Topic: 39 rear end


bills39    -- 08-29-2013 @ 11:03 AM
  I'm replacing the seal in the axle tube.
What is the best gasket sealer to use to coat the gasket ?
Ford lube chart calls for 90w gear oil, is this the best?


supereal    -- 08-29-2013 @ 12:52 PM
  Which seal are you referring to? Any good grade of gear lube will be OK. The 80-90 is most available, as 140 has been hard to find. Any are better than the original used when the car was new.


40 Coupe    -- 08-30-2013 @ 3:49 AM
  I use Permatex High Tack 98H on both sides of each gasket as well as the housings. Use a small amount of black RTV on the threads of each bolt.
NAPA sells 140W EP gear lube, you may have to order but it comes in the next day "Sta-Lube" SL24238 is one gallon size. I use it in both the transmission and differential.


bills39    -- 08-30-2013 @ 9:05 AM
  The seal is at the end of the axle housing.
Thanks for the info on the Permatex I will also check Napa for the 140w.
There is a grease fitting at end of axle housing to grease wheel bearings, what is best grease to use?


supereal    -- 08-30-2013 @ 10:23 AM
  If oil is leaking into the brake drums, the rear axle has been overfilled. The oil level should be maintained just below the filler hole. Old Fords have a habit of leaking oil down the torque tube when the transmission is overfilled. This shows up as excess oil when the rear end filler plug is removed. replacing the axle seals is a big job, requiring the
removal and disassembly of the rear axle, and a special or improvised tool to remove and replace the seals. If the large gaskets on the sides of the banjo are not intact when removed, they will have to be replaced. This requires a special procedure if new gaskets are required. I can give you the protocol if necessary. It is a good idea to lower the oil level to eliminate leaks before tackling disassembly of the rear axle, if you haven't done it previously. As for the grease fittings behind the backing plate, do not use them, as it will result in grease entering the brake drums. They were a carryover from earlier days, and serve no useful purpose. The rear hubs must be removed to pack grease around the bearings inside. If you have been using the fittings on the axle, it may explain the grease in the drums, and eliminate the need to replace the axle seals if it is grease instead of oil.

This message was edited by supereal on 8-30-13 @ 10:30 AM


JM    -- 08-31-2013 @ 5:56 AM
  If you have already dismantled the rear to replace one axle housing seal, I would recommend replacing all three of those seals. I recently did a gear change in a low mileage original '35 rear and all three seals were bad. You will need a special tool to do this properly.
Somewhere around '39 Ford replaced those zerk fittings in the axle housings with threaded plugs probably to prevent folks from pumping too much of the wrong type grease into the wheel bearings. As already mentioned, it is best to pack those wheel bearings with the correct wheel bearing grease. I use a Sta-Lube fiber filled grease.
Another suggestion is do not run a tap in those banjo/center housing threads and make sure you use the original bolts. They were designed to help sealing when properly torqued.
I carefully cleaned and inspected (repaired if necessary) the gasket sealing surfaces on the center section and axle housings and and coated the gaskets (aka spacer shims) with a light coating of grease rather than using sealers, so that shimming thicknesses would not be affected. So far, no oil leaks in 8,000+ miles.

John


bills39    -- 09-08-2013 @ 11:59 AM
 
Replaced the seals at end of axle tube. The gaskets at banjo could not be saved. Can some tell me what the gasket thickness should be to get proper bearing clearance?


alanwoodieman    -- 09-08-2013 @ 1:14 PM
  you will have to experiment to determine what thickness of shims to use and how many. Do you have the old gasket? parts of them? do you rememeber or can determine which side of the banjo they came from, if the answer is yes then you can mike them and mike new shim/gaskets and assemble accordingly, if not then your work is cut out for you.


Stroker    -- 09-08-2013 @ 1:38 PM
  Bills39: It's not just a matter of bearing clearance. Those banjo-to-axle gaskets determine the gear lash between the ring gear and pinion. Total number of shim gaskets
on both sides will set-up the bearings, but you will, (as Alanwoodieman pointed out) need to also adjust the gear lash. This is usually a very time consuming process, wherein you
paint the gears with Prussian Blue, assemble and tighten all the bolts, rotate the assembly a couple of turns by hand, and then dis-assemble and observe the contact marks
on the gears, swap gaskets from side to side to correct tooth contact and then repeat. Long process, but absolutely necessary if you don't want a short-lived axle.


bills39    -- 09-08-2013 @ 2:54 PM
  I took the drivers side axle housing off to sleeve the wheel bearing end, the pass. side is still on.
The old gasket thickness is .006
Will I need to remove pass. side housing and reseat back lash?

This message was edited by bills39 on 9-8-13 @ 3:15 PM


Stroker    -- 09-08-2013 @ 3:41 PM
  Passenger side does not affect gear lash. I'd make up a new gasket pack that measures .006 for the drivers side, mark your gears as previously described, and assemble, rotate
and dis-assemble to double-check where the contact patch is. You want the contact to be
towards the middle of the ring gear teeth. Now all of this is assuming you have a left hand drive car. If you live down under, or anywhere in the UK, just reverse the instructions.


supereal    -- 09-08-2013 @ 5:01 PM
  Here is the drill: assemble the left (driver) side to the banjo with a .008-.010 gasket. Install the right side with a .004-.005. Check the pinion with a dial gauge. Try for .003 to .005 lash at the pinion. Whenever you add to one side, you must subtract from the other, and vice versa. Increasing the left side increases the backlash. decreasing the left side decreases the backlash. It isn't as tough as it sounds, only time consuming, to get the proper backlash at the pinion. If you get the backlash there correct, you don't have to worry about the gear pattern. I've done lots of these, and that is the best and easiest procedure.

This message was edited by supereal on 9-8-13 @ 5:17 PM


bills39    -- 09-08-2013 @ 6:40 PM
  Thanks for the info. I'll give it a try.


Stroker    -- 09-09-2013 @ 5:41 PM
  Supereal: Thank's for providing a "practical" solution. I've done it many times using the "old way", and it is a real pain. We used "white-lead" instead of Prussian Blue in the 60's, but it was still very time consuming.


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