Replacing 4 Speed w/ 5sp.
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Junior User
Joined: May 2006
Posts: 81
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From: New Jersey - SOUTHERN
Replacing 4 Speed w/ 5sp.
Hey Folks,
The truck: 1985 f250 diesel (6.9L) with 4 speed manual, 2WD.
For one, I don't have a tachometer (yet) but I can hear that the engine is not liking me when I try and do 55-60 mph so I try not to do that. Im assuming the rear axl ratio is pretty low (numerically high) because of this.
Anyway, will a 5 speed be able to be swapped in in place of the 4 speed for the overdrive gear? or is it a major conversion? Are there any other alternatives? I'd really like to be drive this truck a little more on the highways. I don't need to speed or anything like that but when im on the highway/freeway, people are constantly up my a$$ for driving "so slow".
Also, is it worth the swap? What vehicles got a 5 speed trans that will fit this motor?
Any Input much appreciated!
The truck: 1985 f250 diesel (6.9L) with 4 speed manual, 2WD.
For one, I don't have a tachometer (yet) but I can hear that the engine is not liking me when I try and do 55-60 mph so I try not to do that. Im assuming the rear axl ratio is pretty low (numerically high) because of this.
Anyway, will a 5 speed be able to be swapped in in place of the 4 speed for the overdrive gear? or is it a major conversion? Are there any other alternatives? I'd really like to be drive this truck a little more on the highways. I don't need to speed or anything like that but when im on the highway/freeway, people are constantly up my a$$ for driving "so slow".
Also, is it worth the swap? What vehicles got a 5 speed trans that will fit this motor?
Any Input much appreciated!
Tuned
Joined: Jan 2006
Posts: 290
Likes: 1
Just a thought here, but I would be thinking of changing the rear end gears. Don't have to shorten drive shafts, mess with differnt cross members and have you priced the 5 speed yet? Never had a desmell, but I think it's got some low end grunt. Don't know if you will miss not pulling logs out of the swamp or not. Not sure what rear end you have but on some Fords a swap could be done in a half day's time, with out lighting your wallet too bad.
Thread Starter
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Junior User
Joined: May 2006
Posts: 81
Likes: 0
From: New Jersey - SOUTHERN
I've done rears before...NO WAY will i do it again unless I absolutely need to! Too many rusted bolts and what not. I also like the gearing in the rear thats' there now, it just needs an overdrive gear for when im on the highway!
Thanks for the input though! Much appreciated!
-Al Conforti
Thanks for the input though! Much appreciated!
-Al Conforti
Elder User
Joined: Sep 2003
Posts: 794
Likes: 1
From: Portland, OR
I'm not a diesel tranny swap expert, but I believe the ford diesel bellhousing has stayed the same from the 6.9 up. You should be able to find a ZF 5 speed for pretty cheap from a late 80's early 90's 6.9/7.3 2wd 5 speed truck. Get the driveline from the same truck and you're set. The only complication I could see would be if your truck has a manual clutch linkage. I've heard ford stayed with the mechanical linkage into the early 80's, but if your 85 is hydraulic you're good to go. Is your 4 speed a granny first gear tranny or do you start in 1st? I know ford used a close ratio T-19 4 speed non-granny transmission from around 83-87 in 460 and diesel trucks. This is a very desireable transmission if you have it and I personally would go through the hassle of swapping rear gears to keep it. Good luck.
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Joined: Apr 2004
Posts: 34,495
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Not cheap, but easy:
http://www.gearvendors.com/
Bolts on to your trans, you now have 8 speeds.
Otherwise, the ZF is the answer.
http://www.gearvendors.com/
Bolts on to your trans, you now have 8 speeds.
Otherwise, the ZF is the answer.
