Rubber on rear shock tower is that right? Options

[michelko]

Hi ,
i found an issue that i think it´s not ok.
The upper mount of the rear shocks has two rubber bushings.
I believe the buschings should be pressed together from the nut on top of the schock.
On my car this is not so. The upper rubber piece is loose an can be moved and turned.
Here is a pic and a video that shows what i mean.
Any thoughts how this must be?



https://youtu.be/4fTn4ur3C0w

Regards Michael

[rhodyguy]

You're missing the metal cap that goes on top of the bushing. Both sides?

[914forme]

PM me I have some just cover shipping and they are yours.

[mepstein]

https://nemigaparts.com/cat_spares/pet/pors...14/570u/502000/

[michelko]

Hi and thanks for the offers but there is a misunderstanding.
I have all the hardware here. The pic was to show that the rubber is maybe not high enough.
If i put the washer and the nut in place there is a gap remaining between rubber and washer.
You can see this in the short video.
I like to if thhis gap is normal or if the lower rubber is bad.
Regards Michael

[JamesM]

Hi and thanks for the offers but there is a misunderstanding.
I have all the hardware here. The pic was to show that the rubber is maybe not high enough.
If i put the washer and the nut in place there is a gap remaining between rubber and washer.
You can see this in the short video.
I like to if thhis gap is normal or if the lower rubber is bad.
Regards Michael

If there is slop in the connection when tightened down, its not normal. either missing hardware or bad rubber (upper or lower) or possibly bad tolerances on the shock, but that seems unlikely)

Two things come to mind because i have seen them missing on a few cars.

1. the stock bump stops (part 6) have a metal washer integrated in them, they install under the upper perch and space everything above them up about ~3mm. Without that washer you wind up with the shaft sticking above the rubber like you are seeing.

2. Washer/spacer (part 9) i see missing a lot would have the same effect.

As you mentioned you have all the parts, im leaning towards #1 as afaik the proper bump stops are not available and all the originals have more or less dissolved at this point. All the replacements i have seen are all rubber and slide on the shaft vs mounting under the upper spring perch.

[914forme]

James that is the nut that supports the rubber I am going with rubber. Your bumpstop idea means that the shaft will extend closer to the hood by the washer width. Several ways the solve the problem.

Cheap way is new rubber or a washer to take up the space. Expensive way, replace the assembly with a monoball upper mount. Can chuck the rubber support piece in a Metal Lathe and take off oh so much.

Let me know if you need rubber business, I have a drawer full of them, as I run monoball shock mounts.

[914e]

Did you replace bushings 11 and 12 in the drawing? The bushing (12) you are turning looks pretty new. The weight of the car is sitting on bushing 11 if that is old and collapsed the nut (10) will be sticking up too high. If the bushings are new compare them to the old bushings maybe there is a part mixup.

[michelko]

Hi,
those rubber parts are old as the car, so now i guess the lower rubberpart is collapsed over the years thhrough the weight of the car.
Looking at the parts diagram i am missing one piece in my setup.
Can´t find the washer #9 and the rupper part of the bumpstop is gone but the metall part of it is still there.
Can´t see how #9 effects the position of the two rubber bushings.
Can someone measure the height of these rubber bushing?
Will see if i can get them here in germany. As a quick fix i thought about making some Washer from aluminium and place them between #12 and #13

Regards Michael

[michelko]

Hm i found this picture in the repair manual. Here is the washer #9 mentioned before not shown

[kroelofsen]

Hm i found this picture in the repair manual. Here is the washer #9 mentioned before not shown

Hmmm I just replaced the rear shocks for Koni's. The originals were still the Boge shocks. But the bumpstop [8] was not there. I suspect the Boge's to be factory original so can't explain why the bumpstop was missing... Any ideas?

[mepstein]

Hm i found this picture in the repair manual. Here is the washer #9 mentioned before not shown

Hmmm I just replaced the rear shocks for Koni's. The originals were still the Boge shocks. But the bumpstop [8] was not there. I suspect the Boge's to be factory original so can't explain why the bumpstop was missing... Any ideas?

50 year old rubber could have cracked and fallen apart.

[davep]

11 perch sits halfway down the shock tube
10 metal cap sits on the top of the shock tube
9 anti-suction plastic washer with grooves against the cap below
8 bump stop sponge rubber with 4mm steel washer on top

This steel washer is what you are probably missing; it seats on the top of the piston rod portion (chromed) and is a good fit to the unthreaded portion of the rod

6 spring cap sits on top of the bump stop washer

So the 4mm you are missing is the metal remains of the bump stop.

[914forme]

Nope that 4 MM does nothing for the spacing of the two rubber pieces. It just moves the shock shaft up 4mm in the collar #5. It is the part that supports #4 and #3. The issue becomes when you do not have enough threads on the shock shaft. Which is not being shown on the original image.

#8 - bump stop is nice to be up top, but Koni / Bilstein is just a rubber sleeve. Just a generic part used across the entire line.



Repaet you are dealing with only #4, and #5. Because #5 can only be shortened, you issue must be #4!

Here is is on 914Rubber site.
Picture added for example

[michelko]

Nope that 4 MM does nothing for the spacing of the two rubber pieces. It just moves the shock shaft up 4mm in the collar #5. It is the part that supports #4 and #3. The issue becomes when you do not have enough threads on the shock shaft. Which is not being shown on the original image.

#8 - bump stop is nice to be up top, but Koni / Bilstein is just a rubber sleeve. Just a generic part used across the entire line.



Repaet you are dealing with only #4, and #5. Because #5 can only be shortened, you issue must be #4!

Here is is on 914Rubber site.
Picture added for example

I agree with that. the Bumpstop rubber is gone but the washer is allways there.
Must be the #4. It is still there and doesn´t look bad but i believe it settled over the years.

Michael

[Mikey914]

My money is the #10 is sitting higher due to a difference in the way the new shock extension is machined. Compare the “shoulder” depth on the old shock to the new. I’d bet you find the new shock is not machined as deep and it makes 10 sit higher. This is why the washer will not hold the rubber.

[ndfrigi]

I think you need to check the ff:

# 3 and 4 if has the right thickness to cover length of # 5
# 5 if the correct length
Or missing # 2 for the washer

Maybe ask someone to measure the thickness for # 3 and 4 and length of # 5 for those has their shocks apart.

[JamesM]

Nope that 4 MM does nothing for the spacing of the two rubber pieces. It just moves the shock shaft up 4mm in the collar #5. It is the part that supports #4 and #3. The issue becomes when you do not have enough threads on the shock shaft. Which is not being shown on the original image.

#8 - bump stop is nice to be up top, but Koni / Bilstein is just a rubber sleeve. Just a generic part used across the entire line.

Repaet you are dealing with only #4, and #5. Because #5 can only be shortened, you issue must be #4!

Here is is on 914Rubber site.
Picture added for example

Ah yes, I was looking at this as an issue of total shaft length. You are correct in that this would have to be isolated to 3, 4 and 5.

[Retroracer]

A cross-section of an assembled strut would help visualize the stack up and dependencies. so:

a) does someone have a detailed diagram they can post, or
b) a large bandsaw and a camera?

BTW I have the same issue on my rear struts as it turns out. So keen to get this resolved...

- Tony

[michelko]

My money is the #10 is sitting higher due to a difference in the way the new shock extension is machined. Compare the “shoulder” depth on the old shock to the new. I’d bet you find the new shock is not machined as deep and it makes 10 sit higher. This is why the washer will not hold the rubber.

no, #10 is to protect the seal. This has no affect to the problem mentioned above.
You just have to remove this thing when you want to disassemble #11 from the strut.

Michael