]

Back to the original question, theres no increase of noise going poly bushes but there will be no improvement at all over a rubber mounted subframe.

These poly bushes last next to nothing if you're a spiritated driver and i wouldnt reccomend the stuff due to them tearing flexing and cracking simply because dont have the elasticity of a rubber mounting. Under stress polyurethane crush and deform and stay deformed, rubber dont do this.

Go rubber, beware some rubber mountings on the market are really poor.

[Gillybobs]

Thanks for the reply's . Think Im going to keep the car rubber mounted. 

[Dusky]

Out of interest, how involving is changing to solid mounts? Id like to do it, but don't want to remove the engine again..;)

[jaydee]

You dont need to remove the engine, you just need to lower the subframe about a inch, its just like replacing rubber moutings.

You might need some teoboard reinforcement though, it may crack if not strong enough, so check its conditions first

[evansisgreat]

I'm 100% changing to solid mountings when my front subframe goes back on and not just because uncle cooperman says so (even though that's reason enough).

My car is a 97 and was fitted with rover rubber mounts and in not much more than a decade cracked the toeboard and both inner wings due to movement. It was taken off the road 5 years ago.

[Cooperman]

I change the mounts to solid on every Mini which passes my way if they are those horrible rubber ones.

It would be easy to make some modified mounts for the rear of the front sub-frame to take the mounting right down to the floor/bulkhead joint line and thus put the loads into the shell where they were on the earlier cars. Then with the bulkhead strengthened inside if it has split, that could never happen again and the sub-frame would be mounted much better. I think I'll look at that next time I do this.

In terms of steering response and 'tight' handling the solid mounts are about the best thing one can do.