manual 5spd v. 4spd
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New User
Joined: Jun 2004
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manual 5spd v. 4spd
I am doing a diesel conversion into my 79 bronco, mostly just to do it, but the extra mileage and alternative fuel options would also be nice.
I am looking for a 7.3 5spd, but they are really rare (in the condition I am looking for). I did find an 86 F250 with a 6.9 4spd all rusted out, but mechanically sound. What is the difference between these transmissions (90's vintage 5spd and the 6.9 4spd)? overdrive, granny gear, etc.
Please help my understanding.
Thanks
I am looking for a 7.3 5spd, but they are really rare (in the condition I am looking for). I did find an 86 F250 with a 6.9 4spd all rusted out, but mechanically sound. What is the difference between these transmissions (90's vintage 5spd and the 6.9 4spd)? overdrive, granny gear, etc.
Please help my understanding.
Thanks
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
Transmission ratios for T 19 and ZF 5
There are several differences.
The five speed is an aluminum housing, the four speed is cast iron which makes it stronger.
The five speed is an overdrive transmission, the four speed is direct drive.
The four speed Borg Warner T19 came in two different gear ratio sets. (5.11,3.03,1.79, 1 used behind gas motors more than diesels)
(4.02,2.41,1.61,1 usually behind a diesel).
The ZF 5 came with four different gear ratio sets and two different models (S42 and S47).
(5.72,2.94,1.61,1,.76 R 5.24)(S47)(S42)
(5.08,2.61,1.53,1,.77 R 4.66)(S47)
(4.65,2.60,1.53,1,.77 R 4.35)(S42)
(4.14,2.37,1.42,1,.77 R 3.79)(S47) this seems to be the most common one behind a diesel
The four speed has a bell housing and transmission.
The five speed is an intergral transmission/bell housing.
Both transmissions will hook up to the same transfer cases, Borg Warner 1345 and 1356 are the most common.
The gas motor ZF 5's will not fit a diesel engine.
The ZF 5 will give much better mileage than the 4 speed will due to overdrive.
The five speed is an aluminum housing, the four speed is cast iron which makes it stronger.
The five speed is an overdrive transmission, the four speed is direct drive.
The four speed Borg Warner T19 came in two different gear ratio sets. (5.11,3.03,1.79, 1 used behind gas motors more than diesels)
(4.02,2.41,1.61,1 usually behind a diesel).
The ZF 5 came with four different gear ratio sets and two different models (S42 and S47).
(5.72,2.94,1.61,1,.76 R 5.24)(S47)(S42)
(5.08,2.61,1.53,1,.77 R 4.66)(S47)
(4.65,2.60,1.53,1,.77 R 4.35)(S42)
(4.14,2.37,1.42,1,.77 R 3.79)(S47) this seems to be the most common one behind a diesel
The four speed has a bell housing and transmission.
The five speed is an intergral transmission/bell housing.
Both transmissions will hook up to the same transfer cases, Borg Warner 1345 and 1356 are the most common.
The gas motor ZF 5's will not fit a diesel engine.
The ZF 5 will give much better mileage than the 4 speed will due to overdrive.
Last edited by Dave Sponaugle; Jun 11, 2006 at 02:42 PM.
Laughing Gas
Joined: Mar 2006
Posts: 1,083
Likes: 1
From: Fitzpatrick Alabama
What gears are currently in the Bronco. If it already has high end gears, (3.55, 3.08, etc.) It will get good mileage anyway. While an overdrive will still help, the direct drive won't be bad. My F250 4sp manual 3.55 gets around 14-16 mpg. Thats better than what that Bronco is getting now.
