Crankshaft modification

1941 - 1945, MB, GPW modifications, sugestions, and ideas, official MWO's and unofficial WWII field mods NO EBAY or COMMERCIAL SALES.
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pkozak1
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Crankshaft modification

Post by pkozak1 » Sat Aug 01, 2020 3:01 pm

What needs to be done to a CJ gear drive crankshaft in order to make it a chain drive crankshaft?


Joe Gopan
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Re: Crankshaft modification

Post by Joe Gopan » Sun Aug 02, 2020 4:43 am

Best make a swap for the correct crankshaft.
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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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Wolfman
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Re: Crankshaft modification

Post by Wolfman » Sun Aug 02, 2020 7:08 am

Lay the crank in like you would a cast crank and check the fit.
Watch the oil galley plugs. If you have the original square head plugs, the "bolt on" counter weights may make contact. Especially behind the center main. Will need to switch to counter sunk plugs.
Watch the clearance between the oil pick up float and the crank counter weight in the the full up position.
Make sure the flywheel fits. Tapered dowel or straight.
And if using the same flywheel on a different crank, be sure the flywheel lays flat against the rear crankshaft flange.
If you have tapered dowels, the flywheel may go on but not tighten up flat against the crank and will wobble.
This is real bad !!
Should be 0 run out of the flywheel.
Had an L-134 come in with a broken crankshaft.
Owner said the engine had a strange vibration from the beginning.
Then after some time, BANG !!
Turned out to be the flywheel fit I just described.
( I didn't do it. Just found it. )
Mike Wolford
CJ-2A
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Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

Joe Gopan
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Re: Crankshaft modification

Post by Joe Gopan » Sun Aug 02, 2020 9:01 am

A passage must be drilled in the crankshaft to feed oil to the inside of the crankshaft socket.
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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