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Old June 14th, 2020, 15:51
DocTremp DocTremp is offline
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Range Fork wearing very quickly and recent failure.

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 canít 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 Iím not convinced either way. Any input would be very helpful, thanks.


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Old June 14th, 2020, 17:52
RCP Phx RCP Phx is online now
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Re: Range Fork wearing very quickly and recent failure.

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)?
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Old June 14th, 2020, 22:03
DocTremp DocTremp is offline
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Range Fork wearing very quickly and recent failure.

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Originally Posted by RCP Phx View Post
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 didnít 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, Iím stumped on what is pushing/pulling. I re-adjusted the shift linkage thinking that may have something to do with it, but I didnít think it would have that big of an impact. Since I changed the fork Iíve driven 1500 miles maybe and itís over half way worn through.


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Old June 23rd, 2020, 13:30
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clydefrog clydefrog is offline
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Re: Range Fork wearing very quickly and recent failure.

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.
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Old June 24th, 2020, 22:22
DocTremp DocTremp is offline
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Range Fork wearing very quickly and recent failure.

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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.

Iím on 33s with 3.07 gearing, so I would think that the case would be spinning slower than normal, right? But what youíre saying makes sense. I put my hand on the the tcase after driving a bit and it was super hot, I couldnít keep my hand on it more than 1-2 seconds.


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Old June 26th, 2020, 10:44
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clydefrog clydefrog is offline
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Re: Range Fork wearing very quickly and recent failure.

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Originally Posted by DocTremp View Post
Iím on 33s with 3.07 gearing, so I would think that the case would be spinning slower than normal, right? But what youíre saying makes sense. I put my hand on the the tcase after driving a bit and it was super hot, I couldnít 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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