Little power and clutch won't hold....trans questions.

R

Ram12vcummins

New member
Joined
Mar 17, 2015
Messages
1,659
Well a little fuel plate grinding and some 4gsk springs and with a clutch that has almost no miles on it, slipped on me in 4th gear when I floored it. I read the stock clutches aren't much for power but I thought it would take more than an empty truck an maybe 300 hp? To do that. Looking for some opinions on where to go. I want to build a set of budget twins in the future with some 5x14 maybe 550-600 hp? And I want to make sure any new work will support this. I picked up a 3850 sbc off here but I think it might be a bit much for what I want. The truck is just my dd and tows a car hauler now and then. Some city driving. I did get the large input and hydros with the clutch. Will the stock nv4500 take that much power?


I also have a parts truck 97 with I'm guessing a 47re? Would I be better off to swap that in? It appears it will cost a bit of coin to maybe build the auto up and get a controller for it. But it would change drivability for the better I would assume.

Do they make a single disc to handle that much power? I'm not liking the idea of a noisy dual disc that's hard to shift.
 
I've had a number of SBC dual disc clutches. The newest one is silent, and shifts like a factory single disc, and I've never slipped it. Unless something has changed drastically in 6 years or so, then a 3250 DD will be the ticket for you. That was with basically your desired setup of twins with 550 hp.
 
Maybe that's the answer then.. With the little tuning I've done the wife can barely d I've the truck without it jerking like crazy in all gears. Lol I seem to be able to drive it fine though
 
Mine never needed it. Good time to check though, definitely easier on a bench to adjust the endplay.
 
Ram12vcummins said:
Any kind of shimming required for installing the large input shaft and retainer?
Click to expand...

We recently did an NV4500 5 speed big shaft upgrade and dual disk clutch for a customer, the endplay opened up from .011" as it arrived to .020"+ with the new shaft so we had to re-shim the main shaft to get it back closer to .005". If you're lucky, the big shaft will tighten up your endplay, if you're unlucky, it will need to be re-shimmed.

As far as stock clutch, we dyno'd the truck with the stock clutch and the most I could get out of it was 280 HP with the slipping stock clutch. As I recall, about 650 ft lbs is all I could get on the torque numbers and the truck came in running healthy and normal, just would slip a little if you rolled into it hard in 4th or 5th gear at low rpm. On the dyno, I loaded it down in the 1200 rpm range and it was slip city!!! Stock 12.25" organic clutch, the clutch looked to have about half it's life left (truck had 90k miles on it) as far as clutch disk wear... lots of hot spots on the flywheel after I purposely tore it up on the dyno trying to extract power numbers.... prior to the dual disk upgrade.

In short, clutch capacity is really a torque capacity so the higher RPM range you make peak horsepower, the more horsepower you can make on a stock clutch because they start slipping around 600 ft lbs....
 
I have no clue where I'm at for power but with this new lift pump it's sure pump up the power. It smokes off the hop then cleans to a haze an pulls hard. It will slip in 4th an 5th say at 1600 rpm at wot. At wide open throttle I can smoke 1400-1600 degrees on pyro as well but only hits there then comes back down.
 
Last edited:
You must log in or register to reply here.
Top