Did something interesting today ~ The project I have been working on is using a FB axle, which is out and sitting in a leveling device. I took out the torch and added some heat to the empty axle housing in a couple spots. Now I have 1/8” of toe in and .75 degree of negative camber, and will be ready for the racing season.

This all came about after welding some brackets on to the axle housing. When it had cooled I checked it to see that it was still true. I found that after the welding all the heat had given me a ¼” of toe out, which would be a bit scary on the track. So, I set it up with a rig to allow me to monitor the progress and took my torch to the housing. I should have taken pics, but did not have the camera in the shop today.

I have spoke with folks that have done this before so it is no big deal, just the first time I have done it and it was pretty easy. I understand that I will go through bearing a bit faster, but I am fine with that.

 

I've read of racers putting their rear axle housings in a large press and bending them to change camber and toe. It does work, just a little hard on the bearings over time.

 

Very Interesting topic!! Care to post more in detail?? I would love to see the end product of your design...

 

I also considered doing this earlier this year, but did not get the time to do it. You can add negative camber up to a certain point (which I do not recall) without having to worry about bearing wear. I'm pretty sure you're not that far yet.

I spoke with Billy from Respeed about this, and he agreed that the way to do it is by heating up certain sections of the housing. Nice to hear from someone who has actually done this. I'll be interested to hear of you can tell any difference in performance.

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Pretty sure SA22C and FB's already have .5° negative camber. Did you heat and stretch, or did you preload heat and quench to compress/shrink? The preload heat/quench method (quench only when cooler than red hot) is much more controllable/desirable and can be done in small increments. We used to do this on semi trailer axles all the time, following the measurement with a laser aligner.

I believe the limit is ~1° before the you really start overloading the bearings... Some guys taper the axles splines (on a lathe) to counteract this and go a little further.

 

Yeah it does. I remember seeing something like that with a little bit of toe in on the screen

 

Thanx for introducing the topic, i would like to investigate more
would you be able to share more details
questions:
- areas to heat (bottom or top of housing, shape of the heating area (round, oval or longer stretch plus the square/inch size of treated area ), and quantity of locations?
-when you measure final offset while treating the housing, do you measure with wheels on from the center to the side for each wheel, or to you check camber as left plus right side in reference to center point (third member)?
-would anybody be able to trace back additional articles about the topic?
thanx. B

 

I am running about 1.25 deg negative camber on the driver side, and about 3/4 deg negative on the passenger side. My axle bearing life is now very poor, maybe 1 road race weekend on the driver side, and 2 weekends on the passenger side. Is it worth it? It sure is a pain having the change axle bearings every time I change rear end ratios going from track to track. The bearing life was not great before I added the extra negative camber, they would last maybe 6 race weekends before I added more neg. However, as Kentetsu will testify, my old blue '79 road racer can run very fast.

I am considering changing to a heavier axle assy.