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Discussion Topic:
Rear differential oil weight
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oatycorb |
03-03-2021 @ 5:52 AM
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Member
Posts: 59
Joined: Oct 2020
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Hello everybody, I'm sure this question has been asked a million times but what weight and type gear oil should I use when refilling the differential in my '37 sedan? Thanks for your help!
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carcrazy |
03-03-2021 @ 1:06 PM
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Senior
Posts: 1667
Joined: Oct 2009
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Use a good quality SAE 80w-90 API GL-5 Gear Lubricant. Pennzoil and Valvoline, among others, offer a suitable lubricant.
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1935fordtn |
03-04-2021 @ 3:35 PM
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Member
Posts: 31
Joined: Feb 2015
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If It's freshly rebuilt with known good axle seals I use 85-140.. If it is a old rearend with leaky axle seals, I used straight Lucas oil stabilizer
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51woodie |
03-04-2021 @ 3:41 PM
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Senior
Posts: 516
Joined: Jan 2017
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I run 85-140 in my stock 46 coupe.
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JM |
03-05-2021 @ 7:36 AM
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Senior
Posts: 823
Joined: Oct 2009
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I also use 85-140 GL-4 or 5 in my early Ford differentials.
John
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oatycorb |
03-05-2021 @ 8:07 AM
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Member
Posts: 59
Joined: Oct 2020
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Thank you everyone! It's the original rear axle, never been rebuilt that I know of.
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TomO |
03-05-2021 @ 8:45 AM
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Senior
Posts: 7256
Joined: Oct 2009
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Before you change the differential oil, you probably should remove the rear hubs, inspect the lower surface of the axle housings and repack the rear wheel bearings. Use Sta-Lube SL3131 Heavy Duty Drum Brake Wheel Bearing Grease. The rear wheel bearings use the axle housing as the inner race. If the wheel bearings have not been maintained properly, the under surface of the axle housing wears and pits. This wear can allow the axle to flex and break. Most of the time the wheel with the stub of the axle will go off in its own direction leading to body damage. If your are worn, you will have to have sleeves pressed on by a machine shop with a lathe that can handle the axle housing. John Connolly, ( http://www.columbiatwospeedparts.com/ ) has the best sleeves.
Tom
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oatycorb |
03-06-2021 @ 8:09 AM
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Member
Posts: 59
Joined: Oct 2020
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Thank you so much Tom, I'll disassemble and inspect everything before I do anything else. Had no idea the inner race was actually part of the axle!
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JM |
03-06-2021 @ 10:50 AM
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Senior
Posts: 823
Joined: Oct 2009
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To add to TomO's good advice, and also the good advice of other folks who have posted, when you remove rear hub/drums, its best to use a KRW, or a repro equivalent, puller that locks into the groove on the outer part of hub. This is especially important if axle and inner hub tapers are a tight fit when axle nuts have been torqued to proper specifications. Another cause of broken axles on these early Ford banjo rears is hair line cracks that can occur at the inner end of the keyway. This is in most cases caused by not having axle nuts torqued to spec. which allows axles to drive hubs/drums/rear wheels on the axle keys which damages the keyways and allows the cracking to develop. I have some axles that I removed from rears that I rebuilt, that have these cracks, but fortunately for the previous owner, these axles were not driven to total failure. So, always torque these axle nuts to the correct specifications as outlined in the Ford Service Bulletins. John
This message was edited by JM on 3-6-21 @ 10:56 AM
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oatycorb |
03-07-2021 @ 3:40 PM
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Member
Posts: 59
Joined: Oct 2020
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Thanks John, very helpful advice indeed as I was completely unaware of this issue. I'm putting the engine back into the car shortly after which I'll deal with the rear axle. Hopefully I won't have any issues. Fortunately I have a spare complete rear axle assembly that appears to be in pretty nice shape if I need anything. Thanks a ton for your help!
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