ABY Coupe rear shock mounting

[orsum]

I have just replaced the fronts shock mounting and based on the condition of what came out I am thinking that I should do the rears.

The front mountings were squashed and both the bearing were smashed.

Part number 8A0 412 323 D is available from Audi but every picture I have see shows it has a bearing.

Can anybody confirm if the rears have a bearing and if it does then why. Its not like the strut rotates like the front.

Would it be better to have a spacer made and replace the bearing with the spacer.

[Greg_S]

Are you referring to the top mounts? If so you can use the same on the rear I think

[Monkeymagic]

The rear top mounts are identical in effect the rear subframe is a rotated version of the front. You are correct in saying that the rear does not need to rotate. However a rears don't suffer like the fronts. As discussed on the forum a lot the front was a poor design. The top mounts are effectively the same used on mk1 and mk2 vw polos etc. Eg nowhere near as heavy or as powerful. I'd just fit standard rears and forget about them. The improvement is needed at the front end..

[orsum]

I agree the fronts are very weak.

I am in discussion with SKF and others to do a mod to the front mount bearing.

It appears to me the rubber mounting is ok but the weak bearing and the bearing press fit is an issue.



Basically I was thinking of replacing the bearing on the rear mounting with a solid bush.

Why have a bearing on the rear mountings if it’s not doing anything.

I will be removing the rear mountings shortly, if the bearing is damaged then I will be looking at a solid bush mod fitted to the new mounting or an alternative style of angular non rotating bearing.

If the bearing is good the I will just replace the 21year old mounting with a new OEM

[Lago Blue]

"Would it be better...?" Perhaps. Part 1

Orsum,

I applaud your enthusiasm sir. You raise some valid questions around this, yes still too oft discussed topic. I think your question deserves more attention, but for the time being please also consider the points in this similar thread:

...from the not to distant searchable archives

I'd like to write a more thorough reply later on. Meanwhile, please just try to ignore my avatar.

[orsum]

SKF can supply the rear mounting, I have placed an order for a set.

Will give more info when the parts arrive.

[Lago Blue]

"Would it be better...?" Perhaps. Part 2

Orsum,

Three questions and a suggestion for you:

To your very first question I would ask you: What is your idea of what your "better" gets you?

Secondly I would ask: Why are the top-mounts' bearings broken? &

Finally: Why "fix" the "bearing issue" if a replacement bearing could be had for free and its breakage could simply/quickly/cheaply be prevented from ever re-occurring again, instead?

I'm afraid, unless you can convince me otherwise, that your current course won't get you to my idea of what IMHO, down the road, I think works "better". Perhaps, a course you might consider, one which I think you ought to pursue, is one of prevention rather than cure, let me explain.

Despite that you have focused in on the top-mount's center bearing and correctly identified that it is less than perfect, know that its' best replacement, whatever that might be, will not prevent a recurrence of the over-arching snag that really needs fixing here; because that bearing is not the central issue, view it as a side-effect or symptom, but not a cause.

I should point out that:

i) In my view, assumed concerns such as bearing rotation, mounting and low-tolerance issues are of no consequence to your current needs, particularly on the rear of the car. For example, it just doesn't matter if this bearing is not held really well in the mount itself because when assembled, the strut's installed top-nut holds everything together, perfectly; and similarly, if you think the bearing doesn't have to turn, why care if it's smashed?

ii) That the current bearings are damaged ought to tell you that they must have been hammered on while driving, long after the mounts had already fully collapsed and was no longer providing a cushioned place for the bearings to rest. Well before the bearings become damaged, on collapsed mounts, your alignment, steering and suspension performance are already suffering. Even an indestructible bearing substitute will not free you from the need to not neglect your top-mounts because they will still suffer from core collapse; &

iii) Replacing that bearing with anything else will not prevent that root cause collapse from re-occurring.

Looking at your overall situation here is what I think you should consider:

a) Take a moment to step back and look at the whole picture. What is the larger current issue that best needs repair, and what is its' likely root cause? I would suggest the larger issue is total vertical mount failure (requiring simple replacement), and that reason is excuse me but, simple neglect;

b) The only top-mount you should consider is the one which, while best ordered at the Audi dealer under the P/N you list above, is however when received, (perhaps -not- obviously) made with the P/N 8A0 412 355A molded into its lower rubber circumference;

c) You are about to do a lot of work to replace a bearing that comes free with every new OEM style mount available from best to worst, yet it is the mounts themselves independent of the bearings, that you are ignoring; and that most importantly, whose replacement certainly needs doing anyhow; and will immediately restore conditions here to brand new!

I humbly suggest to you, with the above detailed, new, dealer-sourced mounts, put your efforts into this: PM me, I'll loan you a set of Ersatz-Savers to install at the same time. If you like them, you can buy them, if not, send then back.

Cheers.

[orsum]

Thank for your offer but I will not take it up at present.

My present task with the suspension is getting it back to OEM.

With the OEM rear part being NLA from my local Audi dealer and my local SKF say the one they can supply was supplied to Audi as an OEM part (That's what SKF say) I will take the SKF mount.

My local Audi dealer was supposed to have done all my shocks etc and yet after 500km the front mount bushings were smashed in bits. And the rubber had compressed by about 10mm. No way can that happen with the car standing for 5 years and then drive for such a short period.

Normally I would take the car back but that was several years ago before I had the trouble with the time it took to get the paint job finished.

To me Audi did not replace the mounts and put the old ones back and I do not think they fitted them correctly (Not torqued)

Hence my present goal is.

Step 1 Get the shock mounts back to standard and correctly fitted.

If they fail.

Step 2 Look at all the upgrades should they fail after being replaced and correctly fitted.

You modification may well be one of the upgrades I would look at.

I think you have put very good and important points in your post and I will put some more thinking into what you have said.

I will monitor my cars performance when all the mounts have been done and give feedback as to how the mount are doing.

If I do not like the look of the SKF mounts I will not fit them but rather buy another set of fronts from my local Audi dealer.

[Bowie69]

Whilst it is not a lot, the rear WILL rotate, as the suspension cycles, in effect the tie/track rod mounted back to the subframe will get shorter as the wheel moves away from ride height, this will cause a small amount of rotation -I couldn't say how much, but wouldn't take too much to calculate from a drawing.

Whether it is enough to worry about is another discussion of course

[Lago Blue]

B3 Coupe's toe change throughout suspension travel...

Bowie,

Thank you for that, absolutely correct sir, and a very good point for you Orsum that I failed to include above (I was to intent on turning your argument back on it self), particularly as you where asking would it be better to replace that bearing, perhaps with something that does not turn.

In fact it appears that the rear hubs turn more than the fronts for a given suspension displacement, seeing as how those rear track rods are shorter than the front links. It would make an interesting video to see the suspension elements in action, singly and in combination, wouldn't it?

Even to do the alignment, that struts' gotta rotate on that bearing. Besides, like I said previously, the slack in that OEM bearing gives the rubber core of the bushing (which is thee core issue here) a bit of a break in torquing its' axis off at an angle relative to the shell axis. You may notice the core & shell axes are co-incident on new mounts, but tilted apart in used ones.

Orsum,

Although you may already suspect as much, you need to know that the top-mount bushing is likely the most well known Achilles heel (or perhaps I should say tendon! Cartilage maybe?) of these cars; and further, that anyone could certainly flatten even the best OEM brand new and freshly installed top-mounts in 50 km or less, let alone 500.

One of the key aspects of the "Ersatz-Savers" design intent (and in fact a key aspect to its' success so far) is that it aids the best original new dealer-sourced Boge/Sachs V6 front mount in functioning as new without physically altering or removing anything from the top-mount itself. Once installed, its' invisible, once fully broken-in it acts as if it has become an integral part of the original mount. Your original mount remains, well, original.

Oh and your root cause does not reoccur. You get to then neglect your mounts! Now here is where we get back to Bowie's point, the top of the rear strut, now more firmly fixed in an mount whose integrity and elasticity remains as new (cuz it has an E-Saver stuffed inside it), allows the links' design arcs to more deftly guide the hubs subtle travel. Because the rear axle is so far from the C of G of the car, like fletching on an arrow, it has an inordinate ability to effect overall steering and stability, and it even gives us a little bit of rear steering, just not quite as much as that car in the Audi museum whose photo I included in that link earlier.

[orsum]

Just received 4 new green mounts from SKF, must they look much better than the OEM from Audi I collected and fitted a few weeks back.