overtight axle nuts

E

eric-France-

Junior Member
Hello !
I made a mistake yesterday. I set up new bearings and axle key at the rear.


But after that I overtighted the axle nut and damaged the thread. Any advice of what I could do now, but cry ? I suspected 125lbft in L.A book was too much but I should have stopped before 70... Too late now...



Could I try to make a new thread with a smaller diameter ?


Thanks
 
If the nut and axle thread are in good condition they are torqued to 100 ft/lbs not 125 ft/lbs . I have never had a failure at 100 ft/lbs with many axles over the years . Have you damaged both axles ? . There were recent posts on this subject looks like you did not see them . Sadly I would replace the axles not sure if cutting a smaller thread would be safe other " barners" might have done it and may respond . At what torque did you feel the axle strip ?

John in sunny morning Suffolk County England .
 
The other forum, under "new to the A hobby" has a list of corrections to Andrew's red book. It includes the rear axle nut torque and says it should be torqued to no more than 75 ft lbs.
 
They make inserts for threads in holes that have been damaged. I wonder if the opposite part is available. I guess you could make one on a lathe. I would have to be silver soldered onto the axle or perhaps glued on with one of the super adhesives. Perhaps you could adapt one that was make for the threaded hole.
 
Watch this Youtube video and you can fix it this way. I have done one of my axles years ago like this and have had no trouble with it. Be certain to only use new Grade 8 hardened nuts (avail from our vendors). Also be certain to file a nice radius in the axle as shown in the video. You can save your axle.

https://www.youtube.com/watch?v=lC_zIvb1Yuo&list=PLav-W1BC-Nj-T6al6Pk5bcpNJQdDfO5H8&index=1

The nice thing about this repair is that you are staying with 18 threads per inch, so you are not cutting across the old thread valleys. Only change is 5/8-18 to 9/16-18.
 
Try a new axle nut and torque to 75lbs. Usually the threads on the nut will strip before the axle threads.
 
eric-France- said:
Hello !
I made a mistake yesterday. I set up new bearings and axle key at the rear.


But after that I overtighted the axle nut and damaged the thread. Any advice of what I could do now, but cry ? I suspected 125lbft in L.A book was too much but I should have stopped before 70... Too late now...



Could I try to make a new thread with a smaller diameter ?


Thanks
Click to expand...

I would cut a new thread. Give it a shot. Torque to 100.

Good luck.
 
Andrew's book was wrong the first time, so what makes you all think his change to 75 lbs-ft of tightening torque is the right amount? My experience of tightening to 50 lbs-ft has not caused me any problems in the past 70 years!
 
ndnchf said:
The other forum, under "new to the A hobby" has a list of corrections to Andrew's red book. It includes the rear axle nut torque and says it should be torqued to no more than 75 ft lbs.
Click to expand...

Can you post a link? I tried a search, but no joy.
 
Before installing the nut, don't forget to install the seal and the hardened washer.
 
katy said:
Can you post a link? I tried a search, but no joy.
Click to expand...

Unfortunately I cannot. There is an ongoing spat between the two and each blocks links to the other. Try googling the letter V, F, F and the word ford. You should find it.
 
That's a video I made when I 1st got my Model A truck. Both axels were stripped. Since the repair they are both still in fine condition today after I rethreaded them and torqued them to 75lbs.
 
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Bob Bidonde said:
Andrew's book was wrong the first time, so what makes you all think his change to 75 lbs-ft of tightening torque is the right amount? My experience of tightening to 50 lbs-ft has not caused me any problems in the past 70 years!
Click to expand...

I have to agree with Bob as it's really the taper that locks things together.
You only need enough torque on the nut to keep the taper from working lose and 50 lbs will be fine.
Also changing it to 9/16 - 18 thread with new nuts will save the axles and work fine.
My $0.02 :)
 
With all due respect guys after hundreds of axle rebuilds I feel fairly schooled from experience in axles to say that 70 lbs is not tight enough to ensure that future tightness and or movement will most likely NOT be maintained at that value. The key and taper of the hub are important and during ran loose and or with poor fitting axles and hubs will get loose and have failure. The axles threads are very important because if they don’t hood the hub on sufficiently wheels and hubs cone off, axles can break. Even if all is fine the latter can happen. Torque value for a 5/8 course is about 140-150 and fine thread closer to 180-190 .
100-125 is totally acceptable and I use to go to 150 but many axle threads are not as good as once new.

I can safely say your 70 lbs torque rate when tested later will be vastly less and the hub and axle and keywqy probably damaged further. Look at axles and you can see results of loose hubs. Galling on axles and hubs, key ways not sharp and enlarged, resulting in loose fitting keys . This all occurs from hub nuts not tight enough.

If your threads are compromised and won’t hold the torque and threads compromised I would replace the axle. Just fix it. The result if not fixes could be a wheel and drum coming off and an accident potentially occurring.
It’s not worth it. Fix it right!
Larry Shepard
 
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I think larrys40 is on target with a 100lbs. I have read of a way to cut new threads. Old time fix. Clean the threads on the axle of grease and grime. Jack car up so the axle in need will spin slowly when is running. Be careful, have chocked so it doesn’t move. Carefully hold a file against the the damaged thread and as the axle revolves you will cut the size of the axle for retreading. Almost like on a lathe. Now here is the interesting part of the job. Before you start figure was size thread you need for the new nut. Probably the next size smaller would be a metric size. (I cant believe even said that). Go buy a Good Metric nut. Not at some hardware store. Try and buy the nut and thread die at the same time from a good supplier. Explained to parts dealer what you are doing. Tolerances must be correct. Remember usually torque numbers are given for dry, no grease, oil or lube on threads. 100 pounds dry is a lot different than 100 wet, meaning a oiled thread will result in a higher torque reading. I would bet most axle nuts are torqued oiled as most won't consider this factor when reassembling. I forgot to mention to get a chart so you know the diameter of the new size shaft for threading and a good micrometer or accurate means for measuring. You only going to get one shot at this. Good luck.
 
There are several acceptable ways to fix an axle thread.
Most back yard fixes are NOT acceptable in the long run.
The first thing to determine is if the axle taper is good enough to warrant fixing the thread. It must be good enough to lap in to the hub with 90% surface. If this doesn't happen, the axle is junk. (The hub probably is also.) It could be fixed but the cost would be more than a new or good used one.

Acceptable repairs for axle threads are:
1 - Find a new or good used axle.
2 - Have a machine shop weld with proper rod and machine a
new thread.

The cost of either method is about the same.

Different books list different torque value for threads.
I go with 150 for A axles. A new USA made axle will go 300 with a lubed hard high nut.
 
I recently had a hard nut with a burr in the thread. It destroyed the thread on the axle and I was NOT happy. I took the damaged axle to a machinist friend who cut a new one at 9/16" (same thread pitch) in his lathe. A new nut tightened to about 75 ftlb and I'm back on the road. I suggest you (OP) do similar.
 
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thank you very much for the advice, I'll try this (actually, i'll ask a friend of mine who is skilled for this kind of work...)
 
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