TR2/3/3A Tightening wheel bearing Nut TR3?

What was the correct setting when tightening the nut. Was it decided that the the nut should only be backed off 1/2 turn rather than 2&1/2 turns? I remember there being a discussion on this but don't remember the particulars.

Way too much.
Mine are backed off 1 flat.

Practical Hints says 1/2 flat, which is what I use. The 1.5 to 2 <span style="text-decoration: underline">flats</span> (not turns) given in the workshop manual was corrected in a very early TSB.

I really, really, really hate asking dumb questions, but I came up with nothing when I googled it: what's a "flat"?

(been regretting not taking shop in high school lately...)

The nut on the spindle, like most nuts, has 6 sides. So "one flat" refers to turning the nut by 1/6 of a turn. "1/2 flat" is 1/12 of a turn.

Usually, you can't insert the cotter pin at exactly that point, so you turn the nut a little more until the holes line up. There are two holes in the spindle, though, so you don't have to turn it very far.

The point here is setting the running clearance for the wheel bearings. They need to have some clearance because the hub gets heated when you use the brakes and expands more than the spindle does. Without enough running clearance, the expansion would cause the bearings to become overloaded and fail.

PS, no dumb questions, only dumb mistakes. It's good you asked, since no doubt there are others that don't know but didn't ask.

I just adjusted mine yesterday. First time I've done this, so I'm interested to hear if I got it right. Before, when I grabbed the top and bottom of the tire, I was able to rock it in-and-out and feel some play (very minor).

I tightened wheel bearing nut using an 8" crescent wrench. The nut very definitely "snugged-up" (very subjective) at about 1 or 2 flats. I was not cranking it with much torque. I then backed off 1/2 flat (per p.80 of my Bentley manual) and inserted new cotter pins.

Wheel spins freely. And when I repeat the test grabbing the top and bottom of the tire, no more play. Sound right?

Thanks

Bob
PS: in your experience how often does this need to be performed - every 6K miles?

Bainesy said:

I really, really, really hate asking dumb questions, but I came up with nothing when I googled it: what's a "flat"?

(been regretting not taking shop in high school lately...)

Click to expand...

Randall's right, Gordon - no dumb questions.

Besides, unless you'd taken shop in England, you still wouldn't know what a "flat" is! :wink:


Mickey

Randall, Mickey, thanks. If I can't find the answer myself, i'll be sure to ask. Great community here on BCF.

I'm enjoying the challenge of learning something completely new. The only downside for me is losing track of time when I sit down with the Bentley manual (or this forum) for a little bedtime reading, and end up having some less-than-productive mornings at work. :tired:

Sounds just right, Bob.

The clearance should not change in normal operation, throughout the life of the bearings. If it does, then something has failed and needs to be replaced ASAP. Even .001" of wear is unacceptable for this type of bearing.

However, you'll need to repeat this procedure every time you clean and repack the bearings. I believe that is recommended every 12,000 miles (though I have a tendency to let it slide).