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Measuring for the correct rear end width

I have in the past struggled to measure the car for the correct rear end width to get the wheels and tires to fit correctly for both appearance and to avoid contact with the fenders, frame and suspension. I would like most people place the wheels and tires under the car and use a tape measure to determine the distance from wheel flange to wheel flange. This method will work but the wheels are always trying to roll away and tip over making it very hard to check for clearance and be sure that your measurements are correct . The other drawback is that you can only check for clearance at the height the jack stands are set to.

I came up with a cheap simple method to confirm the results of the measurement taken with the loose wheels. What I did is shown below in the photos. Once I had determined the desired width with the loose wheels and tape measure I constructed a wood “rear end” out of a 2x4. I cut two “axle flanges” from a couple of short pieces of wood and then used 3/8” lag bolts to attach them to the longer center portion of the “rear axle”. The actual width that I made out of wood was based on both the measurements I had taken with the loose wheels and my research to determine what widths were available for purchase.  There is no point in mocking up the wheels to a width that in not commercially available or one that was never provided by the OEMs unless you are planning on spending a lot more money on a custom width housing and axles. Once I had the wooden rear end made I attached the wheels to the small wood “axle flanges” with wood screws and large washers to stop the screws from pulling through the lug nut holes. Once the wheels and axle was centered under the car I was able to raise and lower the wheels with my floor jack to check for clearance at different ride height and suspension travel. If you would like to compare the fit with a couple of different widths build your wooden rear end for the narrower width and then add shims to the ends to change the width. I used 5” long lag bolts to hold the end pieces of wood on which permitted me to add up to 1.5” of shims to each end. Plywood pieces work well for shims.

My wooden "rear end"

Floor jack permits you to raise and lower wheels to check for clearance.

Fitting brakes to the new housing

What’s wrong with this photo?

If you noticed the axles are missing you would be correct.

I placed the order with Speedway motors in late July for my rear end housing and Currie axles. The housing came in a couple of weeks but without the axles. It is now late November and I still do not have my axles. Yes the axles were “special” in that I wanted to use a 28 spline center section already had rather than buy a new 3rd member to suit the 31 spline axles that Speedway stocked.  Numerous e-mails and phone calls, stories of lost and found axles  finally resulted in an e-mail from Speedway motors November 22nd apologizing for “not handling this order in a timely manner” and that a “refund would be sent today”. To say I was disappointed by the service provided by this company would be an understatement.  

I ordering the axles from  Bear’s Performance who kept thier promise of delivery in about a week. I actually had the axles in less than 4 days! Quality and service was excellent. 

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