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c4 swap

bobzilla

Full Member
Joined
Nov 22, 2006
Messages
298
Loc.
Riverside, ca
looking to replace my stock 3 spd manual for an automatic. I kinda wanted an overdrive trans but the cost looked to be a little expensive. With the cost of the trans, the controler, the driveline changes and everything else i dont think i would ever recoup the cost with fuel savings and what not. So i was just thinking about throwing a c4 in there and calling it a day. What parts would be needed for this swap. Will the drive shaafts work or is the tranny legnth different. Also is the 3 speed worth anything? Its been rebuilt and has a new clutch.
 

ransil

Bronco Guru
Joined
Sep 6, 2003
Messages
8,122
If this is a street only bronco I would stay with the 3 speed.
The old 3 speed is not worth much cant even give them away sometimes.
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
looking to replace my stock 3 spd manual for an automatic. I kinda wanted an overdrive trans but the cost looked to be a little expensive. With the cost of the trans, the controler, the driveline changes and everything else i dont think i would ever recoup the cost with fuel savings and what not. So i was just thinking about throwing a c4 in there and calling it a day. What parts would be needed for this swap. Will the drive shaafts work or is the tranny legnth different. Also is the 3 speed worth anything? Its been rebuilt and has a new clutch.

I agree you probably won't recoup the cost of an OD swap with fuel savings but the versatility of the car is improved a lot. If you want lower gears for good trail performance and don't want to trailer your rig, OD is the only reasonable answer.
 

pcf_mark

Bronco Guru
Joined
Jun 11, 2010
Messages
3,574
There are many threads with the parts list. I did this two years ago almost. The most disturbing item about the swap is the toque converter sucks power and lowers the fuel economy and performance. Your 3 speed takes about 5 hp to drive, the c4 is more like 25 hp.

You need a C4 from a Bronco with the transfer case adaptor / output shaft combination. Once you have that your existing t-case and driveshafts are unchanged.

C4 trans
torque converter
flexplate
A/T style starter
A/T style engine plate
Trans cooler and fan
Shifter
 
OP
OP
B

bobzilla

Full Member
Joined
Nov 22, 2006
Messages
298
Loc.
Riverside, ca
the truck will be a jack of all trades. mild trails and cruiser. just something fun for the family. It has a 351 33" tires and will have a 2.5 lift. the fuel economy is really not that much of a big deal, with this set up i got about 12.5 mpg over about 100 miles going about 70mph. with this kinda of vehicle its not about miles per gallon, its smiles per gallon. again i would love the o.d. but it sounds like a lot of work and money for not that big of a payoff for my dollar.
 

Rox Crusher

Bronco Guru
Joined
Dec 13, 2008
Messages
2,772
the truck will be a jack of all trades. mild trails and cruiser. just something fun for the family. It has a 351 33" tires and will have a 2.5 lift. the fuel economy is really not that much of a big deal, with this set up i got about 12.5 mpg over about 100 miles going about 70mph. with this kinda of vehicle its not about miles per gallon, its smiles per gallon. again i would love the o.d. but it sounds like a lot of work and money for not that big of a payoff for my dollar.

I just did a OD swap (4R70W) and it is pretty expensive, especially if you factor in the need to re-gear.

I didn't do it for the fuel savings as I don't think there is one when your right foot is enjoying a peppy 5.0.

I did it to improve general comfort at hiway speeds. We take ours on long trips which include extended hiway driving and a high revving whining motor doesn't allow your wife to nag you............heh, wait a minute..................why did I do this ?

;D

Seriously, I wanted it quieter and cooler in the cab, lower gears for wheelin', and the ability to create custom shift points for different uses. If I happen to get better MPG then even better.
 
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