More Camber, In a Negative Way

Ozzie · Post by **Ozzie** » Fri Jul 07, 2006 6:37 am

New Puma beam, set at -2". 1 set caster shims. Reused the original trailing arms, new ball-joints & the more excentric bushings. The most negative camber I can get is -1/2 deg. Has anyone else experienced this?

Also, has anyone ever tried to bend their trailing arms (lower out or upper in) to achieve more negative camber? I don't want to shorten the length of the top tube & spring, as that would be un-reversable.
Ozzie

gcorrado · Post by **gcorrado** » Fri Jul 07, 2006 10:36 am

has anyone ever tried to bend their trailing arms (lower out or upper in) to achieve more negative camber?

yup. just not me. har har. seriously though, i've heard it's doable. i'm personaly naive about the techniques and pitfalls though.

anyone?

bigGreen · Post by **bigGreen** » Fri Jul 07, 2006 1:24 pm

Usual method is to bend the top arm inward.
That's what they do it on Formula Vee racers anyway.
And F Vee know more than most people about how to make the front beam work for racing.

Anyway, result is that it affects just about everything in the susp geometry:
You're not only increasing the camber angle you're increasing the king pin inclination and caster angle. Camber changes as a result.

Caster will probably vary more than usual as the suspension moves, but this will depend on how much you bend the arm inward. Not many people seem to realise just how much the caster changes with suspension deflection on a stock VW beam. But bending those trailing arms will definitely change the way the caster and steering changes as the suspension moves.

Bump steer will be affected. Whether that means you'll get more bump steer or less will depend on how you have everything else like ride height and tie-rod angles set up.
But generally I think that more camber variation means that you do get more bump steer problems.
Only real way to find out is to try it and see

. Or put the info into some 3D suspension software

In fact you might be better off asking this on the F vee forums
http://formulavee.proboards2.com/

kdf · Post by **kdf** » Fri Jul 07, 2006 2:45 pm

The usual method that I know of is to bend the bottom arm outward, but the result is pretty much the same.

This is the way I have been told that käfer cup cars decrease camber angle. I know a couple full size vw's that have had their arms bent (real cars, not fvees

), and haven't heard of any failures.

bigGreen · Post by **bigGreen** » Fri Jul 07, 2006 7:42 pm

I've honestly never heard of bent lower arms

kdf, can you post some links illustrating pictures of those lower arms for us? I'd be very interested to see them.

Victor H · Post by **Victor H** » Sat Jul 08, 2006 3:11 pm

I've had my upper trailing arms belt for more negative camber. Took a 7 ton press to get 1/16" of bend. That gave me a nice adjustment range with the extra-eccentric adjusters from about -0.5 to a bit over -3 degrees. I run 1.5 neg. Anything more than 2 and my wheels rub the top of the beam at the upper shock mount

snott · Post by **snott** » Sun Jul 09, 2006 2:32 am

ive just gone through the process of bending the top arms, using alot of heat.
but ive manage to get loads of negative camber now. im running with -3 1/2.
i can really feel the difference when cornering

Ozzie · Post by **Ozzie** » Mon Jul 10, 2006 5:48 am

I would appreciate some discription or pics of the process if anybody has such info. My Fuchs with their inboard offset already cause the tires to rub the upper trailing arm at lock, so I'm thinking bending the lower one out would be better than bending the upper one in. Victor H, I'm glad you put in the 1/16" note, I was heading for 1/4" to start. But is that 1/16" deflection at the bend, or 1/16" difference at the ball-joint?

Victor H · Post by **Victor H** » Mon Jul 10, 2006 5:53 am

It's 1/16" at the ball joint end. You can measure from the ball joint end to the end that goes into the beam. Then bend till that measurement is 1/16" smaller. There's some spring to the trailing arms so you'll have to flex it more than 1/16" to get a final result of 1/16".
I suggest starting small because if you bent it too much it's next to impossible to go back.

Ozzie · Post by **Ozzie** » Tue Jul 11, 2006 12:53 pm

The Formula-V guys are worried about binding. Would that be a king-pin bind?

bigGreen · Post by **bigGreen** » Tue Jul 11, 2006 6:13 pm

Be sure to post some pics when you've done it.

I'd really like to see the end result

fullnoise56 · Post by **fullnoise56** » Sun Jul 16, 2006 8:36 pm

I've got a balljoint beam with the upper trailing arms bent in 2.5mm per side. Combinded with the eccentric I have no problem running three degrees negative camber. Tyre clearence is helped by the drop-spindles which increase the track and I've also clearenced the shock tower. The car has reduced steering lock so nothing rubs. It's enough for the race track but I can't do a U-turn.

The shop that bent the arms use a purpose built jig and the bend the arms cold because they said heat-bending weakens them. Their jig was handy because I found out one of my old arms was bent (Passenger side lower; probably from hitting a gutter). That's why I couldn't get the alignment to match on both sides. Now the camber and castor match perfectly.

I had the car tested for bump-steer when the wheel alignment was done at a race suspension workshop and they said there was none at the rear and almost none at the front.

CYA CT