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Re: 1938/1939 rear axle dilemma.

Jeff, Tony, Bob Thanks for all that info. Wish I had bought spares at the time (1970s).
I now just have to get a diff carrier thrust out of the casing to see its markings and measure it and see what size it is....am hoping a standard size. Will try and put together a single article for posterity and future owners of my car.

Any photo copies of relevant bearing lists, A7 spares list emailed to me would be most welcome. I have an A7 Apr 1937 list 1406D and a couple of earlier ones.

The 38MJT25 drawing by RHP says original customer = British Leyland.....but does not give application.

I have just found on web site a firm "Bearing and Engineering services" that say they have large stocks obsolete and odd bearings. In Skelmersdale and Rochdale UK (as well as an American site.)
Also am awaiting call back from a local firm with knowledgable interested old style bearing man.

Location: W Devon

Re: 1938/1939 rear axle dilemma.

Now taken outer roller race out of casing and confirmed it seats against a lip at the rear end (instead of peg like earlier axles) with a screw in from the outside peg at its front......this may also be to locate/hold the original spacer
Markings are.....MNJ 1 1/8.......SKSFRAM or BKBFRAM. My measurements ID - 1.1240", OD - 2.8105", W - 0.8105"
Pinion 1A 7297 8 tooth
CW 1A3634/7297 S8521 X 24......... it is 41 tooth so 5.125:1
Axle case offside (big half) 1A5645; Nearside 1A7644
The bearing spigot on the diff I measure as 1.3995"

Sorry if odd sizes but all my measuring devices seem to have elastic properties....including the micrometers!!

Location: W Devon

Re: 1938/1939 rear axle dilemma.

Dennis,

R&M MNJ 1.1/8 or Hoffmann UMS11 or SKF RM9 is described in my 1950 bearing catalogue as a 'Self-Aligning Double Row Medium Series bearing' ID = 1.1/8", OD = 2.13/16", W = 13/16"

SKF RM9 appears to be still available, albeit @ £85.29p + VAT !

http://www.qualitybearingsonline.com/rm9-skf-imperial-double-row-self-aligning-1-1-8x2-13-16x13-16inch/

Jeff.

Location: Almost but not quite, the far North East of England

Re: 1938/1939 rear axle dilemma.

For reference- the 30's Austin 7 differential pinion support bearing went from a single row ball bearing SKF RLS 9 to a roller bearing CRL 9- both 1 1/8" shaft.

As noted the bearing you have from your later differential pinion is an inch series SKF RM 9 - which is an inch series double row self aligning ball bearing- which seems wrong and I would think it should be an SKF CRM 9 - (a heavier version of the earlier diff pinion single row roller bearing CRL 9) which has the same dimensions but about twice the capacity of the SKF RM 9 ball bearing.

The CRM 9 bearing has a loose outer ring needing axial location.

SKF CRM 9 should still be available although not common.

You quote- "Axle case offside (big half) 1A5645; Nearside 1A7644
The bearing spigot on the diff I measure as 1.3995" "

I assume these are the differential side bearings- can you measure the OD and width to try to identify - could be either metric or inch series angular contact bearings- possibly SKF 7207 or SKF ALS 7 - could the spigot you measured could be 35 mm.

Cheers, Tony.

Location: Melbourne, Victoria, Australia.

Re: 1938/1939 rear axle dilemma.

The self centring bearing with point contact of the balls is totally inappropriate.

Based both on my own observations and those of a colleague, a retired mechanic who spends his time reviving/restoring older cars simply for his personal satisfaction, the serious assembly errors found in cars never ceases to astonish. It seems that unless working on cars very familiar with, even older school mechanics regularly got/get things very wrong. Turners, fitters and the like, even diligent amateurs seem to often do better. One reason moderns are so reliable is no one works on them.

I was often bemused by cartridge filters; usually washers etc were missing and the filter non functioning; regularly changed (by the apprentice) nonetheless.

Location: Auckland, NZ

Re: 1938/1939 rear axle dilemma.

Quote Bob, One reason moderns are so reliable is no one works on them.
Made me laugh Bob and absolutely true. Ian M

Re: 1938/1939 rear axle dilemma.

Tony
quote -(As noted the bearing you have from your later differential pinion is an inch series SKF RM 9)
Dennis
WOOPS.....had another look....MRJ 1 1/8 or MHJ 1 1/8 (top half of stamping obliterated by radius on outer edge. (Not mNj)
It is definitely a single roller.
Dennis

(- which is an inch series double row self aligning ball bearing- which seems wrong and I would think it should be an SKF CRM 9 - (a heavier version of the earlier diff pinion single row roller bearing CRL 9) which has the same dimensions but about twice the capacity of the SKF RM 9 ball bearing.
The CRM 9 bearing has a loose outer ring needing axial location.
SKF CRM 9 should still be available although not common.)


--------------------------------------------------------------------------
Tony
You quote- "Axle case offside (big half) 1A5645; Nearside 1A7644
The bearing spigot on the diff I measure as 1.3995" "

I assume these are the differential side bearings-
Dennis.....YES
-------------------------------------------------------------------------
can you measure the OD and width to try to identify - could be either metric or inch series angular contact bearings- possibly SKF 7207 or SKF ALS 7 - could the spigot you measured could be 35 mm.
Cheers, Tony.
[/quote]
Dennis..
not yet got out but some u/s from a big 7 are marked
R&M 1 3/8L....
LJT 1 3/8

Sorry for confusion re markings on pinion roller mRj OR mHj but NOT mNj.

Dennis

Location: NW Devon

Re: 1938/1939 rear axle dilemma.

Dennis,

Your - MRJ 1.1/8 is the Rear Bevel Pinion bearing listed in my catalogue as fitted to late Sevens from chassis no. 286571. It's a Single Roller Medium Series, Inch Series - the SKF equivalent is as Tony has suggested SKF CRM 9 - size I.D. = 1.1/8", O.D. = 2.13/16", W. = 13/16"

My 1950 bearing catalogue lists the two differential bearings as follows :-

Austin Seven 1936 to 1939 :-

Up to chassis no. 286570 - R&M LJT 1.1/4 / SKF ALS 10A - I.D. = 1.1/4", O.D. = 2.3/4", W. = 11/16" - Angular Contact Light Series Inch Series

From chassis no. 286571 - R&M LJ 1.3/8 / SKF RLS 11 - I.D. = 1.3/8", O.D. = 3", W. = 11/16" - Single Row Ball Light Series Inch Series

Austin Big Seven :-

Up to chassis no. 7840 - R&M LJT 1.3/8 / SKF ALS 11A - I.D. = 1.3/8", O.D. = 3", W. = 11/16" - Angular Contact Light Series Inch Series

From chassis no. 7841 - R&M LJT 1.1/4 / SKF ALS 10A - I.D. = 1.1/4", O.D. = 2.3/4", W. = 11/16" - Angular Contact Light Series Inch Series

Jeff.

Location: Almost but not quite, the far North East of England

Re: 1938/1939 rear axle dilemma.

Diff carrier AC out on one side.
SKF ALF11

Dennis

Location: NW Devon

Re: 1938/1939 rear axle dilemma.

"Diff carrier AC out on one side.
SKF ALF11"

I think you mean SKF ALS 11.

The 1950 catalogue listed ALS 11A possibly indicates a special with the earlier reduced width outer ring- which is not important in this differential side bearing application and a standard SKF ALS 11 will fit and should be still available (in all these bearing replacement discussions make sure that you get genuine bearings - if possible old stock genuine R&M or SKF not Chinese rip offs)

Jeff, your 1950 catalogue is excellent with full detail of all bearings.

Cheers, Tony.

Location: Melbourne, Victoria, Australia.

Re: 1938/1939 rear axle dilemma.

Dennis,

Just checked online, the price of an SKF ALS 11 would appear to be £147.73p + VAT EACH - I believe you need two !

http://www.qualitybearingsonline.com/ALS11-Skf-Single-Row-Angular-Contact-Ball-Bearings-1.3/8x311/16mm/

A quick online search hasn't found anyone offering the SKF CRM 9

Re the SKF 3305A that Tony and I mentioned earlier, further research has shown some in the pre-war MG fraternity have replaced their pinion bearing R&M 3/MDJT25 / SKF 3305B with an SKF 5305A - Double Row Angular Contact Steel Cage bearing with 8 balls per row, 16 per bearing as opposed the Brass Caged 12 balls per row, 24 per bearing of the R&M 3/MDJT25.

Tony,

Would be interested to hear your thoughts on that - is the 5305A 25.4 or 25mm wide and is it perhaps better or stronger than the 3305A - also how many balls has the 3305A?

Jeff.

Location: Almost but not quite, the far North East of England

Re: 1938/1939 rear axle dilemma.

In Melbourne we found a few bearing stockists handling obsolete bearings- possibly similar in UK - you might find a pair of old stock SKF ALS 11 cheaper than £147.73p + VAT EACH.

The SKF CRM 9 is the early crankshaft front and rear roller bearing and will be available from the UK Austin 7 suppliers.

SKF replaced the double row A/C 5305A series bearings with the double row A/C 3305- same dimensions 25x62x25.4 mm and I would think similar complement of balls and thrust load capacity. Both would have a lower thrust capacity than the split outer ring bearing.

Cheers, Tony.

Location: Melbourne, Victoria, Australia.

Re: 1938/1939 rear axle dilemma.

I would not much worry about relative load ability. With degassed steels modern bearings are rated for much higher loads than the same pre war, hence the small bearings in many moderns. And few cars are going to do another 150,000 miles.

Location: Auckland, NZ

Re: 1938/1939 rear axle dilemma.

Still working on it!
Good news - it appears that I have found a supplier for the 2 X 3MDJT25 but at £110 for the two. However not much more than the modified 38MJT25 at £67. This would make life easier being back to original.

I have even found the pair I originally took out (in the1970s) and they may in fact be ok and useable.

However having found the container with all the old bits I removed (in the 1970s) I still can't find the original spacer to go between the rear roller and the pair of thrusts.......CAN ANYONE SUPPLY ME WITH THE SIZE PLEASE. (larger 1938/1939 rear axle)

SKF ALS11 (LJT 1 3/8???) £140 each....gulp!!!!!!! awaiting quote from my bearing supplier..............though one has said LJT 1 3/8 at £73.87 each.

So do I make do with the best of old ones or spend the kids inheritance

Gasket for this later axle casing halves also apparently not available so intend to use blue Hylomar after careful cleaning/deburing of faces.

Location: W Devon

Re: 1938/1939 rear axle dilemma.

"SKF ALS11 (LJT 1 3/8???) £140 each....gulp!!!!!!! awaiting quote from my bearing supplier..............though one has said LJT 1 3/8 at £73.87 each."


SKF ALS 11 is the same bearing as R&M LJT 1 3/8

The designations are:

SKE- Angularcontact Light Series with 11 x 1/8" bore

R&M- Light Journal Thrust with 1 3/8" bore

So take the R&M bearing !!

Cheers, Tony.

Location: Melbourne, Victoria, Australia.

Re: 1938/1939 rear axle dilemma.

Tony Press
"SKF ALS11 (LJT 1 3/8???) £140 each....gulp!!!!!!! awaiting quote from my bearing supplier..............though one has said LJT 1 3/8 at £73.87 each."


SKF ALS 11 is the same bearing as R&M LJT 1 3/8

The designations are:

SKE- Angularcontact Light Series with 11 x 1/8" bore

R&M- Light Journal Thrust with 1 3/8" bore

So take the R&M bearing !!

Cheers, Tony.


SKE - 11 X 1/8" bore....?????? was that typing error?

Still waiting on quotes for 2 bearings.

Location: W Devon

Re: 1938/1939 rear axle dilemma.

From a small sample I have not seen failed a/c bearings so I don’t know what the typical life of correctly adjusted, uncontaminated bearings was, but is car likely to do another 50,000? Failure unless of cages is slowly progressive and rarely strands. If the balls and tracks are chrome smooth, no pits or significant roughness from particles, and cages OK would reuse. “Wear” is no problem as the rings of pinion pair can be shimmed for very slight preload. What prompted the overhaul in first place?

And stating the obvious, care necessary that assembled right way around. If reusing, abutted bearings with extended inner tracks easily damaged by reverse assembly. Without a gasket the diff halves will be closer so original adj needs backing off.

It is important that the pinion roller is a close fit. New bearings if not at least standard tolerance, may not be.

It is worthwhile to preserve all removed bearings in grease!

Location: Auckland, NZ

Re: 1938/1939 rear axle dilemma.

In SKF inch series bearings the number indicates the bore in 1/8 of an inch hence 11 is 11 x 1/8" = 1 3/8".

Cheers, Tony.

Location: Melbourne, Victoria, Australia.

Re: 1938/1939 rear axle dilemma.

Tony Press
In SKF inch series bearings the number indicates the bore in 1/8 of an inch hence 11 is 11 x 1/8" = 1 3/8".

Cheers, Tony.


Aaah. Another grain of knowledge to be taken in. Thanks

Location: W Devon

Re: 1938/1939 rear axle dilemma.

[quote
What prompted the overhaul in first place?
.[/quote]
Answer...Excessive pinion end float of pinion measured on end with DTI 0.012 inch. And around 70,000 miles on clock including some MCC trialling with around 40bhp from 948 BMC A engine.

I have the RHP drawings for the pinion thrust modification I could email. (I still can't put pics in this forum)
Can scan and forward by email to anyone that could put them up so it would be easier to see what we are talking about.

Location: W Devon

Re: 1938/1939 rear axle dilemma.

Hi Dennis

I am a bit confused by the 25.4, 34 , 20 mm overall length pairs and which has/had the longer inners. (Normally assembled back to back these protrude, as per early models. Is it not practical to accommodate using appropriate spacer to pinion?)

.012 does seem excessive if due “wear” and probably not prudent to reuse even with packing, although from the few I have seen seems the nut often loose and the spacer worn which would account for.

For some of those prices could buy a lathe and adapt to anything!

I think I will try and reassemble all my scrapped ac races and advertise! These often pop part easily. Could replace the balls.

Location: Auckland, NZ

Re: 1938/1939 rear axle dilemma.

Further to above does it require .012 shimming (paper/card) to just eliminate back to back clearance, or was movement elsewhere? Were bearings afully clamped? I dunno what the experts consider reasonable "wear." .006?
The BMC A and B diffs use ac side bearings which seem ok for high mileage.

Location: Auckland, NZ

Re: 1938/1939 rear axle dilemma.

Bob Culver
Hi Dennis

I am a bit confused by the 25.4, 34 , 20 mm overall length pairs and which has/had the longer inners. (Normally assembled back to back these protrude, as per early models. Is it not practical to accommodate using appropriate spacer to pinion?)


Jeff is hopefully putting up scans of the drawings sent by RHP which should show all dimensions and gives instructions for fitting.

Dennis

Location: NW Devon

Re: 1938/1939 rear axle dilemma.

Bob Culver
Hi Dennis
.012 does seem excessive if due “wear” and probably not prudent to reuse even with packing, although from the few I have seen seems the nut often loose and the spacer worn which would account for.


The inner track each of the 38MJT25 pair looks rather worn and scored so I expect that is where the end float is caused.

I did tighten the nut up a little ( about 3 degrees of turn to check if spacer between thrust pair and roller had "shrunk" a bit but no difference.

I am a retired electronics professional and my mechanical engineering knowledge has only been gained over the years from playing with old cars and reading up on various aspects and some from experience when working on our ships on the mechanical bits involved with the electronics e.g. radar scanners and various sizes electric motors etc.
So my mechanical engineering knowledge is quite well down the information scale!
I have a medium size lathe but lack the skill/knowledge to do anything really meaningful/skilful with it and certainly not precision work!!

Dennis

Location: NW Devon

Re: 1938/1939 rear axle dilemma.

Uploaded via Photobucket are Dennis' RHP drawings - not sure how long they'll stay up given Photobuckets recent policy changes, so make the most of them while you can.







Jeff.

Location: Almost but not quite, the far North East of England

Re: 1938/1939 rear axle dilemma.

Thank you Jeff.

The one thing I do not fully understand the meaning of is the wording:-

"Groove side of inner to be flush to 0.025 mm above stamped face of outer when a gauging load is applied to stamped face of outer".

I believe this is the wording on the original drawing and was aimed at British Leyland as a technical part of the bearing description, rather than as part of info to me for the modification by me when using in the A7 axle as a pair of thrusts.

I have just looked at the 38MJT25 pair and the balls and raceways that they run in are quite pitted. I can't see a "groove" to distinguish the "groove side".


Dennis

Location: NW Devon

Re: 1938/1939 rear axle dilemma.

I am not sure why these drawings were made- it appears that the two R&M bearings suggested were a wheel bearing in the early style with reduced width outer ring of 10 mm vs 17 mm inner ring.

Could have almost been as easy to use a standard SKF 7305B at 17 mm wide, but if the original bearing was a R&M 3MDJT25 with 25.4 mm width seems a lot of messing about with spacers and a serious risk of ruining the pinion/crown wheel mesh.

Simpler to fit an SKF 3305A and the original spacers. although a lower thrust capacity.

Also eBay seems to have old stock 3MDJT25 bearings often listed for MG/Morris use as well

http://www.ebay.com/itm/NOS-R-amp-M-BMC-Front-Bevel-Pinion-81933-3MDJT25-MGTB-MGTC-1935-1948-Morris-/331756047117

I would suggest go back to the original design and not mess about with the drawings which use the two A/C bearings.

Cheers, Tony.

Location: Melbourne, Victoria, Australia.

Re: 1938/1939 rear axle dilemma.


Thanks Dennis and Jeff.

Generally back to the start!

Had drafted this much as Tonys answer.

The 38MJ... with protrusion on the back face and proportions so unusual I thought I was misreading.

I think I would have opted for a spacer ring instead of reducing!

Considerable mods have obviously been accomplished before. If the one piece assemblies are not reasonably available, and common metric a.c not too expensive, is it not possible to go further and move everything toward the pinon and accommodate 17mm outers? Means remaking the bearing housing piece, a bit of a mission; finishing to .00025 for bearings is tedious, altho not sure if essential.

The spacer needs be got right first time to avoid repeat removal of the bearing. Dummy bearings would be helpful. With roller pinion diffs the pinion can be easliy removed to check mesh.

Location: Auckland, NZ

Re: 1938/1939 rear axle dilemma.

Update.

Pinion Angular contact dual purpose bearing single inner 2 outer Original 3MDJ25 located and 2 bought (1 for use and one for future) £45 +VAT @20% = £54 each.

Pinion Roller MNJ 1 1/8 £32 + VAT @20% = £38.40.
finally should be on way in post after I collect a wrong one (ball) then a problem between the supplier and retailer trying to identifying the right one. (so far no price adjustment).

Diff thrust (Ball) ALS11 (LJT 1 3/8 inch) located and a pair bought £35 + VAT @20% = £42 each = £84 for the 2 required. (Old ones removed may be ok...not yet minutely scrutinised).

Hub bearings SKF6207 (R&M LJ35. 35 X 72 X 17mm ball) Located and bought £6.55 + VAT @ 20% = £7.86 X 2 = £15.72


See next post for next problem oil seals

Location: NW Devon

Re: 1938/1939 rear axle dilemma.

Next problem - Oil seals
The next problem is to identify modern lip seals in the axle casings for the larger half shafts to replace the old felt seals.
I note from previous correspondence with Coopers Payen Ltd that I eventually used their NB084 (now obsolete of course!!). There was a big question mark because they are handed with a helix as well as the lip seal so one shaft would be rotating the wrong way in the seal....HOWEVER I went ahead and fitted one on each side and over many thousand miles have had no problem with leak down casing to brakes.
I am just about to take one out to see what state it is in and how I fitted it (in axle case or in the felt holder?)

Hope to save vast amount of research time by someone knowing of a supplier of the modern seal suitable. Bearing in mind it is the larger 1.015 inch half shaft (earlier pre July 1938 were thiner)

Same for the oil seals to replace the felts in the larger hubs. with the 35 X 72 X 17 mm bearings (may just have to continue using felts?)

Location: NW Devon

Re: 1938/1939 rear axle dilemma.

Dennis,

"Same for the oil seals to replace the felts in the larger hubs. with the 35 X 72 X 17 mm bearings (may just have to continue using felts?)"

Why not use double sealed bearings SKF 6207 2RS instead of Hub bearings SKF6207

Shouldn't cost much more than the open bearings (£6.55 + VAT @ 20% = £7.86 X 2 = £15.72) and save on grease !

Location: Melbourne, Victoria, Australia.

Re: 1938/1939 rear axle dilemma.

Tony
Too late as already have the SKF6207........I didn't think about it at the time of ordering.

Will however be putting in prop front end ball with one shield on front of bearing.

Location: NW Devon