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NV 4500 Broken Again

6.2 turbo

6.2 turbo

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Since I put the Nv 4500 in my Cummins powered 97 chevy trk ,counting today, it broke 6 times in less than a year. Several 5th gear clutch rings a counter shaft and 3rd gear,and now countershaft again and also the Haisly Machine billet input shaft . I had all of these parts cryo treated the last time ,didn't help . I'm about ready to go with an Eaton Fuller 6spd,that has overdrive,and divorced transfer case.:mad2:
 
Crossed my mind,but I like the Cummins, It just has to much low end power .
 
do you know how much power your putting through it. I've heard of cummins guys holding around 500hp or so and being able to keep those transmissions alive with some good billet parts and taking care of then. If you don't mind me asking, who does your cryo treating? If whomever did it is doing something wrong it can actually make the part weaker than before it was tampered with. When shifting gears are you one to backout of the clutch real fast or gradually engage it? All depends on how your treating the trans.
 
which version of the nv4500 do you have? gm/dodge or the dodge HD version. the HD setup was designed for the Cummings/ V10

EDIT: the difference between the 2 is the input shaft. standard is 1 1/8. HD is 1 1/4. there is a difference in torque rating but I can find it now.
 
It is the Dodge version and has the billet 1-3/8 input shaft,this is the only part that I know of that can be upgraded. Also I'm running a Valair twin disc full ceramic clutch with no damper springs. The motor has a 11 mm P pump with no fuel plate,and marine 370 injectors,and Hx 35 turbo wastegated by exhaust pressure and makes 45 - 50 psi boost. I would guess around 350 hp. I try not to use 5th under 45 mph,or full throttle in 5th either. 4th gear is direct which is very strong. I have done a burnout from a dead stop in 4th . Guess you could say I abuse it some. The input shaft had some chunks of teeth missing before,so this didn't help the mating gear on the counter shaft last any longer. I was barely on the throttle in 5th when I heard the teeth break off,probably were all ready cracked. I have a used ,non aftermarket counter shaft that will be going in as a replacement. And probably I will get a 1-3/8 non billet input shaft. So the next time it should have all NV gears,except the input gaer. All the parts that ever broke were aftermarket,except the 5th gear clutch ring,one time was a NV one, but was my fault. The input shaft,counter shaft,5th gear clutch ring,and 3rd gear were cryo treated at Cryo Technologies in Willkes Barre PA . Super nice guy that seemed to know what he was doing,and has done entire motors for racing and a Powerstroke motor for truck pulling. He also did some ring and pinions for top fuel drag cars,and lots of brake rotors for the local police cars.
 
sounds to me like you need to upgrade in sheer size. would the NV5600 fit? you get a six speed to play with but a strong setup.
 
I believe the NV 5600 would fit in the Chevy,especially since it has a 3 inch body lift,and no torsion bar cross member. Trouble is finding one,it was hard enough finding a NV 4500.
 
5600 isnt any stronger really, it does however weigh alot more, longer, is it alot more expensive, you may have other problems with your tranny, constant issues like that arent typical of the NV4500, an Allison would be a pretty cool swap, there going cheaper and cheaper on ebay now too.
 
I was reading up on the Gear Vendors ,sounds like they have the best over drive unit . Very expensive though. One of these with a medium duty 5 spd and a divorced 205 case would be cool,but I don't have the time or money. I can get the NV 4500 non billet input shaft for $400 , the billet one is $650 and the one that is in the tranny when I bought it was an $800 Haisly Machine. . I wonder if the non billet will break for me ? Guess I can give it a try. I think I exagerated on the times it broke , it is was only 4 times ,the other 2 was the NV 3500 .
 
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why did you got to the 1 3/8 input? Just so you could run the dual disc clutch?. i have always heard that these tranny are pretty stout. but i guess when you start pushing more power they can only take so much
 
It had the 1-3/8 when I bought it . I heard of the 1-1/4 shafts breaking. The harmonics of the 6cyl is what helps break things . I often wondered if a Fluid Damper on the motor would help save the tranny ? I know some Dodges also have a damper on the drive shaft . Valair has recently came out with a twin disc with sprung hubs,mine are solid . If I am towing and get on it to hard in 4th gear at to low rpm,it sounds,and feels like the tranny will explode. Massive gear rattle ,sounds like chain falling on a steel trailer deck. With a V8,gas or diesel,this is not a problem . They are so much smoother.
 
The Fluid Damper may help.

I have a 427 gas grain truck that had a rattle in the tranny, When the crank broke in two pieces I put a new damper on in the rebuild. The rattle was gone after that.
 
The solid hub is not good for street, alot of the shock is being transfered into your tranny. a sprung hub clutch might help, i have a southbend 450hp clutch in mine. i know i should of went to a double disc set up, mine slips bad. southbend has a new sprung hub double disc they came out with thats im looking into, its on there web site
 
I wonder if mine could be upgraded to the sprung hubs,might not be enough clearance .
 
according to southbend you only need a spacer if you go triple disc. if you have the dodge bell housing and a external slave cylinder it should fit.
 
I moved the truck with no oil in the tranny ,it did have 80/90 . It went in gear way easier. Maybe next time I will run what belongs in or thin it with some atf ? One winter I ran 90/140 ,that was pretty much impossible to shift when cold . The main reason for the thick oil was to help save the chipped input shaft, which wined, and cut down on the gear rattle at idle.
 
Mine are brass,and were reused every time the tranny was apart. I will reuse them again .
 
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