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Blown C4 transmission

JAFHR

New Member
Joined
Oct 15, 2012
Messages
62
Loc.
Bend Oregon
Hello, I blew up my C4 auto transmission playing on the dunes. I don't think it was too healthy prior. Not sure what blew but I lost all forward gears. Should I be looking to get a replacement, rebuild, modify or get a C6.

Thx
 

71Broncitis

Jr. Member
Joined
Dec 1, 2014
Messages
152
Rebuild with some upgrades. The C4 is a good transmission and can be made even better during a rebuild.

Sent from my XT1254 using Tapatalk
 

garberz

Bronco Influencer
Joined
Jun 24, 2007
Messages
6,861
Loc.
Conejo Valley, Ca.
If you were in the sand then it got hot! Rebuild the one you have. Have the torque converter rebuilt also. Most importantly, get a trans temp gauge to keep an eye on it. It's tough to keep a C4 properly cooled, especially working them hard in the sand.

Mark
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
What is your tire size and axle gearing. Mismatched tires and axle gearing may over load the transmission.
 
OP
OP
JAFHR

JAFHR

New Member
Joined
Oct 15, 2012
Messages
62
Loc.
Bend Oregon
I'm running 35x13.5 15's but I don't know the gearing on it. I'm running a 351W and it is very lack luster so I'm assuming it may be stock gearing. I'll be checking on it tomorrow.
 
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JAFHR

JAFHR

New Member
Joined
Oct 15, 2012
Messages
62
Loc.
Bend Oregon
What is the stock gearing on the 74? I had the tires off and spun the axle with the lug at 12 o'clock position. When it got back up to 12 o'clock, the drive shaft spun twice around. This seem like a very high gearing.
 

DJs74

Bronco Guru
Joined
Apr 1, 2014
Messages
1,135
What is the stock gearing on the 74? I had the tires off and spun the axle with the lug at 12 o'clock position. When it got back up to 12 o'clock, the drive shaft spun twice around. This seem like a very high gearing.

Probably 3.50s


DJs74
 

sanndmann3

Contributor
Bronco Guru
Joined
Jun 13, 2007
Messages
1,790
I'd recommend 4.56 gears atleast to go with the 35" tires. I ran almost exclusivly in low range when out playing in sand. Helps keep trans cooler.
Definitely get a temp gageon it and rebuild. there are some good upgrades to do as well while you are inside. C4 is a great little trans and fairly easy to work on as well.
 
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JAFHR

JAFHR

New Member
Joined
Oct 15, 2012
Messages
62
Loc.
Bend Oregon
I'd recommend 4.56 gears atleast to go with the 35" tires. I ran almost exclusivly in low range when out playing in sand. Helps keep trans cooler.
Definitely get a temp gageon it and rebuild. there are some good upgrades to do as well while you are inside. C4 is a great little trans and fairly easy to work on as well.

Thanks, all great recommendations. I've got a rebuilt C4 coming with higher rated clutches and valve body upgrades. I'll be ordering 4:56's . I'm assuming Yukon is the favorite.

I'd forgotten, but I have ARB lockers front and back on this rig. I gotta assume that someone had changed the gearing in this. What should I be looking for in numbers or ?
 
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