Pinion Bearing clearance, changed subject.

[Bob Grunau]

Attachments :Talk of pinion bearings, has anybody else thought the .015 ( .381 mm ) feeler clearance between the rear roller bearing rollers and race was EXCESSIVE??

References to this clearance are:

1-Brown Book Bible, TC Instruction manual , Page 24, top of page, says .015 : ( 381 mm ) ,.

2-Blower, 5th Edition, 1955 and others, page 197, last sentence in adjustment says .015

3-MG TA Workshop Manual, Page 35, last sentence says .015 .

 

BUT, The Instruction Manual for the MG Midget series TA and TB , August 1939 (Revised ) . T.B. Incorporated , page Seventeen, top of page says .0015 . Now that is 1-1/2 Thou, a long way from 15 thou as other manuals say.

 

Seems to me, the TA and TB 1939 revision of .0015 ( 1.5 thousands ) should be correct?? Why would you allow 0.015 feeler clearance when the crown wheel clearance is supposed to be 7 to 10 thou? . A bearing clearance of 15 thou. can allow the pinion to drift WAY out of mesh?? I would guess Crown wheel clearance could be between 22 and 25 thou if the rear pinion bearing clearance was .015 .

Is this a possible reason for some gear failures?? Or did anybody ever actually measure this clearance??

Or am I missing something obvious??

 

Happy New Year and may your MGs run well all year.

Bob,

 

Bob Grunau

150 Pinewood Trail,

Mississauga, Ontario

Canada, L5G-2L1

905-274-4136

 

[b][Attachment(s) from Duncan included below][/b]

Andrea-

The original factory installed brass caged R&M double row angular contact (ball) bearing is well known for falling apart and causing diff failure in the TC.  Brass cages turned out to be a bad idea in the post War.  Fortunately it is the only brass caged bearing in the differential, and can be accessed by removal of the pinion carrier if suspect.  

 

This can be done with the differential still mounted on the chassis.   Of interest is the other original pinion bearing.  It was a cylindrical roller bearing with bronze cage, and it was not known for disintegrating.  Good bronze vs brass?  The other 4 angular contact (ball) bearings inside the differential had steel cages.  While any bearings will eventually wear out, only that one particular R&M (brass caged) pinion bearing is known to fall out.  Once it is replaced with a good quality steel or bronze caged bearing, the original pinion setup should go a long time.

Duncan-

 

I agree with Roger- The big bearing of my Pinion (original bronze cage) was in great apparent conditions when I begin the dismantle

but collapsed and disintegrated at the first attempt of separation from the pinion, in very little pieces. I think that bad oil chosen fro P;Os, have corroded the bronze- I consider me very lucky that this happened during the revision-  and not with the car on the road-  Lesson Learned 

ALL NEW BEARINGS must be used on a 70 years old car rear axle

The reason of the R,A dismantle was the obvious flooding of oil on the rear brakes- that stopped in the garages this car for more than 10 years

NOW all right with the -R.A.seal kit- new shafts-new hubs.and ALL new BEARINGs

controlled few weeks ago -after a year of severe use - all right. no flooding  brakes-very little oil infiltration on the opposite face of the brake covers...... (suggestion well accepted)

 

I hope that on the MG TC that go to the M-C-rally,  same works was done from P-O. and experienced engineers have

only controlled "if all are right" on this ACHILLE Heel of our MG

 

 

I see that they have worked on the engine, clutch & gearbox, but have done nothing to the back axle...big mistake, they could have quite a can of worms in there!!! 

 

Recently I received a diff. for rebuild which had obviously never seen the light of day for many years: the oil was black, very thick and VERY smelly! It would not have lasted long with normal road cruising, let alone on an arduous winter rally. So letg us hope the Monte Carlo TC is in better shape axle-wise.

 

I'm sure we all wish the Blue Diamond lads every success, but would not be surprised to hear that they had to retire due to diff. or half-shaft problems...

 

Season's Greetings

 

Roger

 

On Sat, Dec 30, 2017 at 9:32 AM, David Wardell dwardell@talktalk.net [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:

 

You can read more about the TC in the Monte Carlo Classique on the T Register s website which contains links to where you can see John Lomas and Dan Hunter whilst travelling through the UK, and links to the live tracker they will have in the car for the whole event.

They are extremely welcoming of T Type owners giving them support in their venture and good places to meet them are at their departure from Bicester Heritage on 30 January and at the Banbury departure on 1 February, as well as at Paisley Abbey in Glasgow for the main start of the event.

 

http://www.mgcc.co.uk/t- register/news/

 

David

 

 

 

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[Duncan]

I think Bob is on to something here.  My 1970 edition of Blower says on page 196 the pinion roller bearing (rear) should be renewed if .015" can be measured.   Would the car even be able to move itself with that bearing so out of whack?  Duncan- From: "'Bob Grunau' grunau.garage@sympatico.ca [mg-tabc]" mg-tabc-noreply@yahoogroups.com> [b]To:[/b] 'Duncan' morelists@yahoo.com>; mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, January 1, 2018 8:14 AM Subject: [mg-tabc] Pinion Bearing clearance, changed subject.   Talk of pinion bearings, has anybody else thought the .015   ( .381 mm ) feeler clearance between the rear roller bearing rollers and race was EXCESSIVE?? References to this clearance are:1-Brown Book Bible, TC Instruction manual , Page 24, top of page, says  .015 : ( 381 mm ) ,. 2-Blower, 5th Edition, 1955 and others, page 197, last sentence in adjustment says .015 3-MG TA Workshop Manual,  Page 35, last sentence says .015 .  BUT, The Instruction Manual for the MG Midget series TA and TB , August 1939 (Revised ) . T.B. Incorporated , page Seventeen, top of page says .0015 .  Now that is 1-1/2 Thou, a long way from 15 thou as other manuals say.  Seems to me, the TA and TB 1939 revision  of .0015  ( 1.5 thousands ) should be correct?? Why would you allow 0.015 feeler clearance when the crown wheel clearance is supposed to be 7 to 10 thou? .  A bearing clearance of  15 thou. can allow the pinion to drift WAY out of mesh?? I would guess Crown wheel clearance could be between 22 and 25 thou if the rear pinion bearing clearance was .015 . Is this a possible reason for some gear failures??  Or did anybody ever actually measure this clearance??Or am I missing something obvious??  Happy New Year and may your MGs run well all year.Bob,  Bob Grunau150 Pinewood Trail,Mississauga, OntarioCanada, L5G-2L1905-274-4136   Andrea-The original factory installed brass caged R&M double row angular contact (ball) bearing is well known for falling apart and causing diff failure in the TC.  Brass cages turned out to be a bad idea in the post War.  Fortunately it is the only brass caged bearing in the differential, and can be accessed by removal of the pinion carrier if suspect.    This can be done with the differential still mounted on the chassis.   Of interest is the other original pinion bearing.  It was a cylindrical roller bearing with bronze cage, and it was not known for disintegrating.  Good bronze vs brass?  The other 4 angular contact (ball) bearings inside the differential had steel cages.  While any bearings will eventually wear out, only that one particular R&M (brass caged) pinion bearing is known to fall out.  Once it is replaced with a good quality steel or bronze caged bearing, the original pinion setup should go a long time.Duncan-  I agree with Roger- The big bearing of my Pinion (original bronze cage) was in great apparent conditions when I begin the dismantlebut collapsed and disintegrated at the first attempt of separation from the pinion, in very little pieces. I think that bad oil chosen fro P;Os, have corroded the bronze- I consider me very lucky that this happened during the revision-  and not with the car on the road-  Lesson Learned ALL NEW BEARINGS must be used on a 70 years old car rear axleThe reason of the R,A dismantle was the obvious flooding of oil on the rear brakes- that stopped in the garages this car for more than 10 yearsNOW all right with the -R.A.seal kit- new shafts-new hubs.and ALL new BEARINGscontrolled few weeks ago -after a year of severe use - all right. no flooding  brakes-very little oil infiltration on the opposite face of the brake covers...... (suggestion well accepted)  I hope that on the MG TC that go to the M-C-rally,  same works was done from P-O. and experienced engineers haveonly controlled "if all are right" on this ACHILLE Heel of our MG    I see that they have worked on the engine, clutch & gearbox, but have done nothing to the back axle...big mistake, they could have quite a can of worms in there!!!   Recently I received a diff. for rebuild which had obviously never seen the light of day for many years: the oil was black, very thick and VERY smelly! It would not have lasted long with normal road cruising, let alone on an arduous winter rally. So letg us hope the Monte Carlo TC is in better shape axle-wise.  I'm sure we all wish the Blue Diamond lads every success, but would not be surprised to hear that they had to retire due to diff. or half-shaft problems...  Season's Greetings  Roger  On Sat, Dec 30, 2017 at 9:32 AM, David Wardell dwardell@talktalk.net [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:  You can read more about the TC in the Monte Carlo Classique on the T Register s website which contains links to where you can see John Lomas and Dan Hunter whilst travelling through the UK, and links to the live tracker they will have in the car for the whole event.They are extremely welcoming of T Type owners giving them support in their venture and good places to meet them are at their departure from Bicester Heritage on 30 January and at the Banbury departure on 1 February, as well as at Paisley Abbey in Glasgow for the main start of the event.  http://www.mgcc.co.uk/t- register/news/  David         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[Roger Furneaux]

Attachments :hi Bob - you have uncovered what is probably repetition of somebody's mis-reading of the original (correct) data! But for the last 25 years ort so, I have discarded ALL the original bearings in the diffs I have set up (well over 100 now) and replaced them with taper-rollers. These are far superior because, apart from the larger contact area of the rollers, both bearings provide lateral as well as longitudinal support. The front double row ball bearing (only single row in MMM and early TA) has to take all the longitudinal thrust, and I think this is the more likely explanation for the break-up of the bronze cages (rather than the oil attacking them). Rather amusingly, a completely broken up cage splits into lots of little [b]T[/b]-shaped pieces, a bag of which I show at my Rebuild talks on the rear axle. Not so amusing for the poor T-type owner with a chewed-up pinion though! Since these bearings, especially the original type 3MDJT25 front one (which has been obsolete for years, last list price was 150GBP, although I have a few for only 40GBP) are more expensive than taper-rollers, it's a no-brainer really. Setting up is not too difficult using shims (which I have) and my booklet (which is on Doug's website). oc[b]T[/b]agonally Roger

On Mon, Jan 1, 2018 at 4:13 PM, 'Bob Grunau' grunau.garage@sympatico.ca [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote: [u][/u] Talk of pinion bearings, has anybody else thought the .015 ( .381 mm ) feeler clearance between the rear roller bearing rollers and race was EXCESSIVE?? [u][/u][u][/u]

References to this clearance are:[u][/u][u][/u]

1-Brown Book Bible, TC Instruction manual , Page 24, top of page, says .015 : ( 381 mm ) ,. [u][/u][u][/u]

2-Blower, 5th Edition, 1955 and others, page 197, last sentence in adjustment says .015 [u][/u][u][/u]

3-MG TA Workshop Manual, Page 35, last sentence says .015 .[u][/u][u][/u]

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BUT, The Instruction Manual for the MG Midget series TA and TB , August 1939 (Revised ) . T.B. Incorporated , page Seventeen, top of page says .0015 . Now that is 1-1/2 Thou, a long way from 15 thou as other manuals say. [u][/u][u][/u]

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Seems to me, the TA and TB 1939 revision of .0015 ( 1.5 thousands ) should be correct?? Why would you allow 0.015 feeler clearance when the crown wheel clearance is supposed to be 7 to 10 thou? . A bearing clearance of 15 thou. can allow the pinion to drift WAY out of mesh?? I would guess Crown wheel clearance could be between 22 and 25 thou if the rear pinion bearing clearance was .015 . [u][/u][u][/u]

Is this a possible reason for some gear failures?? Or did anybody ever actually measure this clearance??[u][/u][u][/u]

Or am I missing something obvious?? [u][/u][u][/u]

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Happy New Year and may your MGs run well all year.[u][/u][u][/u]

Bob,[u][/u][u][/u]

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Bob Grunau[u][/u][u][/u]

150 Pinewood Trail,[u][/u][u][/u]

Mississauga, Ontario[u][/u][u][/u]

Canada, L5G-2L1[u][/u][u][/u]

905-274-4136[u][/u][u][/u]

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[b][Attachment(s) from Duncan included below][/b] [u][/u][u][/u]

Andrea-[u][/u][u][/u]

The original factory installed brass caged R&M double row angular contact (ball) bearing is well known for falling apart and causing diff failure in the TC. Brass cages turned out to be a bad idea in the post War. Fortunately it is the only brass caged bearing in the differential, and can be accessed by removal of the pinion carrier if suspect. [u][/u][u][/u]

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This can be done with the differential still mounted on the chassis. Of interest is the other original pinion bearing. It was a cylindrical roller bearing with bronze cage, and it was not known for disintegrating. Good bronze vs brass? The other 4 angular contact (ball) bearings inside the differential had steel cages. While any bearings will eventually wear out, only that one particular R&M (brass caged) pinion bearing is known to fall out. Once it is replaced with a good quality steel or bronze caged bearing, the original pinion setup should go a long time.[u][/u][u][/u]

Duncan-[u][/u][u][/u]

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I agree with Roger- The big bearing of my Pinion (original bronze cage) was in great apparent conditions when I begin the dismantle[u][/u][u][/u]

but collapsed and disintegrated at the first attempt of separation from the pinion, in very little pieces. I think that bad oil chosen fro P;Os, have corroded the bronze- I consider me very lucky that this happened during the revision- and not with the car on the road- Lesson Learned [u][/u][u][/u]

ALL NEW BEARINGS must be used on a 70 years old car rear axle[u][/u][u][/u]

The reason of the R,A dismantle was the obvious flooding of oil on the rear brakes- that stopped in the garages this car for more than 10 years[u][/u][u][/u]

NOW all right with the -R.A.seal kit- new shafts-new hubs.and ALL new BEARINGs[u][/u][u][/u]

controlled few weeks ago -after a year of severe use - all right. no flooding brakes-very little oil infiltration on the opposite face of the brake covers...... (suggestion well accepted)[u][/u][u][/u]

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I hope that on the MG TC that go to the M-C-rally, same works was done from P-O. and experienced engineers have[u][/u][u][/u]

only controlled "if all are right" on this ACHILLE Heel of our MG[u][/u][u][/u]

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I see that they have worked on the engine, clutch & gearbox, but have done nothing to the back axle...big mistake, they could have quite a can of worms in there!!! [u][/u][u][/u]

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Recently I received a diff. for rebuild which had obviously never seen the light of day for many years: the oil was black, very thick and VERY smelly! It would not have lasted long with normal road cruising, let alone on an arduous winter rally. So letg us hope the Monte Carlo TC is in better shape axle-wise.[u][/u][u][/u]

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I'm sure we all wish the Blue Diamond lads every success, but would not be surprised to hear that they had to retire due to diff. or half-shaft problems...[u][/u][u][/u]

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Season's Greetings[u][/u][u][/u]

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Roger[u][/u][u][/u]

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On Sat, Dec 30, 2017 at 9:32 AM, David Wardell dwardell@talktalk.net [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:[u][/u][u][/u]

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You can read more about the TC in the Monte Carlo Classique on the T Register s website which contains links to where you can see John Lomas and Dan Hunter whilst travelling through the UK, and links to the live tracker they will have in the car for the whole event.[u][/u][u][/u]

They are extremely welcoming of T Type owners giving them support in their venture and good places to meet them are at their departure from Bicester Heritage on 30 January and at the Banbury departure on 1 February, as well as at Paisley Abbey in Glasgow for the main start of the event.[u][/u][u][/u]

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http://www.mgcc.co.uk/t- register/news/[u][/u][u][/u]

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David[u][/u][u][/u]

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[b]Attachment(s) from Duncan[/b] | View attachments on the web [u][/u][u][/u]

[b]1 of 1 Photo(s)[/b] [u][/u][u][/u]

[img]cid:image001.jpg@01D382ED.E06EBC90[/img][u][/u][u][/u]

IM001003..JPG[u][/u][u][/u]

Posted by: Duncan morelists@yahoo.com> [u][/u][u][/u]

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