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TA Rear Axle Hubs
Re: TA Rear Axle Hubs
Rob- If your pinion cap still has the scrolls intact, then likely no serious damage was done, unless some of the scraps ended up in the wrong place. If the cap is the same as used on the TC it is quite rare to find one with the scrolls intact, and nobody makes new ones with scrolls, just with rubber seals. I was able to re-use my scroll cap, lucky me. It does not leak. Your 2X bearing is in better shape than what most find back there. .
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ROGER FURNEAUX
- Posts: 1435
- Joined: Fri Nov 29, 2019 5:49 am
Re: TA Rear Axle Hubs
Bob - you have a really well smashed-up front bearing there! I have repaired many diffs. over the years, and very rarely see them like this: usually one of the bronze cages is broken into lots of little T-shaped pieces. You are very lucky that there appears to be no other damage: usually the pinion is dragged further into mesh with the crownwheel and loses one or more teeth. These can then jam between the gears and cause breakage of the diff. centre housing.
Early TAs (like the MMMs) had a single-row front thrust bearing, obviously a weak point, so it was uprated to a double row. These original bearings, MDJT25 with split outer race and 12 balls, are now obsolete (although I have some, either new or good used) so Moss and others sell a non-split version with only 8 balls, which is not as good as the original.
And because the rear roller bearing can only take lateral thrust and not longitudinal, a much better idea is to use two taper-roller bearings which work in tandem, with both taking thrust in each direction. I fact every diff. that I have rebuilt (well over 100) has had taper-rollers fitted, and apart from two that ran out of oil, none has ever failed.
Roger Furneaux
Early TAs (like the MMMs) had a single-row front thrust bearing, obviously a weak point, so it was uprated to a double row. These original bearings, MDJT25 with split outer race and 12 balls, are now obsolete (although I have some, either new or good used) so Moss and others sell a non-split version with only 8 balls, which is not as good as the original.
And because the rear roller bearing can only take lateral thrust and not longitudinal, a much better idea is to use two taper-roller bearings which work in tandem, with both taking thrust in each direction. I fact every diff. that I have rebuilt (well over 100) has had taper-rollers fitted, and apart from two that ran out of oil, none has ever failed.
Roger Furneaux
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Rob Reilly
- Posts: 363
- Joined: Sun Feb 07, 2021 2:05 pm
- Location: Indiana, USA
Re: TA Rear Axle Hubs
My local bearing shop had the bearing in stock, so my axle is back together and restored, ready to go onto the chassis frame which is next in the restoration schedule.
There was some discoloration on the pinion housing, so the cause of death on that bearing has to be overheating, lack of oil. Looking at it, it seems to me that using the oil level plug as is will give you very little oil in the pinion housing, and less margin for error when you begin to lose some in normal operation.
I wonder if we might be better to fill it a little higher, maybe 1/4", so you could just begin to see it in the filler cup.
The Instruction Manual page 8 lists British branded oils from 1937, a little vague on what oil we should be using these days. One of my other books says SAE 140, but what is the original source of that information?
There was some discoloration on the pinion housing, so the cause of death on that bearing has to be overheating, lack of oil. Looking at it, it seems to me that using the oil level plug as is will give you very little oil in the pinion housing, and less margin for error when you begin to lose some in normal operation.
I wonder if we might be better to fill it a little higher, maybe 1/4", so you could just begin to see it in the filler cup.
The Instruction Manual page 8 lists British branded oils from 1937, a little vague on what oil we should be using these days. One of my other books says SAE 140, but what is the original source of that information?
- Attachments
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1937 TA 1271
Re: TA Rear Axle Hubs
Rob, the TC calls for 140 weight. These non-hypoid diffs run cool, or, take a long time to warm up. Using too light an oil in the engine or transmission will cause problems, so probably same for the diff. Many use a 140 multiweight like 85W140, and many use straight 140.