D type rear axle pinion angular contact bearings

D type rear axle pinion angular contact bearings - Printable Version

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D type rear axle pinion angular contact bearings - Dave Mann - 19-01-2021

Had a phone call query yesterday from an owner with a spare rear axle where there was a gap between the pinion angular contact bearing housing and the torque tube. I've not come across this problem, are these special narrow bearings?

RE: D type rear axle pinion angular contact bearings - bystander - 19-01-2021

They are.

I believe 1/32" off the face of the outer race (i.e. similar idea to the AC front crankcase mains). RHP 8/LJT1 or Hoffman N1917 is the special bearing number - ideally should be a matched pair.

RE: D type rear axle pinion angular contact bearings - Stuart Giles - 19-01-2021

As bystander says, the A7 pinion thrust bearings are narrower on the outer track.

https://www.theaustinsevenworkshop.com/products/ra0394-pinion-bearings-int-8ljt-ac-thrust

Should be possible to narrow down the outer track of the existing bearings using a toolpost grinder in a lathe. Some care would need to be taken to make sure they clock up true before getting to work in this case.

RE: D type rear axle pinion angular contact bearings - Tony Press - 19-01-2021

We had a specialist workshop turn 1/32" off the outer ring non thrust face on SKF ALS 8, RHP LJT 1" with a ceramic tool while still assembled.

My list shows the original bearings were SKF W6898, R&M 3LJT 1". With the outer ring narrowed all other dimensions are the same. It is unlikely you will find a matched pair but the standard pair are usually acceptable.

If you are keen, the standard bearings can be shimmed to give around 2 thou preload.

RE: D type rear axle pinion angular contact bearings - Stuart Giles - 20-01-2021

(19-01-2021, 11:58 PM)Tony Press Wrote: We had a specialist workshop turn 1/32" off the outer ring non thrust face on SKF ALS 8, RHP LJT 1" with a ceramic tool while still assembled.

My list shows the original bearings were SKF W6898, R&M 3LJT 1". With the outer ring narrowed all other dimensions are the same. It is unlikely you will find a matched pair but the standard pair are usually acceptable.

If you are keen, the standard bearings can be shimmed to give around 2 thou preload.

That's really interesting Tony. Do you know if they used CBN (Cubic Boron Nitride) tool? Can't think of anything harder for machining steel. I would have thought that the bearing race's hardness would be somewhere north of 60 Rockwell "C"

I used a CBN insert to machine this (non A7) pinion to make it fit in a different axle, even the CBN tool started to struggle a bit immediately behind the glass hard pinion gear.

[Image: 50855773211_22097ef9ab_z.jpg]

I might try machining an old bearing race with the CBN insert if I can find where I put it -they're far too spendy to buy them in boxes of 10

RE: D type rear axle pinion angular contact bearings - Tony Press - 20-01-2021

Stuart, I don't know tool details and you are correct, SKF bearings are 60 Rockwell C.

RE: D type rear axle pinion angular contact bearings - Stuart Giles - 12-07-2021

(20-01-2021, 11:26 AM)Stuart Giles Wrote:
(19-01-2021, 11:58 PM)Tony Press Wrote: We had a specialist workshop turn 1/32" off the outer ring non thrust face on SKF ALS 8, RHP LJT 1" with a ceramic tool while still assembled.

My list shows the original bearings were SKF W6898, R&M 3LJT 1". With the outer ring narrowed all other dimensions are the same. It is unlikely you will find a matched pair but the standard pair are usually acceptable.

If you are keen, the standard bearings can be shimmed to give around 2 thou preload.

That's really interesting Tony. Do you know if they used CBN (Cubic Boron Nitride) tool? Can't think of anything harder for machining steel. I would have thought that the bearing race's hardness would be somewhere north of 60 Rockwell "C"

I used a CBN insert to machine this (non A7) pinion to make it fit in a different axle, even the CBN tool started to struggle a bit immediately behind the glass hard pinion gear.

I might try machining an old bearing race with the CBN insert if I can find where I put it -they're far too spendy to buy them in boxes of 10

(20-01-2021, 09:36 PM)Tony Press Wrote: Stuart, I don't know tool details and you are correct, SKF bearings are 60 Rockwell C.

Resuscitating this thread as I had cause to use a CBN turning insert on another job today. Once that was out of the way, I fitted a wheel bearing from another (non A7) restoration project in the lathe chuck. It's a Nachi Ball race, was glass hard when tested with a file. Before and after pictures below.

[Image: 51306105747_97c1e58f32_z.jpg]

Last one's a bit of a poor photo, but you can see the near mirror finish on the bearing face. The swarf comes off dull red! thankfully the (rather spendy) tool tip still looks like new.

[Image: 51306105002_5e2d0c3f1f_z.jpg]

Surface speed was about 300 SFM, manufacturer instructions are to machine dry with these tips; flood coolant is likely to cause cracking of the CBN tip.

RE: D type rear axle pinion angular contact bearings - Charles P - 12-07-2021

Good to know. I have the OD of a cam centre bearing to shave down and don't have a tool post grinder. Well I did have one and after 5 years unused in a box under the bench I got rid of it. Doh!