hello i have broken input shaft. upgraded to valair billet. seems to work. blown all bearings. cryo treated them seems to work. brand new 3rd gear 400 miles an it blew an destroyed my counter shaft. im making some decent power, an tow an tug on heavy stuff all day. im not speed shifting or raping the trans an yet every month i break something else. or the same thing over again. i have had the tranny in an out 8 times in the past year. with only like 6k on it. does any one have any suggestions? how do the tractor pullers keep their tranny from blown? im so tired of working on this thing an really want to fix it so i only have to pull it like once a year, that would b nice.

 

so no one here has a truck with over 1000tq an a 5 speed that they have kept together for over a year? is that why no one has any input?

 

Maybe a little more info....

What are your power numbers? What kind of loads are you pulling and in what gears, up what kind of grades? What is your rear end gearing, tire size? How often and in what manner do you use the exhaust brake (keep in mind the exhaust brake lashes everything backwards in the transmission, basically output becomes input and visa versa, so if not setup properly it could cause some issues over time)?

Have YOU been rebuilding the transmission personally, or taking it in professionally (I'm not judging your rebuilding skills, but I understand these transmissions can be very tedious to set up properly)? What do you mean by "cryo treating"; what parts and what process? Have totally fresh parts been put in every time, or could this just be a matter of the most worn out part keeps giving in after every "fix"?

I'm not a professional transmission guy by any means, just thinking out loud so maybe others will chime in...

 

If i was you i would go and buy an ATS build NV4500 and if it breaks before warranty let them deal with it.

 

ATS dosn't have a good reputation around here

 

i would probably switch trany shops. if your bringing it to the same place and its been in and out 8 times in one year maybe its the guys putting the parts in. just a thought

 

sorry been out of town working. no access to computer in the woods. im not sure on the power. with the cam, turbo, exhaust, injectors, dvs, an everything else, im guessing mid 400hp an around 1000ft lbs. i have 3.54s in the diffs, 35'' tires. decent grades around CA an in every gear. my good friend is a professional tranny builder an well known in northern ca. he builds all of mine an every one elses that i know. he builds everything from daily driver to full race. i have replaced different parts each time. a lot of the same parts tho too. bearings ect. i have confidence in my builder. he has gotten better every time with this trans to wear it shifts like butter. but then blows up randomly. i know there is basically 3 weak points to the 4500. input shaft. 5th gear falling off, an 3rd gear to counter shaft. which is what went this last time. im kinda hard on the truck i guess. i run a metal salvage bis. there is alot of pulling stuff out of the woods where it has sat for 20 years. but still i dont beat it, an i would think it would b able to hold up a little better. an as far as the cryo treating this last time i sent down all shafts, bearings gears an small hard parts that didnt have friction material on them. im hopping one of these sled pullers will chime in with some tricks of the trade.

 

The first problem I see is 3.54's and 35"s. Probably good for mileage and all, but that's a lot of torque being left solely to the transmission. A set of 4.10's would likely do wonders for the pulling characteristics and alleviate the transmission a bit. Secondly, bearings are spec'd to fairly specific hardness numbers, and I'd be leary of sending out spec'd bearings to be re-treated, but that's just me. Also, if you are trashing bearings, then I question the preloading of them during assembly, and also question if you are running the right fluids and amounts. Are you using the same transmission case every time? Could something be out of line with the case itself maybe?

 

Yup, the gearings a huge issue. My friends got an overfueled set of tow twins with 37s and 3.54's and can break inputs at will, he ended up pulling the lift out and just running 33's so he could tow his fifth wheel better but 4.10's would be the solution if you want to keep the larger tires.

 

I broke 7 NV4500's in a 1 year period, turned out my tranny had a cast iron tail housing, mine is a 4wd and that 90% plus of those were machined wrong from the factory, puting the shafts in a bind. I went back to aluminum rear housing and haven't broken another. There is some info on this located on the quad4x4 web site. Might not be your problem but might be worth looking into.