Strut top mounts - ball bearing or not? And what else to change?

[zcacogp]

Chaps, 

Further to my last thread about suspension brands to buy or avoid I have a couple of other questions. (Previous thread is here:) 

While I am in there it makes sense to change anything that may be past it (within reason). Strut tops are one such thing that is probably worth a swap. I notice that there are two variants of the Meyle offering, one with a ballbearing and one without. The one with is nearly three times more expensive but other than that they seem identical. Can anyone shed any light on which one I should buy? I'm not averse to buying the more expensive ones if they really are better, but simply don't know what I am choosing for and against. Details from Autodoc are here: 

https://www.autodoc.co.uk/car-parts/strut-mount-and-bearing-10471/porsche/cayman/cayman-987/19546-2-7

What else should I be changing while I am in there? The reason for the work is that the current setup creaks (front ARB bushes I think) and knocks a little. I've done the ARB drop links and the tie rod inner and outer joints recently and have coffin arms and tuning forks from Spyder Porsche waiting to go on. I have no reason to think that the shock absorbers are past it, and as PASM models they will be fiendishly expensive. 

Also, is there anything to look out for when doing the job? I've done a lot of suspension work on cars before so is there anything unusual about 987's? Or do I just unbolt everything old and bolt on the new stuff and then take it for an alignment? Are the torque specs from the manuals about right? Does anyone have any how-to's or helpful YouTube videos they can point me to? 

Thanks! 

[½cwt]

Creaks are most likely ARB and top mounts and possibly coffin arm bushes.  The knocks as probably the tuning forks.

For the top mount on my 986 (same components) the bearing were fine and I refitted after stripping cleaning and re-greasing.  Top mount was originally by Sachs and can be obtained on eBay for around £60 a pair.  For arms look at Spyder Performance.  Many on here have used them without complaint.

[Deano37]

Replaced my top mounts with Sachs purchased from Autodoc, if you are happy to wait they took about a week to get @£39 the pair. Also replaced dust covers and bump stops while i was in there. Bearings, same as above, stripped down, cleaned and re-greased. Everything else was Spyder Performance parts.

I pretty much unbolted everything and then replaced it. Only thing i made sure of was the eccentric bolts were torqued up when the suspension was under load.

Nothing unusual about doing the job on the 987. I followed the torque settings from the manual and then had it re-aligned.

No rattles, clunks or creaks now. Drives like a different car. Well worth the effort and expense.

[zcacogp]

Thanks for the answers. 

Interesting that the bearing can be cleaned and re-greased. Is the top mount separate from the bearing then? If so then what is it about the top mount that fails? I can understand the bearing being worn, and I thought that it was integral to the top mount hence the need to change them. Is this not the case? 

[edc]

The rubber in the top mount delaminated or tears. And yes the top mount bearing is separate. 

[zcacogp]

3 minutes ago, edc said:

The rubber in the top mount delaminated or tears. And yes the top mount bearing is separate. 

Thanks - that explanation helps my understanding immensely!

[Deano37]

Mine was separate to the top mount.

The top mount rubbers were perished on mine.

[sa utah]

I think it’s probably incorrect to assume your dampers are ok.  As the whole lot is coming out you really should just go for it.  Mine were gone at 85k and 14 years old so I swapped them for fresh.   Totally with the expense and virtually no added time to swap when done it the same time as top mounts etc.  
 

  
 

[Ninesomething]

They can be tested on a shock dyno so you can be sure without lashing out £800 on new shocks. Was talking to a guy that does it today. I believe that centre gravity can test them on the car.

[zcacogp]

JonSta and sa utah - I hear you. And agree. However PASM shocks are fiendishly expensive and I have no reason to think that they are worn out. Of course I could be wrong but new ones would more than double the cost of the project and I'm happy to take a chance and save the money for now. 

It's also worth pointing out that the shocks on 987's were (I believe) made by Bilstein and Bilstein stuff is usually excellent and very long-lasting indeed. While I hear stories about old shocks being worn out I wonder how the person knew that they were worn; I wouldn't be surprised if much of any perceived improvement from a suspension refresh is from the new bushes and alignment, both of which which will make a big difference. (For reference, I had some Koni shocks on a 944 for around 100,000 miles and when they came off they were as stiff as new ones when compared side-by-side. I'd suspect that anything from Bilstein is at least as well made as Koni kit and probably quite a lot better.) 

I'm prepared to be proved entirely wrong on this and will be genuinely interested to see what the dampers are like when they have been removed. 

Thanks for your help. 

[½cwt]

986 and not PASM, but even so the difference between old and new shocks (of the originals one was clearly weeping and another damp around the top seal so on the way out if not gone) is night and day particularly when  done with eh rest of the suspension as you say, however I know from another car when only the rear axle was done that fresh shocks make a massive difference.

[Buzzlt]

As 1/2 cwt says knocking is almost definitely the tuning forks. Might want to pop some new bump stop rubbers in too as one of mine turned to dust !

[zcacogp]

Thanks for the answers chaps. 

I've called Bilstein and asked about rebuilding the standard PASM shocks and they say that this is not possible and new ones are the only option. These seem to be between £400 and £550 per corner from Autodoc so we'd be looking at adding around £2k to the job cost on parts alone, hence I'm not in a rush to go and buy them unless I'm convinced that they are dead. (An aside but this is a car that only cost me a little over £9k to buy, so as a proportion of value this is bonkers). I'll take the old ones out and have a good look at them. If they are clearly very loose then I'll shop around for replacements but hopefully that won't be the case. 

If the worst comes to the worst then I'll take it apart again in a couple of years and swap them then. An alignment is only just over £100 which is the wasted cost, which isn't huge in the scheme of things. 

Thanks for your input - it's all helpful. 

Edited June 16, 2021 by zcacogp

[Lennym1984]

12 hours ago, zcacogp said:

Thanks for the answers chaps. 

I've called Bilstein and asked about rebuilding the standard PASM shocks and they say that this is not possible and new ones are the only option. These seem to be between £400 and £550 per corner from Autodoc so we'd be looking at adding around £2k to the job cost on parts alone, hence I'm not in a rush to go and buy them unless I'm convinced that they are dead. (An aside but this is a car that only cost me a little over £9k to buy, so as a proportion of value this is bonkers). I'll take the old ones out and have a good look at them. If they are clearly very loose then I'll shop around for replacements but hopefully that won't be the case. 

If the worst comes to the worst then I'll take it apart again in a couple of years and swap them then. An alignment is only just over £100 which is the wasted cost, which isn't huge in the scheme of things. 

Thanks for your input - it's all helpful. 

If it makes you feel better, the 100k shocks on my Cayman were fine (and tested on a dyno by the person I sold them to) when they were removed (I swapped them for a Cayman R setup to make it more capable on track). Bilstein used to claim that their shocks would still be 97% efficient after 100k miles and so this idea of shocks being scrap as soon as they hit 100k miles (a number which is somewhat meaningless to a German manufacturer dealing in kilometers - 160934.4 km doesn't have much of a ring to it) is probably just a myth being perpetuated by companies selling shock absorbers. Are 100k shocks going to be as efficient as 10k shocks? Probably not, but I did a load of track days on my old suspension and it felt good enough to drive far beyond what anybody will ever do on a public road. As you say, new bushes are a more likely reason for cars feeling good after a susension refresh.

That said...

If you are going to the hassle of rebuilding the rear suspension (I haven't read the thread fully), I'd swap out the rears. It's a ballache disassembling the rear suspension and whilst a 100k shock may still function, whether it will last another 1k or 100k is a bit of an unknown. On the front, you can swap the shocks in less than an hour per side and so I wouldn't be too worried about having to do this again.

[red rocket]

13 hours ago, zcacogp said:

I've called Bilstein and asked about rebuilding the standard PASM shocks and they say that this is not possible and new ones are the only option. These seem to be between £400 and £550 per corner from Autodoc so we'd be looking at adding around £2k to the job cost on parts alone,

In case it helps Design911 are actually (and amazingly) the cheapest source of B4s. Bought standard shocks from them recently. Just looked and a set of front PASM are approx £675 and a full set £1250.

[½cwt]

10 hours ago, red rocket said:

In case it helps Design911 are actually (and amazingly) the cheapest source of B4s. Bought standard shocks from them recently. Just looked and a set of front PASM are approx £675 and a full set £1250.

D911 are often quite reasonable from non OE parts, it is just the genuine Porsche parts that are usually cheaper from your local OPC.

[Arfur]

As my spring project was to replace the shocks on my 2005 108k mile boxster I can probably offer some observations. 
My history suggests the shocks and top mounts were original and there were no obvious knocks or looseness. But the front shocks looked very rusty, which was part of the reason for doing the work.

Front shocks were clearly worn once removed from the car. No gas return-to-position evident and a big difference in pressure needed to compress them compared to the new bilstein b4 replacements. Test drove the car after replacing just the front and an immediate improvement in steering and general reaction to bumps. Old bump stops had almost disintegrated so these were replaced at the same time. Original top mounts and bearing looked horrible with rust but actually in good nick (replaced anyway). The shocks were a bugger to get out but now I know the trick I could probably do springs or top mounts fairly quickly.

Rear socks were in much better order with no obvious differences between old and new. Shocks and top mounts seemed to be in good condition but replaced anyway because we had got this far down the line. Bump stops had also disintegrated and replaced. 
 

in terms of other work, worth replacing the coffin arms at the same time (I’d already done mine before) as these are likely to be worn and you can get one alignment done afterwards. Indeed I think the ball joints are likely to be the reason for creaking.

[MAC99V]

Just having my front pasm replaced, along with major service and all the other ancillaries required for changing front suspension.....OUCH !!!!! Wasn't expecting that much, guess I'd better keep the car after all......