Competition 5 or 6 speed for pulling and racing???

[RyanB]

Hey All-



I am in the works of doing a cummins conversion into a 1989 GMC 1-ton Dually. I am building this truck for everyday driving/truck pulling/drag racing. I am putting a 12valve into it and a manual transmission. My question is which trany to go with? I was really wanting the NV5600 because of added strength seeing I am looking at putting around 500-600HP to the ground but I am also thinking about for drag racing and pulling... . do I need that extra in between gear or will it be a pain? I can bet both trany's from my supplier and there is a $1000CDN difference. For the extra $1000 I figure it will be worth getting the 6-speed just for the added insurance of strength.



What do you all think???

 

[HOSS]

Those I know of who race with manuals like the 5 speed better, that is after the fully splined shaft is installed and 5th gear nut is fixed.

For pulling either one will do since you do not want to shift anyway (most likely you will use 3rd gear in 4 low) and the ratio is the same for both.



a five speed with the right stuff and a good clutch would be the way to go if you are dead set on a manual IMHO

 

[RyanB]

Anyone else? I pretty much have to make up my mind by tomorrow as to which I am going to go with. And I am pretty sure everyone has a view on this subject.



Thanks again... Ryan

 

[GO 4LO]

Originally posted by HOSS



a five speed with the right stuff and a good clutch would be the way to go if you are dead set on a manual IMHO

From looking at what the big guys run, I'd be inclined to agree with Hoss. Scheid runs a 5-speed in their big puller, and if I remember correctly, so does Mitchell. With the 1 3/8 input, no doubt...

Chris

 

[Cumminsman]

IMHO if you want a manual for both racing and pulling. the five speed is better for quarter mile racing. the 1/8th mile a 6 speed is pretty good. you just use 3rd and 4th gear for racing. mitchell is using a 6 speed now. for pulling the 6 speed gives you a couple of different options where the 5 speed you are limited to 1 pulling gear. if you go with the 5 spd you must do the fully splined mainshaft and 1 3/8ths" input shaft.