Adjusting Back Axle

[Ian Vincent]

My TR3a has quite lot of play in back axle. I can rotate the propshaft back and forth about what feels like 1/4" without the wheels moving. It is however totally silent apart from the click as it takes up the play, both in drive and overrun situations. Living in Devon I get to drive between stone walls quite a lot and would soon hear any noises.

 

I am planning to remove the back axle next winter and strip it down. I am assuming that because the axle isn't whining or howling, I won't need to replace the CW&P, it will be sufficient to adjust out the backlash by checking / adjusting the pinion depth and shimming the diff to achieve the recommended .003" backlash and checking the contact surfaces with engineers blue.

 

Is this correct, or is there anything else I should be looking for?

 

Rgds Ian

[mike3md]

No expert, Ian, but from your description I don't think you have a problem.

 

If it ain't broke, why fix it?

 

Mike

[BlueTR3A-5EKT]

A reshim of the axle is a fairly simple task with the axle on the bench. It is time consuming as you build it up measure it and then take it to bits again to get the clearances right and to finally fit seals.

 

You need the factory repair manual for the type of axle you are working on as it gives clearance measurements and torque settings.

You need suitable hand tools, torque wrench and imperial measuring equipment including a magnetic block and dial indicator plus a micrometer or vernier. Plus a method of removing bearings without destroying them.

 

The simple and easy trick to reshim an axle to tighten the clearances and remove backlash is as follows.

 

-Assuming your car is a TR3A with a Girling axle -

 

Before you remove the axle from the car - Check the axle shaft endfloat - if not to spec you will need to adjust. You can either do it now and know its done or wait till it is on the bench. The shafts will have to come out if you want to re-shim/re-build the axle anyway.

Unless you think the rear hub bearings and inner seals are shot do not attempt to remove the drive flanges from the axle shaft ends, as tears will be forthcoming and expense inevitable without the correct Churchill removal tool.

 

Remove axle from the car.

 

Proceed as follows:

 

1. Re torque the pinion to factory spec - this often brings it back to the correct bearing preload. - NO SEAL FITTED.- fit a new one when set. If not it will be pinon out and adjust the shim pack on the pinion shaft accordingly. < Do not mess with the shims under the bearing outer race in the casing unless you intend to renew the pinion bearings.>

 

2. Now re-check crownwheel back lash - 4 to 6 thou is the spec. - if too big move the thinest shim from one bearing side to the other to move the cw in the desired direction - trick here is pulling the bearings without ruining them. - often they are no more than a hand push fit. This will often cure the excessive backlash - again a shim pack shuffle may be needed - do not change the total thickness of all the shims as they set the preload of the carrier bearings - ie if there is 30 thou one side and 35 thou in the other, the total is 65 thou - you can shift as much or as little from one side to the other to get the cw mesh with the pinion clearance correct. The carrier levers out with a couple of tyre levers - in my experience no diff case spreader is needed on a TR axle.

 

3. Set the planet and sun gears running clearance in the differential - time consuming - start by fitting a pair of new shims under the sun gears and a new pair of cupped planet gear washers. The planet gear shaft is held in place by a locking cross pin that must be fitted and locked in place with a chiselmark on the carrier casing.

NB Do not forget to fit the thrust button on the diff cross pin if the car is rigid axle Girling type.

 

4. Set the axle shaft end float before fitting new tube seals if you did not do it before removing the axle from the car. Time consuming but once you know it is right you can fit the new seals. Shafts, backplates and drums will usually need to be removed to get the axle in and out of the car. This may be different with post 60k cars with toy 9" brake drums - I have never done one so do not know if they will lift over the chassis and not hit the dog shelf in the body.

 

Fit all new seals and rear gasket - 3 places for seals - two axle tubes and the diff drive flange. Fill with favourite gear oil.

 

Drive to pub and discuss the heroic efforts you have undertaken to quieten down the axle.

 

Cheers

Peter W

Spares http://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/clutch-transmission-drivetrain/axles-differentials/girling-rear-axle-tr3-from-c-ts13046-tr3a-tr4-tr4a-usa.html

[Ian Vincent]

Many thks for this Pete, it's exactly what I was looking for.

 

Rgds Ian

[jocklow@aol.com]

If by any chance you have wire wheels, you might want to check how much you can rotate the wheels on the splines. Ans also the u/j's and spline on the prop shaft. It all contributes.

I started worrying about a noise going on and off the throttle in top gear last year. Over the last 12 months it gradually became more obvious and eventually a marked noise from the diff. On strip down by Moss it proved to be a chip in the crown wheel. (And I found metal slivers in the oil to confirm this.)

Hopefully your problem will be cheaper to resolve.

[TR24178]

A reshim of the axle is a fairly simple task with the axle on the bench. It is time consuming as you build it up measure it and then take it to bits again to get the clearances right and to finally fit seals.

 

You need the factory repair manual for the type of axle you are working on as it gives clearance measurements and torque settings.

You need suitable hand tools, torque wrench and imperial measuring equipment including a magnetic block and dial indicator plus a micrometer or vernier. Plus a method of removing bearings without destroying them.

 

The simple and easy trick to reshim an axle to tighten the clearances and remove backlash is as follows.

 

-Assuming your car is a TR3A with a Girling axle -

 

Before you remove the axle from the car - Check the axle shaft endfloat - if not to spec you will need to adjust. You can either do it now and know its done or wait till it is on the bench. The shafts will have to come out if you want to re-shim/re-build the axle anyway.

Unless you think the rear hub bearings and inner seals are shot do not attempt to remove the drive flanges from the axle shaft ends, as tears will be forthcoming and expense inevitable without the correct Churchill removal tool.

 

Remove axle from the car.

 

Proceed as follows:

 

1. Re torque the pinion to factory spec - this often brings it back to the correct bearing preload. - NO SEAL FITTED.- fit a new one when set. If not it will be pinon out and adjust the shim pack on the pinion shaft accordingly. < Do not mess with the shims under the bearing outer race in the casing unless you intend to renew the pinion bearings.>

 

2. Now re-check crownwheel back lash - 4 to 6 thou is the spec. - if too big move the thinest shim from one bearing side to the other to move the cw in the desired direction - trick here is pulling the bearings without ruining them. - often they are no more than a hand push fit. This will often cure the excessive backlash - again a shim pack shuffle may be needed - do not change the total thickness of all the shims as they set the preload of the carrier bearings - ie if there is 30 thou one side and 35 thou in the other, the total is 65 thou - you can shift as much or as little from one side to the other to get the cw mesh with the pinion clearance correct. The carrier levers out with a couple of tyre levers - in my experience no diff case spreader is needed on a TR axle.

 

3. Set the planet and sun gears running clearance in the differential - time consuming - start by fitting a pair of new shims under the sun gears and a new pair of cupped planet gear washers. The planet gear shaft is held in place by a locking cross pin that must be fitted and locked in place with a chiselmark on the carrier casing.

NB Do not forget to fit the thrust button on the diff cross pin if the car is rigid axle Girling type.

 

4. Set the axle shaft end float before fitting new tube seals if you did not do it before removing the axle from the car. Time consuming but once you know it is right you can fit the new seals. Shafts, backplates and drums will usually need to be removed to get the axle in and out of the car. This may be different with post 60k cars with toy 9" brake drums - I have never done one so do not know if they will lift over the chassis and not hit the dog shelf in the body.

 

Fit all new seals and rear gasket - 3 places for seals - two axle tubes and the diff drive flange. Fill with favourite gear oil.

 

Drive to pub and discuss the heroic efforts you have undertaken to quieten down the axle.

 

Cheers

Peter W

Spares http://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/clutch-transmission-drivetrain/axles-differentials/girling-rear-axle-tr3-from-c-ts13046-tr3a-tr4-tr4a-usa.html

I would add to the section about the shaft clearances, I stripped mine down after getting a leaky mess in the RH brake drum, on pulling the shafts found a noisy bearing and worn seals and badly pitted shafts, the flanges needed heat and my 10 ton press before they popped, speedy sleeves were fitted and the clearance was restored exactly to ST tolerances by the new bearings.

 

This is quite a job if you don't have a press, I suggest the Churchill tool would struggle if it is only powered by man!!

 

John Worthing

[stuart]

I would add to the section about the shaft clearances, I stripped mine down after getting a leaky mess in the RH brake drum, on pulling the shafts found a noisy bearing and worn seals and badly pitted shafts, the flanges needed heat and my 10 ton press before they popped, speedy sleeves were fitted and the clearance was restored exactly to ST tolerances by the new bearings.

 

This is quite a job if you don't have a press, I suggest the Churchill tool would struggle if it is only powered by man!!

 

John Worthing

With the Churchill puller wound right up turn the shaft puller side down and then drop it in the pit, the shock works every time!

Stuart.