89 GMC 5 speed?
 

I own a 1989 GMC 2500 with a 5.7l and a 5 speed manual transmission.... I don't know anything about these 5 speeds and was wondering if they are weak or real durable. I would like to get more power outta my truck but don't know if this transmission can take a beating. (hard on vehicles) What would be some good bolt on goodies for this truck?

RE: 89 GMC 5 speed?
 

From what I recall they are relatively weak. I think they had an issue with heat in overdrive. The splash effect of the fluid was not enough to properly lubricate the transmission so there was a relatively high number of transmission failures. Maybe I am confused with another transmission but somebody should be able to help with more details.

RE: 89 GMC 5 speed?
 

GMCrunner, welcome to the forum!!!

RE: 89 GMC 5 speed?
 

GMCrunner,

I have a 96 K1500 w/ a 350 and a 5 spd manual. My tranny is a NV3500, and I believe that yours is the same. These Trannies are not know to be very strong, but the fact of the matter is, mine has 120,000 on it and has been trouble free. My 350 is a vortec motor w/ 250 hp and 335 ft-lbs of torque, as advertised from the factory. Performance add-ons include custom dual exhaustand a K/N air filter. Not sure what kind of hp you want to generate, but your non-vortec motor, if stock, probably has about 200-210 hp. If you're looking for a 250-275 hp motor, you ought to be ok w/ the NV3500 trans.

The NV3500's had numerous tweaks during production, and I believe that mine is near the end of their development. I too have looked into a swap, with the most popular being the NV4500. Tranny, belhousing,and misc.parts is about $2500 not includinglabor. Not sure if the drive shaftsneed to be modified, but I'd bet that they do. This wouldbe an added cost/factor. Of course, these are true "truck" transmissions with a granny low and long shift throws, especially when compared to the NV3500. I've decided to stick with what I got... the "if it ain't broke" mentality...

Another sweet deal would be to drop in a T-56 6spd tranny from the 93-97 TPI Camaros/Firebirds... This wouldn't be too difficultif your truck is 2wd. Mine's 4wd and I couldn't find anyonewho makes an adapter for the transfer case...

For more info on the tranny itself, due a search on NV3500 or New Venture 3500.

Regards,

RE: 89 GMC 5 speed?
 

Wow suprised me I thought they were tough trannys but now i know other wise... T-56 bolt right in with few majors mods? cuz mine is a 2wd and was thinkin of taking it to the track a few times. thanks for the info!

RE: 89 GMC 5 speed?
 

GMCrunner,

I looked into this a little further... If your 2500 is a light duty, you most likely have the NV3500. If it's a heavy duty 2500, then you have the NV4500, a rather stout, but truck-like (slow shifting) transmission. Light Duty 2500's usually have6 bolt rims while the heavy duty 2500 rims will be 8 bolt.If your tranny has a low first gear (one youwouldn't normally use to start) it's the NV4500.

I haven't swapped aT-56, buthave read about it being done. I'd guess that you would have to (at the very least) address input and output shaft compatiblity issues along with altering your drive shaft length.

If you do have the NV3500, you might want to install a Hurst shifter on it. Although it won't make the tranny stronger, itwill decrease the travel of yourshift pattern, allowing for quicker shifts. I installed one on my NV3500and love it. Easy install, don't have to drop the tranny,I was able to do it in about an hour or so w/o specialtools.

Good Luck.

5 speed
 

I do know 5 speed is an overdrive transmission like on automatics you NEVER haul or tow anything in overdrive it is strictly for gas economy ONLY.
I you want to haul or tow anything heavy you use 4 gear on manual transmission and Drive on automatic transmissions.

I tow in overdrive on flat ground just downshift before the hill starts and you're fine. My sonoma with a t5 and 4.11 in the rear with recurve helper leafs pulls more than most half tons at 1600 rpms in 5th not bogging so I do it. If the engine doesnt complain send it. Never turned od off in my 4l60e either just drove right like a manual and put my foot down before the hill. Towed an 8k camper with a 94 half ton