Rear End Leak

FirstA

FirstA

Member
I am slowly making progress restoring my 29 CC Pickup. The rear end was rebuilt following Les Andrews instructions. Quite a job! My leak problem is between the Differential Housing and the Axle Housing. The 600 weight drips a couple times a day. It has not been driven yet.
I suspect that the gasket got damaged ( Murphys Law) and I did not notice it. I hate to go back into the rear end but maybe there is something I am not thinking of.
 
Did you use the original banjo bolts?The original bolts should screw in a couple turns with fingers but require a wrench to tighten up as threads are a tighter fit than std 3/8 N/F threads.Never chase the banjo threads with a tap.If you use the nice looking cad plated bolts,they are std N/F.You could try a wrap or 2 of Permatex coated string under the bolt heads on lower 1/2 of banjo to seal the leak.Dont use lock washers.
 
I think 35 fp is a bit too much for the banjo bolts.I just tighten them with a 1/2" ratchet & dont have a problem.The only place I use a T-wrench on an A is the cyl head.Were the axle hsg flanges flat or were they bowed slightly between holes?Sometimes if not enough gaskets are used,the diff brgs wil be too tight & hsg will bow between bolt holes.
 
I built the rear end with parts from three others and Les Andrews book. I did not check the axle housing flanges for bowing so that may be my problem. I tell everyone, on my Model A, that I have never worked on anything so simple but so complicated. I will keep learning. Thanks for the help.
 
I had a very slight leak between shaft housing and banjo. Tryed several times to fix but still slight leak on to cardboard. Clean the area as spotless as posible. Give it two coats of rustolium. Oil does not effect rustolium as it also has an oil base. No more leak. John
 
John K., that is an excellent idea that I have never tried, thanks for chiming in! To others, 35 lbs. is not too tight for these bolts.
 
When rebuilding a rear axle assembly I check that the axle housing flanges are flat by setting them on a steel plate and eye balling the gap between the flange and the plate. Quite often you can hammer the flange back into shape. I run a file over all the mating machine surfaces lightly to remove any burrs.

When setting the carrier pre-load I make sure I have at least a .010 gasket on both sides. If I don't I shim the carrier bearings until I do.

I use Indian Head gasket sealer applied liberally to the gaskets so that it will run into the threads. I always use original banjo bolts as they do not have threads directly under the head of the bolt. Folk lore has it that there is something magic about the banjo threads and you should never run a dye or a tap. It may be true, I would never argue against it. However, I have used both a dye and a tap on occasion in order to salvage a banjo or original bolts. You never want to put lock washers on the bolts as it will surely leak oil.

One thing you can do without taking everything apart is to remove each of the 20 banjo bolts one at a time and coat the threads with Indian Head gasket sealer. 35 ft. lbs is the recommended torque specified in a number of how-to books. It is the value I have been using for the past 25 years when rebuilding a rear axle assembly.

Tom Endy
 
A quick fix, which can be long lasting, is to wire brush clean the surface at the banjo and axle housing. Apply a thin bead of JB Weld on the clean surface of the joint between the axle housing and the banjo. Repaint and you are good to go.
 
What I am finding is that many housings are warped, --and even some diff. housings have the threads crowned as someone has tried to overtighten the bolts trying to get them to seal. Use a flat file over the differential housing just to remove the crowned areas. Often times we have found it takes .030"-.040" to clean up that flange. Notice how in the 2nd picture below, the flange has material removed on one side yet on the opposite side the tool has not touched the flange yet.


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The rear end is one part on the Model A I have never disassembled or reassembled, and I hope I never have to. What a collection of mysteries and close tolerances! :eek:
 
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So how does that work in conjunction with the gaskets. As Tom Endy says he starts out with .010 on each side, would the permatex take up some of what a gasket would?
 
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