Aluminum Control Arm Answer?

[Neunelfer]

Hi Gang,

I'm looking for the definative answer regarding my Aluminum control arms for my 71T conversion car.

I have the control arms, these are the early models with the sway bar ball joints. I have a set of Koni's with the 14mm bolt hole. I have an early (76) Turbo 18mm bar. I've heard:

1. Everything will bolt right up.
2. Everything will bolt right up but you'll need to take the dust cover off the Koni's
3. You'll need to weld in a new rear crossmember with the proper shock angles.

Anybody BTDT before who can offer some insight before I hit the garage and attempt the final install?

Many Thanks!

E.

[rst73]

Hi Eric,

Yes, they will bolt right on. I suggest also installing later model adjustable rear spring plates and 26mm torsion bars at the same time. I don't know about any mods needed for Koni's, all the cars I've done the update on I've used Bilsteins's with no issues.
Hope this helps, email or call me if you need anymore info.

All the best!
Roger Grago
R Gruppe #27

[Neunelfer]

Thanks Buddy,

I have the 26mm bars and adjustable plates sitting on the car waiting to bolt the control arms on.

E.

[admin_old]

E,
Your '71 and my'69 share the same rear shock geometry. The factory moved the upper and lower shock mount points slightly in '72 ('72-'86 geometry the same). The result is that with the alloy control arms installed in the early chassis, the dust cover on the Koni Sports interferes slightly with the shock housing sheet metal. Don't know about Bilsteins.

You can partially compensate by removing said dust cover as well as some material from the lower shock mount boss on the control arm. This isn't as drastic as it sounds. The actual threads (14mm) are a steel insert in the control arm and the necessary amount to remove is merely aluminum, in effect a spacer and not threaded either. Remove the excess material on a milling machine or carefully, by hand. This was Kevin Buckler's (TRG) recommendation when I researched for a piece in Excellence.

In addition:
- If the engine is installed, you'll probably have to yank it for this upgrade. The control arm pivot bolts are factory-installed from the inside.
- You'll need late model camber/toe eccentrics and slightly longer control arm-to-spring plate bolts.
- There may be some physical contact between the lower shock mount and the heat exchanger sheet metal when the suspension is at full drop. A large hammer is the solution.
- You may or may not have any issues with matching CV joints and axle stubs (4 vs 6 bolt) with your early alloy arms, but be aware there might be differences. Porsche used the ball type sway bar mount up until about '77.
- Control arms (steel or alloy) can be bent in their previous life. It won't be obvious until the car is being aligned. There is a rare factory jig to check alignment off the car.
- Roger's recommendation for larger torsion bars and late model spring plates is a good one. I'd go 26 or 27mm.

That's my experience. I think you now have enough anecdotal info to proceed. It'll either be a complete bolt-on or "some work necessary."

Sherwood
http://members.rennlist.org/911pcars

[Neunelfer]

You can partially compensate by removing said dust cover as well as some material from the lower shock mount boss on the control arm. This isn't as drastic as it sounds. The actual threads (14mm) are a steel insert in the control arm and the necessary amount to remove is merely aluminum, in effect a spacer and not threaded either. Remove the excess material on a milling machine or carefully, by hand. This was Kevin Buckler's (TRG) recommendation when I researched for a piece in Excellence.

Sherwood,

Does your car actually have the aluminum control arms on it? The reason I'm asking is this: I'm dropping the car on it's suspension this weekend and the shocks don't fit... at all.

The difference isn't side to side where you would shave off part of the control arm but rather front to back. The mount on the control arm seems to be too far back to use the Koni's. The body of the shock actually hits the rear edge of the oval shock recess. If the shock were to fall naturally into place it would want to be mounted roughly 1" forward of the current mount on the aluminum control arms.

They installed but once I went to drop the car the angle of the control arm pushed the shock into the rear edge of the recess on the body.

HELP! Do I need to go Bilstein?

[GreenT]

I did this same conversion a few months ago onto a 1970 model, with Bilsteins. Not sure if this is the exactly the same 'rubbing' problem you are describing - on mine the changed geometry causes the scraping you see as the car is being lowered. I thought I was screwed, then realized once the car is all the way down with full weight, it's ok. Close, but ok. This picture is with the car on the ground, and taken right after a 50 mile drive today. You can see there are no fresh scrapes from regular use, in fact a little surface rust has formed on the scraped spot since it was last on a lift.

[Neunelfer]

While they look similar, it seems like mine scrape is higher on the shock body. The problem I'm having is the car won't go down on the suspension. I set the ride heigth w/o the shocks. Now with the shock on it rides about 2" higher and it doesn't move. Period. The shock and the body are hitting like a "y". The branch off the y being the body shock hole. If the mount on the control arm were moved about 1" forward (bottom of the y moves toward the right in this example) you can see how it would clear.

My control arms seem to be milled to the metal insert and again, that isn't the area I need to remove...

Puzzled. I'd like to hear from anyone who has Koni's with aluminum control arms. If it doesn't work then I need to switch over to a full Bilstein system.

Anyone interested in a Koni front suspension lowered 18mm?

[GreenT]

I did the conversion on the front as well, so it was SC parts with Bilsteins all around. Nothing had to be done out of the ordinary to get the back done, other than welding in the later style gusseted sway bar mounts. I did the ride height and corner weighting and alignment all after the new parts were installed. I drove immediately after installation (very slowly) for the alignment work. It was definitely wacky on the way in. The way back it was like 'dang, I shoulda done this ten years ago, this is the way the car is SUPPOSED to be'.
There was an earlier thread about corner weighting where I posted my before/after pictures that you might want to reference at

http://d240157.u39.zeonhost.com/foru...=corner+weight

Another reason I wanted to get rid of the Koni's up front in my original struts was because the Koni's kept failing. The specified model was a combo oil/gas unit, and the seal between the two would fail. I'd call Koni and they'd say 'We've sold a million of these and they never do that, send them back and we'll replace them'. I did - twice - the third time it happened, I said heck with this. BTW - the replacements were never new units in boxes, they were scratched up returns or seconds, which didn't help to endear me to the Koni brand. The SC pieces and factory sway bars and Bilsteins transformed the car, not to mention the bigger SC brakes. Keep plugging away, the end result is well worth the effort.

[Neunelfer]

Thanks Sherwood,

If the engine is installed, you'll probably have to yank it for this upgrade. The control arm pivot bolts are factory-installed from the inside

I lowered the tranny to get the old ones out. Both engine and tranny need to come out anyway as I have a rebuilt 915 ready to go in the 911's place and the 930/07 engine is on the stand waiting for pistons for the S-cam/MFI conversion. Here's the question. Should/could I simply install those bolts the other way around this time (the control arm pivot bolts)?

You'll need late model camber/toe eccentrics and slightly longer control arm-to-spring plate bolts

I made sure they were included with the control arm purchase. Parts Heaven had the best price for this BTW.

You may or may not have any issues with matching CV joints and axle stubs (4 vs 6 bolt) with your early alloy arms, but be aware there might be differences

I'm rock'n there... no problems, early 915 and the early arms had the hubs still loaded. Bolt on.

the dust cover on the Koni Sports interferes slightly with the shock housing sheet metal

This is now consistent with what I've heard. Probably not a problem with Roger's Bilstein installs

[admin_old]

Eric,
Sounds like you've got the bases covered. Yeah, install the pivot bolts from the outside in.

We'll wait for your 915 questions. :-)

Sherwood