I have a 97 3500 with the 5 speed NV4500 and the transmission went out for the 4th time in 390,000 miles I love this Truck but hate this transmission. I have been doing a lot of reasearch on what to do since it went out the last time 40,000 miles ago. There are a lot of fixes out there but only a few that seem to address the spline problem not just the Nut.

What I did this time was I bought a Jaspar remain unit. They claim to have an upgraded spline and nut on this trans and the fact they offer a 100,000 mile waranty I decided to try this route. Figured they rebuild a lot of them so they proabally have it figured out. Only downside was the price.

Has anybody had any sucess with a Jaspar remain trans pulling heavy loads for a long period of time?

Thanks Kerry

 

What keeps on going out?

 

Thats weird...Kerry,that your having these type of problems...I too would like to know what parts are going also...I seen these 5-speeds go through alot of abuse..Maybe something mis-aligned in your drivetrain...that maybe killing your 5-speed.

Your not racing the teenagers ......Just joking...

 

The first three times it was the 5th gear failure this last time the output shaft snapped. It looked like it was a flaw in the metal. I really baby this truck the engine has not been turned up. It has pulled a 10,000 pound trailer 80% of the time, however I do put it in 5th gear and roll at 75 to 80mph.
That drivetrain alignment issue might have some merit shortly before this last failure I replaced all three universal joints due to excesive wear they were the originals with 390,000 miles on them.

Kerry

 

Wow, that is a lot of failures. I just replaced mine a couple years ago and it never failed me. I do drive highway a fair bit and it towed for a good 4 years before I got the newer truck. I too went for a straight swap with a local vendor and decided against rebuilding it.

 

Any one know what the percentage of the 5th gear failure is with the upgraded shaft. I have heard pros and cons. Mine has 115,000 and from what I have read its not if but when. I have talked to standard trans but by the time I ship it to them and back and replace the clutch it will be around $2K or more and then don't know if it will hold up.

 

The biggest killer for 5th gear nut is lugging (if you can call it that) below the 1700 mark. If you are pulling hard at that engine speed, there is a higher potential to hammer the nut off. I always kept away from that speed and lower in 5th. Not sure if that helped or not but I never had an issue with 5th gear and 400 hp.

 

I try to never lug. The truck has a sweet spot so to speak of about 62-65 mph with 354 gears running in 5th when towing. If it gets below that I start hunting another gear. I haven't had a problem yet but every time I get on a forum someone has lost 5th. I am going to pull the trans in a couple of weeks and check the pilot bearing it has got notcheeee in 2 to 3 to 4. I have checked the slave cylinger and it seems ok. If it is the syncros which I hope it isn't then is when I will consider doing the shaft. I would hate to get away from home and that thing go out.

 

If the synchros go out, or you lose 5th, its not gonna leave you stranded. The 5 spd in my dually lost 5th a number of years ago, I drove it for another week putting on 140km a day, then another 300 km back home to fix it. Synchros failing, I find it easier to just float the gears than clutching it.