Even with the extra camber eccentrics I've only ever been able to get about 1.5 to 2 deg neg camber on Jezebel, and I really wanted more.

I'd seen a few posts on here about bending the top torsion arms on a BJ beam to get greater neg camber.

There was no real info on HOW to do it tho on here, stf, samba etc., and asking direct questions hadn't gotten my much either... so I just decided what the hell - time have a
crack.

Here's how it went if anyone's interested...


Step 1: Do some maths.
At it's simplest, the way the steering knuckle mounts is basically this. (drawing not to scale, but the measurements are good. Obviously the top and bottom rectangles are where the ball joints mount into the arms).



I wanted to add about 4 degrees of neg, which high school maths (Sin = Opposite over Hypoteneuse) and a bit of stuff in Excel tells me I should aim for a bend to bring the balljoint in 8mm.

Best of all since my camber eccentrics have ~12mm of adjustment in them, so with only an 8mm bend I could still get back to my current 1.5 deg neg if I wanted (beyond actually to right around 0 camber)


Step 2: Get and measure some arms.
Pictures tell a thousand words, right ?
1 x shiny, straight top arm with new balljoints already pressed in - thanks Marcus !!!



Measured square at just shy of 271mm to the center of the ball joint.



Step 3: Bend some arms.
1 x 20T shop press
1 x 25mm steel plate as a work surface (I wanted something that wouldn't bend after all)
2 x Cast steel dolly's to act as supports to bend in the valley
Quality shed time = priceless.



Measure and marked to get the load from the press midway between the two support points, and some very tentative pumping of the handle later...


Step 4: A bent arm.



Measured square at just on 263mm to the center of the ball joint, which means 8mm of bend... gotta be happy with that !!!



Step 5: Rinse and repeat for the other side.

Step 6: Fit and check measurements on the car.

Before - original non-bent arms with adjusters at max neg camber (-3.5). Without a spindle adapter and properly levelling the car off it's not the most accurate method of measuring, but good enough for before and after at least.




After 1 - freshly bent arm, adjuster at minimum neg camber (-2.5)



After 2 - freshly bent arm, adjuster at max neg camber (gauge maxes out at -6 deg... but should be about -8 deg I think)




Step 7 : Crack a coldy !!!
Now just pull my finger out and bolt up the other side, then get a proper wheel alignment done !!!

Cool

Good work Dave.

Cheers Col

Cool Dave, I sent mine to rod and he gets shimo to do it.

Nice write up Dave, thanks.

I like the unconvensional thinking, could you just shorten the top tube the little you need?

Cheers for comments guys !!!



I thought about shortening the top tube Nils, but renotching the springs in only 8mm per side didn't really look doable to me... looked to need to be 10mm or more to get a good notch with my springs at least.

Other benefit is this way is pretty easily reversed too - just change back to the stocko arms.

Nice; I wonder how braking up front will be affected with the change

I had about 4 1/2 degrees on the front of my old bug no problems with braking probaly one best braking cars in the class

Cheers for the pics and detail Dave.

I'll be wipping mine back off to do this before going too far.

Good work there, Dave. That's the sort of stuff that this forum should be about, IMHO.

I ran - 4.5deg in hillclimb without any problems

I have run about 3' camber on my race bug for some time now, the current experiment is to give it a whole lot more caster and have less camber when the wheels are neutral. The caster also gives camber as soon as you turn the wheels. I'm using 3 sets of caster shims on the bottom tube with offroad braces on the bottom arms and shock tower extentions that fasten onto the roll cage.

4.5-5 degrees,wow. I run 3.5 and get pretty even temps across The tyre when I do a supersprint so I have never tried more. What do you find it helps with having 5 deg col?? You run a 205 tyre?
Bit of a hijack here but has anyone done about Bumpsteer?

Cheers Fabo..........

Great sharing of info all!! Nice to see the forum operate this way

Had a Test & Tune session at Mt Cotton yesterday, and definitely happy with the change.

Running 4 deg neg for the moment - Jezzi feels much more pointy and can actually feel her sort of roll onto the tyre on turn in. Needing a bit more effort on the wheel has lead me to changing my style slightly - more short sharp movements now compared to a gradual winding on and off of lock previously.

Didn't have a pyro to check temps, but the wear pattern looks nice and even across the face so I think the 4 deg neg has to be close to right.

Best of all I chipped away at my times each run, by end of the day lowering my PB by another 0.25 seconds - so obviously shed time well spent !!!

Dave, one reason for improving your times each run, could be the tyres.......they need to be 'cut in' after each major camber change.

Yeah, someone else came up with that theory too Greg, but admit it wasn't something I'd heard of before.

My thinking is probably just me taking time to warm to the different feel and style, but whatever it is I'm happy to take the 50.53 s... now the new target for the year is a 49 !!!

Quote:

Originally posted by Sides Yeah, someone else came up with that theory too Greg, but admit it wasn't something I'd heard of before. My thinking is probably just me taking time to warm to the different feel and style, but whatever it is I'm happy to take the 50.53 s... now the new target for the year is a 49 !!!

Constant improvement Dave!

Awesome effort

i agree with the change of styles as ive done a fair bit of circuit stuff with the same car and ive found that the adaption of style is the biggest improver of times!