A-arm bushing SOLUTION

1.2gees · 1.2gees's Garage

Well, I've done a bit more research, and it looks like I'm going with an aluminum bushing, with steel sleeves...

Anybody have opinions about this?
Thanks
Ahmet

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It's all the driver...

Panzer909 · Panzer909's Garage

Do you think they'll be any noisier? I just went with urethane bushings on my TR6 as aluminum ones are known to squeak a little. Might not be the case for yours, though(?)

p0r2chby · 04-06-2001, 07:53 AM

Please take some photos and detailed notes of your adventure and share. Your a-arm problems and solutions would make a great article fro on-line posting or pulp print.

What made you decide to go with aluminum bushings and steel sleeves...

1.2gees · 1.2gees's Garage

Noise? I could be less concerned with noise coming from the a-arm bushings on this car...

+Steel rubbing on steel, at that slow a speed cannot produce too much noise, can it? I'll keep lubricated at all times, to try to reduce this. I'll wrap the assy. with some insulator to keep moisture/possible noise subdued, whatever. In short, noise isn't the biggest concern. I'll let you know if it makes noise, and if lubrication/insulating the area makes a difference.

I'll definately take some pics, trying to meet the deadline at the moment though, track event is next weekend, and right now I have the suspension, steering rack, etc. off the car, engine supported by the oil pan. My mechanic just said I won't be getting the engine hoist until Sunday afternoon, and then I need to make these bushings, (I receive control arms on tuesday), put them in the control arms, on the car, and then get an alignment! Simply put, short on time, very!

What made me get these? Well, every other bushing I've tried gets eaten through, and the control arms end up hitting the subframe, and go through the subframe as well!!! I've got a new subframe right now, and I'm changing the oil pan gasket +lower bearings while I'm at it.

But anybody have anything -/+ to say about using aluminum bushings?
Ahmet

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It's all the driver...

todd951 · 04-06-2001, 08:29 AM

Are you still going to be competing in stock class at the autocross events? If so, either aluminum bushings or monoballs are out since they're not allowed in stock or even street prepared classes. I've also heard that these are very harsh for a street driven car.

1.2gees · 1.2gees's Garage

I suppose I can switch out of street class, it's more fun in street prepared anyway!

I can't believe I'll be doing this all over again, but I need some springs, shocks, sway bars...

Harshness on the street? Well, I guess I'll just have to live with that! This car's intended purpose will likely be occasional track/auto-x, and back up car normally. As long as it's bearable, I should be OK. I got thinking about modifying the spindle (tie rod end pick ups) a little too, so I don't get too much bump steer when the car's lowered. We shall see about that.

I know I should go to a 44 turbo, but I just can't stop. Specially if I get a 944 turbo, instead of a 968 next year, I hope I stay sane, and don't put every penny I've got in it...
Ahmet

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It's all the driver...

todd951 · 04-06-2001, 08:50 AM

Those bushings aren't legal in street prepared either. From the 2001 SCCA SP class rules, section 14.8: "Suspension bushings may be replaced with bushings of any materials (except metal) as long as they fit in the original location." No metal bushings for you unless you intend to run in prepared or modified class.

1.2gees · 1.2gees's Garage

Neither is messing with the spindle... (allowed in stock, OR street prepared).

I guess I could switch the bushings later, on a different set of arms but I doubt that.

My goal isn't to win in a certain class, I know a lot of people are cheating anyway, I'll be running street tires, in whichever class anyway! My goal is to make the car handle tighter, better, spending the least amount of money, and to have fun, become a better driver in the process, etc.

I'll most likely get these bushings, or I could suspend getting the other plastic bushings to a later date, running new bushings for this event, hoping they won't eat into the subframe, in two day's worth of track time. (or I could put large metal washers in there to be sure)
Ahmet

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It's all the driver...

redNeckarsulm2 · 04-06-2001, 10:11 AM

Ahmet, who cares about the noise? as long as the PROBLEM is solved. Who cares about the rules, as long as your car isn't destroying itself!
That really shouldn't be happening on your car, regardless. From the pic, the a-arm isn't wide enough where the bearing slides through, or there are some piece missing there, or something. I bet some parts guy somewhere ok'ed the VW arm as a replacement when it wasn't EXACTLY the same as the Porsche part, or something.
It's hard to believe racing -oriented car manufacturers would put that together that way, only to have it tear up AUTOCROSSING!
I say do what it takes to get it right, and I won't say anything. Wouldn't bother me if you were running stock with the corrected bushing set-up, as you are fixing a DEFECT...

3sonfather · 04-06-2001, 02:03 PM

1.2 - I would not advise aluminum-to-steel contact in any automotive design concept unless you're going to keep it isolated by rubber or plastic. The reason being galvanic corrosion, or pitting on the aluminum member.
Scott

drew1 · 04-06-2001, 11:17 PM

Scot is right about galvanic corrosion. But, steel & alumninum are used together in cams & cyl heads, etc. You will probably have to put a grease fitting & grease regularly to make them last and retard the galvanic corrosion.

drew1

AMCPorsche924Powerhaus! · 04-07-2001, 05:24 AM

noise as in road noise, stiff, bumpy jolts of noise, louder highway noise.

drew1 · 04-08-2001, 05:28 PM

Ahmet,

Got to thinking, the cross member where the front bushing is, is aluminum on a 944, isn't it. If so you'll need thrust washers to stop galling at high pressures.

drew1

marksportcts · marksportcts's Garage

How much are the metal bushings? Are these the spherical bushings by Racer's Edge?

1.2gees · 1.2gees's Garage

These bushings WOULD've been made out of block aluminum, and steel. Aluminum would be machined to shape, and steel sleeves added.

However two things, first this would cost me about $110 (up from $90 for both) a piece, and not be allowed in stock classes. I've heard that it's not uncommon for them to cause cracks around the mounting, and bend the steel control arms as well.

So I think I'm going to buy a Delrin bushing and have that macnined to shape. My car is coming along quite nicely, and for this weekend's DE, I'm going to put two used factory control arms, with factory bushings, and hope they hang on for the duration of the two days.
Ahmet

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It's all the driver...

mike944 · 04-09-2001, 09:15 AM

Ahmet-

I was under my car this weekend looking at my bushings, and i think i have an idea what might be your problem. If your front bushings slide in the arms, the problem is likely in the rear bushing. The rear bushing is supposed to take all the thrust load. This is evidenced by the large washer welded to the a-arm just on the front side of the part that slides into the rear bushing. This rides on the front face of the rear bushing. If this thrust area is not taking the thrust load, the front bushing will be forced to do something it wasn't designed to do. Specifically, taking a thrust load, which causes the bushing to slide. Maybe there is some unknown damage to the suspension mounts of your car. If the rear bushing mounting portion of the frame has moved toward the back of the car it can no longer provide the necessary thrust support for the arm.

Mike

p.s. you didn't remove those welded washers while trying to reduce bushing friction, did you?

1.2gees · 1.2gees's Garage

Hmm, I haven't removed anything, but do remember NOT having this problem, until I clipped a curb (bad enough to bend a control arm, and fender)...

I proceeded to replace EVERYTHING in the suspension with new factory parts, including struts, springs, strut mounts etc. But I think what you're suggesting IS a possiblity, I will be looking at my new control arms more carefully, thaks for the idea. Ofcourse I'll update everybody.

(PS: My control arms eat into the rear bushings too, but perhaps welding a large washer ON the control arm will be a better solution to this than other things I could come up with so far)...
Ahmet

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It's all the driver...

3sonfather · 04-09-2001, 05:28 PM

1.2 - if you're going with plastic / aluminum, I would recommend a plastic called Ertalyte (PET). This plastic is strong, easily machined, and has great wear resistance. It's superior to Delrin.
Scott

drew1 · 04-09-2001, 06:58 PM

The rear bushings have washers to absorb the thrust but they are supported by rubber.

drew1

mike944 · 04-09-2001, 07:57 PM

Ahmet -
you shouldn't have to weld a large washer ON the control arm, it should already be there.

when you reassemble the suspension, with everything in it's normal position, (i.e. front bushing centered properly) the thrust washer should just be resting against the front face of the rear bushing.

It sounds like you might have tweaked your frame a little. to determine this, you could measure the distance between the front bushing mounts (the engine support crossmember) and the 2 rear bushing bolt holes. Compare the good side to the bad side. it's probably off by at least 1/2" A possible solution might be to add a few large washers to the rear of the control arm to act as spacers, and make up the difference.

good luck

Mike