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911 Rear Suspension Bushing Replacement

Pelican Technical Article:

911 Rear Suspension Bushing Replacement

Chuck Moreland


6-7 hours






Razor knife, vice, vice-grips, propane torch, sandpaper, brake parts cleaner, shop rags, soap and water, aluminum colored engine enamel paint, gloves, pencil, metric wrench and metric socket set, torque wrench, floor jack, jack stands, wheel chocks, safety glasses, lug wrench, special thin wall hex head wrench for turning eccentric bolts,

Applicable Models:

Porsche 911 (1965-89)
Porsche 912 (1965-69)
Porsche 930 Turbo (1976-89)

Parts Required:

Neatrix rubber bushings, steering rack spacer

Performance Gain:

Better handling, especially in the corners

Complementary Modification:

Have a professional four-wheel alignment done on your 911 after completing this project

My weekend project is new tbars (27/21 mm), neatrix spring plate bushings, lowering, corner balancing, and some detailing. Good thing it is a 3 day weekend.

Well, day one is over and I thought you guys might like to see the progress so far. The rear tbars are out, the bushings are off, everything is cleaned up and ready to put back together tomorrow am.

Here is a picture of the rear driver side tbar and spring plate coming out:

The removal is pretty straight forward. Just unbolt everything and pull them out.

Here is a picture of the spring plate bushings showing the wear:

The car has about 85k miles and you can see there is considerable wear on the side of the bushing that is carrying the weight. With this much wear I can imagine there is considerable play when the suspension is loaded in a turn.

Here is the other side of the same bushing:

That is the side that carries no weight and you can see it is still squared up nicely. Based on my experience I would suggest anyone with 100k miles should thing about replacing these bushings.

I am replacing these with the Neatrix bushings. I chose these because they don't squeak like the plastic bushings, but are a bit harder compound rubber than the factory bushings.

I had my first ride in a car with plastic bushings yesterday. Boy did it squeak, I am really glad I chose the Neatrix. The squeak made the car seem like a rattle trap, even though it was plenty tight.

Anyway, the factory bushings are a bitch to remove. There are probably as many ways to get them off as there are people willing to do the job. The tool that comes with the bushings is useless, throw it out.

This worked for me:

Use a razor knife and start by slicing across the bushing. Then run the razor knife around the shaft, kinda like coring an apple. Then run the knife around the radius.

Now grab the flap with a pair of vicegrips as shown, and use the knife to slice the rubber away from the metal, peeling the rubber off in one peice.

I imagine this is not unlike scalping someone.

Anyway, you can now use the razor to shave off most of the remaining rubber. I then used a torch to burn the last bits of rubber, making them brittle, then sanded off with sand paper.

Takes awhile but works fine.

No pictures, but then I cleaned up with brake parts cleaner, then soap and water. Then painted the spring plates with aluminum colored engine enamel making them look like new.

Everything is ready to go back in.

No real problems yet, just a lot of work. I definetly made the job bigger by cleaning up and painting the spring plates. But I couldn't imagine having them out and not detailing them. Call me anal.

That's it so far, I post another update tomorrow.

Chuck - '86 Cab, '77 Targa, Family Truckster

Here is the day 2 update. Didn't get the post up yesterday because of the server being down.

I cleaned up the spring plates and installed the Neatrix bushings. The clean up added a of time to the job, but I think you will agree it was worth while.

The large hex head is the eccentric bolt that will be used to perform fine tuning of ride HEIGHT later on.

This shot compares the old 25mm rear bars (black) with the new 27mm bars (white). The size of the bar is stamped into the end and they are marked for Left and Right side.

I'm doing my Micheal Jackson impression with the glove. I used that to coat to the bar with grease.

The new rear bars are about 35% stiffer than the old. The new 21mm fronts are about 55% stiffer than the old 18.8mm fronts.

The factory has kept the fronts at 18.8mm since, I believe, the late 60s cars. The rears have gotten progressively stiffer over the years, reaching 25 mm on the Carrera and 26 mm on the late turbos.

The rears went together pretty easily. I set the factory adjustable springs plates in the middle so I could adjust either direction for fine tuning HEIGHT and corner weight.

This shot shows the springs plates going in.

The key to doing this right is getting the proper angle on the spring plate so that when loaded you have (approximately) the correct ride HEIGHT. Fine adjustments are made with the eccentric bolt.

You will note the pencil marks on the wheel well. One is where I marked the position of the plate before I dissasemble. This was used as a point of reference when putting it back together. Scribbing that mark is VERY important, it would be hard to do this without that reference point.

The second mark was scribbed after installation. The difference in angle will result in the change in ride HEIGHT. I carefully compared the angle difference on driver and passenger sides to make sure they were the same.

This is supposed to be the hard part. You take a guesstimate on the angle, put it all back together, lower the car and see what you have. Then if it not right, you jack it up and do it all again, and again, and again until you get it close to right. Fine adjustment can be made with the eccentric bolts.

I got lucky and hit it right the first try.

Here is the fully assembled wheel well:

The cleanup was well worth it. Can you hear my brakes? They are screaming to be detailed. That is coming up.

You can also see the SSIs that I previously installed, and the previously detailed valve covers.

I put the wheels back on and checked the rear HEIGHT. Close. I tweaked the eccentric bolts a couple times to dial it in. These eccentric bolts have a total adjustable range of around 3/4 inch. They are great for fine tuning, but to make any serious ride HEIGHT change you must re-index the t-bars.

Note, the early cars did not have adjustable spring plates. The process of setting ride HEIGHT is much easier with the adjustables. I recommend upgrading to adjustable when you do this, either factory or aftermarket.

Note, turning the eccentric bolts on factory adjustable spring plates requires a special wrench. It is a regular hex head, but it is thinner than a standard wrench. The wrench must fit between the spring plate and the inner wheel well, a standard wrench is just too thick and won't fit. Order the wrench before you start this project, it is available from a variety of Porsche specialty suppliers. You will need it.

With the back end out of the way, I dived into the front. This is a much easier job. Easy to get the tbars out, easy to adjust.

Here is a shot of the removal:

This is a simple matter of removing the tbar adjusting caps (left side of image) and withdrawing the bar (right side of image). You do need to move the sway bar out of the way.

Installation is "the reverse of removal" as my Hanes manual is so fond of saying.

I also popped in a steering rack spacer to reduce bump steer.

The spacers are the shiny and thick washer looking items. You can also see the turbo tie rods that had been installed previously.

The front went really fast, maybe 1 hour. 'course I didn't do any detailing.

Adjusting the front HEIGHT is very easy, you just turn the bolt on the tbar cap. I had to tweak it a few times to get the ride HEIGHT correct.

The tough part about adjusting the ride HEIGHT is that every adjustment changes all 4 wheels. You need to think about all 4 wheels before deciding to make an adjustment, and consider how your change will impact the 4.

That was it for day 2. Day 3 will be corner balancing and final re-assembly of the rockers.

Chuck - '86 Cab, '77 Targa, Family Truckster

Checking around I am getting prices of about $350 to do a 4 wheel alignment and corner balance. Okay if I do it once, but if I make suspension changes over time I don't want to have to pay this everytime. Plus I have a couple cars and this starts to add up. Plus I like to do things myself.

So I have been thinking of ways to do a "home corner balance" without the expensive scales. I have an idea and want to see what you guys think.

As I understand it, a proper corner balance should achieve two things:

1) Same front / back weight ratio on left and right sides. Note the weights wont be the same, just the ratios.

2) Desired HEIGHT at all four corners.

So here is the technique:

a: adjust suspension to get desired HEIGHT all around

b: Drive car a few blocks to get suspension into "relaxed" state, park on flat surface

c: Measure distance from ground up to jack receiver plate on passenger side of car. Write down measurement.

d: Use factory jack to raise passenger side of the car. Remove wheels on passenger side.

e: Lower car so that the reciever plate is the same HEIGHT as in step "c".

f: Measure fender HEIGHT on driver side, front and rear. Write down the measurements. It may not be the same as when the car is off the jack, thats okay. Determine the heigth ratio Front/Rear. Write this down.

g: Put the wheels back on the car. Repeat from step "b" for the drivers side of the vehicle.

h: Compare the measurements taken in step "f" for front and rear. The driver side Front/Rear ratio should match the passenger side Front/Rear ratio. I would guess the individual HEIGHT measurements would match as well, but it is the ratio that is important.

If they don't match, you are not balanced. You need to tweak a couple of corner HEIGHTs then start the process over from step "a".

This should work because the jack creates a tripod. The jack is a fixed HEIGHT and will have an equal influence on the front/rear ratio for both driver and passenger sides. Hence the measured front/rear ratio will be determined only by the two remaining wheels.

What do you guys think?


'86 Cab, '77 Targa, Family Truckster

Comments and Suggestions:
Freiherr Comments: Re corner weights / ride height setup without scales: quick & dirty way is based on the car's inherent even weight distribution side to side. Place trolley jack under gearbox jacking point the square lug sticking out under the gerbox centreline and jack rear wheels off ground. Now measure distance from ground to top of rh and lh front wheel arch openings. They should be the same: if they aren't then adjust front torsion bars accordingly until wheel arch measurements are the same. Now measure distance from ground to rear tyre tread on each side: if they are also the same height off the tarmac, you're all set: have a beer, you've saved $350
This is fast and cheap: done carefully your corner weights will be within 20 kilos left to right. If yo need accuracy, buy some scales especially if you race the car...
July 27, 2016
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
jamzboy Comments: job well done
March 8, 2016
  Followup from the Pelican Staff: thanks - Nick at Pelican Parts  
Trv Comments: Is it possible to have the spring plates/cover zic-electroplated for corrosion protection with bushings removed. Im currently doing this to my calipers.
April 23, 2014
  Followup from the Pelican Staff: I would imagine so, if you can find a plater to do it for you. - Nick at Pelican Parts  
red77911s Comments: On my 77 you can re index the torsion bar without removing it, the problem is when you wanted the other end of the T-bar to come out of the splines as there is at most, 2in of the bar exposed before the spring plate hits the body. It makes it very tricky to grab the bar and wiggle it out of one spline set and into the other. You still don't have to take the bar out but you may have to take out the body plug to allow spring bar enough exit to manipulate the T-bar. This is not to mention that you have now lost your reference point in indexing.
March 25, 2014
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
naples911 Comments: Hi Chuck, Great write-up..thanks. Question: Is it possible to remove just the spring plates on the rear torsion bars and move them 'up' clockwise on the torsion bar endings in order to lower the car significantly? Or, do I have to pull the whole torsion bar out for 're-indexing'? Thanks..
December 4, 2011
  Followup from the Pelican Staff: As far as I know, you have to remove the entire torsion bar. - Nick at Pelican Parts  
Cjp5 Comments: Chuck, I wish you lived inDallas, could use your help!
August 13, 2011
  Followup from the Pelican Staff: Ok thanks. - Nick at Pelican Parts  

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Page last updated: Sun 2/18/2018 02:20:25 AM