Engine/Transmission (1998.5 - 2002) nv 4500 5th gear

[MKresch]

help! i was driving in 5th gear today and it felt like it slipped out of gear. then there was nothing there, it felt like it was in natural. but it was still in gear. could the nut have came off and the gear slipped off? would it have hurt anything? what do i do to repair it? any help would be greatly appreciated. :{ :{ :{

 

[krs]

"the nut have came off and the gear slipped off?"



You got it. It hasn't happened to me (yet) but apparently you can fix it, temporarily, by going in and reassembling everything and maybe peen the nut or the output shaft to help keep it there, or you can fix it permanently by installing a splined shaft and gear. Some people have had longlasting luck with the first way and the second way requires trans. removal and more disassemby/reassembly.

They say that there's no harm having the gear loose - you just have a 4 speed.

 

[rfcom]

5th gear nut

I'm wondering if the same thing will eventually happen to me. I've read that the torque vibration due to running too low an RPM in 5th will cause the nut to loosen off. If it happens, I hope it happens during the warranty period. Anyone know if DC did anything to correct this situation for the 02 models?



Jim

 

[Rebel_Horseman]

I was wondering about this same thing too. I try to keep my rpm's up if at all possible. What should I run at to prevent the nut from working off? I usually try not to shift into 5th unless I'm going about 45 to 50 which is right near the 2k mark. In the event that it does come off, what is the procedure to fix it?



Reb [><]

 

[MKresch]

i'm hoping someone has done the fix and can tell me what to do to fix it. i don't wan't to drive it until it get's done!

 

[MKresch]

another question do i need any special tools to do the job?

 

[SRadke]

It should be really easy to fix in your 2wd. Just pull the driveline, remove the tailshaft housing and screw the nut back on. When I lost it on my 96 I did a transmission rebuild and clutch while I had it out (4x4). For you, there is no need to remove the transmission.



DC is aware of the problem and does offer a upgrade kit. I think it was about $45. I bought it and put it in. The kit consisted of a split nut and a bottle of Loctite. "Split nut" is a term I just made up to describe the thing. Picture a nut with a slot in one side and a small bolt drilled in at an angle to squeeze the two sides of the nut together after installed. I think the torque spec they listed was 250 ft. lbs. That seems high but I do recall having to borrow a torque wrench because mine didn't go high enough. I don't see any reason why the stock nut couldn't be replaced with the Loctite treatment and do about the same thing. Hope this helps.

-Scott

 

[Rebel_Horseman]

I've got a 4x4, so what does it take to fix it if mine ever goes out? The truck has 140k on it so I'm thinking that either the old owners were lucky and didn't have to fix it, or it's already been fixed and I won't have to worry about it. If it goes out am I going to have to remove the t-case? Seem s like I read somewhere that you could go in from the top side and fix it with the trannie still in the truck. Was I dreaming?

 

[SRadke]

Sorry Rebel, you're dreaming. The gears and sinchros for fifth and reverse are behind the main case of the trans. They sit inside the adapter between the trans and t-case. You definitely have to take the two apate to get to it. This requires pulling at least the t-case. I pulled them both at the same time (still hooked together) because I bought that truck at 110k and I wanted to get a look at the clutch while I was there. Sorry to be the bearer of bad news.

-Scott

 

[Rebel_Horseman]

:{ :{



It wass worth a shot. Thanks for the info.

 

[Briar Hopper]

Even a fully splined mainshaft won't solve your 5th gear problem if you're at high horsepower/torque, or towing very heavy loads, or both.

We've had the inner teeth on the countershaft syncro clutch strip out on no less than three trucks, under various driving conditions, they all had fully splined mainshafts. . On my own truck, I've also had the mainshaft thrust plate break off three of it's four bolt heads, and crunch into the countershaft fifth gear.

I'd go with the upgrade nut kit, definitely.

It's not really a 5 speed transmission... . it's a four speed with a "pretend" fifth gear .....

I don't mind fixing it, as I know at these power levels and my driving situations, it's going to happen, unless I lighten up.

 

[rfcom]

TSB

According to this TSB , this problem does not affect 2000 and up trucks. The repair procedure is also described.



Jim

 

[John Berger]

Briar Hopper, it doesn't sound like what your are describing is near the same problem as the infamous 5th gear nut problem. Your description of the damage(problem) sounds alot more involved than just a gear backing off the mainshaft. Correct me where I'm wrong. As an owner of a 5 speed truck, I've been following this problem on TDR since it first surfaced about 5 years ago and I've not yet read of any other internal damage or problems related to that nut backing off, other than losing 5th gear. By the way, I've had the fully splined mainshaft on since 91K. I'm at 101K now.

 

[SRadke]

I think Briar is trying to point out other weaknesses in this transmission. Even if you get the fifth gear nut secured there are more potential issues in high HP applications.

-Scott

 

[John Berger]

I was thinking that as well Scott. Briar, what kind of horsepower and load are you putting on these trucks that have had the problems you described?