Why does my NV4500 always die?

[956bt]

I have a 1995 Ram 3500, 12 valve with the NV4500 manual. We're on the 4th or 5th transmission to fail. This last time it appears the front bearing failed and the 4th gear gears ate themselves. I see pother people having no issues with the NV4500. The truck is not abused or over worked, its only been used as designed. Why do these transmissions keep failing for me?

 

[crabman]

Where did you get the previous transmissions rebuilt or purchased? Was the correct lubrication used?

 

[956bt]

I honestly don't know, it's my dad's truck, I think they've been rebuilt, no idea on the fluid used, maybe the better question is what company can I get a good replacement transmission from?

 

[crabman]

http://www.standardtransmission.com/contact.html
I have not done any business with them so I can not give you a personal experience. Some one else might have a source for a quality rebuild.
How many miles on the truck?

 

[956bt]

I don't know right off hand, full back story is it's sat for a couple years because no one has had the money to fix it, I'm hoping to begin getting it back together this year but I want to learn what I can about the NV4500 before getting another

 

[BigPapa]

I have read posts of several people complaining about the durability of the NV4500. In my personal experience, I have found the NV4500 very durable. In the 18 years that I’ve owned a CTD I’ve known many people that have also owned them, many of which were equipped with the NV4500, and many of those were WELL over factory power. I also worked a repair shop for several years where we specialized in Dodge and Ford diesel pickups. Out of all those trucks I only know of four that had to be replaced. One was in a pulling truck and one was admittedly mistreated. Two of the four replacements came from Standard Transmission. The other two from salvage yards.

- Scott

 

[Shiner]

My last NV4500 had an input bearing failure. I believe my son had something to do with it. Or it was his unlucky day to borrow truck.....As with the known 5th gear issue, I think lugging the truck with this trans is always a bad deal. But, if bellhousing hole and pilot bearing are not perfectly aligned, will cause front bearing failure. Been awhile since I did mine, but it is in the service manual. I believe it is referenced in most clutch kits too. Somebody else will chime in, I am sure.

 

[KATOOM]

The 4500 is very sensitive to fluid type because of the composite lined synchros. If those synchros were abused then rebuilds contained nothing but the Chinese made reman parts...which are horrible. So its very important to find the right rebuilder. Over the years people have tried different fluid brands and types but it seems only a couple are acceptable replacements for the OEM SyntorqLT fluid.

A couple years ago Mopar1973man got a rebuilt unit and its proving to be a well made one. Here's a link to contact him: https://mopar1973man.com/

 

[Joe Mc]

if bellhousing hole and pilot bearing are not perfectly aligned, will cause front bearing failure. Been awhile since I did mine, but it is in the service manual. I believe it is referenced in most clutch kits too. Somebody else will chime in, I am sure.

I've been watching this and just didn't have time till now. Shiner's thoughts are what kept bounding around in my head. He's dead on with dialing in the bell-housing hole to the pilot bearing. It's been a while since I've installed a std trans and it certainly wasn't in anything like our trucks, mostly hot rods, regardless I always install new components. IE: pilot & throw-out bearings, clutch liner and psi plate and resurface or new flywheel as well as fasteners.

FWIW - A buddy of mine had an 01, 3500, 4X4, QC/LB, 6 spd. he switched everything over to Amsoil. It was pretty hopped-up, he had Mach 5 sticks, twin turbos (non-gated), Drag Comp, head studs & water meth inj. I believe he had a double disc clutch. He never had problems with his trans., original to the truck.

 

[956bt]

I've been watching this and just didn't have time till now. Shiner's thoughts are what kept bounding around in my head. He's dead on with dialing in the bell-housing hole to the pilot bearing. It's been a while since I've installed a std trans and it certainly wasn't in anything like our trucks, mostly hot rods, regardless I always install new components. IE: pilot & throw-out bearings, clutch liner and psi plate and resurface or new flywheel as well as fasteners.

FWIW - A buddy of mine had an 01, 3500, 4X4, QC/LB, 6 spd. he switched everything over to Amsoil. It was pretty hopped-up, he had Mach 5 sticks, twin turbos (non-gated), Drag Comp, head studs & water meth inj. I believe he had a double disc clutch. He never had problems with his trans., original to the truck.

Pretty sure his truck has the NV5600 if it's a 6 speed, which from what I've read is a stronger trans then the NV4500. I'm still debating whether or not to just throw a 6 speed in it, I know it's make my dad happy.

 

[BigPapa]

Well, I did forget about the 5th gear nut. It is a known issue and I think you’re right on Shiner about the lugging. Mine came off early on after I bought the transmission used and converted my auto. I put in the updated nut with the clamping screw in it, always kept my RPMs over 1500 in 5th, and I ran the Amsoil MTG. Never had another problem with it in 350K then I sold it and I’ve never heard that the buyer had any issues with it.

-Scott

 

[KATOOM]

There have been many theoretical ideas as to why the 4500 5th gear has issues for some and not for others... A well debated topic too and since there was no real proof of the cause besides the crappy design flaw of leaving a gear supported by only one bearing hang out on a shaft with only half the splines under it.
The suggestions were that lugging the engine was the problem due to harmonic drivetrain pulses and towing in RPM's too low and too heavy in 5th gear.
I...disagree. I believe that its because some people unknowingly are very on/off with their throttle release while driving which can create massive deceleration jarring in the drivetrain. Then only to accelerate and throw all that force in the opposite direction. When you have the leverage of a 4 ton truck and a very torquey engine working hard on the tallest gear ratio in the transmission...and repeat the event many times over, you can easily see how this would beat the weakly supported 5th gear right off the end of the shaft.

 

[Ozymandias]

Pretty sure his truck has the NV5600 if it's a 6 speed, which from what I've read is a stronger trans then the NV4500. I'm still debating whether or not to just throw a 6 speed in it, I know it's make my dad happy.

Probably the best solution if you want to keep truck.
Stop throwing money on the second best solution.

 

[956bt]

Probably the best solution if you want to keep truck.
Stop throwing money on the second best solution.

I believe that may be where we're headed honestly.

 

[BigPapa]

The 5600 has it’s issues, too. The lubrication issues are the rear bearing in the main case. There’s a good article here about Standard Transmission’s “Power Lube Package” they developed to solve the issue.

http://blog.genosgarage.com/wordpress1/wp-content/uploads/2012/05/TDR67_MyNV5600.pdf

The G-56 has issues, also. From what I’ve been told they’re due to the length of the shafts and the case without center support.

Personally, if I was going to go to the trouble of a conversion, I’d go with the ZF-6.

-Scott

 

[956bt]

What about the G56? It seems to be a popular option too.

 

[BigPapa]

Must not have read the complete post:

The G-56 has issues, also. From what I’ve been told they’re due to the length of the shafts and the case without center support.

-Scott

 

[Chief USA]

I would suggest that you contact and have a talk with Cody at Superstick Transmissions.

https://www.facebook.com/SuperStickTransmissions/

 

[Shiner]

orrrrrrrrrrrrrrrrrrrrrr, you could also do an eaton/fuller swap....I guarantee you ain't gonna break that one!

 

[GAmes]

What about the G56? It seems to be a popular option too.

I went through 12 NV4500s in about 800,000 miles. I've put roughly 500,000 on my G56, doing the same job and only had it out once for an input bearing, and it was only making noise, no real failure.

https://www.turbodieselregister.com/threads/mission-g56-pictures.221115/