Alloy trailing arm update: Eccentric bolts, hardware

Shuie · 10-28-2005, 05:27 PM

Subject: '79 SC trailing arm update on a '72 T

Do steel trailing arms use different eccentric bolts than the later alloy trailing arms. I think I learned the answer with my trailing arm swap this weekend but I wanted to confirm here before I order new eccentric bolts. Ouch. Didnt see this one coming. Is it just the camber bolt? The toe bolt looks fine. Im guessing I can just buy the longer springplate bolts at the hardware store? Is there anything special about those?

What about the bolt that attaches the trailing arm to the shock? Is that the same as the bolt on my old steel trailing arms? If not, can someone please tell me the correct length?

This has been a great project. After 3 weekends and 6 parts orders its still not done. The good thing is that I will have all new hard brake lines within a couple of more weeks since I managed to break and/or strip those on disassembly.

Avery · 10-28-2005, 05:36 PM

Sherman: I suggest you go with the Porsche bolts to attach the T/ A to the spring plate. They are a stronger bolt than what you would normally find at OSH. Kinda pricey at around $13 a piece but at least you know you have the correct bolt holding your T/A in place going through a fast turn.

mmastro · 10-28-2005, 08:31 PM

Hey Souk, this thread may help...sorry I sold the only extra I had to Matthew. The Ecc. bolt is longer for the Alum arms. I would imagine the spring plate bolts are longer as well.
Good luck.

WTB: Camber excentric bolt

Evans, Marv · 10-28-2005, 08:54 PM

Souk:
You can buy the bolts that attach the swing arm to the spring plate. I think you need 40mm (or maybe a little longer). The standard EOM bolts are 10.9, m12x1.5. I bought 40mm, 12.9 capscrews for mine at a fastener place. If they don't have them, they can order them - that is if you have a place you can go to that doesn't insist on you buying a lot of 50 for them to make the order.

Shuie · 10-29-2005, 04:55 AM

Im not Souk, but thanks guys!

Is the Toe eccentric any different? Mine seem to fit okay.

What about the bolt that attaches the trailing arm to the shock?

mmastro · 10-29-2005, 06:44 AM

Quote:

Originally posted by Shuie
Im not Souk, but thanks guys!

Is the Toe eccentric any different? Mine seem to fit okay.

What about the bolt that attaches the trailing arm to the shock?

Sorry Shuie, I totally brain farted!

randywebb · 10-29-2005, 10:44 AM

after this, you'll know enough to open a souk type shop in La. ...

MotoSook · 10-29-2005, 06:24 PM

Quote:

Originally posted by randywebb
after this, you'll know enough to open a souk type shop in La. ...

LOL..

Oh...can you clarify, Randy?

Shuie · 10-29-2005, 06:35 PM

If there were more than a dozen of these cars here I would seriously consider opening a shop.

Bobboloo · Bobboloo's Garage

Sherman,

I just did this swap on my 73'. All the bolts you have will work except for the camber eccentric bolt. Even the shock mount bolts work.

You can also reuse your hard brake lines if they are in good shape. They just need to be re-routed. When you go to re-route them make sure you loosen the line where it meets the caliper so you can swing the first bend toward the front of the car since it will no longer go thru the trailing arm. If you try to just bend it in that direction it will break off.

randywebb · 10-29-2005, 09:24 PM

clarify -- He will have done so much work that he'll know enough to rebuild other peoples cars (unfortunately or fortunately, depending on your point of view). When he gets to that point people can swap y'all's names ....

jpahemi · 10-29-2005, 10:00 PM

I would hate be the car behind Shuie if standard 8.8 bolts are being used to attatch the spring plate to the swing arm. Porsche up'd the bolt spec and torque for those bolts in 1983. The old bolts were 10.9 with a torque of 65 ft/lbs; the new bolts are M12X1.5X40 12.9 with a torque of 87 ft/lbs. The nut and Schnorr washer were rplaced with a grade 10 lock nut. The bolt # is : 900 083 066 08 ($4.62),
the nut is :N 022 141 4 $(2.39)
The shock bolt is M14X1.5X85 8.8 ($5.70) 900 082 054 02
Don't forget to use the thick steel washer on both sides of the spring plate.
j.p.

Shuie · 10-30-2005, 01:48 AM

Thanks guys.

The hard brake line that I ruined was the one that comes off of the T thats bolted to the torsion tube. It goes up and around the tube from the T to the driverside bracket for the brake hose. I bought a complete set of hardlines that needed to bent and I wound up stripping the T fitting when I reinstalled this line. I used the flare nut wrench like I was supposed to, but this stuff is old and crusty. Kudos to the engineers for using the hardware they did. This obviously a dirty and nasty area of the car and most of the hardware that I have removed is 34 years old and still looks great!

Thanks j.p.! Thats what I needed. There were two stray spring plate bolts in the boxes with my '79 trailing arms and I was really surprised at how thin they were (M10). The bolts that came off of my steel trailing arms are M12, they are just too short. They do say '8.8' on them. Thanks for the measurements!

randywebb · 10-30-2005, 11:05 AM

jp - should people with the older spec. hardware replace it with the newer, stronger stuff? Seen any Tech. Bull.s from P AG on it?

[those Wevo spring plate assemblies are looking more cost effective all the time...]

jpahemi · 10-30-2005, 05:45 PM

Randy:
Yes, the update took place as of 12/83, and is reflected in the Factory Carrera Workshop manual, volume 3 page 42-1. You will see the bolts affected with the corresponding bolt grade change as well as the increase in torque values. The nut/Schorr combination was replaced with grade 10 steel lock nut.

304065 · 10-31-2005, 03:45 AM

Don't feel bad about destroying the brake line. I accidentally sawed through the starboard line when I was cutting the trailing arm bolts. It can be easily replaced with no permanent ill effects.