ALU trailing arm upgrade 69E ??
 

guys;
looking to do some suspension maintenance and upgrades on my '69E. which ALU trailing arms will fit ? are some more desirable than others ? do i need more stuff than just the arms or will my existing stuff swap over ? anything else i need to know ?
THANKS!
best
jerry

Jerry-
There are some issues with this upgrade. John Luetjen as done it to his '69E, and it wasn't easy. I'd do a search with his username, as he posted the gory details. I have decided to forget it for my '70 bsed on his experiences.
-Scott

The main difference is the move to bolt on rear sway bar mounts on the 78 and newer units. The 84-89 had larger rear calipers too, so a pressure limiter will have to be installed on the system.
In either case, when fitting alu arms to the 69-71 chassis, the upper shock mountings will be a) tight b) different angle than the lower mountings of the replacement arms. Just installing the later shocks will cause the dust covers to grind away on the inside of the towers and outside of the shock tubes <enough so that it will go all the way through!
We make the following modifications to the arms and shocks: 1- cut down the dust sleeve so it just caps off the rubber bump stop 2- cut off 5/8" off the alu arm shock mounting points- take care to make your cuts parallel and check bolt engagement length so it does not bottom out. This mod will approximate the angle that they are mounted in 1972-89 cars. It won't be perfect- you will see some angulation on the lower shock mount bushings- but you won't have any more interference and unwanted "spring rate" from binding parts. It certainly is less expense than replacing the entire shock bridge to a later unit.
Finally, check the clearance between the heat exchanger on the driver side and the shock. On a lot of cars, the heat exchanger needs to be "clearanced" a little with hammer and pliers so the parts do not rub

There are also issues with drive flanges and wheel bearings, right, TRE?

Jerry,
Dave is correct - it's doable. Most of the issues discussed are covered here.

You'll have to do an archive search to get more info on matching inner and outer CV joints from output to drive flanges. I also upgraded to a 915 gearbox, so late axles/CVs were a direct bolt-on.

Sherwood
('69 911)

Yup. But nothing that a different set of axles, CV's and slightly modified output flanges can't help ;)

no- the wheel bearings are fine. There may be a difference in the stub axle/ hub area if late arms are used. The 69 had a different sized spline arrangement and its not easy to swap hubs. if you do, then you would need new wheel bearings< they get damaged/ destroyed removing them. My suggestion is to remove a complete axle from the early car and take measurements of the splined area, count the teeth so you can compare to the potential replacements

hi Sherwood;
this looks like a little more than "...while i'm in there" kind of stuff :D
it *is* something i may want to tackle down the road, tho. the link above didn't do the trick. any chance you have that again ?
thanks!
jerry

sure is nice to have a resource like this board handy. from (some) "routine" maintenance to mods like this and more... i'd be screwed :D
thanks all AGAIN!
best
jerry

Hi Jerry,
There was some excess ASCII garbage on the end of the URL. Here it is again.

http://members.rennlist.org/911pcars/AlloyContrlArms.htm

Sherwood

I have been wondering about this also.
Do these problems aply to 72 and 73 year models.

hi John;
just out of curiosity are you running a rear sway bar and if so... OEM or aftermarket ?
thanks!
jerry

Dave;
based on what you've indicated here and this;

http://forums.pelicanparts.com/showthread.php?s=&threadid=123485&highlight=traili ng

i'm not clear re: the sway bar issue. can you clarify, please ?
thanks!
jerry

You can use your stock 911E rear calipers. The bolt spacing is the same on the aluminum trailing arms and then you do not need a pressure regulator. I have done this with my 69E. The swap sounds alot harder than it really is. Go for it.
I machined about an inch off the rear shock mount. The angle is now correct for the shocks. See pic.
http://www.plavanracing.com/2004-11-26%20002.JPG
My conversion did not require me to change CV joints or axels. I guess I got lucky with what I had.
Here are some more pics:
http://www.plavanracing.com/2004-11-18%20002.JPG
http://www.plavanracing.com/2004-11-26%20006.JPG
http://www.plavanracing.com/Resize%2...1-12%20002.JPG
http://www.plavanracing.com/Resize%2...1-26%20012.JPG

I also had to change the hard brake line to the caliper when I did my conversion. There are photos and part numbers in this thread.

http://forums.pelicanparts.com/porsche-911-technical-forum/191148-brake-lines-alloy-trailing-arm-conversion.html

I'm not sure if this applies to all (69-73) models. Mine is a 73, and you'll notice that the thread is about another 73. It may be just a 72/73 thing, but it is something that should be on the list of possible issues when doing the Aluminum arm conversion.

Joe

Editted to correct thread

Your right. I had to change mine also because the "bends" were not right.

1974 model would be the easiest and most-compatible ... CV/axle-wise and used the same style ball-studs for anti-roll bar attachment.

Seems to me that if you went to the Weltmeister rear bar that attaches to a new toe (or camber, I forget) adjuster bolt, that the sway bar issue is solved rather easily. I did and I have these ball studs just sitting there doing nothing. Furthermore, I had some issues with the NEW bushings popping off the ball stud. I don't like the idea of those anymore because of that and the non ajustability factor. Of course, the new adjuster nuts have been reported to break. I suspect using big rear bar can do alot of things under heavy loads like rip the mounts off the pan.

So, like anything else, one thing leads to another.

The ball studs for the anti-roll bar can be screwed into the later aluminum arms if you want to stay with the stock anti-roll bar. They are welded on the steel arms but on the aluminum ones they just screw in so any year aluminum arm will do.

What year did the halfshafts go to 6-bolt? I thought it was 74'?

I had the choice of either the early 4-bolt or the later 6-bolt halfshafts for my conversion. I would have prefered using the 6-bolt shafts since they are lighter but I didn't have 6-bolt flanges for my tranny so I opted to swap out the stub axles with the 4-bolt ones from my steel arms. Later I may switch the halfshafts to 6-bolt if I can find some 6-bolt flanges for my tranny.

I had no problem using my old hard lines from the calipers on my 73'. I found that if you loosen the hard line where it exits the bottom of the caliper you can swing it out and re-tighten it so that it clears the new arm. If you try and bend it at this point without loosening it it will break. Then you just need to bend the middle a bit to aim it at the connection for the flex line.

Here's my install.http://forums.pelicanparts.com/uploads6/DSC000071125695326.jpg

Bobby.

The change from four M10 bolts to six M8 bolts came mid-year 1975 production.