Layshaft End Play

[McI]

Hello to members, hope I'm in the right place. I'm hoping someone can suggest a fix for my transmission issues.

I'm currently rebuilding the gearbox in my '55 Healey and it seems to be in reasonably good shape except it has too much end play in the layshaft. The manual calls for .001" to .003", and I have .012". The fix was thicker thrust plates, but apparently those are now unpbtainable. There are bronze plates for newer models available from Denis Welch, and I have read of people making and modifying new ones, but mine seem to be hardened steel and I'm not set up for heat-treating.

I could just add a .010" ring of shim stock, but this doesn't seem like the place for that.

I also plan to replace the bearings as they have some small play between the races, and wondered about replacing the synchro rings. AH Spares sells rings that just press in. I wonder if anyone had thoughts re: these rings versus the ones that must be machined.

The bushings appear to be good throughout. I can get no play in any of them. The synchros appear to be almost undamaged, but it seems this might be a good time to replace them while I have the thing apart.

I would appreciate any thoughts people may have. Thanks!

 

[Healey Nut]

The thrust washers are available from AH spares and AH4H . You may have to lap one of them to suit what you need for end float . I just rebuilt my gearbox and went through this process .
Look for wear on the three lugs of the baulk rings and flattening of the interior ridges .

 

[McI]

Thnx for your reply, Healey Nut-my car has the 3 speed and at Moss they're all NA and AH Spares doesn't even have an item number. Bn2 and up seem to be available but not mine. I don't know of AH4H. I guess I was hoping I could adapt thrust plates from another model.

 

[Healey Nut]

This is screenshot right off Ahead4Healeys site in the UK

you could also contact Autofarm in Canada , they have a lot of good used parts .

GEARBOX 3 SPEED

GEARBOX 3 SPEED

www.ahead4healeys.co.uk

 

[Healey Nut]

Austin Healey 100 (BN1) Laygear thrust washer (front) 0.155" thickness 1B3380 | eBay

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Michael Salters E-bay store , he has all kinds of stuff . Very knowledgeable and helpful guy .

 

[McI]

I have been advised that 0.009" wear, though out of spec is not uncommon wear, and I could just reassemble the box and drive it. I am trending this way, just replace the bearings and drive as is. My other plan was to make one, which I don't see a problem with but am not sure what material to use-heat treatable tool steel of some sort. Since i'm in the middle of a frame-up resto it makes sense to get it running and revisit problems as they arise on the road. I don't have a problem pulling the transmission back out, since I'm retired-what else am I doin'?

 

[Side mirror]

McI, I also began a frame-up resto in October. While the frame/tub is getting de-rusted out of the garage, I have taken apart the gearbox. The layhaft end float is a tight .010 and slippery .009. I, too, am debating reassembling since the manual lists .012. I read from the forms that .005 to .012 is good and that .012 is the outside limit. I think .005 is tight, considering the heavy loads and heat that the transmission experiences.

Are you going to work on your OD unit? If so, please keep me posted. Rusty Beauties has some helpful YouTube videos on TR4 gearbox and OD unit.

 

[McI]

McI, I also began a frame-up resto in October. While the frame/tub is getting de-rusted out of the garage, I have taken apart the gearbox. The layhaft end float is a tight .010 and slippery .009. I, too, am debating reassembling since the manual lists .012. I read from the forms that .005 to .012 is good and that .012 is the outside limit. I think .005 is tight, considering the heavy loads and heat that the transmission experiences.

Are you going to work on your OD unit? If so, please keep me posted. Rusty Beauties has some helpful YouTube videos on TR4 gearbox and OD unit.

Hello Side mirror! Cheers and good luck with your resto. It sounds like our gearboxes are differnet-I have a bn1 3 speed, with layshaft endplay tolerance of .001-.003 per the shop manual. I'm opening and checking everything since this is a barn find and pretty much everything is dry or seized (there was a mouse living in the #3 combustion chamber), and making everything factory tolerance if I can. It sounds like you're within tolerance but I'm out .010. so I'm hoping to improve that.

Regarding the OD, I pretty much just did the inspection items per the manual and I was lucky, I had very little wear except the pump cam, which I replaced, and the clutch springs which were sacked a little bit. Probably would've been ok but they were cheap and available. It's gonna be awhile before I'm on the road but I'll try to keep you posted.