Rearend Leak
 

I have a leak between the Right Axle Housing and the Center Section. Is there any way to fix this without completely disassembling the rearend? Tightened the bolts and that didn't help. They weren't loose.

Re: Rearend Leak
 

I had the same problem after a rebuild. I removed paint from the seam Cleaned the area well and put a light coating of Permatex PX 90min Right Stuff on it it’s been fine for a year now :D

Re: Rearend Leak
 

Typically what we find is the housing flange is warped/bent which requires installing in a lathe to true the flange for a better seal. Unfortunately, you cannot do this operation without disassembly. Also, we find many housings are bent requiring straightening. I suspect this happened over the years as people threw chains around the housing to pull things, -or to be pulled out of places. How this affects things is the two rear hubs do not rotate parallel with each other causing the rear axle shaft to bend ever so slightly on each rotation. Not only is this tough on axle shaft longevity, this can also affect braking and tire wear because of the hub not in alignment.

I have placed a few pictures below showing how the housing flange is trued on a lathe. Notice how the area cleans up on one side of the flange yet not the opposite side. This is because some housings are tough to get 100% straightened. The housing tube is straightened using torch to heat and water to cool the area to shrink it back into alignment. The axle housing is held between centers and indicated off of bearing races on each end and in the tapered area of the tube. In the case of when a housing is within a few thousandths of being true, it does not hurt if the housing retains a slight bend as long as a new race is installed for the hub bearing as it will be machined where the centerline is corrected. I hope this makes sense.

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Re: Rearend Leak
 

Another source of a leak is someone chased the threads with an ordinary tap. I have a rear end the "restorer" did that to. I drained the diff and one by one, I removed the bolts, thoroughly cleaned the threads (male and female) and put them back with some Permatex #3 on them. That helped but it still leaves a little oil on the ground over time.

Re: Rearend Leak
 

There is an easy trick you can try that might be successful. drain the oil from the banjo and remove each of the 10 bolts on a side one at a time and coat the thread's with sealer and reinstall before removing the next one. Torque each bolt to 35 ft. lbs. If there are lock washers installed remove them and discard them.

Tom Endy

Re: Rearend Leak
 

Same reply as #2 except I used JB Weld. Ten years later and no leak....

Re: Rearend Leak
 

Thanks for the tips. It seems to be leaking from bolt holes.

Re: Rearend Leak
 

The bolts are a machine fit and are very carefully made they are not a common UNF bolt . I am not sure if the reproductions are made to the same tolerances so could be you have repro bolts installed by someone because they look pretty . No lock washers should be fitted .

John in Suffolk County England .

Re: Rearend Leak
 

I love JB, but I would have guessed that it would be to brrittle to work on this application. I would have reached for Perm2.

Re: Rearend Leak
 

John, you have hit on something that many are not aware of. The former Roy Nacewicz bolts were manufactured correctly however I cannot speak for other vendors, however it is typically not the bolts that are the problem. The Differential Housing's hole thread pitch that Ford used was a Class 4 which is a size that is typically not used commercially any longer since the advent of thread locking compounds. I think most pitches go from Class 1 - 5 with a Class 5 being almost a locking fit. The standard bolts will seal when the holes are threaded with a Class 4 cutter. Below is a PDF I made off of my A-4025 print that shows the specs for the holes.

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Re: Rearend Leak
 

Thanks guys. I went ahead and ordered a new set of bolts from Bratton's. Will try just replacing the leaking bolts and add some kind of sealer.

Re: Rearend Leak
 

I use clear Flex Seal.Guaranteed to stop the leaks

Re: Rearend Leak
 

Read post 10.

John

Re: Rearend Leak
 

Maybe I just got lucky, but I hand filed the trumpets flat where they mate up to the banjo housing,and 11 years and many miles later no leaks. Whatever you do use original bolts without lock washers.

Re: Rearend Leak
 

While we all agree that the bolts originally did not have lockwashers, the use of lockwashers should not have any affect on whether it will leak or not, ...providing everything is within specification.

Think about it, if the gasket mating surfaces are truly flat and parallel, -and if the threads are the proper size, the 600 wt. lube will not penetrate the threads nor the flange area.