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TR2/3/3A Tightening Front Wheel Brgs - TR3A

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Don Elliott

Don Elliott

Obi Wan
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I've done this so many times, but I can't rememember and I can't find where in the world (I mean the manuals) are the details how to do this. I remember you have to pre-tighten the castle nut - but how tight ?

Then you have to bring it back a half a flat - or something like that. What is it exactly ?
 
As nearly as I remember, tighten until brgs are seated with slight resistance to turning of the wheel. Back off one flat or until you can insert cotter pin.

Jim
 
Don, the procedure is given differently in different places! Practical Hints 6th ed, page 20 says to tighten the nut until resistance is felt to hub rotation, then back off 1/2 flat (meaning 1/12 of a turn). Not mentioned, but implied IMO is to do that as a minimum, and move the nut more if necessary to line up the cotter pin hole (IOW, 0.5 to 1.0 flat). This is the way I do it.

Earlier manuals (like the workshop manual) I think gave larger clearances; while at some point (TR4 maybe) they said to torque the nut to 10 ftlb before backing off.

Also someplace it notes that if you are replacing the felt, to check the bearing clearance BEFORE installing the felt and mark the nut's position. Then remove the hub, install the felt, and put it back with the nut in the same position. This is because some new felts are so thick that they bind and cause a false clearance reading. This is in a later manual (maybe TR4A, don't recall offhand), but IMO is good advice for all TRs with that felt seal.
 
I think there is a very low torque number I've read somewhere, but as I never can remember it and I don't have that good a torque wrench I just do what Jim does and it works for me (so far!). The other thing, of course, is to be careful if you've put in new felt seals, better to do a trial fit first without them to make sure you are seating properly.

Randy
 
"1/2 flat (meaning 1/12 of a turn"

1 flat ='s 1/6 turn. 1/2 flat +'s 1/12 turn.

Just looked in my original factory manual (new to me in 1961):

"The front wheel brgs. should not be preloaded.

The castellated nut should be tightened to a torque reading of 10 lbs. ft. and then slacked off 1 1/2 to 2 flats according to the position of the split pin hole."

Jim
 
Don,
10 ft. lbs. is correct but there were Triumph service letters that came out making a correction on the manual. 1/2 flat back off is all that is required. If you back it off 1 1/2 to two there is serious slack in the hub (pull back/forth) as per Randalls practical hints.
 
prb51 said:
If you back it off 1 1/2 to two there is serious slack in the hub (pull back/forth)
Click to expand...
Exactly. They started out with the larger clearance documented in the workshop manual (and other places) then later decided it was not necessary and revised the clearance downwards.

Practical Hints for the Maintenance of the Triumph T.R.3 (P/N 501528) was the place where the factory documented the specification changes (like wheel bearing clearance) for the end user. The sixth edition would have come out in 1958 or so; as it shows the wide grille, door handles and dash rheostat; but not the Lucar connectors that came in at TS60000 in late 1959. I've never found a 7th edition though, so I assume they didn't bother to update it again.

There was also a Technical Service Bulletin in late 1956 that said to tighten the nut with your fingers while rocking the wheel to determine when all rock has been eliminated, then back the nut off only until the pin can be inserted. "It will not be necessary to rotate the nut more than half a flat."
 
"The sixth edition would have come out in 1958"

I was quoting from 2nd edition. Thanks for the clarifaction.

Jim
 
The 2nd edition is kind of an oddball; it mentions the front disc brakes, but doesn't have the wiring diagram for the self-parking wipers (which came out before the disc brakes). So I theorize it was written in late 55 or early 56, when the brakes were already being tested for production but the wiper change had not happened yet.
 
2nd Ed., publication part # 502602. Can't find a date on it. Has a TR3 supplement in the back but does not mention disc brakes or wipers. Guess I really didn'd realise how old it is.

Thanks.

Jim
 
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