Ally Bushings ?

[Stevin]

Good day, guys.

I'm wondering if I can use Ally bushings on my Subframe, Trailing arms and Diff ?

Also anywhere else I could use ally bushes ?

I plan on using Polyurethane ones on the engine, and std BMW one gearbox ?

[kevo]

hiya mate,
you can use ally bushes wherever you like but you're gonna have cracks appearing everywhere after a while because you're going to be putting alot of strain on your shell.
Kev

[Stevin]

Cranks where ?

in the subframe itself, or in the body or something ?

bearing in minds it's a completely stripped and caged track car.

[Colonel Sanders]

all over the seams of the car, as you wont have any give in the suspension!! polybush is tough enough

[kevo]

couldn't tell you exactly where as it's very difficult to guess accurately, but just think of when you're going round a bend full tilt and the ally bushes are pushed firmly up against the bush housing which is not giving at all, this then puts alot of strain on the point where the housing and the shell meets, then imagine that you hit a small bump where it be a piece of debris or a red and white chicane section of the track where is this shock going to travel? through your solid ally through the housing and into the shell and it's going to take it all out on the weakest section of the setup which is usually just to the side of one of the welds. the more this happens the more it'll flex and we know what happens when you keep flexing a piece of steel. as i said you can go whichever way you'd like as they are simple to make and cheap but you'll pay for it somewhere else in the longrun.
hope that helps
Kev

[Stevin]

Hmmm... ok I'll have to think about this a little.

Maybe have a look at my subframe and see if I can beef up the mounts...

otherwise Poly is the way I will go... whats this I hear about Delrin ?

[oakey]

Many people use Ally gbox and engine mounts without issues

[TRACKM3]

i have had alloy rear beam mounts for two years and done 3k track miles no cracks and the cage doesn't pick up on the beam mounts ?????

[Andreas]

... then imagine that you hit a small bump where it be a piece of debris or a red and white chicane section of the track where is this shock going to travel?

When you remove the 'play' from the rear subframe mounting points, it does not mean that nothing is left to give way to absorb shocks. Let's not forget that there is still the shockabsorber & spring present to do exactly that job.

Actually 'play' in itself can be destructive. The E46 M3 suffers from massive tears in the body around the rear subframe mounting rubbers - I know, we have two race car M3s here. Replacing the rubber mounts with solid aluminium bushes actually helps the chassis in this area. Now instead of having a relatively loose subframe which knocks on the chassis, you have a nice big stiffening support.

But yeah, I guess the car will suffer somewhere over time due to the increased stiffness. That also holds true for stiffer suspension, yet we still stiffen the suspension for improved handling. So if you want even better handling, you will stiffen everything up even further with solid subframe bushes.

The ideal would be if the wheel only moved in the planes designed into the suspension. Anything else, e.g. body flex and rubber bushing movement, is not welcome for ultimate performance without comfort.

A dedicated track car will lead a hard life and one cannot expect it to last as long as a normal road car. How far one should go is a matter of personal taste and willingness / ability to spend money.