Replacing Rubber Bumper without removing Strut

bodmin · 4 Sep 2015

I have a question for the 911uk 993 technical team.

While checking the front suspension on my 993 I noticed that the rubber bumper on the nearside front strut has disintegrated.

I was looking to removing the strut to replace the bumper and boot. However some research indicated that camber adjustment would be required after the strut was reinstalled.

My question is - is it possible to remove/replace the bumper rubber and boot without removing the strut completely from the vehicle?

My plan would be to compress the spring, then release the top bolt of the damper, push it down though the hole in the top mount, and replace the rubber.

Opinions gratefully accepted!

Picture of disintegrated bumper attached:

colt · 4 Sep 2015

correct

That is entirely possible to do and exactly the way i have done it many times when only the sponge bump stop needs to be renewed.
just jack up both sides of the car (front) and then loosen one top strut nut to the end of the thread and then remove the opposite side nut completely, no need to touch the top mount bolts, (wheels removed is best but possible without removal) pull down strut or push piston rod down with !/4 drive long extension or similar ,then keep top spacer and top hat in order, place on the ground, compress piston and before it extends ,remove the bumpstop, leave the springs in place, no spring compressors needed for the comparatively light front springs. the rest is of course the reverse of removal. Don't undo the top nuts with an impact wrench(air gun) You need to feed the water gaiter on to the new stops before you put them back on as its rather difficult to get your fingers between the spring coils in situ! If carried out this way , the geometry will remain within five minutes of its original settings.
christian..............

bodmin · 8 Sep 2015

Thanks for the information Colt.

Using a 21mm impact socket, 12" pipe wrench, 7mm x 1/4" drive allen key, 1/4" x 3/8" adaptor, and 3/8" swivel I was able to release the top nut of the shock absorber. There was no requirement for the special tool.

There was also no need to compress the spring. I supported the lower ball joint with a large axle stand.

Pushing down on the polished rod allowed removal of the damaged rubbers along with the spring and spring retainers.

Just waiting on new parts to arrive before putting it back together.

Some pictures for the record:

ChrisT70 · 8 Sep 2015

i was going to do the same as mine are also split, but figured i'd just do the struts at the same time as they have done 73k now, its on my to do list for 2016 as it looks a fairly easy job at the front at least, rears may be more involved.

decgraham · 8 Sep 2015

Hi,

I need to do the same on mine, both bump stops and toast. Could you post up a few more pics please as you put it back together?

Much appreciated if you can.

Can you tell me which stops you ordered, the 964 or the 993 ones.

ATB

Citori · 9 Sep 2015

Interesting post guys.
I was wondering if something similar can be done for the rear struts. I have replaced the suspension on a 93 before so I know what's involved.

I was wondering if you released the rear anti roll bar and droplinks whether it would allow you to swing down the struts far enough to get the top mount and spring off. I should imagine trying to undo the rear top mount in situ is a right royal PITA.

bodmin · 11 Sep 2015

New bump stops arrived today and successfully installed.

The only issue I had was whether the correct stops were supplied. My car has the M033 option (lowered suspension), but comparing new and old bump stops they weren't the same. I fitted them any way, not sure if the previously fitted ones were incorrect.

Anyway very easy job. I borrowed a couple of spring compressors to shorten the spring allowing around 30mm of shock absorber rod to protrude past the upper perch. I placed and axle stand to support the suspension, and lowered the car gently on the scissor lift and guided the top of the rod though the strut support. After achieving a few threads with the upper nut I removed the spring compressors, checked the sping was sitting correctly on the perches, and tightened the nut to approx. 24 ft-lbs.

The whole thing is really a 10 - 15 min job with the knowledge.

Not sure about rear suspension though!

kerb scraper · 12 Sep 2015

Well done. Good write-up and photography.

Don't be intimidated by the rear struts: swopped mine for Bilsteins yesterday and it was really pretty easy. Just mark the eccentric on the toe control arm then unbolt and remove the arm which releases the bottom of the strut. Reaching the top mount bolts is not as bad as it looks; since the car is jacked up the bolts are at a comfortable height to work and all you need is a 3/8 socket set plus a small torch.

You need a T40 torx used with an adaptor so it can be turned with a 1/2 socket handle to hold the outer toe arm bolt as you remove the nut. To withdraw the inner bolt of the nearside toe arm I had to jack the engine up slightly and gingerly undo the central bolts of the engine mounts to drop the sub frame a fraction in order for the bolt to clear the left header.

There was no need to compress the springs to dismantle the struts. I had the same 033 option as you.

Do it. Will be easier to sleep knowing all four corners have fresh gaitors and bump stops.

dommorton · 7 Feb 2016

I sorted this little job on the front suspention today, as like others the bump stops were looking a little past their prime.

Weirdly one was totally shot to bits, and the other complete but showing signs of age.

Stuck new both sides as well as new bellows to smarten it up a bit.

My 4S has standard lowered M033 suspension and the PN's as follows:
964.343.301.00 is the correct longer Rubber Bump Stop for the front
993.343.505.00 is the Bellows

Improvised tooling comprising of a 21mm Plug Socket, 22mm Spanner, 7mm Allen Key and a Jack Handle.

Worst of the old Vs new

All done and looking as it should. I didn't require spring compressors, as the the springs were short enough to get the hats back on, and the strut tucked back in place without.

I think Bodmin might have some rear Bump Stops there, as I ordered these at the same time as the fronts and they look the same at around half the height of the front ones.

Rear PN's were:
993.333.105.00 for the Rubber Bump Stop
999.333.107.01 for the Rear Bellows

Johnnybean · 7 Feb 2016

Special socket

For those of you with OCD like me!
I did make some enquiries re the socket with the side cut away for allen key access, but the price was silly money.
I went to good old Halfords and bought an impact socket of the correct size and then took it to my local engineering company who used a very high pressure water jet to cut away the side of the socket and hey presto a job well done and a very useable bit of kit albeit not something I will use every day, hence thats why I didn't want to spend over £50 for a single socket.
all told it was the prices of the socket from Halfords plus a tenner to have it cut away.
Hope that helps some one, on the other hand if you live near Chester you are welcome to PM me and you can borrow it any time.

bodmin · 8 Feb 2016

Hi Johnnybean - I'd be very interested if you could post a picture of your cutaway socket.

Bashman · 13 Apr 2023

I too would be interested in a picture of your modified socket please

- also; why is there mention not to use an impact wrench/air gun on the 21/22mm strut nut??

mday · 13 Apr 2023

You could use a lambda (O2) sensor socket.

mday · 13 Apr 2023

Bashman said:
I too would be interested in a picture of your modified socket please

- also; why is there mention not to use an impact wrench/air gun on the 21/22mm strut nut??

Because if you do you might (will) end up with a fractured strut shaft.

mday · 13 Apr 2023

http://911uk.com/viewtopic.php?t=60765&highlight=bilstein

Replacing Rubber Bumper without removing Strut

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