rebuilding a NV 4500 at home.

[meanchev]

Have any of you rebuilt a NV 4500 at home. I am wondering cause it seems mine is bad because we have ruled out everything else. So now i am on a budget and cant afford a new one and cant afford to have someone rebuild it for me so it is up to me and i am wondering if it is a very dificult tranny to rebuild. thanks

[a5150nut]

Thinking on the same line as you. I did some research for parts and found Drivetrain.com (http://drivetrain.com) out of Las Vegas to be good. havee gotten other parts from them before.

[Turbo Al]

MeanChev,
The NV4500 is a hard trans to kill, I have 180,000 miles on mine and it is as good as the day it was made. What are the symtoms you are having. I strongly suspect that you have a pivot ball/release fork problem or a pilot bearing issue. Please fill me in a little bit more on what it is doing,=.
Al

[Inspector]

Turbo Al:
This was my old truck that has been handed down to one of my sons.
First of all it had a ceramic clutch that was in need of replacement. When we did it the flywheel, clutch disc and pressure plate were replaced along with the pilot, through out bearings. The fork pivot was in good condition as it was always greased with the rest of the truck when due.
Before doing all that work the truck had begun to make a bad shudder when power was picked up out of a second gear take off. It felt like a gear was slipping or a spline shaft was slipping within a slpine coupling. After the work on the clutch the same shudder is still present. The clutch works very smoothly.
When the original single mass clutch broke about 5 years ago another thing happened with it. The spline coupling in the input planetary of the 4401 T case stripped out and would not through put power to the drive line after it was all back together. I replaced the planetary in the T case and all was well.
I feel that somthing is slipping either a spline coupling for a gear in the trans is bad.
By process of elimination we disconnected the rear drive line and used 4W HI to move the truck down the street. It slipped and shuddered. That took the rear end and GearVendors out of the equation.
I talked to a mechanic at the local GMC dealer as well as took him for a short ride (50 ft) and he suggested that that particular T case could and has broken the shift forks before and could cause the problem that we are expericing.
I ordered the forks and pulled the T case, split it only to find that it shows no wear of breakage. Clean as a pin inside and works well.
Which now leaves the Transmission as the last possible item in the drivetrain.
Now we are up to expensive.
Denny :confused:

[Turbo Al]

Denny,
Well this is just about a first for me, someone who has covered all the other bases before blaming the trans. With all you have said and done I would pull the trans and see if there is any obvious damage to the internals. But please pay close attention to the pilot bearing and shaft when it comes apart. Also before you take the pressure plate off check the bolts and see if they are all tight. This will also show up on the pressure plate as a worn spot on the loose side. The average life of the pivot ball is about 100,000 miles so if it looks worn at all get a new one, greasing them does not seem to be the end all on these parts.
Some other parts that will cause vibration/shaking;
1. dirty fuel filter
2. weak fuel pump
3. broken (cracked) trans mount -- the metal bracket.
4. Torsion bar rubbing on trans cross member.

most of those are LONG shots but worth a look.

Best of luck getting to the bottom of it and let us know what you find.
Al

[meanchev]

About 2 weeks ago i put in a new pilot bearing it is one of the oillite type. I also replaced the clutch and the pressure plate so they are in good shape. I do hope it isn,t the trans but we are running out of other possible causes. the shutter you feel is very violent and causes the whole truck to shake. as soon as you depress the clutch pedal it goes away but if you get back on it too fast it will do it again. it is possible to drive it without having it happen at all stop and restarts but it scare the crap out of you when it happens.

[Turbo Al]

MeanChev,
Did it shudder before the clutch replacement? Dual Mass flywheel or solid? Is it a "conversion" from one to the other? The last time one of my trucks shuddered that bad the drive shaft ended up on the ground -- defective U-Joint - broke in half.
Al

[meanchev]

Yes it did. but it had the solid mass flywheel conversion done a few years ago. when i did the clutch i replaced the flywheel again with a new solid mass flywheel so everything inside the bellhousing is new except eh throughout fork. it seemed ok but i am not exactly sure how it should feel, but like my dad said it had been greased evrytime he greased the rest of the truck. i also changed the ujoints when i put the drivetrain back in after the clutch.

[Turbo Al]

I think the jury is still out on the "dampener" but do you know if it was done when the conversion was done? With all the Trouble shooting already done it is about time to bite the bullet and pull the trans and see what's going on in there.
Clutch pedal should be smooth and fairly easy (consistant) all the way to the floor.

Best of luck
Al

[meanchev]

Dampener was done and clutch works awsome. So i am going to pull the trans but will only take a few minutes being as it is the only thing still attached to the bellhousing at the moment.

[meanchev]

Trans is out again and there is a noticable ridge at the back of the shaft where it comes out of the trans. it looks to be almost 1/16th of an inch high so i think we may have found our problem. the inside of the trans looks great, no serious wear on any of the gears, syncros or shift forks so the output shaft is the only thing that needs replacing.

[Turbo Al]

On the imput shaft?

[Inspector]

Al:
Its on the Output shaft. I'd say maybe a total of 1/16th total off the diameter. The spline edges are pretty shiny. Me thinks that the output shaft has been slipping within the input shaft of the transfer case.
Denny :(

[Turbo Al]

I have never heard of that one! At least you found the problem and hopefully it won't cost too much to fix.
After looking at my drawings it looks to be your Main Shaft, I could have sworn that that shaft was split in two but my drawings don't show it -- only one long solid shaft.

There are some specs on the drawing for torque values etc if you get stuck and need (can't find them) let me know.
Al

[meanchev]

Thanks for the info it probably won't be till next week before we can get to it. But hopefully we will have it back on the road by the rendevous.

[dspencer]

I have the same transmission in my Dodge/Cummins truck. A few experts on these transmissions are Blumenthals in OK City and Standard Transmission of Ft Worth. Quad 4x4 also.

Hope you get it sorted out.

[Turbo Al]

The Chev and Dodge NV4500 trans are actually quite a bit different from each other. They are not directly interchangeable. Why New Venture didn't give them different model names is beyond me but Chev and Dodge did. If the shops are good they will know all the differences.
Al

[Inspector]

I had the trans and transfer case checked out by a specialist today and my diagnosis was comfirmed. The output shaft spline is worn off to the extent that land to groove mesh is practically nonexsistant. The mainshaft in the trans as well as the input planetary gear of the transfer case will have to be replaced. There was enough wear in the input shaft that a good mesh of the splines would be iffy and most probably we would have to do the job again if only replaceing the mainshaft. Now it is just a mater of getting the money together for the work to be done.
Denny :(

[Turbo Al]

Denny,
Sorry to hear you need so many parts. Did a bearing fail or did they give you any idea as to what caused the problem in the first place.
Thanks
Al

[Inspector]

Possible explanation is that the case hardening was not suffienent in the splines on the output shaft (mainshaft) to hold the splines.
Denny
:confused:

[Turbo Al]

Well I hate to say it but I thought that was a FORD problem -- at least the last ford I had (1989)did that at @ 18,000 miles.
AL

[Inspector]

The tranny is in the shop for a main shaft replacement. Can't be done at home. I don't have the special set up tools. At the same time we will be changing out the input carrier in the transfer case so that all the mating splines will be new.
Ain't cheap though. :eek:
Denny

[Inspector]

Went down to the shop and viewed the carnage in the tranny. Not to bad but showing signs of past heavy towing. The input to countershaft gears are pitted and worn pretty good. The sycros are begining to loose friction material. The bearing races are piting. We will probably go ahead and rebuil it complete. If we don't we will be back into it in about 20K from now. Its not worth not doing it right. We could probably get away with shorting the rebuild but I'm not built that way.
Denny ;)

[Turbo Al]

The sycro's are a carbon fiber material and worth a fair bit of $$$. They are the only thing that have actually worn out on mine in 170,000 miles.
Al

[meanchev]

Well it wasn't cheap but it is now back on the road and running strong. Just got back from a 250 mile trip and it ran well. Haven't figured mileage yet but aside from the hills cruise set at 70 the rpms stayed at 1900. Got back with more then a half tank reading on the gauge, so should be decent.