Girlin Rear Axle

[Colin Fairhurst]

I have recently aquired a TR3a chassis complete with "Girling Axle". The end-float of the hubs measures 0.021" when the manual states between 0.004" and 0.006" and is critical because the hub bearings are taper-roller and interact from one side to the other of the axle.

Is it reasonable to assume that the increase is all down to wear in the hub bearings?

 

There is quite a lot of wear in the sun and planet gear's thrust washer/spacers although the gears and the crown-wheel and pinion all look in good condition with good footprints.

The hub bearings feel very smooth but I have not removed them yet. I have removed the axle shafts and back-plates and there isn't any evidence of anything such as oil seals having been replaced.

The oil which I drained out of the diff. was very dark brown with some sticky goo at the bottom but no metal particles.

Any experience and opinions welcome.

 

Regards, Colin

 

 

 

[Ian Vincent]

If the crown wheel and pinion mesh patterns look good and assuming the backlash is in spec, I would just re shim the sun/planetary gears to remove the play and replace and re shim the bearings to bring the hub end play in spec.

 

Rgds Ian

 

Ps check the drag on the pinion bearing.

[Colin Fairhurst]

Hi Ian,

Thanks for that.

Can you explain how to measure the Crown wheel and Pinion back-lash. Do I use a dial gauge on the crown wheel? The pinion rotates about 4 degrees to take up the slack.

Their is no drag at all on the pinion. The manual states 15 to 18 ibs in". I will also have to re-shim the pinion bearing.

If the back-lash on the Crown wheel and pinion is excessive is it feasible for me to re-shim the pinion without special equipment or is that a job for the specialists?

Do you think that the 0.0021" end float on the hubs is normal for the age and assumed typical mileage of the axle?

 

Regards, Colin

[Ian Vincent]

Hi Colin,

 

If there is no drag on the pinion then it needs to be re-shimmed and for what it costs, you would be advised to rebuild the axle replacing all the bearings. Rebuilding an axle is pretty straightforward provided you have the tools and are a competent mechanic but you do. need to get it right otherwise you can destroy the CW & P.

 

You measure the backlash between the CWP with a dial gauge on the CW and from memory it needs to be between 3 and 6 thou. 4 degrees at the pinion sound too much. To reduce it, you adjust the shims behind the bearings that the CW runs in.

 

There is a section on rebuilding an axle on the technicalities CD. The bit that i found trickiest was setting the pinion depth without the special Churchill tool.

 

Rgds Ian

[Colin Fairhurst]

Thanks Ian.

 

I am coming around to the idea of rebuilding the axle. What about the quality of the new bearings that are available?

 

I feel capable of doing the job, other than changing half shafts and hub bearings rebuilding the rear axle is probably one of the few jobs that I haven't carried out over the years.

What I have learned is to is to get advice and knowledge about a job before delving in too deeply.

The "technicalities CD" does seem to skate over the bit about setting the pinion depth which is critical.

I was thinking that maybe new bearings may take it back to original although I don't know how to check that.

 

Any advice and information welcome.

 

Regards Colin

[Ian Vincent]

Hi Colin,

 

Most suppliers seem to offer two alternatives for bearings. Timken or equivalent and Indian or Chinese. Obviously there are significant price differences. I must admit that I took the view that for the limited mileage I would be doing, the cheaper variety would do the job. I bought them from Revington.

 

Setting the pinion depth is pretty straightforward if you have the tool. The problem is that it has to be set from the centre line of the bearings. I used some round silver steel bar of known diameter located at the bottom of the bearing housing with some home made clamps and repeated the measurement enough times to get a statistically sound answer.

 

Rgds Ian

[arthur r]

I've rebuilt my diff twice once in the 1970's using toolroom equipment and just recently at home using parallel bars across the diff face and a set of slip gauges to measure the distance between the crown wheel centre and the pinion face. A bit tricky but it worked the bluing marks were spot on after adjusting the crown wheel bearing shims and the diff runs silently. you can buy imperial size bars and slips quite cheap on ebay. The key is to buy the best bearings you can get.

[Dave Larnder]

Hi Colin

 

Send the whole axle to Pete Cox, he is the wizard with Girling axles.

 

Dave

[Ian Vincent]

I recently got hold of an old American pinion depth tool for Buicks from 1938 to 1946. It consists of a couple of steel discs about 1" thick, each with three stepped diameters that slide on a centre yoke with a built in depth micrometer. The idea is you clamp the discs with the CW bearing caps and then measure down onto the top of the pinion. At the moment the micrometer part is seized so I have it sitting in a bath of ATF and paraffin to see if that will free it off. Assuming I can get it to move, I then only need to get the end discs turned down to the diameter of the TR Crown Wheel bearing (2 27/32") from their current 3" minimum and I will have a pukka piece of kit (it will almost certainly need calibrating but that shouldn't be a problem).

 

Rgds Ian

[mjdearing]

Hello chaps I would love to be able to do all this measuring stuff, iv rebuilt a few diffs in the past but used the pinion and crown wheel in and out a hundred times jugeling shims to get the desired blueing marks i.e. inward and lowish can anyone point me to any internet info that I may study and hopefully take in to help me. Ta Martin

[Ian Vincent]

The key dimension is 3.4375" from the ground bearing face on the back of the pinion to the centre line of the CW bearings. It is specified in the workshop manual. Other than that it's standard stuff. There is also some info on the Triumph Technicalities CD.

 

Rgds Ian

 

PS The following link should take you to Macy's Garage instructions for setting up a diff. http://www.macysgarage.com/myweb6/diff-overhaul.htm

Edited November 9, 2017 by Ian Vincent

[Colin Fairhurst]

Hi Colin

 

Send the whole axle to Pete Cox, he is the wizard with Girling axles.

 

Hi Dave,

Thanks for that but every time I put a question on the forum about gearboxes and axles sooner or later I get told to send it to Pete Cox.

I am aware of Pete's reputation but some of us prefer, for various reasons, to do the job themselves as I have always done for more than 55 years.

I am still learning and researching for more information and apart from anything else I find it good for both mental and physical exercise.

I hope I will continue to have the ability to do this for some time to come.

 

Regards, Colin

[Colin Fairhurst]

The key dimension is 3.4375" from the ground bearing face on the back of the pinion to the centre line of the CW bearings.

 

I am well on my way to completing this job. The problem that I had was measuring from the ground bearing face. I can't see how this can be done without removing the pinion head bearing and measuring the depth of the pinion gear and adding that to the measurement from the crown wheel centre line to the face of the pinion gear.

 

Regards, Colin

[Dave Larnder]

Hi Dave,

Thanks for that but every time I put a question on the forum about gearboxes and axles sooner or later I get told to send it to Pete Cox.

I am aware of Pete's reputation but some of us prefer, for various reasons, to do the job themselves as I have always done for more than 55 years.

I am still learning and researching for more information and apart from anything else I find it good for both mental and physical exercise.

I hope I will continue to have the ability to do this for some time to come.

 

Regards, Colin

Colin

I don´t know how old you are, but I wish you well to do the job, I am 79 and I would not attempt it, but I have done the wheel hubs seals and bearings so I am not a stranger to tricky work.

Dave

[BlueTR3A-5EKT]

 

I am well on my way to completing this job. The problem that I had was measuring from the ground bearing face. I can't see how this can be done without removing the pinion head bearing and measuring the depth of the pinion gear and adding that to the measurement from the crown wheel centre line to the face of the pinion gear.

 

Regards, Colin

Do not forget that there is an element of compression on the two pinion bearings when they are correctly pre-loaded, dropping the pinion height a thou or so. It is detailed in the ROM.

Peter W

[Ian Vincent]

 

I am well on my way to completing this job. The problem that I had was measuring from the ground bearing face. I can't see how this can be done without removing the pinion head bearing and measuring the depth of the pinion gear and adding that to the measurement from the crown wheel centre line to the face of the pinion gear.

 

Regards, Colin

Thats exactly how Ive done it in the past and then check the bluing pattern to confirm Ive got it right. The manual suggests using a dummy undersized pinion to get the shim thickness before fitting the real one. Saves keep pulling the bearing off. I didnt bother.

 

Rgds Ian