M37 driveline drag

[rickv100]

How much drag on the M37 driveline would be considered normal? It seems like I loose a lot of momentum when taking foot off of gas while driving. I have checked the wheels for drag and they are fine. My next check would be the transmission and transfer case. Transfer is in 2 wheel drive, high

Rick

[PoW]

Methinks you're experiencing the "80 Hp & 6,000 pound" drag....hard to get in today's vehicles.

DDG

[Chris P]

I've noticed the same thing with my truck. I have not installed lock out hubs, but from what I've read on this forum they make a noticeable difference. That would suggest that driveline drag is considerable overall. On the positive side, the drive line drag should help a little with braking

[rickv100]

Thanks. Without having a driven a new M37 it is hard to know what "normal" is with these after 60 years of service. I am running a rebuilt engine, new clutch, new u joints. so it should be in good shape.

Yes, I find that braking is no problem.

Rick

[T. Highway]

Rick,

I agree with the comment above, about lockouts. It helped my truck allot in coasting and steering. I would also double check that all of the drive shafts are timed correctly in the spline area because that will cause severe driveline drag.

Bert

[refit1701]

It's the weight and the gearing. With lockout hubs, I can coast down a fairly steep grade and not speed up enough to worry about not stopping. This is why you should be using the transmission to brake the engine on steep hills.

[RMS]

besides the 6000lbs and bias ply tires there is also pre load on all the components Tcase, diffs, wheel bearings that add to the drag. I noticed a big reduction in drag by running radials and proper fluids (50w)in the trans and Tcase.
lock out hubs are great they reduce drive line drag and vibration but I believe they shorten the life of the front drive shaft slip yoke splines

[Jess]

RMS, I'm running Selectros on my M37CDN but don't put any real miles on it. What do you feel contributes to the spline wear?

Jess

[RMS]

with the front drive shaft being so long and heavy, as the suspension moves, the 16 splines slide in and out with very little surface area supporting the shaft and since it is not turning it is constantly wearing in one spot.

soft springs add to the wear and I have noticed less wear since installing ambulance springs