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Range Fork wearing very quickly and recent failure.

DocTremp

NAXJA Forum User
NAXJA Member
Earlier this year I had a range fork failure in my 90 XJ NP231J. I attributed to low fluid as I had a leak that I tried to fix several times but was unsuccessful. Any way a couple weeks ago my tcase chain began to slip and thought it was worn out due to low fluid as well. So I opened the case to change the chain and sprockets and found the range fork half worn out again. I can’t make sense of how the range fork is worn again already when the fluid was full. I have read that if the rod that the fork slides on is worn out that this will cause the range fork to wear but I’m not convinced either way. Any input would be very helpful, thanks.


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That's a tough one because there are tons of things that could be causing your problem. Can you tell which side has the most wear? Something is either pushing or pulling things, it could either be in the shift fork or the range hub itself. When it blew up last time had you done anything before that to the t-case (ie:sye)?
 
That's a tough one because there are tons of things that could be causing your problem. Can you tell which side has the most wear? Something is either pushing or pulling things, it could either be in the shift fork or the range hub itself. When it blew up last time had you done anything before that to the t-case (ie:sye)?


Yes, the front side of the fork is where the range hub is wearing the fork. I did an SYE 4-5 years ago and that is when the problems started sort of. The chain was stretched then started skipping teeth and I didn’t change the sprockets so I had to redo that. After that I was good for 2 years at least and then I accidentally ran it out of oil due to a leak I mentioned before. Yeah, I’m stumped on what is pushing/pulling. I re-adjusted the shift linkage thinking that may have something to do with it, but I didn’t think it would have that big of an impact. Since I changed the fork I’ve driven 1500 miles maybe and it’s over half way worn through.


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What gearing and tire size are you running?

I had this problem too but only on very extended trips (more than 2 hours driving) doing 70 mph plus. What i found is that with my gearing the t-case was spinning at a rate that was equal to about 112 mph if it was stock. I put a temp sensor in my case and found that over 70mph the temps would climb and keep climbing until i slowed down, this would melt the shift form plastic wear pieces and cause metal on metal on ultimately cause the failure. Normally the temp can get to 180-220 range but if i drove over 70 they would climb up to and over 300.......Depends on your gearing though.

Just a thought.
 
What gearing and tire size are you running?

I had this problem too but only on very extended trips (more than 2 hours driving) doing 70 mph plus. What i found is that with my gearing the t-case was spinning at a rate that was equal to about 112 mph if it was stock. I put a temp sensor in my case and found that over 70mph the temps would climb and keep climbing until i slowed down, this would melt the shift form plastic wear pieces and cause metal on metal on ultimately cause the failure. Normally the temp can get to 180-220 range but if i drove over 70 they would climb up to and over 300.......Depends on your gearing though.

Just a thought.


I’m on 33s with 3.07 gearing, so I would think that the case would be spinning slower than normal, right? But what you’re saying makes sense. I put my hand on the the tcase after driving a bit and it was super hot, I couldn’t keep my hand on it more than 1-2 seconds.


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I’m on 33s with 3.07 gearing, so I would think that the case would be spinning slower than normal, right? But what you’re saying makes sense. I put my hand on the the tcase after driving a bit and it was super hot, I couldn’t keep my hand on it more than 1-2 seconds.


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You are correct. With 3.07's i wouldn't suspect heat to be the issue. That seems about normal for temp.
 
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