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Words and photos by Jay Roeder
Hi everyone and welcome back! I promised I would be back in December and looky here! It’s December! Yaaa! It’s 9 stinking degrees outside with 5 inches more snow predicted for tomorrow. Not a good start to winter if you ask me but I guess it could be worse. As a matter of fact I bet it will get worse at some point. I digress…
Last month I covered in detail the fabrication of the Competition Engineering wheelie bars and finally got to sit Muscrate back on its own wheels for the first time in a year! Man, did that feel good! Since then I have actually gotten quite a bit done and it feels good. I’m actually starting to see some light at the end of the tunnel. Hopefully it’s not a fast approaching train carrying a load of “surprises”!
Anyway, this month we will cover the final welding of the 9-inch rear housing in detail, the mock up and fabrication of the wheel tubs, floor between the new frame rails, and the addition of a couple more gussets to the four link. On to the ’taters!
The first thing to cover is the final welding of the rear end housing brackets and new Competition Engineering billet housing ends. As you recall from last month I had a slight “snafu” when I rolled the car outside and the passenger side housing end tack weld broke. I temporarily re-welded it enough to hold but didn’t even make an attempt to weld it on center because I knew it didn’t matter at the time. So, the first thing I did was to cut the tack welds and remove the housing ends once I had it on my bench.
The proper way to narrow a housing and weld the new ends back on is to use a fixture that accurately locates the new ends to be exactly on center with the center of the center section carrier bearings. If you don’t use a fixture and just use the “calibrated eyeball” method from last month you will not get a good result no matter how good you are. What you will probably end up with is a housing that is bent after all the heat from welding “draws” it whichever way it wants, and when you go to install or remove the axles it will require a little “persuasion” with a BFH. It will also have a constant bind in the axle and carrier bearings and besides costing unnecessary HP losses could actually cause a bearing to break. So, do it right and do it once!
There are a few rear end narrowing fixtures available for purchase and they will all do an adequate job for most applications. The only thing I don’t like about most of them is they use a spindly little 1-inch diameter bar as the alignment bar. I know I’m being picky, but I think I can do better. Years ago my dad made a fixture for just this reason. It works great, costs very little, and you can make it! Basically, you need a donor center section. Doesn’t matter if it has the usual broken pinion support casting either! Then you need a housing gasket. Next, go to a local steel yard or salvage yard and purchase a 4-foot length of 2-inch diameter bar stock. If you get real lucky you may even find an old hydraulic ram that is chrome plated. Obviously, try to find a straight piece.
The next step will cost a little if you don’t own a lathe but any competent machine shop can easily handle it. Take your 2-inch bar and have them check it on V blocks to make sure it is straight. Maybe .010” total run out is acceptable from end to end. If it’s not straight enough either go get another one or have the shop true it up on a lathe.
What you need to have made is two what I would call “pucks” that are the exact OD of the carrier bearing bores in your donor center section and then the ID should give a nice slip fit for your 2-inch bar.