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FRONT HUB LIP SEAL
#1
Oh dear! Seal will not fit in.
Front Hub Felt Housing A3-39 taking bearing 2K5507 (BL63)(listed also BO89 on back axle) size 1 1/4" X 2 3/4" X 11/16" as fitted late A7 and Big 7.  Felt rings in spares list 2K6759.

A couple of years ago I got the a7c lip seals BL62a (says 1926 - 1939) ready to fit during my big rebuild. Size 1.5 X 2.5 X 3/8.  I have now just tried to fit one and find it is extremely reluctant to fit in fact even with an exact fit socket/tube to push it in with I feel it would need too much pressure possibly distorting the whole thing.  I have resorted to, at first,  all round hammer taping on back/base ring with a blunt drift, then even harder blows but no progress and fear I may have possibly distorted the seal too much for it to be of any use.

Has anyone else tried fitting BL62a and if you succeed how?  How much pressure?  (One person I phoned who is good with engineering and A7s had same problem and overcame by mounting felt carrier in lathe and skimming a small amount off till new seal went in but with enough friction to hold it tight.....I don't like modifying parts like that in view of future problem possible with correct size seals being then too small so free to rotate)

Using a micrometer, With difficulty on the felt items, I have the following O/D sizes:-

New BL62a lip seal   O/D 2.502 to 2.509 inches

Old lip seal that I took out and was a good fit - with metal outer that had no rubber around outside and was marked RTB1179 - 2.483 to 2.489
An old felt seal that was good push fit - O/D 2.485
A new felt seal that fits snugly - O/D - 2.4835
second new felt.                       O/D - 2.495
This seems to indicate that the BL62a is really too large to be able to force in??  The Jan 1946 spares list shows the same A3-39 felt housing and felt ring  2K6759 and bearing 2K5507 continues.

Being ready for centenary run seems to be looking a bit dodgy!

Dennis
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#2
Have observed similar odd sizes with earlier. I presume tolerance not much mattered for felt. Unless wading the front hubs only require the races to be packed with grease and no additional so the sealing requirement is not great. Note the steel washer must not be ommitted. The hub halves should clamp the bearing. Main problemis usually wear of the stub axle.
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#3
Further investigations.  Idea
March or July 1938 the back axle hub bearing changed to larger 2K5678,  35MM X 72MM X 17MM which for the sake of convenience of interchangeability was reflected in the change of the front hub to take the same larger bearing.  This is presumed to be hub 1A4074 change to 1A4462 BUT both 7 and big 7 spares list still show the smaller bearing         1.25 X 2.75 X 0.6875 and the same felt carrier (we call the inner hub)!!!!  The felt carrier should have been a different part since it houses half the outer diameter of the larger bearing.
It looks like the spares list never fully caught up with the changes??

Has anyone got one of the larger bearing hubs that they would measure the seal housing I/D with an internal mike to let us know the size and also the smaller bearing hub seal housing I/D to compare.
I am wondering if this is the cause of the new lip seal not going into the earlier smaller hub??  Or are both hubs turned to the same felt seal holder diameter??

I have not even begun to look at the stub axles which would also have to have changed to a larger diameter.

Dennis
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#4
Dennis, I have had trouble fitting lip seals on both hubs and rear diff seals they were always too large to be a push fit and had damaged both types of seal in trying.
My solution, probably not what is considered perhaps “good engineering practice” but I simply dressed the outer rubber of the seal with a very fine flat faced needle file, ensuring I was extremely careful to just take very little off at any time and obviously ensuring you kept moving around the seal to ensure it didn’t end up like a thru’penny bit.
I kept trial fitting until I could eventually press, with some effort, into its seating.
The seals installed were a tight fit into their housing and could not easily be removed, at no point was any of the internal steel in the seal exposed.
Denis S
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#5
hi dennis,

the bearing od in the hub didnt change.

the change in part numbers is to cover the drum moving onto full girling. the ones without location pegs. they had a larger ID were they fit the hub. SO the full girling hubs have a lip. the part number changes are to covers this lip.

i dont recognise the seal part number you give, unless this is a suppliers list number.

i used to supply modern lip seals, but stopped when everyone else started stocking. there isnt a problem in useing them if they are still being offered in the correct size. they were always supplied in metric. so likely to be 4 thou over on the OD. but they were always a rubber coated seals. so they were tight. but pressed in fine with some grease to ease them.

ive moved on from useing this method nowadays, and use a far easier better method.

tony.
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#6
The larger metric bearing you mention 35mm x 72mm x 17mm would have been R&M LJ35 / S.K.F 6207 - it was apparently used in the rear hubs of the Big Seven from chassis number 7841. This LJ35 bearing was also used in the rear hubs of the Austin 8 from 1938 to 1947.

My bearing catalogue also notes that Big 7's from chassis number 7841 the two differential bearings changed from R&M LJT 1.1/4" / S.K.F ALS10A to R&M LJT 1.3/8" / S.K.F ALS11A.
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