aaddpp

Quick question about parts to replace when doing the rear shocks / brakes. Parts I have / am planning to change include: shocks (Boge), rotors (mine have 0.1mm of spec left), pads, ABS harnesses, and a new set of springs. All this makes for a pretty comprehensive upgrade, but I was wondering if there are other parts that also wear, like the two rubber parts found in the shock / spring assembly (parts #10 and #12 in the diagram below). Do those typically get changed? Anything other parts to consider?

Thanks

Rob Edwards

Dave-

Besides the shocks, rotors, pads, springs, and the ABS harnesses (are yours cooked or something?), I would also replace:

#7 definitely, and maybe #17 (Boges don't come with a new top nut) and #20 (though the replacements from Porsche are not yellow cad plated, if that's going to bother you.

WSM says to replace the top shock nut #17 and #20, dunno why they're single use, but that's how they're listed.

I don't think it's necessary to replace #10 and #12, mine have always been fine.

sendarius

What about:

928.331.588.15 x 4 - lower hub to A-arm bush
928.331.588.10 x 2 - A-arm to body rear bush
928.331.089.02 x 4 - upper hub to upper control arm bearing & upper control arm to body bearing

That leaves the A-arm to body front mounting point as the only contact point not re-furbished.

PET has 928.331.111.00 & 928.331.112.00 as the left and right "link bearing", but that appears to be the actual body mounting.

To each of these is bolted 928.331.085.00 "rocker bar", which appears to have a bushing in it, but I have been advised to replace only "if you have money to burn".

StratfordShark

My Boges came with new top nuts.

I replaced parts 2 and 3, the threaded adjustment collar and adjusting nut. On an old shock they are likely to be seized solidly together, ditto collar to shock body. Very difficult to separate without damage to aluminium.

New ones - with smear of optimoly on threads and on top of nut where it meets lower spring perch - make for easy and silky smooth height adjustment.

Mrmerlin

why are you replacing the springs? they should be fine.
unless they are very rusty.

Why are you replacing the ABS sensors? they should be fine.

Usually the parts that go bad are 6, 7 ,8 though you can usually see if 8 is bad,
the other two not as easy till things are cleaned up.

The shocks should come with fresh piston nuts ,
otherwise you can reuse the 3 shock mount bolts at the chassis for each shock.

The top shock mounts should also be fine so reuse them

NOTE the shock dust boot fails more on the front shocks.

NOTE I wouldnt be swapping any bushings unless your feel the back of the car changing track as you accelerate heavily and then let off.

NOTE the common reason for the rear end to sway is usually due to a loose bolt,
this bolt holds the lower control arm to the lower rear cross member it gets tightened to 140 ft/lbs.
Its quite common for these bolts to be loose simply look at the eccentric for wear from the eccentric sliding back and forth.

NOTE the bushings that do show the most wear are the dog bone bushings these will need swapping if the camber cant be properly adjusted
( dogbone bushings go into the upper rear control arms)

NOTE if you using Boges make sure the inner adjustment collar fits tightly onto the shock body, you might consider some loctite red, its quite common for the inner collar turn with the adjuster thus requiring shock removal to adjust the collar nut.

FWIW I would suggest to replace the shocks with Bilstiens they are more expensive but here you do get what you pay for,
Roger is selling full sets again for a good price

fraggle

ABS Harness insulation can flake off and leave just the wires out there. they still work but cosmetically it's awful. I rebuilt mine with a mile of heatshrink.

aaddpp

Rob, my shocks came with a new top nut so I'm good there, the three top nuts seem odd to replace, but I'm sure they're cheap enough to not give it a second thought. For 10 and 12, I'll assume no change if they appear decent.


Thank for those suggestions, but I'll have to keep anything beyond the shocks and brakes on the back burner for now, unless really needed.


Thanks, will also consider 2 and 3 if they come off messy. I've been pretty lucky with most things comping apart easily on the car...maybe this holds true here too.

Stan, thanks for all the tips and suggestions. I've added 6-8 to my list of parts to swap - they're not that pricy so I might as well start fresh with those. I'm changing the springs because I have new ones (I was part of the group purchase few years back) and want to clear as many parts from my garage as possible - we're aiming to move soon, so less to pack if I do it now. For ABS, I'm replacing the wire harness only, the sensor looks fine. Like others, my wires have lost their outer sheath, and since I was able to pick up an excellent set of used wires I figured I would swap them out.

Bilstiens, would be nice, and if I were buying today, I'd probably get the Bilstiens, but I've replaced the fronts with Boge already.


Thanks again for the suggestions guys, that was a huge help.

Dave


PS, one follow on question...The top of the shock (part #18) looks like it had a sealant applied to the top of it (between it ant the body of the car). Any suggestions on what to use here? Haven't seen mention of it in any of the threads / DIY's I have looked at so far.

Mrmerlin

its a sealing putty and its usually stays stuck to the upper area of the mounting point just put the shock into position or of you must put something there,
use a thin strip of 3M body caulk

Rob Edwards

Good question on the sealant, I've not used anything on R&R'ing 3 sets of rear shocks now, nor have I ever seen mention of anyone else using it. Perhaps one could use a thin bead of 3M strip caulk (?)

The factory uses some sort of thin layer of whitish-gray stuff, sorta visible here:

BC

Spring wear out. They are a wear item just like a shock, which on our cars last about 50,000 miles. The springs can last longer but its steel, and steel wears out.

aaddpp

Thanks for the sealant recommendations. With parts already on order I should be good to go.

Dave

aaddpp

Totally missed your post, sorry. How did you get the shrink wrap past the film canister sized ends? I've looked into heat actives tapes as an alternative, but most reviews of the tapes are mixed at best.

Hilton

I just used 3m Strip Caulk on the rear shock swap on my '87 - it squishes nicely when bolting on the shocks to the body.

Of course, we can't get 3m Strip Caulk here in Oz.. I had to import a pack of it from the USA.

Its also good for resealing the heater box for the HVAC system too, and next time I'm doing a recirculation flap I'll use it too as its less obnoxious to remove than RTV.

fraggle

To re wrap the the ABS harnesses I cut one end about 5" from one end, then fed it through the shrink. I used multiple layers of heat shrink in two different diameters. When nearly done, I left a foot or two of unheated material, crimped the wires back, then slid the shrink over the splice.

If you do this, note that the rubber bosses that are used to hold the ABS harness against the frame are directional! Note how they come off and you should be able to get away without cutting any.

aaddpp

This weekend I'm planning to put my rear shocks back together. I have everything I need - turns out the plastic washer was included in the shock box, along with a new nut. Only part that looked warn / unusable was #7. #2 came off easily with a press (no way it was coming off any other way) however one had damaged threads so I replaced one of those as well.

One question I have is on the spring length. I was surprised to see that the new springs were a bit shorter than the originals.



I assume the difference in length is correct, and that there's no error. Any thoughts in setup here? Do I just assemble and torque the top nut, or do I need to take up the "slack" on #2 the threaded collar? I've posted a photo of the previous collar setup measurement. Also, is it correct to assume that the three tighter coils (as shown in the photo below) are oriented toward the top of the assembly?

Thanks - Dave