4spd overdrive
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Junior User
Joined: Mar 2006
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4spd overdrive
I have a 4spd od tranny (manual trans) out of a straight 6 any Idea on the ratios in this trans? dont have the case#'s but can get them if it helps! It seems that there is a gap in the gearing IE: rpms drop way down shifting from 2nd to 3rd, as opposed to 1st to 2nd, any help would be appreciated!!
Elder User
Joined: Sep 2003
Posts: 926
Likes: 3
From: SE, Michigan
It sounds like it could either be a Single rail four speed overdrive (SROD) or a Top mounted shifter 4-speed overdrive transmission (TOD). If the shift pattern has reverse to the left and up its the SROD, if reverse is to the right and down its a TOD. Here's some pictures from my shop manuals with the pictures and diagrams of the two transmissions. Hope these help.
https://www.ford-trucks.com/user_gal...&albumid=20257
Oh, I also know about the large gap in between 2nd and 3rd as I have a 82 F100 with the SROD. I believe the gear ratios might be:
1st 3.29
2nd 1.84
3rd 1.00
OD 0.81
Not completely positive but I know its close.
https://www.ford-trucks.com/user_gal...&albumid=20257
Oh, I also know about the large gap in between 2nd and 3rd as I have a 82 F100 with the SROD. I believe the gear ratios might be:
1st 3.29
2nd 1.84
3rd 1.00
OD 0.81
Not completely positive but I know its close.
Elder User
Joined: Dec 2005
Posts: 557
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Hey, ive got a 4 speed in my 84 F250 with the v8. I got a C4 manual tranny, i dont know why the gear ratio changes so much from 2nd to 3rd but its the same way for me. 1st gear is the tow gear for me, max rpm is like 6mph maybe. When im in 4th goin 70 its 3,000 on the tach.
Cargo Master
Joined: Apr 2003
Posts: 2,057
Likes: 424
From: Too close to Houston
I found this info about the single rail overdrive. Yours is probably one of these.
It is important to also know that truck versions of these transmissions exist and sometimes cannot be told apart by someone who is not knowledgable. They use larger front and rear bearings and a large front bearing retainer. They came in cast iron, the SROD alloy configuration and as a top cover shifted or tower shift design mainly in 4 wheel drive Broncos.
Ratio #1: 3.01 1st, 1.78 2nd, 1.00 3rd, 0.79 4th and 3.01 Rev.
Ratio #2: 3.25 1st, 1.92 2nd, 1.00 3rd, 0.78 4th and 3.25 Rev.
It is important to also know that truck versions of these transmissions exist and sometimes cannot be told apart by someone who is not knowledgable. They use larger front and rear bearings and a large front bearing retainer. They came in cast iron, the SROD alloy configuration and as a top cover shifted or tower shift design mainly in 4 wheel drive Broncos.
Ratio #1: 3.01 1st, 1.78 2nd, 1.00 3rd, 0.79 4th and 3.01 Rev.
Ratio #2: 3.25 1st, 1.92 2nd, 1.00 3rd, 0.78 4th and 3.25 Rev.
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Super Moderator
Joined: Apr 2004
Posts: 34,470
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I have one that is all iron, with side mounted linkage.
As to why the ratios are what they are, well, that was a Ford "Better Idea" I suppose. 1st to 2nd is good, just like an old 3 speed. 2nd to 3rd sucks, just like an old 3 speed. 3rd to 4th is fine. As it should be.
With a V8 and some rpms, the gap can be jumped. Sucks with a six between 30 and 50 mph. Add a hill and some curves to a 35-40 mph road, and you just want to go trade it off....
Info:
\
http://www.davidkeetoploaders.com/imposters.htm
http://www.motivegear.com/tech_info/...nny_guide.html
As to why the ratios are what they are, well, that was a Ford "Better Idea" I suppose. 1st to 2nd is good, just like an old 3 speed. 2nd to 3rd sucks, just like an old 3 speed. 3rd to 4th is fine. As it should be.
With a V8 and some rpms, the gap can be jumped. Sucks with a six between 30 and 50 mph. Add a hill and some curves to a 35-40 mph road, and you just want to go trade it off....
Info:
\
http://www.davidkeetoploaders.com/imposters.htm
http://www.motivegear.com/tech_info/...nny_guide.html
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Postmaster
Joined: May 2004
Posts: 2,854
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The overdrive trannys have a 1.00 third gear, so you don't have alot of options in design. Some users are gonna want a stump puller 1st, so with just two gears to work with, you compromise. For me, I'm just thankful for the over drive....1600 rpm at 60 mph.
Lead Driver
Joined: Oct 1999
Posts: 6,767
Likes: 547
From: Kalispell, MT
Yes, my 86 150 4x4 has a TOD behind a 5.0 EFI with 3.50 9" ltd slip rear.
The TOD is not as heavy duty as the 4 spd/granny low. This one has been rebuilt twice in 300K miles and I'm pretty careful shifting it.
The TOD is not as heavy duty as the 4 spd/granny low. This one has been rebuilt twice in 300K miles and I'm pretty careful shifting it.