The Stovebolt Site Forums The Shop Area Engine Shop 1960's Factory Four on the Floor, with O.D.?

Hello guys. After discussing with all you about trying to find a solution to my highway speed problems I decided to go and find a factory period 3spd OD for my truck (My truck a 1960 C10 has the 4spd on the floor) that would bolt right up. In my search I ran across a man who has a 1960 C10 6cyl. and swears it has a 4spd floor shift OD. (factory I believe). did they make this?? Before I go look at it I'd like to know for sure. I know about the 3 spd OD and that's what I'm gonna probably go with. (another small question,They do make floor shifter kits to convert a 3 on the tree , right? I just haven't looked hard enough I guess.) So once again thanks for you help in advance and hopefully I'll have a highway cruizer in no time!
-Danny

look at summitracing.com. they will have floor shift conversions for your 3 speed.
i've seen saganaw 4 speeds with a 3 speed overdrive tail section. that gives you a 4 speed overdrive. i don' think ut was ever a factpry option though

Danny,
There are a number of folks that believe that by having a 4 speed transmission that 4th gear is an overdrive. Even if he has a passenger car 4 speed - Muncie, Saginaw, or Warner, these were all 1 to 1 in 4th gear just as a standard 3 speed or your original truck grannie gear 4 speed is 1 to 1. That means that whatever your final drive ratio is in the top gear, that is as good as it gets. An overdrive will increase speed and reduce RPM's as it is less than 1 to 1 - generally 30% less. Example: 3.90 rear end ratio less 30% = 2.73 final drive ratio in overdrive.
It is entirely possible your friend has something like lms suggested but it certainly is not a stock application. Post a picture of it and someone can tell you what it is. Fred

Apacheman, here is a pic of a SM420 (4onthefloor) tranny used at that time matched up with a modern 2sp auxillary transmission AKA "overdrive unit". It is made by Gear Vendors. http://rides.webshots.com/photo/2234118210071636143MfdrhX I chose this route to get the best of both worlds. The granny gear, 4th over, and the 5 other gears inbetween.

Nice setup big.

I didn't know that it was a "married" unit. I thought another intermediate drive shaft was needed to connect the two trannies, like the old "Brownie boxes".

What is the shift linkage like for the o.d. unit? Looks like you'd need to reach out the back window to shift the overdrive. Got anymore pics with the whole unit installed in the truck?

It shifts with a button next to my gearshift knob. http://rides.webshots.com/photo/2266511980071636143qnJiTs It has a computer that will shift it out of gear should the rpms get too low to protect the inner clutch. http://rides.webshots.com/photo/2930756100071636143vpdbIM You can wire it without the computer and use anything for a switch including the one it comes with http://rides.webshots.com/photo/2651634760071636143PytRhX , but you can't screw up and leave it on when you slow down. I need the computer. To go thru the gears, I typically start in 2nd. Granny is hardly ever needed but nice to have it. Then I shift from 2nd to 3rd the way I normally do. I could go to 2nd over and split 2 and 3, but it's just not necessary. Might work well when racing 3rd over isn't always necessary but is a nice gear. As many of you know, there is a big gap between 3rd and 4th. At 30 mph, the rpms are getting big in 3rd and not enough for 4th - if you want to accelerate or are going up a hill. 3rd over takes care of that. Then to 4th. Then to 4th over if cruising on the highway. To engage the overdrive, I simply push in the clutch pedal and flip the button on. To disengage, just push the clutch pedal and flip the button off. Or just slow way down and it will do it by itself, but not recommended.

Ah...I see, it must shift with a solenoid like the factory units. I guess I was thinking it was more like an auxiliary tranny with a mechanical shifter and linkage. Do you know the ratio of the overdrive? I used to run one of the old Borg Warner 3sp. + od units in a '57 1/2 ton. I found that 1st + od was virtually identical to 2nd, and 2nd + od was pretty close to 3rd. Splitting gears wasn't really practical unless accelerating up a hill with a heavy load. For racing, I think the extra shift would lose more speed than it gained you. Depends on the ratios though. If the o.d. splits the gears more evenly it could be a big plus.

The split between the gears is very balanced. This thing rocks. I think the O.D. is 27 or 28%. Or 72 or 73%, however you look at it.

Look here on ebay.

http://cgi.ebay.com/ebaymotors/MUNC...itemZ150075107497QQrdZ1QQsspagenameZWD9V

Wow apachetrucks, if that one sells I will go up to the old junkyard & get that one sitting inside an old schoolbus fulla trannys. I thought about one in old black truck, overdrive woulda been nice. Brian

That ebay trans is actually a Chrysler trans, Chevy did use them in some of their late '70s 1/2 pickups a vans. Chrysler called them the A833, even though they had a dozen variations with most being non-OD. Do a search and you will find several guys on this forum using one of them.
The Chevy versions have 10 spline input. Most of the Mopars are 23 spline. The one in my '69 Roadrunner has 18 splines with straight cut gears, a longer tail housing and referred to as the Hemi 4spd even though they were also used behind 440's

There actually was a 4 speed with OD on 4th. gear, 3rd. was direct drive. Just one problem- - - -it was installed in Ford pickups, behind the 300 cubic inch 6 cylinder. The trans was pretty flimsy, and the too-high rear end ratio made it necessary to slip the clutch badly to get moving. You might get it to work on a Chevy with some creative adapting on the bellhousing bolt pattern and the center hole for the input bearing retainer. Use a Ford clutch disc, and a GM pressure plate to make things hook up.
Jerry

They used that transmission in 81-86 Chevy trucks. I picked one up for $200 from someone that had too high a rear end ratio. Chrysler designed them and used them behind everything from the slant six to the Hemi, passenger cars to 3/4 ton trucks. Ford did use them too, I've got afriend wih one in his truck. Mine has the Chevy bolt pattern. If I remember right OD is 26%. You will need a bell housing for the 465 for the for the input bearing retainer to clear. Here's a link for the Chrysler version.

http://www.slantsix.org/articles/4-speeds/ODA833fourspeed1.htm

If you buy one get the shift linkage with it, they are very hard to find. Note that the 3rd and 4th shift lever on the tranny is upside down (or is down sideup :confused: ) a give away that is an OD.


Larry

That must be the tranny I had in a short Dodge 1/2-ton, a '78 I think, with a 318. I liked it, because it felt exactly like a 3-speed, but with a whole, long top gear above the 3rd. If you put it in at, say, 55 mph the engine speed would drop to a fast idle, and she made phenomenal fuel economy.

My friend once put 50 miles on it following our bikes on a canyon road before he found the top gear.

I've got one of those 833 Chrysler transmissions for the Chevy truck application. The only thing stopping me from using it is that I'd have to fab a cross member and get the side motor mounts installed.
I may end up doing it yet...but I'm still torn between an Auto trans or 4spd OD.

I scored my trans, shifter and bellhousing from a guy at work cleaning out his garage--$50!

Hey Hot Rod Lincoln: When you say they had a too-high rear gear ratio and you needed to slip the clutch badly to get it rolling, what exactly do you mean?
I always ask for clarification when guys talking about "high" gear ratios: would your "high" be 3.23, or 4.11?
Either way, why would a 3spd manual have any more problem getting rolling than a 4spd Granny, starting out in 2nd gear?

Brad

Brad, I can remember those Fords-they had no power & very high(low numerically) rear ends. You had to slip the clutch or they would shudder so bad you would think they were coming apart-kinda like when you try to start off in second instead of first. Ford called it a 3 speed w/od. A buddy of mine had one behind a 225 in a 84 Dodge Ram back in the 80s, same deal. They were rough in town but OK on the highway. Brian

I seem to remember the Fords having a 3.00:1, or possibly a 2.85:1 rear end in some of them. I just put a clutch in one a couple of months ago, and the setup hasn't gotten a bit better with age. Back in the early 80's, I used to swap rear end gears to 3.55's to get some pulling power for my friends who tried to tow bass boats with those rigs. They would burn out clutches on launch ramps regularly.
Jerry

The aluminum case topshifter Ford fourspeed, overdrive transmission, T170FT (TOD), was only available in the 1984-1985 six cylinder pickups. It is being modified by at least two companies for use in Model A's with tourque tube adapters. I'd love to have one modified for Chevrolet torque tube use, but haven't heard of anyone doing that modification.

Was that the one Ford called a SROD? Brian

No, the SROD was a side shifter, iron case transmission. Some people called them pseudo top loaders. SROD = Single Rail OverDrive.