GMC CCKW MORE SPEED

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Randal
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GMC CCKW MORE SPEED

Post by Randal » Fri Jun 30, 2017 5:37 am

Dear friends
How to get more speed with factory GMC CCKW split axles, transmission and transfer case?
Changing the axles gear ratio? Is there an upgraded pinion and gear supplier for the split model?
Or modifiyng the transmission components?
Suggestions are very welcome!
Thanks!
Randal


radarsgunner1
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Re: GMC CCKW MORE SPEED

Post by radarsgunner1 » Fri Jun 30, 2017 6:35 am

What speeds are you looking for? We milled out our front hubs so we're not dragging the front axle and reset the governor. We run 55 with no problem and get 10mpg
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Re: GMC CCKW MORE SPEED

Post by Joe Gopan » Sat Jul 01, 2017 2:01 pm

I wouldn't advise altering a CCKW into a turnpike cruiser. The truck was designed with a suspension configured for off road operation and 45 mph on hard surfaced road design from the 30's-40's.. 70 years takes a toll on these old trucks. If you want to go faster, buy a modern truck.
Split transfers will not take the pounding.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
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Re: GMC CCKW MORE SPEED

Post by Dr Deuce » Tue Sep 05, 2017 8:08 am

Ben, I thought that the Splits would take abuse better because they have shims in the xfer whereas the banjo you just throw the parts at it?
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John Neuenburg
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Re: GMC CCKW MORE SPEED

Post by John Neuenburg » Wed Sep 06, 2017 8:33 pm

Randal, do not be deterred by the "speed police" (fun police??) on the G who would have you obey the manuals, and others who will bad mouth any mods to a MV, especially the mods you can't see or hear. It's your truck and if you want to go faster just understand what your truck does and doesn't do at 50 or 60 with regards to stopping and steering.

I don't know much about jimmys but seems to me increasing the engine rpm, if it is happy, could be a good option. Decreasing driveline friction losses and fiddling with the governor makes sense. I hear there is a 302 that can drop in, and speed parts are available for those. That should get you to a higher rpm plus make more power up there so you don't slow down as much on the hills. That means higher average speed if you drive in hills.
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Re: GMC CCKW MORE SPEED

Post by Joe Gopan » Thu Sep 07, 2017 4:32 am

Split CCKW (TIMKEN) Transfers had a chronic problem of insufficient lubrication to the uppermost gears and ran super hot at increased speeds, there are bulletins in the Army Motors, etc., that warn not to use heavier lube than GO-90 as 85/140, or plain GO-140 cause more heat.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO


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