GM manual transmissions

[nubuilder]

I'm a little confused about the manual transmissions found in the late 90's GM trucks.

My S10 has the RPO code M50 which is a NV3500 with the following gear ratios:
(according to Wikipedia)
1 = 3.49
2 = 2.16
3 = 1.40
4 = 1.00
5 = 0.73
R = 3.55


Also according to Wiki, the NV3500 had 2 gearings, the one above (M50) and a MG5 with 1 = 4.02 and 2 = 2.32; the others the same. It says the M50 is for small trucks and the MG5 is for full-size light-duty trucks.


I looked at a '96 K1500 today (rusty and 307k mi) that had the M50 code.
According to this calculator, 3.42 gears with 31" tires will turn the engine 50rpm slower (at 60mph) than my 3.08 with 27" tires S10. WIN!!



Can anyone explain why the same trans is used in both trucks? Are there differences with the quality of the internals?
I would think a heavier truck with a larger engine would require a different trans from my small and light S10.

Thanks!

 

[drperry]

There's the "wide ratio" and "close ratio" GM versions of this transmission...

The 1/2 ton trucks got the wide ratio.

The GVWR of the transmission is somewhere around 11k lbs
It was also used in 2500 LD Dodge pickups.

The same trans was used because of it's "power rating" It's "officially" safe for about 300 ft.lbs of torque

The 350, stock put out less than 300ft/lbs, IIRC, or at most 300... I think.

Even though, it shows M50, it'll still be the wide ratio trans if it's a 1/2 ton... Or it should be, anyway.

The only differences are the gear ratios, everything else is the same, internally.

Externally, the 1/2 ton one has the shifter in a different location.

The only differences on internals comes from the years it was made... Newer ones are better.

 

[nubuilder]

Dennis, that sounds a lot like what Wiki was saying. They were calling the "wide" the MG5 and the "close" as the M50.

• GM RPO codes;
  • Wide-ratio MG5
  • Close-ratio M50
• Dodge order code DDC
• Rated for 300 ft·lbf of torque
• Weight 110 lb with oil

Wide Ratio Gearing Option in Dodge 1500 & GM Fullsize Light Trucks:
1 = 4.02
2 = 2.32
3 = 1.40
4 = 1.00
5 = 0.73
R = 3.55

Close Ratio GM S/T Small Trucks& 2500 Light Duty Dodge Ram Truck Gearing:
1 = 3.49
2 = 2.16
3 = 1.40
4 = 1.00
5 = 0.73
R = 3.55

I'm looking for a '96-'98 K1500. Will those tranny's be OK?

 

[drperry]

People have reliably put 400 ft.lbs with daily flogging, with no issues...

But once you go past the power rating, it's a crap-shoot...

That's why I'm changing my transmission

 

[nubuilder]

Well, a 5spd K1500 won't be my performance truck. That's what my green one is for! Besides, I don't think I would ever see 400ft/lbs in this particular truck.

The most a second truck would get is a BBP tune, possible CAI, and mufflers whenever they would go out. The second one needs to be my winter-beater so its not gonna be anything fancy.

 

[drperry]

Well, a 5spd K1500 won't be my performance truck. That's what my green one is for! Besides, I don't think I would ever see 400ft/lbs in this particular truck.

The most a second truck would get is a BBP tune, possible CAI, and mufflers whenever they would go out. The second one needs to be my winter-beater so its not gonna be anything fancy.

Then you'll be fine!

Just be sure to baby the clutch... She's not meant for abuse

 

[nubuilder]

Well, a 5spd K1500 won't be my performance truck. That's what my green one is for! Besides, I don't think I would ever see 400ft/lbs in this particular truck.

The most a second truck would get is a BBP tune, possible CAI, and mufflers whenever they would go out. The second one needs to be my winter-beater so its not gonna be anything fancy.

Then you'll be fine!

Just be sure to baby the clutch... She's not meant for abuse

I take it you know this from experience of dropping the clutch a lot.


How is towing occasionally (if at all) with a 5spd? Never done it before.

 

[drperry]

Well, a 5spd K1500 won't be my performance truck. That's what my green one is for! Besides, I don't think I would ever see 400ft/lbs in this particular truck.

The most a second truck would get is a BBP tune, possible CAI, and mufflers whenever they would go out. The second one needs to be my winter-beater so its not gonna be anything fancy.

Then you'll be fine!

Just be sure to baby the clutch... She's not meant for abuse

I take it you know this from experience of dropping the clutch a lot.


How is towing occasionally (if at all) with a 5spd? Never done it before.

Actually, it's down shifting that messed up my clutch!

I've never had a problem towing with my truck... If it's a heavy load, you stay out of 5th gear, that's about it
Tows nice, actually.

 

[bobkyle2]

I had a 95 k150 with the 5speed... Absolutely worse manual transmission ive ever had.... I had a 380 horse 350.... And i could not keep a clutch in it.. It did not hold up raceing dirt drags...

I pulled it out and put a 4speed out of a 88 k2500... never had another problem with it