Engine/Transmission (1998.5 - 2002) 5 Speed Shaft Nut & More

[FASTERTHANU]

My search attempts yielded little info on the 5 speed shaft nut. Can someone bring me up to date on the fix for this problem.



A) Outline the procedure as i will be doing the operation myself

B) Where can I procure the parts required and what is cost?



I'm not even sure I need to do this. As I read the TSB it did not apply to my ride. Do all the 5 speeds have this problem? Or is the TSB correctly aimed at only a certain production run? I tow about 13k and do not need a failure of this sort with my family in the middle of the desert.



That brings us to the next question... Does a six speed swap in?



And finally... . Can an exhaust brake be used to warm the motor up faster?? Is there more than one fuel filter on these things... . maybe a full flow in addition to the cannister?



After all those questions I should probably provide some info too.

105,000 still on first lift pump with good pressure. Have diablo puck and Jardine 4" exhaust only, so maybe i'm not taxing the system.

Thx

 

[John Berger]

Standard Transmission has the parts you want, including the fully splined mainshaft. You won't beat the customer service, either. They treated me well, when I dealt with them earlier this year. Since you are going to be doing this yourself, but not knowing what kind of funds you have available, why not get the fully splined mainshaft and permanently fix the 5th gear problem. It might be worth your while. Do a search for fully splined mainshaft (if you have not already) and go from there.

 

[TPlasek]

Check your PM's. . I sent you some info. I have already been down this road...

 

[Deezul1]

The 5th gear fix is easier on a 2wd when all that has to come off is the tail shaft and the nut is right there. I presume the transfer case has to come off to get at the nut. The nut should run about $35 and there is no fix that is permenent except replacing the main shaft with one that is fully splined under the 5th gear. Check with Blumenthals for a good price on a shaft. They have a web site but I dont have a link for it. The nut replace is easy except getting to it. It has to be torqued to something like 285lbs. I did mine and 3 mos later it came off again. If it comes off you can drive forever without it in 4th gear so you wont be stranded. I drove mine 600 miles when it came off the first time. All that happens is the nut backs off and the gears slides rearwards and just floats on the output shaft and does no damage.

Yes the E brake can be used for quicker warmup.

 

[TPlasek]

I second what Deezul said. It is easy to replace the nut only, but in most cases it will fall off againg in the next few thousand miles. You can replace the gear AND the nut and even get a few more thousand miles out of it, but once the splines on the mainshaft are laid over, there is no repair except replacement with a fully splinned shaft.



Again read your PM I sent you on where the cheapest place to get replacement parts. If you go with the fullly splinned shaft, you may as well buy the bearing and synchro kit to go with it...



After you get it rebuilt, then the HARD part comes, deciding what kind of oil to put back in there. I don't even want to start a war here, but I don't use the kind you are supposed to. I have a friend who is using the same oil as I and has 145k on that rebuilt transmission. Both of our trannys only lasted 100k before they went into self destruct mode...

 

[FASTERTHANU]

Thanks to all that provided info... so far i've had no problems, but it sounds like they may be coming. I'll probably wait until I have to do a clutch if this thing hasn't failed by then. Nobody chimed in on the 6 speed swap?

 

[John Berger]

When I had the mainshaft installed, I did not buy the bearing and synchro kit. If they had been in bad shape, my warranty would have covered them. The service manager and the mechanic who did the work told me this. I'm running with a new mainshaft and fifth gear nut, but everything else in the transmission, other than the input shaft (which was the original problem in this situation) are original parts. The mechanic said that the synchros and bearings were in excellent shape for having 91K miles on them. I give all the credit in the world for that to the Amsoil lube I've run in the transmission for the last 65K miles.

 

[TPlasek]

At 92k I lost two bearings in my NV4500. The fifth gear nut was still on, but the two bearings on the lower cluster gear were both shot... This is what made me question how good that stock syntorq oil really is...



I just threw in the shaft for good measure... .