Donut Strut Mounts (front)- Need Lesson

[Uwon]

I moved my tried and true standard issue camber plates with rubber donuts in them, Konis, etc. from my donor car to my new build. Suspension was set up at about the same height. Today the donut popped out on both sides while driving on a smooth highway.





The rubber donuts are not dry or cracked. In fact they are smooth and firm as one would expect. There is the steel shaft in the donut that the shock goes thru, a washer and a nut that tighten the shock to the shaft but nothing "squeezes" the donut to prevent it to eventually dropping down out of the camber plate as the shock works to dampen.
Obviously I've done something wrong.What am I missing?
Thanks in advance.
Johan

[HaroldMHedge]

You appear to be missing the support washer 901-341-629-00 and the washer does not appear to be the tab washer 900-038-002-01. Check out your PET for the proper stacking order.

[Uwon]

Thanks Harold. You are right. Anybody have a pic of it or at least the outside diameter so I can hopefully find them or at least temporarily substitute.
Thanks in advance.
Johan

[HaroldMHedge]

Here is a photo but darn I'm missing the tab washer. The large washer is about 61.5 mm.

[75 911s]

[chris_seven]

What year is the car?

It looks as if you have early type bushes in a late type camber plate so the washers are not going to help.

Camber plates changed in early 1970 , which is when the profile of the inner wing was modified.

The early camber plate did have two individual loose bushes one above and one below a steel retainer that was a feature in the camber plate.

This feature was provide by making the camber plate from two pressings which were projection welded together.

The later camber plate had a much larger one piece bush that was more of an 'hour glass' style and the camber plate lost the mounting flange. The bush is always fitted into the steel housing and sold as a complete part and the housing is a one piece pressing.

Many early cars have been mistakenly fitted with the later camber plates as Porsche simply sell the later parts as an 'update' even when the correct early part is ordered.

The diameter of the bush retaining part of the later camber plate is larger than the original part and when it is fitted to an early shell restricts both the camber and caster adjustment capability.

the caster setting is most affected and if a late plate if fitted to a pre-may 1970 bodyshell the maximum caster that can be set is typically 4 degrees.

Early cars typically should be set at 6.5 degrees and any less negatively impacts on turn-in behaviour although it does lighten the steering.

It has become common practice to fit Koni Shock absorber bushes to the early camber plate and they are commonly sold as the 'correct' part but this is not accurate.



They do work but are not the same as the part originally used by Porsche but this has been NLA for some time.

We have recently re-manufactured the correct bush in an HNBR material and we are also in the process or pressing new camber plates to the original design and have made a small batch of prototype parts.



Pre-production prototype - tooling mods currently in progress



The Part Number which explain these changes are as follows;

Original rubber bush: 901.341.965.03 (This was initially used on early cars without the adjustable camber plate facility.)

Original Camber Plate: 901.341.018.01

Original Support Washer; 901.341.629.00 this washer has a smaller OD than the washer currently being supplied which fits the later camber plate mount.

Post 1970 Camber Plate: 911.341.018.00 The hourglass rubber bush is intergral to this part.

Late Support washer: 901.341.629.00 This is the same part number as the original part but the washer supplied is quite different to the part used on the early cars.

There is also another camber plate design but that was used with the Boge Hydropneumatic Struts and not relevant to this thread.

[Uwon]

Harold and Duane, thanks for the pics.
Chris, it's a '78 chassis with camber plates from an '86.
I've been rattling my brain as to why I have missed these washers and it finally came to me. I exchanged the Weltmeister bar for the Rennline one into my new build. The Weltmeister does not use the big washer. I should have seen this. One of the shortcomings of working alone.
Any idea how to press the donut back in? I'd imagine it would be a bugger and I don't have a press.
Johan

[75 911s]

Johan,
How about carefully placing a jack under the A arm - slowly raise with one arm while pulling and aligning with your other arm.

@chris_seven. Great part for early cars!

[Uwon]

Originally Posted by 75 911s

Johan,
How about carefully placing a jack under the A arm - slowly raise with one arm while pulling and aligning with your other arm.

@chris_seven. Great part for early cars!

Good idea but since I do not have coil overs the shock would just compress.
Good news is that I did get them in but you'll have to wait until tomorrow when I can retrieve a couple of pics.
Johan

[Uwon]

How do you get the donut back into the camber plate.
First try- big vise. Lots of grease. Not enough force. Upper lip of donut just expands.
Second Try- 20 ton press. Same result.
Old School- enlisted help of Brent, a local heavy equipment mechanic who used a wire wrapped several times around the waist of the donut, stuck the wire ends thru the hole in the camber plate, twisted some screw drivers onto the end of the wires to be used as handles, jammed the camber plate into a large vice, and pulled like hell working the wires around the upper lip while I pushed by counter levering a crowbar from below. Key was to get a small portion of the upper lip partially up the hole. And then, Voila! The rest made it thru with ease.
lots of grease.




Brent also just happened to have two new yellow zinc played large washers for the top of the donut.

Special thanks to my savior Brent! Good old school knowledge.
Cheers,
Johan

[ClickClickBoom]

Monoballs!

[Uwon]

Originally Posted by ClickClickBoom

Monoballs!

Sorry, not in my car. Too hard and uncomfortable for street driving IMO. Anyway, the point of this thread was to find out why this happened in the first place, and, how to get the car back on the road quickly.
Johan

[pors1968]

Nice work learn some new trick THANKS