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junglejustice · Post by **junglejustice** » Sat Jul 16, 2005 8:28 pm

OK, get the stones ready!

I want to dial in some rear negative camber while I have the DeDion in my hands and a good fabrication/machine shop at hand....

I have seen the cut and weld solutions - the fabricator recons that he can do the smallest alterations in a press essentially bending the center of the rear axle down in the middle by any number to create negative rear camber of the axle points in any degree increment...

What I would like to know from the tribal fathers here is:
a) How much? 1 degree? 1.5 degrees? Are 2 degrees – optimal?
b) Does anybody see any cracking or other issues happening here - doing it this way...?

My big burning question of the gurus is this: Does the fact that increasing the negative camber on a solid rear-axle also creates toe-in under an exaggerated movement of the axle downward and toe-out under exaggerated movement of the DeDion downward have any negative impact on the conversion?

Or, is the range of movement on the tube to short to ever reach the stage where that angle-switch point has any effect...?

Think about it: With the axle laying flat on the ground - negative camber becomes toe-in as soon as you stand that DeDion on its nose... Yeah it never does that naturally, but, that angle if I pick say, 1.5 degrees changes as the suspension compresses back there! (It turns into toe-in under compression and turns in to toe-out as the suspension off-loads!

What point then do I pick to say OK, here is the horizontal point where I am doing the 1.5 degrees - here is that "neutral" point...?

ar4me · Post by **ar4me** » Sat Jul 16, 2005 9:31 pm

Have no answers, but links to the carbon fiber dedion with adjustable camber - was quoted $6000 (I think it was from Bianchi-Kopp, long ago).

http://www.bianchi-kopp.de/BK-041001/bk ... 01-300.jpg

http://www.bianchi-kopp.de/BK-041001/bk ... 02-300.jpg

Show Jon these pics and ask him if can create a similar mod to facilitate adjustable camber

Jes

Mats · Post by **Mats** » Sun Jul 17, 2005 2:12 am

camber values is not absolute, varies with tires and application (which track and so on) so no tips there.

The de-dion will bend in the plane defined by the two front legs, any toe variations must be taken care of after bending it. Toe will vary with bump but only very little, I did some calculations in the old forum for reference (I'm too lazy to search right now). Then you need to figure out what toe value you want...

junglejustice · Post by **junglejustice** » Tue Jul 19, 2005 12:18 am

Thanks.
Will bending it impact any of the "telescoping" function of the tube and/or the watts?

Mats · Post by **Mats** » Tue Jul 19, 2005 12:29 am

Andrew.b · Post by **Andrew.b** » Tue Jul 19, 2005 6:57 am

Don't worry too much!

Unless you're going to be racing for wins in a competitive series, save all the hassle and leave alone. Seriously.

There is no optimal setting, each track will need a different setting to really take advantage. Thats why the factory IMSA's were fully adjustable for rear camber,toe, and roll centre. See link above!

neg camber in the rear will give you more understeer in the corners, as a result of increased rear grip, which leads to running stiffer rear springs.

This leads to you going off backwards into the nearest armco if you're not careful, as the car now gives you EVEN less warning when the rear let's go, and becomes more twitchy on the limit.

Ask Ron Simons why he leave all his cars at 0 degrees on the ring!

If anything, you should brace the existing rear tube, as this flexes plenty already.

MerrilGordon · Post by **MerrilGordon** » Tue Jul 19, 2005 3:58 pm

When I had alignment checked, each rear wheel had -0.5 degrees camber. I don't remember what the toe setting was.
Merril

Kunta · Post by **Kunta** » Thu Jul 28, 2005 9:19 am

MerrilGordon wrote:When I had alignment checked, each rear wheel had -0.5 degrees camber. I don't remember what the toe setting was.
Merril

Same as for me then. This is a protocol for my car when i still used it on the streets

Edit: sorry, some text is in swedish but ithink you guys can sort it out.
Fram = front, bak = rear, aktuellt = present, före = before

Gerry · Post by **Gerry** » Thu Aug 04, 2005 4:40 pm

I ran about 1 to 1 1/4 degrees negative in the rear for many years on my track car. It greatly helped even the tire wear but I don't know that it really did anything for the handling. It does run very well, in fact the car just won class D at the recent SoCal Buttonwillow time trial so it certainly didn't hurt. You don't need to cut and weld, any alignment shop that works with solid axle motor homes has a machine that will grab it in place and "adjust" to any angle you like. That's how Tom Zat makes his cambered axles and it was easy to duplicate locally.

junglejustice · Post by **junglejustice** » Sun Aug 07, 2005 1:41 pm

Gerry, thanks - can you tell us more please?

This machiene bends the axle...!!!?

Gerry · Post by **Gerry** » Mon Aug 08, 2005 7:23 pm

If you look at alignment shops in the yellow pages, you will find a few that specialize in motor homes. These shops have a special device, usually built right intio the floor of the shop, that has the capacity to grip a solid axle in 6 (or eight if you count the hubs) positions and precisely adjust the geometry to whatever the operator dials in. Some years ago, in discussion with Tom Zat at Alfa Heaven regarding his cambered axles, he mentioned that was how he had the ones he sold done. I did a little research in my area when I wanted to have my front end checked and sure enough the shop I took it to, said the rear would be no problem. I wanted to true up a hair of toe that one side had from the factory and they easily did that and added about a half degree of negative camber while at it. I looked very close and other that a few clean spots on the axle there was neber any notable surface indenbtation from the machine so I guess given enough influence over a broad enough area the assembly will yield a bit. That was over 10 years (and dozens of track events) ago so it seems like a sound enough process.

grant · Post by **grant** » Thu Apr 19, 2007 11:32 pm

Sorry for dragging this back up...

Having the rear axle bent seems OK. But is it imperative to get the toe corrected afterwards? Suppose the rear axle was only bent to -1.5 degrees. I don't know how to do the math for this...will that bring alot of toe-in?

Micke · Post by **Micke** » Fri Apr 20, 2007 12:25 am

If it brings something it's toe out.

You need to check while doing and correct if necessary.

Maurizio · Post by **Maurizio** » Fri Apr 20, 2007 1:15 am

I actually run front and backside both toe-in and like the result.
Tires warm nice evenly over the width during a faster ring lap.
Maybe could be a bit less toe afterwards needed because outside is warmer.

Post by **Zamani** » Fri Apr 20, 2007 8:30 am

Let's say I get 1-1.5 deg. of camber in the back, will that have a significant impact in handling?

BTW, Grant who can do the work in our area?

Rear Negative Camber;