Hi everyone. So I was replacing a pressed in wheel bearing and had to remove a transaxle shaft from a front wheel drive car. The nut had an indent for its locking mechanism. I spread it out with an air hammer and small punch. Pb blasted the assembly well. Gave me some but only a small fight. Had it off in a few seconds. Now when using an impact, and the threads well cleaned beforehand, any nut should come off fairly easy. Which it did. However, the nut threads are damaged. I got the indent (thread locking mechanism) out before did it. I possibly didn't well enough things happen. I will be using another nut but here's my question. The nut was a 30mm 12 point. A lot of threads. When I comes to nut and bolt strengh, we all have to re thread or tap from time to time. Sometimes we lose a thread or so. This nut had half of them damaged which I'm guessing is from me not taking out the notch enough. So half of the threads on the outside are gouged. But the nut still threads fine using a rachet. The axle threads are close to perfect still (trying to figure that out myself, makes no sense). It almost as it oversized until the halfway. I'm going to use a new one but how (in any application) many threads are actually needed on a nut or bolt to secure a proper clamping force? Because technically the important half of the nut still will hold it to the hub/spindle. What determines how many threads are needed for something? And judging would you use this nut? It appears to still hold very well. Thanks and happy wrenching.
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Nut thread question
- Thread starter FbodyMIKE
- Start date
Very difficult questions because the jury is still out on that. Rule of thumb is the nut should be 1.5 X the diameter of the threaded bolt. Fine threads are stronger than coarse. There is a general consensus amongst machinists that the 1st thread bears 90% of the burden.
Some damage just can't be seen so it's very hard to determine the extent of damage. On a blue print a thread can be made to 100% tolerance but in the real world threads are commonly made to 75% efficiency of specs. What is your used one at now? If it was me I'd use the new one. You don't want to have to deal with it again if it were to fail.
Some damage just can't be seen so it's very hard to determine the extent of damage. On a blue print a thread can be made to 100% tolerance but in the real world threads are commonly made to 75% efficiency of specs. What is your used one at now? If it was me I'd use the new one. You don't want to have to deal with it again if it were to fail.
Nuts like these aren't intended to be reused, so the "official rules" for fasteners in general don't apply. Add to this the possibility of the threads not being any standard dimension (meaning, not just diameter and pitch, but the shape of the thread itself) and the only people who can answer this are the people who designed it. If you really want to get into it, look for "Engineer to Win", by Carroll Smith. Won't answer this particular question, but will tell you everything you'd ever want to know about the question you asked.
That said, I'd imagine the load on an axle nut isn't really very much, so if it goes on tight, and you can *reliably* stake it in again, odds of a failure are probably not much. In this example, I'd go with my gut- in either direction.
That said, I'd imagine the load on an axle nut isn't really very much, so if it goes on tight, and you can *reliably* stake it in again, odds of a failure are probably not much. In this example, I'd go with my gut- in either direction.
shockwave
Well-known member
I have never had an issue with reusing the axle nuts before if both threads are good on axle and nut
But properly I suppose it's best to replace nut
But properly I suppose it's best to replace nut
jimbbski
Well-known member
The axle nut on FWD cars is very important. Tightening it to the proper torque preloads the wheel bearing and can lead to long life of the bearing if done correctly. IF not the bearing can wear out quickly.
Most hub nuts see a factory torque spec of 150-225 lbs. I road race a FWD car and I torque the nut to "very tight" by using a standard breaker bar and put all my weight on it to torque the nut. I have not had a failure of any part of the hub, CV, or wheel bearing.
I also recheck the torque each time after racing the car.
For a street car you should recheck the torque after the car is driven.
Most hub nuts see a factory torque spec of 150-225 lbs. I road race a FWD car and I torque the nut to "very tight" by using a standard breaker bar and put all my weight on it to torque the nut. I have not had a failure of any part of the hub, CV, or wheel bearing.
I also recheck the torque each time after racing the car.
For a street car you should recheck the torque after the car is driven.