Worn countershaft, don't let this happen to YOU

(Mitchell Andrus) #1

I have a heightened awareness of the dangers of driving with a worn counter shaft. In '74 my '64 MGB blew it’s trans due to a worn shaft. I wish I had kept it - it got pretty ugly. Teeth on the road.

I am getting along on the clutch job. Digging into the trans is one of those might as well jobs (new syncros, seals, gaskets and a look around) and now I’m really glad I did. Shaft and needles are readily available.

These transmissions are primitive enough, there’s no reason not to at least inspect the innards when restoring a British car. I always do.

There must be tremendous pressure on this square inch:

(Phil.Dobson) #2

yup just been thru this with my Mk2

(Ole Würtz) #3

Wouldn’t there be some noise to indicate this amount of wear ?
My gearbox made some serious noise and I had it overhauled by John Esposito, who found similar wear.

(Mitchell Andrus) #4

No noise, at least not in the cockpit. Don’t forget, the cluster (counter) gear is only bearing any force when in 1, 2, 3, R. In 4th where we do the vast majority of our driving, the input and main shaft are locked. In 4th you can remove the cluster gear entirely from the gearbox as it’s no longer being used.

'sides, the wind noise and my giggling at the sheer joy of driving an E again would drown out a stampede of buffalo.

(Mitchell Andrus) #5

In MG-land, there are stories of these shafts failing in very short order after having been replaced. It seems a boatload of soft shafts hit the market a few decades ago. We are now very wary of cars with rebuilt transmissions and any shafts purchased. Any shafts laying around are being tossed like spinach without a date code.

I would be royally pissed.

(L.Lynn '68 OTS, '73 2+2) #6

Not that you need anything more to worry about but IIRC the last MG magazine discussed this very issue and they mentioned that the aftermarket shafts had a slightly smaller diameter as well.

(Mitchell Andrus) #7

That extra space allows the evil humors to escape.

(Nick Saltarelli) #8

Btw, don’t trash that spalled countershaft. It may be used as a dummy shaft during gearbox rebuild or, after welding a large bearing ball on one end, a handy double-ended bodywork tool:

The countershaft is heavy - more that a kilogram - and used with a dolly is effective for taking out dents in bodywork where a hammer won’t reach.

(Mitchell Andrus) #9

Agreed. I’ve the heck out of the MGA shaft I replaced sometime in the 90’s. …but first as a dummy. Welding a ball bearing (hardened)… hadn’t come up with that one.

I just went out the the shop, I think I’ve got 20+ drifts made from shafts, axles, steering arms volunteered into service in their afterlife.

(Nick Saltarelli) #10

The ball bearing allows delivering glancing blows at a range of angles without the danger of creasing the metal. It’s come in handy fairly often.

(Bill Bilotti 1966 S1 OTS (in boxes)) #11

mine made no noise shifted fine, but had John check it out while trans was out of car. Said, main shaft was bad. I bet they are all bad.

(L.Lynn '68 OTS, '73 2+2) #12

I’ve rebuilt 3 and they all had the same pattern of ‘spalling’.

(Mitchell Andrus) #13

I wonder if adding a second row of needles at that end would help. Note that spalling always occurs under the first gear end when the torque is highest, from dead stop.

Of course, given that my shaft lasted almost 60 years, the benefits would only be seen after we’re all dead… So…