I have an 02 RCSB with a 4.8L, 5spd, & 250k miles. I bought it with 90K about 5 yrs ago from the original owner. My only go faster mods are CAI, catback, and a generic 91 tune. The engine and tranny are still running good on all stock, & factory clutch other than slight bottom end knock when ice cold and occasionally missing a shift at high rpms or having trouble going into first once the light turns green (once a month). I drive very aggressive shifting at 6k rpms on first and second almost every time I can find a reason to, but I don't track it, slam it into gears, or try to ever spin tires. It has enough power for my DD and don't want to lose mpg for those 1,000 mile drives I do 2-3 times a year. The torque curve not kicking in until 4k rpms is annoying at times. I have not yet towed, but I would like to retain the option (a first 92-00, or second gen 99-06 Tahoe with a MT is a future consideration) on a flat trailer. So NO t-56 talk needed in this thread, and I really don't mind the extra 1/2 second or less to shift. Once my engine goes, I would like to do a 5.3/LM7 and keep the mods simple mostly due to not wanting to spend too much; intake, exhaust, cams, and custom tune (for now) seem they would be great.


I have read that many people claim that it can handle much more than the claimed 310ft even up to 400ft lbs on a nv3500 just fine, and many who claim that they are having trouble with them on stock 4.8s. Those who claimed problems were many years ago, and never specific on if it was the older version rated less. I see that different people had problems with different gears, and not sure if that should tell me enough to know where the problems are. I don't plan on replacing either until they go, and when I do I plan on getting rebuilds.


I see that at some point, in 97-04 the Dodge Dakota had an nv3500 HD that was rated at 340ft lbs of torque, (as opposed to the GM's 310 ft lbs and only gearing difference is .02 in 2nd and 3rd). Is this problem that people are having related to this gear? Is there a specific component that is allowing this torque increase? I really don't know **** here, and wondering if this is a different shaft size or if this is an interchangeable component??

Long-term outlook, If my engine goes first in the next couple years, I plan to replace that and run the trans till it goes, but once it does, is there an upgraded rebuild option, (which I have not seen), or do I need to just plan on a nv4500 (which looks like a $1500-2000) rebuilt buy.


(I did search and read about 30 threads from "nv3500"), or if there is another way for me to find this out. Thank you.

 

It's a good question, But I don't believe there are any upgrade parts for these transmissions.

Without having the units or a breakdown of the units it's hard to say what's different between the Chevy and Dodge version or if you could interchange any of the different parts.

As far as the engine, The 4.8 always has to rev higher to get it into the power band due to the shorter stroke.

A 5.3L with the small comp 265 cam and a tune to maximise it, Is probably what you would be looking for as far as performance. You don't need anything else special for it to work.

212/218 .525/.529 114+2 It's been proven to mimic the factory low end torque range while making more power and allowing it to rev out a little higher on the top end

Look at the curve's in this thread to see what I'm talking about. comp cams XR265 low lift dyno sheet

The other thing would probally be changing the rear gear ratio.

 

I had a NV3500 with about 110k miles behind a 4.8 with bolt ons and tune. When I got it there was a rattle coming from it that got progressively worse but didn't seem to effect anything. It didn't like to go into 3rd at high rpm but it never died on me. I eventually got tired of the rattle and the clutch was about gone and did a NV4500 swap. Night and day difference on smoothness and quietness. Goes into gear no matter what rpm your at and the clutch is so light and easy for DDing. Put about 5k miles on it now and couldn't be happier. The swap was nearly bolt in except for a reverse sensor and the cross member needed to be flipped.

 

Thanks for that link. That gives me a great idea of where I would be about. I was thinking it would be just a little higher, but I would be good with that. I still have a lot more reading to do, (have this on the way, "How to Build High-Performance Chevy LS1/LS6 V-8s (S-A Design)" by Will Handzel) to see how much I can figure out. It seems like that is where I am looking at, and any more than that is going to be a big budget increase for the NV4500. I would still be on the threshold of what the nv3500 is rated for, but would feel comfortable if within its rated torque. When it comes time, I wouldn't even mind losing a few if I could improve mileage a little. Other than those for the go faster mods, I plan on doing the E-fan, and already have the TB spacer. Both of those are not for power, strictly for response and fuel mileage. Other than that, I just want a well rounded daily, and don't plan on anything further. Its got 3.42 in it, and those seem great for how I drive. Not sure if I will want to change that after an eventual 5.3L