26 replies to this topic

[minimissionary]

I've just replaced all of my front subframe mounts, apart from the top tower ones. After about 30 miles of driving, I seem to be getting a noise that closely resembles someone rubbing a piece of polystyrene.
The new mounts are all Unipart standard rubber mounts.

Any ideas?

[Twisty]

could it be the mounts be settling in?

Edited by Twisty, 15 September 2012 - 08:09 PM.

[minimissionary]

No idea. I hope so, but just wanted to make sure they weren't about to turn my toeboard into cornflakes

[Twisty]

Im sure that the ones on the toe board should be fine, i solid mounted my subframe and welded in some extra metal to strengthen the area for the reason you just mentioned. but with standard rubber items you should be ok as they are located by the bolts. the ones i wasn't sure on was the front mounts with the spacers behind them.

[mike.]

Why didn't you change the top mounts? If they're worn out and you didn't replace them you'll be getting movement

[minimissionary]

I did the teardrops too. Didnt do the top ones because they didn't mention having them in stock at Unipart. Will sort them. Is it possible the movement at the top is making the bottoms work twice as hard, hence the noise?

[mike.]

Yeah i'd say so they should all be renewed at the same time, or switched to solid mounts.

[MiniLandy]

I would say this was the metal around the rear mounts creaking... The top mounts wouldn't make any noise, really.

[minimissionary]

Why is it doing this though? They're brand new.
After a good, hard (and bloody exhilarating) drive, I am 100% certain that it's the lower mounts. I can only imagine that they've started doing it since being replaced, because the top ones are gone, as mentioned. The old lowers must've been pretty buggered too, and so had enough play in them to not make noise.
I suppose I'll replace the top ones on monday and see. Bet I'll need to redo the lowers before too long....

On the subject of solid mounting, did the later cars have reinforcement plates? Mine seems to have an 8"x2" (ish) plate in the footwell, which the bolts go through.

Also, my fronts didn't have spacers on them. Is this normal?

Edited by minimissionary, 15 September 2012 - 10:13 PM.

[minimissionary]

Also, is this going to be dangerous?

[tiger99]

YES, IT IS VERY DANGEROUS!

If you drive it like that, you will quite rapidly get fatigue cracking, in your case probably in the subframe itself. The creaking is likely to be movement of the subframe at some of its welded seams.

A front subframe MUST have a full set of solid mounts or a full set of rubber mounts. (Forget the badly designed and unsafe poly kits.) If not, dynamic loads will force something to flex, until it breaks. Typically, it is failed toeboard mounts that cause fatigue cracking in the inner wings just ahead of the subframe towers, but any mismatch in the mounts will result in cracking somewhere, and if it is the subframe or the bulkhead crossmember that goes, sudden failure is possible.

Check the entire area, including the underside of the bulkhead cross member, very carefully for cracks when fitting the top solid mounts.

[minimissionary]

Righto. Was worried tholis might be the case. Will get it sorted tomorrow morning!
Are we talking tiny fractures or proper cracks?
Also, what is the likelyhood they've formed in the past 2 days?

Edited by minimissionary, 16 September 2012 - 06:47 PM.

[tiger99]

Sorry, I misread your post and thought your teardrop and toeboard mounts were solid, which is one of the most dangerous conditions. I guess I did not think that anyone would actually fit standard rubbers.

If it was as I thought, cracking will possibly not happen in 2 days, but in a few weeks, certainly. And, we are talking about big cracks here, if they happen in the inner wing, which fortunately is the easiest place to fix. With a mixed set of new and old rubbers, the stress distribution will not be good, but should be ok for quite a few thousand miles.

Having read more carefully, I would suggest that your new toeboard mounts may have failed already (not unknown, the design is very poor) or are under some excessive stress. Maybe loosening all the mounts, including both sets of bolts, mounts to toeboard and mounts to subframe, as well as the tops and teardrops, and bouncing the car a few times before doing them up again may help.

Solid mounts are the ultimate fix, of course.

[minimissionary]

I fit standard rubbers as I can't afford the cost of getting strengthening plates welded in. Certainly a plan for the future, however.
I'm not convinced the toeboard mounts have gone again, it feels solid when steering. Is there any checks I can make while stationary other than taking them off?
Glad its an easy job!

[MiniLandy]

Since you've fitted new toeboard mounts, it's probably the metal that they bolt to.

It's a problem area for rust, worth giving it a look not only from the inside, but taking the mounts off one at a time and looking for cracks in the metal underneath them.