Boxing front control arms?

[ToddK]

I am starting to rebuild the front subframe on the track car I bought. I have seen alot of posts about boxing the rear arms. Has anyone boxed or added extra welds to the front ones. I'm looking at a set of new arms and I can't believe how flimsy these are. I can bend them with a pair of channel locks. What do you racer guys do? Any pics? Or am i worrying about nothing?

[TobyB]

Not needed-

the arms are in straight compression or tension, and do fine as long as you don't use them to tow the car with! They really don't take any bending loads.

That said, the earlier arms have another bent flange to them, and are quite a bit stronger-

as well as heavier. Instead of a simple H pattern, each leg of the H is longer, and bends away from the center to form more of a beam.

fwiw,

t

[bmw02rally]

Todd,

If its a track car stick e3 arms on, they are forged so much stronger with the added bonus of being longer so giving you loads of negative camber. You'll also need the front tierods but apart from a bit of persuading its a simple mod.

On the original works rally cars they welded plates on the front and backs of the originals to give added strength. I have also welded a strengthing brace to the back of my steering idler as I'm fed up of it bending when landing off jumps.

Hope this helps.

Mark

[KFunk]

I believe someone did stitch up the front control arms to strengthen them. I think its on one of the project cars in the project/blog forum. I can't remember which one.... but it was for a mostly track car project.

I doubt they have it driveable yet, so they might not know whether it helped much.

[KFunk]

Todd,

If its a track car stick e3 arms on, they are forged so much stronger with the added bonus of being longer so giving you loads of negative camber. You'll also need the front tierods but apart from a bit of persuading its a simple mod.

On the original works rally cars they welded plates on the front and backs of the originals to give added strength. I have also welded a strengthing brace to the back of my steering idler as I'm fed up of it bending when landing off jumps.

Hope this helps.

Mark

Mark, sorry to hijack, but can you tell me if you think it'd be fine for my car to run a few rallycrosses? (like an autocross, but in a field)

It's a '74 with high miles, but minimal rust. Some rust around the window frames, nothing really structural.

I've got new tie rods, fairly fresh steering box, Bilstein Sports with H&R springs, big 23 mm sways with urethane endlinks. Ball joints seem ok. New front bearings, old rear ones. Right now I have stock bushings, but hope to have urethane in it soon.

I'll be using a set of studless snow tires on E30 BBS wheels.

Any precautions I should take?

[KFunk]

Back to original topic, found it.

See the pics at the end of his second post here:

http://www.bmw2002faq.com/component/option,com_forum/Itemid,50/page,viewtopic/t,269491/

[racebmw]

I run heavily reinforced control arms on my racecar. They are also modified to eliminate the rubber bushings and to be adjustable for track, camber and caster.

Some pictures on Flickr

http://www.flickr.com/photos/02racer/47528125/.

When I am pounding over the curbs at full speed I am glad I have the stronger arms.

I am not sure if this is necessary on a street car. But if you are serious about tracking the car with today's sticky R compound tires then I would reinforce everything. The state of the art in race tires when the 2002 was designed were not nearly as good as current R compound tires.

Jeff

[bmw02rally]

Kfunk,

The only thing I would say is try and get your car up as high as possible. The problem with this is it causes positive camber which ruin's your turn in. Another reason for the E3 Bottom arms.

Also fit a sumpguard and if you can some kind of fuel tank guard if your going to keep the standard one. I run a separate alloy tank in the boot which negates the need.

Apart from that change your driving style for the loose, I have fitted a hydraulic handbrake which I tweak just before the bend to eliminate the initial understeer on turn in and then steer it using your right boot!!

Whatever happens have fun!!

Mark

[ToddK]

Thanks guys. I think I'll add a few welds like the ones in the project blog photos. It can't hurt. Maybe sometime in the future I'll make up something fancier. Right now I'm still not sure where this car will end up. I don't want to spend money on things that won't be legal. The car was set up as a very highly modified autoX car by the PO. He died and the car kind of found me for short money. No offense to you cone dodger guys, but sitting in a hot parking lot for hours on end isn't my thing.(unless there are a bunch of NOPI chicks in and out of their bikinis) My background is in SCCA IT racing. I figured that the BMW would be a good way to get into vintage racing, or maybe SCCA EP or GT3. For now I just want to go thru the basics and take it to a few track days. After that I'll start making the expensive decisions, or just sell it. The car came with a CR5 speed, a gutted and caged interior, a built motor with Webers, and a nice race suspension. What it needs is some going thru. In particular the rubber suspension components, and the paint.

[KFunk]

Kfunk,

The only thing I would say is try and get your car up as high as possible. The problem with this is it causes positive camber which ruin's your turn in. Another reason for the E3 Bottom arms.

Also fit a sumpguard and if you can some kind of fuel tank guard if your going to keep the standard one. I run a separate alloy tank in the boot which negates the need.

Apart from that change your driving style for the loose, I have fitted a hydraulic handbrake which I tweak just before the bend to eliminate the initial understeer on turn in and then steer it using your right boot!!

Whatever happens have fun!!

Mark

Thanks Mark. I left my stock springs in Hawaii so I can't raise it too much. I'm thinkin maybe I could put my strut spacers back in (the ones to raise the headlights for american standards). Plus I could maybe pickup some of those rubber spring wedges to raise it some more (if they'll hold in there....). Is a guard for the oil pan really necessary? It doesn't look too vulnerable with that big subframe below it. I don't like the idea of welding anything in there, but maybe I could bolt a heavy piece of metal somehow...

[bmw02rally]

I'd say its more to protect the steering, gearbox and exhaust than the sump because as you say its protected. When your going quick you tend to glide off things with a guard.

I used a piece of dural alloy bolted to the subframe and made a angle iron crossmember to bolt it to the front.

[bmw1602.com]

NICE car !!! great buy!! more pictures please!!!

I agree with today's tires I'd rather be safe than sorry!

I will be boxing my new control arms.

by the way, Mine are BENT!!! I will post pics soon....

ANYBODY attempting to do this!! please be sure to clamp the control arm down in a fixture as to prevent warping when welding.......

[boxy02]

Nice ride Todd!! MORE PICS!! (or is it in your blog already?) 8^)

I cranked my front control arms in the vice before stitching them and I vice-gripped the ball joint end prior to welding it up. The fronts are only spot-welded channel pieces, I'd definately stitch them and weld the ball joint head.

Todd, a bit off topic, do you know the size and et measurements of the rims under those great-looking box flares? Tire size?

Have fun!

[ToddK]

The rims are widened steelies 13X8. The tires are crappy goodyears that are only good for rolling it around. They are 235/50/13. There are also a bunch of spacers behind the rims to push them out even farther. It was an autoX car. I'm keeping my eyes open for a cheap set of 13X7 or 13X8 alloys. It's too bad the bolt pattern isn't the same as on my Triumph TR8. The SCCA has allowed all ITS cars to run 15 inch rims. I have 22 13X7 Panasports in my garage. They are 4X95mm and only fit TR7, TR8, Lotus, and spitfire/GT6. I'll start a project blog for you guys who want to see more pics. I'll even throw in a couple of the TR8. Look for Todd's track car.