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MG TD TF 1500 - Stripped Axel Nut

I recently experienced a catastrophic event, the rear left axle nut of my 1950 TD ( with replaced axels 14 TPI) suddenly came off, with the subsequent total loss of L rear tire. Fortunately tis is really little damage. At stops I heard a rear rattle, investigated noticed by striking wheel cover had rattle, assumed that a lug had come loose. Actually less that 1/4 mile from local repair shop, which I have contact. Slowly proceeded when L rear tire launched ahead of me into lovely ladies hydrangea bush. Car came to screeching halt, with little damage. Actually came down on and rode elongated ends of u bolts with no other under carriage effect. My question is on examination axle shaft threads perfect, inner threads ( no castellated ends) stripped smooth what caused this, is there something else other tan replacing axle nut and torqueing to 150lbs that I should attend to. In conclusion I would also suggest routine examination and torqueing of axle nuts, mine never seemed loose and contrary to what Bud K reported were secured with a cotter pin ( the broken ends had been discarded when he inspected). Another note is that when the flat bed came we mounted the tire just with the nut backwards with the four threads of the castellation holding it on
Jon Levine

jON,
Did you oiginally replace the axle? Did you purchase the axle WITH a nut?
It seems that the nut worked loose so the castelated section was off of the axle, then the rest of it stripped??????

SPW
Steve Wincze

the fact that the axle threads are fine but the nut was stripped smooth suggests to me the possibility of an oversized nut being used. I can imagine that an oversized nut rattling on the axle (with cotter pin holding it all together) might result in the wearing of the threads on the nut but not the axle... You could measure the remaining threads and diameter of the nut...
Geoffrey M Baker

Jon - If your axle is one of the later ones, with the UNF threads, I have a spare nut that I could send to you. There should also be a thick washer that goes on before the nut that spaces it out so that the castellations are moved out far enough that the cotter pin goes through them. Contact me at SUfuelpumps@donobi.net Cheers - Dave
D W DuBois

GOEFF,
That's why I asked the question if the axle was purchased WITH the nut,, Might be that the old nut was forced on the new axle,,causing the threads to get destroyed,,,

SPW
Steve Wincze

Thanks for offer & advise. Actually nut that came off stripped is 14TPI, coincidentally a Moss replacement just drove up. Would seem only source AS has only replacement that requires to be "ground down ??) Have the TPI down, but is UNF the standard for 14TPI or is another unknown that I have to check out. Seems at this point, take home actually check torgue to 150
Jon Levine

Something funny here. I suspect the nut and axle were not a good match; there is no way a correct nut would strip if torqued to 150 and held with a cotter pin. I would be very suspect of such parts, ESPECIALLY if the shaft threads are still good.

You might have considered one of Dave Clark's superior axles and nuts... Did you find the large washer that goes under the nut?

Tom Lange
MGT Repair
t lange

The large washer, axle nut and the three pieces of a substantial cotter pin were all in the wheel cover, the axle seems tight in he housing (also checked by Bud K ) and free turning. I just placed the 14TPI nut supplied by Moss and it was tight on, but did not strip ( removed after placed to check). ???? Just don't know am going to check frequently

Jon Levine

I'm really gettin' confused,,,,

WE still don't know why or when the axle was replaced,, and we don't know if the new axle was installed with the old nut, or some other nut that was "hanging around the shop" (which might have already been stripped) or if the new axle came with a new nut,,,. AND we still don't know how long (in mileage)this new axle has been on the car before this happened.

SPW
Steve Wincze

If the axle threads are good, and if the new replacement nut is the correct diameter and tpi, and if the correct thickness washer is used (so that the castellated section doesn't thread too far up the axle leaving the cotter pin barely holding it) and if it is torqued correctly, then you should be good to go, whatever happened.... but I'm with Steve, there is still a mystery here, as to how this could have happened.

When I examined my axles, I found one was 11tpi and one was 14tpi. the 11 tpi needed a thicker washer because the nut threaded so far down the threads that the cotter pin was almost free of the castellated section of the nut. When replacing and resetting, don't just go with the factory specs... if the axle has taken enough wear, you may need a thicker washer (or multiple washers) to do the job correctly and ensure that the cotter pin can seat in the castellated section correctly at the proper torque.
Geoffrey M Baker

Steve, to clarify (1) don't know when axle changed out, I've had vehicle +10 years and know that it was off road +10 years (2) don't know origin of nut other than came with vehicle to me and that it is a 7/8 14TPI (measured on remaining castle threads. Do know that axle and nut appeared in tact ~ 3 years ago when Kevlar brake shoes applied and that nut was torqued to 150 lbs and cotter pin applied. t this point new nut applied everything tight, with the intention of checking often Did note that cotter pin hole on axle seemed a bit elongated and not perfectly round ,is this normal ???
Jon Levine

Carefully check the splines on the shaft and drum for wear. You can sight down them and see if any tapering etc. Try placing the drum over the shaft and rotating by hand, there should be pretty much no movement, and with gentle inward pressure minimal to no up and down movement. Having driven my car back in the day with worn splines, the nut would never stay tight. Also check the split collar, and make sure that the big flat washer is tightening against the drum and not bottoming on the end of the splines. George
George Butz

Jon, I suggest you check the tpi on the axle threads, not just the nut. It might be possible someone threaded a 14tpi nut onto an 11tpi axle, causing this problem! If the nut is softer metal than the axle, it could deform and strip the threads on the nut... but leave the axle intact.
Geoffrey M Baker

This thread was discussed between 21/07/2014 and 22/07/2014

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