Rear trailing arm bushing

[zooklm1]

I had my 968 up in the air last night, starting on changing the timing belt and saw what looks like a rubber bushing failure. When I looked it up on the version of PET I have, I don’t see a bushing associated with what looks like the failed area/item. Does anyone have experience with this bushing failing? This is on the right. The left look normal.
Thanks

[BasHenneman]

Yes mine have failed in the past too although I have not looked at stock rubber to replace them as I used these:

https://www.elephantracing.com/porsche/ ... s-for-944/

[zooklm1]

Thanks for the link. I saw they have rubber options. How long did it take you to do the swap?

[walfreyydo]

Those are the spring plate bushings. There are options from elephant racing for going either stock rubber or solid polybronze, as well as polyurethane from powerflex (I opted for the poly ones).

Replacing will require dropping the entire rear suspension and there will be a whole host of "while you are in there" tasks you can look at doing such as: rear shocks, stiffer rear torsions, rear torsion re-index (ride height change), transaxle related upgrades (short shifter, etc), rear brakes, rear brake lines, rear trailing arm bushings (where the rear arm attaches to the torsion tube), torsion carrier bushings (where the torsion tube connects to the chassis).

Its a fairly big job so best to combine with other needed updates which I listed above, if applicable. How long depends on a lot of factors (and the while you are in there stuff you are also going to undertake). For me this was a winter project I spent a number of months working on little by little. Overall I would say its 20+ hours depending on all the things youll be replacing.

[johnb]

I agree it's a big job. One thing you can do to speed it up is get a set of spring plates and housings and clean them up and install new bushings in advance. Getting the old bushings off the spring plates is a lot of hassle so this minimizes down time if that's a priority.

In addition to those bushings, the aluminum housing has a big bushing where it's bolted to the chassis a little forward of the spring plate. Those are usually in better shape, but if you do want to move them it won't be easy without some kind of press.

Then the trailing arm has a bushing very similar to the one on the front control arm - when you remove the rubber there will be a steel sleeve left in the bore and you'll probably have to cut it carefully to get it out.

If you want to remove the trailing arms completely to make this easier, then you'll have to remove the handbrake cable from the trailing arm, which can be hard. I didn't do that - this just meant I had to replace the trailing arm bushings with the arm detached but still tethered to the car via the cable. Not too hard.

Finally there's another rubber/metal bushing at the tip of the blade that attaches the torsion bar tube to the chassis (it's hidden up inside the body above the wheel arch - you can ether reach it, or see it...your choice

Unfortunately that last one is NLA I think but I don't think they're typically in bad condition. The spring plate and trailing arm bushings are the ones that do all the work, and they tend to get neglected because they're hard to change. It'll probably make a big improvement to the ride quality and handling if you replace them.

I used Elephant Racing polybronze for the spring plates, and spherical trailing arm bushings (same company), and kept all the other ones (they didn't seem to be in bad shape). It was a big improvement - far from a harsher ride, it got much more comfortable and handles better too. You have to grease them from time to time but who cares? It's not like it's otherwise a low maintenance car. You'll be under there for something anyway.

[944m3]

It’s not a fun job for sure, but in my opinion it’s not that bad. It’s just a bunch of bolts. I procrastinated for months with fear. But I managed to get the entire axle and trailing arms off in an afternoon. Now, if everything is rusted and seized up then it will add frustration. Take your time with the brake lines and emergency brake cables.

I purchased spring plates from Prekom which had the rubber bushings pre installed. I did not want to deal with removing them. The trailing arm I took to gas station and had them press out and install the new bushings.

But I’ll tell you what the worst part is, reindexing the torsion bars. Make sure you understand that before you take everything apart. I messed that up and the car sat to low, I ended up adding coilovers so I didn’t have to take everything apart again. Thankfully it all worked out pretty well.

[zooklm1]

Thank you, everyone, for the input. I can definitely see this as a winter project for the convertible (want to enjoy some fall weather with the top down). Seems like it will spend some time on the lift. I am thinking about doing some springs/suspension upgrades on my 86 944 turbo. These upgrades could be practice for the 968.
Lee

[walfreyydo]

Yeah if you have a lift it will be helpful and make the job less painful.

I used two floor jacks on the torsion tube and an assortment of cinder blocks/bricks to rest the rear hubs on and lowered/raised in tandem to install/reinstall.