Why are polyurethane bushes regarded as a waste of time?

[len_beach]

My 172 is in need of a little TLC at the mo'.

As it's worth peanuts, it's not worth selling so i'm going to treat her to some new bits and pieces.

The plan at the mo' is K-Tec engine mounts, 182 manifold, new exhaust, coilies of some description.

Now this little lot will require some semi-major work. While the subframe etc. is off, I thought about replacing all bushes with polyurethane jobs but have read that they are pointless.

Why is this or would it be worth it while doing other jobs?

Car is on 66k BTW.

 

[mini-valver]

Wishbone bushes etc are fine, its the poly bushed dogbone mounts that can casue problems.

 

[jack_davey]

how do they cause problems?

 

[RichCup]

Search mate, there's loads of threads! Some people say the bolt snaps off in the hole, or moves around and makes it oval etc. IIRC the only people with problems were the ones who fitted them to non RS models.

I've fitted one to mine, no probs yet. If you're worried, get a higher grade bolt and helicoil the gearbox hole. Fitting it makes a lot of improvement!

 

[bmh.01]

They're probably be fine on RS models due to the 4th mount on the gearbox but the idle vibration will drive you up the wall for not enough benefits. The standard mounts are soft for a reason and theres nothing wrong with them as long as they're in good nick imo.