Back axle pinion shaft conundrum

[Urgent Austin]

Evening all,

I haven't posted for a while, being busy with other things (or something!). I'm rebuilding a back axle and have hit a snag with the pinion shaft - very grateful for any advice, as ever.

The axle is one I bought, rusty and broken several years ago. Broken halfshaft keyway, cracked crown wheel tooth, the usual stuff... It is an early d type, with the ball bearing at the gear end of the pinion shaft. 

I'm rebuilding it with another cwp, a 4.9:1 short pinion shaft with lefthand bearing retaining thread. 

The long and the short of it (well, mainly the short) is that the pinion shaft doesn't seem to be long enough. Our cherished supplier D Cochrane has confirmed that according to his data, a short 4.9 of this type ought to fit. However, the taper barely protrudes through the ball bearing at the taper end. Putting the flange on, it just grips enough to turn the shaft, but tightening it down will surely push it onto the ball bearing inner race. Is that meant to happen? I'm worried it'll wreck the bearing. Photo attached shows the protrusion at the taper end; everything is shoved in tight at the other end. 
I've double checked everything according to Woodrow. The only unknown is whether I've got the wrong ball bearing at the pinion gear (ie too wide). I can't see any other variables I can adjust!

All suggestions gratefully received.

Many thanks,

Urgent Austin

[Tony Press]

The early pair of Angular Contact bearings on the pinion gear end had the strange Austin Seven standard narrow outer ring bearings.

http://www.austin7club.org/How%20To%2015.htm

[Parazine]

The early pair of Angular Contact bearings on the pinion gear end had the strange Austin Seven standard narrow outer ring bearings.

http://www.austin7club.org/How%20To%2015.htm

I think Tony's got it. If you use a pair of standard width angular contact bearings, it will put the pinion in slightly the wrong place, just enough to snag the axle.

Don't ask how I know 

[Urgent Austin]

Many thanks for your help - never knew that!  I looked at the link.  I can get the bearing housing machined out to take the wider bearings.  Can anyone tell me how wide the outer rings should be, just so I can be sure the ones I've got are too wide?  And for belt and braces, how deep is the original housing pre-machining (to avoid re-machining one that's already been done...).

And, even with this modification, what do people think about the taper end in that photo?  Should it only come out 1/32" further?  

Many thanks,

Geoffrey

[Parazine]

Much better to get the bearings machined, any workshop with a Jones & Shipman 540 surface grinder will do it for you. Just knock them apart (take care to keep the bits in separate bags and coded so you can put it together in the same way) and take the outer rings to an engine machinist. I can check the correct bearing width for you if you like....

[Parazine]

The bearings are type 3LJT1. The inner is 5/8" wide for each bearing but the outer is reduced by 1/32", making it 19/32" wide. Combined width of the two is therefore 1 1/4" on the inner but 1 3/16" on the outer, i.e. outers of the pair, back to back are 1/16" narrower than the outers (and inners) of a standard pair.

So the best solution is to have the width of the outers reduced by 1/32" each on a surface grinder.

Simples!

[Urgent Austin]

Many thanks for the measurements.  The mystery continues I'm afraid.  I've had it apart and the bearings are correct, with the narrower outer rings.  I also noted that the bearing carrier is probably scrap (should have looked more carefully before).  The rearmost bearing has been turning in the housing and worn a noticeable grove.  I'm guessing there's not much I can do about that?  So I need a new one of those.  Anyone got a spare they might part with for a suitable price?

Back to the insufficient protrusion of the taper if I may.  The only remaining variables are the two ball bearings (taper and pinion), and the distance piece, which is the one that came out of the axle.  Does anyone have the widths of the two ball bearings so I can check those please?

Many further thanks,

Geoffrey

[Parazine]

No! That's not wear in the housing!

Someone at Longbridge finally noticed that the housing was incorrect; the bearings should be laterally held and the outer lightly held. They arranged one end to be machined out to allow the outer to find it's own centre. This is dealt with on P168 of the green companion book (750MC publication) in an article by Jack French, written in 1952.

MJ1 - 3/4" wide

LJ7/8 - 9/16" wide.

Not sure about the spacer, can't find one at the moment.

Have you compared the old and new pinions on the bench, side by side??

[Stuart Giles]

I also noted that the bearing carrier is probably scrap (should have looked more carefully before).  The rearmost bearing has been turning in the housing and worn a noticeable grove. 

If you're talking about the relieved area in the "top hat" where the two Angle Contact bearings live, later ones came from the factory like that, the AC bearings are there to take the axial load, the ball race immediately behind the pinion takes the radial load.  Have you got the "old" pinion  ball race available to compare the widths.

Edit: should learn to type faster.

[Parazine]

Just been up to the "Attic of Wonders", the spacer is 5/8" wide.