Torsion tube bushings first time question

356 Porsche-related discussions and questions.
Post Reply
Message
Author
User avatar
Dan Mazur
356 Fan
Posts: 296
Joined: Wed Mar 26, 2008 12:50 am

Torsion tube bushings first time question

#1 Post by Dan Mazur » Tue Oct 09, 2018 10:45 pm

Hi Folks,
Ive read up on changing the torsion tube bushings in my C coupe and have the car jacked up, axle rod free of the spring plate, and the cover plate off.
The spring plate is resting on the lower cover plate attachment boss, so it is not free to take an angle measurement.
I assume I can just pry it out a bit until its free of the boss, but since its my first time to do this and the car has been through more than one prior owner, just want to make sure it looks normal before I attempt it.
Thanks for your advise!
Dan
Attachments
IMGP2458.JPG
Wear on the inside of cover plate from contact with spring plate. No wonder it makes a banging sound over bumps.
IMGP2456.JPG
Old rock hard and deformed bushing
IMGP2455.JPG
Spring plate resting on cover plate boss
"I never leave Ann Arbor. The real world is too hard to face."

Robert Vaughan
356 Fan
Posts: 326
Joined: Fri Dec 03, 2010 7:42 am

Re: Torsion tube bushings first time question

#2 Post by Robert Vaughan » Wed Oct 10, 2018 5:20 am

What time capsule did you extract that car from? The bushing appears excellent. The cylindrical load bearing surface of the spring plate appears excellent. There are no signs of deep rust pits or flaking rust. No signs of rust at all.

With a pair of nearly parallel eight foot long wood two by fours and other scrap wood and an eye-bolt you can make a lever to twist the torsion bar and thereby lift the rear end of the spring plate with human hand forces.

Put a bolt in the threads shown in your second photo. Put that bolt through the eye-bolt's "eye". That bolt and the now dangling eye-bolt then anchors the front end of the long lever.

Build a short bridge between the two nearly parallel two by fours beneath the rear end of the spring plate, near the axle bearing housing. Pile blocks of wood on top of the "bridge" to get the right height.

Now you can twist the torsion bar upward, un-load the shock absorber, un-bolt the axel bearing housing, detach the axel bearing housing, and prepare to pull off the spring plate.

In the 911 the boss you are pointing to is removable, allowing the spring plate to drop easilly for angle measurement.

In the 356 there is not yet the design mod. The spring plate must be pulled outward before its angle can be measured and set.

Re-assembly is the reverse of the above.

Be sure to mark the position of the axel bearing housing on the spring plate with a pencil or masking tape before you un-bolt it. That controls the rear suspension toe-in.

User avatar
C J Murray
356 Fan
Posts: 7263
Joined: Fri Oct 23, 2009 7:24 pm
Location: 30MI WEST OF PHILA

Re: Torsion tube bushings first time question

#3 Post by C J Murray » Wed Oct 10, 2018 6:34 am

I just changed all 4 bushings on a 62 coupe that was very difficult. Usually the spring plate will slide out with a moderate degree of force. This car took excessive effort to get the splines to release and in that case if you are not careful you can damage the sheet metal where you may be prying. You may need to use strong metal scraps to reinforce the area where you intend to pry. Robert is right to suggest wood or anything else to move the depth of the point from which you are prying. Patience is the key.

Before you loosen the 3 axle tube bolts you should be certain that the stops are against the tubes and tight so that the assembly process is easy and you maintain your toe adjustment.

IMPORTANT, before you start this job you need to evaluate the stance of the car and decide if you are happy with it as it is. It should be approximately the same from side to side also. Jack the car up so that you can do the work and when you have it in position and the axles are disconnected you need to measure the angle of the spring plates on each side with a simple Home Depot angle gauge. They should be within 1* side to side. It is considered ok for the driver's side to be a TINY amount more angled to compensate for the driver weight but I shoot for equal because of the crown on roads. You decide.

There are specs in the book for the stock angle settings but use caution with that data. It doesn't always work well. If you use the specs you need to take an angle reading from the doorsill and factor that vs your actual spring plate reading as the car sits.

The result should be even camber side to side with the ride height you prefer.
'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car - Finally Finished!
'63 GS 2133 coupe
'64 Elva Courier mk4T
'67 911 S Original Owner

User avatar
Vic Skirmants
356 Registry Member
Posts: 6758
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan

Re: Torsion tube bushings first time question

#4 Post by Vic Skirmants » Wed Oct 10, 2018 7:58 am

That bushing looks pretty well squashed at the top.

User avatar
Greg Scallon
356 Fan
Posts: 648
Joined: Thu Mar 27, 2008 1:12 pm
Location: Los Altos, CA

Re: Torsion tube bushings first time question

#5 Post by Greg Scallon » Wed Oct 10, 2018 10:08 am

Hello Dan,
This write up I did awhile back on lowering my speedster may help give you a frame of reference.

viewtopic.php?f=1&t=24968&hilit=lowering+rear

Good luck.
Cheers,
-Greg
'58 Speedster
'56 VW Deluxe Microbus 

User avatar
Doug McDonnell
356 Fan
Posts: 3495
Joined: Sat Apr 05, 2008 8:21 am
Location: Augusta,Michigan

Re: Torsion tube bushings first time question

#6 Post by Doug McDonnell » Wed Oct 10, 2018 10:20 am

Great photos Dan Keep them coming and turn this into an article.
1965 356C There is never enough time to do it right, but always enough time to do it over.

User avatar
Daryl Bruhl
356 Fan
Posts: 61
Joined: Sun Mar 30, 2008 8:55 am
Location: Grand Terrace, CA

Re: Torsion tube bushings first time question

#7 Post by Daryl Bruhl » Wed Oct 10, 2018 10:53 am

Before reassembly apply some form of lubricant to the moving surfaces to prevent squeaks later.
Daryl 63 super 90 SoCal
Daryl Bruhl

User avatar
Dan Mazur
356 Fan
Posts: 296
Joined: Wed Mar 26, 2008 12:50 am

Re: Torsion tube bushings first time question

#8 Post by Dan Mazur » Wed Oct 10, 2018 10:54 pm

Thanks for all the advise on this. My wife is out of town so I got to play in the barn again tonight.
I used a jack to raise the spring plate off the boss and put a 1" X 4" piece of wood below the bosses to protect the dog leg metal while I used a pry bar to lever the spring plate outward to clear the boss. Then released the jack and measured the spring plate angle with a protractor.
I didn't want to remove the torsion bar so in order remove the spriing plate I pulled on it while I tapped the end of the torsion bar with a ball peen hammer until the spring plate came off. All the splines look great and the torsion bar looks like its been replaced recently.
The interesting thing was that the inner bushing had actually extruded itself and squished out toward the top. The bottom side looked normal but the top was remarkably deformed. I took a few pics to share.
The other thing I noticed were the two holes at the base of the inner bushing cup. They seem to lead into the torsion tube. Any ideas what the purpose of these holes are?
Attachments
IMGP2462.JPG
IMGP2474.JPG
IMGP2471.JPG
"I never leave Ann Arbor. The real world is too hard to face."

User avatar
Doug McDonnell
356 Fan
Posts: 3495
Joined: Sat Apr 05, 2008 8:21 am
Location: Augusta,Michigan

Re: Torsion tube bushings first time question

#9 Post by Doug McDonnell » Thu Oct 11, 2018 7:39 am

Too late now but you can get an inclinometer app on a smart phone and measure your angle with that.
1965 356C There is never enough time to do it right, but always enough time to do it over.

Robert Vaughan
356 Fan
Posts: 326
Joined: Fri Dec 03, 2010 7:42 am

Re: Torsion tube bushings first time question

#10 Post by Robert Vaughan » Thu Oct 11, 2018 7:59 am

Re the two holes: I assumed the holes were there so that water that entered the rear suspension joint could drain into the torsion bar tube (and rust it out). There is no weep hole in the bottom of the torsion bar tube. It is a dead space with no air circulation.

Painted an greased torsion bars can look good after 50 years in the dark.

Robert Vaughan
356 Fan
Posts: 326
Joined: Fri Dec 03, 2010 7:42 am

Re: Torsion tube bushings first time question

#11 Post by Robert Vaughan » Sun Oct 14, 2018 5:13 pm

Regarding the question "The other thing I noticed were the two holes at the base of the inner bushing cup. They seem to lead into the torsion tube. Any ideas what the purpose of these holes are?"

Here is another question: Did the 356C get dipped in a tank of primer at the manufacturing plant?
If the bodies were dipped in primer then those holes would let primer run out of the rear torsion bar tube.

User avatar
DonCichocki
356 Fan
Posts: 360
Joined: Thu Aug 22, 2013 4:29 pm
Location: Lafayette, NJ

Re: Torsion tube bushings first time question

#12 Post by DonCichocki » Sun Oct 14, 2018 5:47 pm

Robert,
Boy, I wish!

Post Reply