j_schwaa

So my 1999 (NBS) 4.8L (now a 6.0L) 4x4 NV3500 transmission has been making that whining noise for longer than I've owned it. Everyone in town thinks the truck is supercharged because of the noise. Bought it 3 years ago from my brother, and the noise has steadily gotten worse. Does not make it in 4th gear (that I can hear). If the clutch is in, it doesn't make the whining noise. If I let the clutch out in Neutral, it makes the noise.

I have replaced the throw out bearing and pilot bearings already. (when we swapped the 6.0L in) Also has newer slave cylinder (needed a new one)

I've been told it's probably the main shaft bearing that's making the noise. I was told that launching the truck a lot, and hard launches will cause that bearing to wear out and make that noise (and my brother beat the **** out of this truck when he owned it)

Any suggestions on where to start? I don't have the money to take it to a transmission shop, or GM Dealer. I was hoping to install a new bearing if that's the problem. How hard would this repair be to do, if it is the problem?

topfueljim

I have a 2006 rcsb that I bought new in '05 that has that trans. It is a noisy, clunky, horrible trans. While still under warranty I had it in the dealer's several times--no change. I put Red Line MTL in it at about 45K, slight improvement, but not much. I am old, and I have owned about 15 stick shift cars, from a '49 Ford to a VW to a Saturn to a Corvette, etc. and this is by far the worst manual transmission I've ever had. On the other hand, there is less to go wrong than with an automatic, and when it does it's a lot cheaper to fix. They do have small parts with close tolerances and I have been told by a local trans guy not to even attempt it. Sorry, but no real first hand knowledge of the insides of one of these.

PathfinderJr

iTrader: (6)

Yes, it's the main shaft bearing. I was told the same thing and promptly decided to ditch it in favor of a T56.

j_schwaa

Thanks for the responses!

From what I've read of the T56 swap, I would have to ditch the 4x4, and the middle seat (?) I say, screw that! I love my 4x4 too much to lose that! Besides, this thing is a beast in mud and snow. I haven't even driven it in mud or snow since the 6.0 swap.

Back to the topic at hand... Anyone have any more information on the main shaft seal? Like how to replace it, what special tools it will require, etc, etc...

Thanks
-Josh

j_schwaa

As far as performance, I have not had any problems with this transmission. It's the only chevy stick in a truck I've driven, but from what I've experienced, this tranny still holds strong, and shifts smooth every time. Even with the whine, which is more annoying than anything else.

I'm just wondering if this is a ticking time bomb that's going to completely destroy my tranny, or if it's just something that will wear out and continue to make noise, without any trouble elsewhere.

I won't trade the stick for any automatic. I'll drive this till it dies, then get another one if I have to. But I'd prefer to maintain it, and keep it in as good of shape as I can.

topfueljim

Mine is a 2wd and a "city truck", but that is my plan. Drive it until it breaks and then get another one. Even though it is annoying, it probably won't completely quit for a long time. It's going to be cheaper to replace than an auto when it does.

TurboGibbs

iTrader: (6)

I broke this bearing in my 95 NV3500 on a hard shift. If it has been doing it a while, it has probably worn the input gear and cluster gear due to the input shaft moving around.

j_schwaa

Honestly, I've driven with it making that noise for so long that it's not even annoying. When the day comes that it's fixed, I'll probably be worried that something's wrong the first time I drive it cause I won't hear that noise!

Anyone know of any specials tools I might need to do the repair? Or if there is a special tool, if I can just make it myself?

slowride454

Input shaft bearing. Reason for no whining in 4th is 1:1. No side loading in 4th gear. Replaced it twice in my '90. Looking to do it in my '05 soon.

_zebra

iTrader: (5)

super-old thread - i know, but i'm thinking about doing a rebuild on mine when i get a new clutch next month (216k miles now), and i'm curious if they normally install new input/main bearings & if those will fix the noise. or will i need a new input shaft, too?

mine's been whining since i bought it 10+yrs ago - bad enough that i've also had people ask if it's supercharged! it still drives fine, but it'd be nice to hear more exhaust & engine noise than trans whine.

then again, i've also contemplated an nv4500 swap instead.