correct shocks for aluminum control arms?

jchatfield · 07-02-2004, 08:19 AM

I have a 1972 T that has steel control arms and no sway bar.

I just purchased aluminum control arms and adjustable 2 piece spring plates - I am not sure what year the doner car was, but the arms have the old style ball peg to attach the rear sway bar to.

I currently have Boge's shocks all around, but I believe I've read that I cannot use the same shocks with the Aluminum arms as with the steel arms. Is this correct?

If so, I have the old Rear Boge's from the donor car, but they appear to be much older than the ones I currently have. They may be fine, but I won't know until I take my current Boge's off and compare.

Thanks,

jpnovak · 07-02-2004, 08:26 AM

If the arms still have the ball type connector they are likely 74 or 75 arms. I don't think they had adjust. spring plates until 78. I could be wrong. The only difference in the rear shocks will be the diameter of the mounting bolt. i think the 72 has the same size though.

304065 · 07-02-2004, 09:39 AM

Jim,

First, to determine the year of the arms there are two ways. The first is, how many bolts in the stub axle, if they were included. Four bolts and two pins up to mid-75. As far as the arms go, there's a casting date, a number in a circle, cast into the arm. Look closely and you'll find it. The ball-stud for the sway bar is another way to tell, though it can be changed.

The mounting bolt diameter changed from early to late, 14mm to 12mm I think.

The issue is the shock tube diameter- if you go to the aluminum arm, there may be clearance issues with the heat exchanger. Sherwood recommeded using the shocks from an earlier car (through 71) to clear, but I'd try it first before you spend $$$ on new Bilsteins.

See this thread for the article.

Article from April '96 Excellence -- aluminum control arms

And how about some play-by-play photos of your conversion process?

jchatfield · 07-02-2004, 10:46 AM

Thanks for the article and information!

My car is at a repair facility right now awaiting the insurance adjusters determination after an engine fire.

I hope to have it back in a couple of weeks and start the control arm upgrade, and I will be sure to post pictures and commentary on the play by play.

911pcars · 07-02-2004, 11:23 AM

"... recommeded using the shocks from an earlier car (through 71) to clear"

John,
I don't think I quite said that (or if I did, I deny it :-)). All alloy rear control arms use the same late-style shock; the lower shock mount is different than in earlier years. The type of sway bar mount (threaded or ball-type) merely helps identify the year car (up to ~'76, ball type; thereafter, threaded). Other than that, the arms are the same.

In my particular case ('69), the upper shock towers are narrower than in later models and thus had to remove the dust covers from the Koni Sports for needed installation clearance. There is an add'l mod to the shock mount boss on the control arm to help re-establish some shock geometry and also provide more clearance when used with early heat exchangers.

Hope this helps,
Sherwood

304065 · 11:48 AM

"Another option is to modify earlier, smaller diameter shocks (69-71) to fit." -Sherwood Lee, Excellence, April 1996, p. 71.

[Ted Kennedy Voice]"Er, ahhh, er, are those, err, ahh, your words, Mr. Lee?"[/Ted Kennedy Voice]

Just kidding Sherwood, you can tell I've been spending too much time in the OT pit.

Well, anyway, the shock mount recesses are narrower in the early cars, hence the need to remove the dust cover so it will clear. I don't know the diameter of the recesses on my '71, I suppose I will find out.

Then again, if I'm going to the trouble of this mod for reduced unsprung weight, the shock could be changed to a JRZ/Moton/Penske type. . .

jpnovak · 07-02-2004, 11:47 AM

I have later Konis on 78 trailing arms and they fit with the hats in my 71 tub. Its tight by does not rub. YMMV

304065 · 07-02-2004, 11:51 AM

Thanks Jamie- that boosts my confidence that once I start the job, I can finish the job!

What do you do about the ball stud on the arm? I have the early style rear bar. Can a new stud be installed by heating the arm?

jpnovak · 07-02-2004, 11:56 AM

if you have the ball stud and an early sway bar they just "snap" on. Otherwise use the late style bar with the bolt on drop link. I am using the 18mm bar and droplinks from the same donor that gave up its rear suspension, engine, tranny...

I don't know if the early ball studs on Al arms are removable or not. I think they may unscrew but am not sure. Maybe the archives have something on that.