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Top mount replacement

Joined
29 May 2009
Messages
193
I have had a look in my Bentley manual re removing the front struts and it looks like a relatively straight forward task, however I have some concerns about removing the 32mm driveshaft nut which is torqued to 430Nm and then it mentions a special tool for pressing out the driveshaft from the wheel carrier (its a C4S). Consequently I am thinking why remove the strut at all, if I put spring compressors on the spring and undo the top mount and disconnect the strut from the coffin arm I could replace the mount without removing the strut. Or am I missing something here?

Also whilst replacing the top mount is it a good idea to replace the bearing? The car had done 107k and the top mounts rattle if I don't spray them with oil.

I know that Chris at Cof G can change them in about an hour so presumably there must be a shortcut as opposed to pulling out the whole strut.

Any tips on how to do this job will be much appreciated.

Thanks

Graham

The car will be going to Cof G after I have replaced the top mounts for a full geo.
 
Hi Graham,

When I had my suspension refresh done at Bristol OPC recently, we replaced the self-contained bearing assembly on both of the front struts, as they were showing signs of wear at 83k miles. They were only about £30+VAT each IIRC and very straightforward to replace when rebuilding the strut assembly. I'd definitely recommend doing this when you replace the top mounts.

As an aside, I also found the OPC prices for OE top mounts the cheapest around and more than competitive with aftermarket options, especially when you factor in the 'Classic' discount.

PM me if you want any more details on prices etc., as I'd be happy to look these out for you :thumb:
 
I changed both top mounts (£58 ) and the bearings (£26) on my '99 C2 not long ago.

One side I took the strut out as it needed a wheel bearing too, the other I did in situ as you say.

I had to use mole grips on the damper shaft (wrapped in tape) and an impact gun on the top nuts as they would not shift otherwise. This is a last resort as you risk damaging the damper shaft, I got away with it with care.

Spring compressors on, as the dampers are gas filled the damper rod keeps springing back up so its a bit of a fiddle to get old top mounts out and new in but not so bad once you've done it once!

I bought top mounts from design 911 their "oem brand product" not genuine at almost 1/3 of the price, and one of the nuts sheared off. I had to drill this out and replace as I needed to use the car.

http://www.design911.co.uk/fu/pt385...996--911--1997-05/Shock-Absorber-Parts-Front/

A C4 uses different parts, but I suspect you will be fine!
 
Thanks Pete and Wasz

I stopped at the OPC in Bristol today and spoke to the team there and they were very helpful and confirmed what I wanted to do was possible (as did Wasz). The parts pricing was also very reasonable.
So if I get a chance this weekend I will have a look at the top nut to see if I can remove it, I will use Wasz method below although I don't have an impact gun
I had to use mole grips on the damper shaft (wrapped in tape) and an impact gun on the top nuts as they would not shift otherwise. This is a last resort as you risk damaging the damper shaft, I got away with it with care.
 
It's definitely a last resort to use mole grips on the damper shaft- there a risk of damage then the damper is toast.

You can put an Allen key in the top and use a ring spanner.

If that doesn't work stop by a garage and ask them to buzz the nuts with their impact gun.

Then if the nuts still spin the whole shaft you might have to use grips...
 
wasz said:
You can put an Allen key in the top and use a ring spanner.

Or a pass-through socket set if the top mount prevents access with a ring spanner, which is often the case.
 
oh dear this is turning into a nightmare

I took the car down to a local friendly garage to apply their impact wrench to the top nuts as I couldn't shift them with my 1/2 drive socket set.

They gave it a try and they didn't move. He recommended that I remove the strut giving more access for more aggressive intervention. I said that I would do as he recommended, I mentioned my concern about the 430Nm drive shaft nut and he loaned me his 3/4 drive socket set.

Back to the house and the drive nuts were slackened off with no trouble.

Car jacked up (I really must get round to buying a low entry trolley jack), nuts removed from coffin arm ball joint , bolt removed from stabiliser bar not too much trouble although access isn't great for getting a socket on to the coffin arm ball joint nut.

Time to remove the ball joint from the coffin arm and here is the first snag my screw driven separator is too small. Off to the motor factors to buy a bigger one (16mile round trip) and the unit I have bought made by laser has a scissor action and is just big enough (50mm). Relief it works and off pings the ball joint.

Time to move on to the next ball joint for the tie rod, the nut came off easily but 3 hours of extreme effort with the separator yields nothing more than a bent threaded shaft on the ball joint!

Not sure what to do now. I will review in the morning. What would make a ball joint seize? I guess a lot of heat is the answer or put it back together and take to the garage.

What a waste of a day off
 
Did my top mounts a few months back, one thing I read in the workshop manual was do not use impact gun, it may damage the threads, you are into a new shocks then. Mine were showing signs of surface rust so I split the nuts once I had got the top out. Its not an easy job on a C4 due to the drive shaft, but is possible if you compress the strut fully, it will come out with a lot of grunting and care.

One tool that made it possible was a Dremel with carbide cutter, take a little time but ensures you can remove the but with out damaging the strut top threads. Once reassembled, having cleaned out and regressed the bearings, the car sounded so much nicer, lots of odd noises disappeared. The final part was to go to see Centre Gravity to sort the suspension settings out, transformed the feel of the car totally.
 
I did one side of my C4 today. I was told by my brother in law who is a mechanic that the top mounts were seized onto the strut as he attempted to do it for me a few months back. Anyhow the plan was to remove the whole unit and melt the rubber out of the top mount and grind a slot into the sleeve to remove. Anyhow I split the steering joint, bottom ball joint and removed caliper and disc. Spring compressed and out came the strut. Took the unit to my friendly local garage to use the air gun to undo the top nut, which they did and the top mount came straight off, no longer seized it would appear. I did discover the front discs were in terrible condition only on the back side so replaced those at the same time. I hope the drivers side is as easy tomorrow.
 
A quick foot note to this, my local garage with a larger ball joint separator removed the track rod end with no trouble and swapped out the top mounts in 3 hours. (Message to myself get the right tool for the job)
I then got the car to Chris at C of G who after a bit of fun with one seized adjuster at the rear sorted it out and effectively transformed the car into something that doesn't just look good!

Chris really is first class and well worth a trip.

What do I do now its almost perfect?
 

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