I have a 2002 2500hd 6.0 with a 5 speed manual and I would like to know if there is any easy way to increase the speed that I can shift gears. 1st to 2nd needs to be double clutched when under acceleration, and impossible to shift into from second when slowing down. I rarely use 1st just because it is too short of a gear, and it's more of a pain than a help getting me to about 10 mph. 2nd to 3rd is also slow but can be sped up slightly if I ram it into place. However this makes me feel like I'm punching my truck each time I do it. I saw someone with a 4.8 and their truck had what looked like a car transmission, butter smooth. Had the clutch replaced once so it's properly disengaged while shifting.
Hopefully someone can help me, I'm just tired of having a totally useless first gear, and only being able to shift to 3rd aggressively with some sort of wwe move...

Thanks

 

A NV4500 is a heavy duty transmission, not a sports car tranny like a T56 that can just be shifted like a boss all the time. I don't see how you'll be able to make it work any different than it does now, other than a rebuild to make it fresh.

If the 4.8 truck had a T56 then that's why it was butter smooth.

 

Get a short throw shifter. I have one on my '95 NV4500. It's noticeably faster. It's still a truck transmission but this is the best you can get without doing some major swapping.
https://core-shifters.com/products/c...ant=9158576835

I actually just had to rebuild my NV4500 because of similar problems. They started out like you are describing but got worse over time until the 2nd gear syncro was completely toast forcing me to double clutch and rev match to get it into gear without grinding. How many miles do you have on it? When was the last time you changed the fluid?

 

I recently swapped in a brand new NV4500 to replace my dying NV3500 that I had similar problems with. The new NV4500 with OEM clutch shifts very smooth and I can nail gears nearly as fast as anything else I've driven. Throws are rather long but always smooth. It may be time for a rebuild.

 

Thanks for the I formation. 135XXX miles on it, clutch was rebuilt around 90000. Can't remember the last time the fluid was changed, although a lot of stuff was serviced last winter and it may have been included. What is the worst it will get? A transmission rebuild? Second gear is getting tough to shift to downshifting. My dad bought the truck when I was born and he drive it for 4 years and then put it I to storage knowing it was one of the last years of the manuals to save for me. He remembers being able to shift out of first, to second with no problems. The shifter feels like it is bouncing while I am pushing from first to second, and if I hold it there for a second it will go in but this is slower than double clutching.

 

My clutch has been rebuilt and master cylinder replaced recently. How is the use of first in the fresh tranny? Second to third under hard acceleration? I feel the synchros are totally gone in first and on their way for second. If this is the truth a trans rebuild will need to be done.

 

Also did you do the rebuild yourself or did you have someone do it? What was involved. Looking to do one now, as it's probably something that's going to needed badly very shortly. Probably going to have someone do it because my dad and I have no time these days. Would a truck shop be an ok place to trust with the task or should I look for a transmission specific shop?

 

I commend you and your dad for having the foresight to save the manuals!

I had a local transmission shop do it. You'll be surprised, it's getting hard to find a local shop that rebuilds manual transmissions. That said I did manage to find a quality shop that did the job for $1500. That's on the higher end of the spectrum and I had to pull the transmission myself. Another option is getting a reman'ed tranny on eBay. They go for around $1000 + shipping + core charge. For me with the freight shipping the eBay ones were within about $200 of the local shop price so I figured I'd rather support the local economy and have a place to bring it to if something goes wrong with it while still under warranty.

Before I rebuilt it, I couldn't shift from 1st to 2nd at high rpm, the 2nd to 3rd shift was okay but sometimes it wouldn't go at high rpms, then downshifting from 4th to 3rd (like for passing someone) would require rev matching in order to get it to go in gear. Then 2nd continued to get worse until it started grinding no matter what and would sometimes just pop out of gear too. The shop said the 2nd and 3rd syncros where shot and they replaced the gears as well.

Now post rebuild it works just like it should and with the short throw I can redline shift 2nd to 3rd no problem literally as fast as I can throw the shifter.

Another point to add: LUBE
It sounds like the fluid isn't that old in yours but it's worth checking to make sure it full and see if it's dirty. The NV4500s are very picky about their gear oil. They require a GL-4 rated gear oil. Anything else and it will quickly destroy it's syncros. You can get this fluid through a dealer for an arm and a leg or what I use is RedLine Synthetic MT-85. It meets/exceeds the dealer lube specs and is a little cheaper. I ordered 5 quarts off of Amazon.
I also added a street-el to the fill plug so that I can add in another 1/2 quart of oil or so. This helps keep the input bearing submerged and well lubricated. I also fitted a filter to the side of trans on the passenger PTO port. It's a passive filter that scoops off some oil that is slung around by the gears and drains it through the filter. It definitely helps keep the oil clean. You can find it here:
filterkits - Torque King 4x4

 

First gear is a very low gear and sometimes I find myself starting in second on the street. However if I feel like launching in first and nailing second then third the shifts take mild effort and go into gear no problem. That would be shifting at about 6,000-6,500RPM.

I have reaad that one of the only problems people have with these trans besides the 5th gear nut backing off. Is the synchros get worn from improper fluid or I'm sure just the breakdown of old fluid.

I think your best bet might be to get a rebuilt trans. I got mine from midwest trans along with new clutch and flywheel and couldnt have been happier. You could call them and ask them what they think their customer service is supurb.

 

You should always start in second unless towing or going up a hill. You should never downshift into first while moving unless you are only going 2-3 mph max. The 5th gear nut was never a problem in gm trucks.