The Stovebolt Site Forums The Shop Area Driveline Transmission swap

Last time I took out a transmission was in the 80's with my dad. I'm going to attempt to remove the standard 3 transmission and put in an R10 overdrive trans. I would be grateful to know if anyone has any hints or advice before I start. Chevy step van with 261. Thanks

Hy Chaz 58, I am going to assume this project is on a 1958 step van. Drain transmission, remove driveshaft, remove shift rods from shift levers on transmission, remove speedometer cable, remove the flywheel cover from under the flywheel, remove the four bolts which retain the transmission, the top two are on the outside the bottom to have to be accessed from inside the bellhousing. Now the transmission can be removed by pulling away from the engine until the transmission input shaft clears the bellhousing, depending on your strength this can be done by hand, but I would recommend a floor jack to support the weight of the transmission, good luck.

Coming back to me. Thanks pal!

Cheap Harbor Freight transmission floor jack is worth the investment. Saves on visits to the back doctor. 🛠

Transmission came out easily, but I noticed the shift arms are opposite of the original transmission. Reverse and first are where second and third are. The other thing is one arm is pointing up and the other down. Seems like I just need to point them both down and make sure the arms are hooked up correctly, but a bit strange.

The shift arm configuration has to do with how the 3 on the tree shift levers are designed. Some used a bell crank which reverses the direction of the throw at the transmission lever, some did not.

If I remember correctly my stock torque tube transmission had the front shift arm pointing up. Now current transmission both are pointing down
It’s 3 on the tree don’t have any shift issues just gears are close so very short shift pattern.
Just a little adjustment on the shift rods on the shift box.

There are about 20 different side cover configurations for those transmissions depending on year, car, or truck application. Some have different shaft lengths on the 2/3 and 1/R posts and clocking position depending on the vehicle it was designed for. I suggest you use the side cover from the transmission you removed. Also be aware that the 2/3 shift fork is a high wear component, it would be a good idea to replace it.
Fred

I'm having difficulty in finding part numbers for the front & back u-joints. The front is obviously smaller. Does anyone have a cross reference book for these? 58 Chevy 3400 - 3/4 ton.

If you can find a parts store with the old school paper catalogs instead of a computer, (and an old geezer counter man who knows how to use it) Spicer and a few other driveline component makers have dimensional charts that allow you to use measurements from the old U joints to select the right application. There are even "adapter" U joints with different diameter and spacing of the cups for the shaft and yoke for special applications.
Jerry

Thanks Jerry, I thought I might have to go that route. The Napa guys here have the catalog and know their stuff.

So I was anticipating putting in the bottom mounting bolts, but no threads! I guess what I've read is these are for dowels for lining up transmission. Anyone know what size these are usually?

Transmissions intended for use in cars as original equipment don't have threads in the bottom mounting ears- - - -passenger car bellhousings have threads in all the holes and the bolts go in from the rear. You'll need to use bolts and nuts on the bottom. Try 1/2-13 grade 5 or grade 8 bolts.
Jerry

Neither the bellhousing or transmission have threads on the bottom ears.

Yep- - - -you're combining a car transmission with a truck bellhousing. Just put nuts inside the bellhousing and screw 1/2-13 bolts into the lower holes in the transmission. Problem solved! Use lock washers under the bolt heads and/or blue LocTite on the threads when you install those lower bolts.
Jerry

Will the dowel pins not hold it good enough on the bottom Jerry?

Definitely not! You need four TIGHT bolts to hold the transmission to the bell housing! Trying to use just the two top bolts to hold the transmission on will result in breaking the ears off the transmission case in just a few miles of driving.
Jerry

Sounds good. Appreciate your wisdom.

Swap is almost complete. I'm looking on the side of the transmission with the oil fill holes and there are three on the side and a drain at the bottom. Why three? Is one a drain for the overdrive end?

With the shift arms opposite on this transmission what is the difficulty level for changing the side cover and putting in the one from the original? I've not opened a transmission before.

I went ahead and took off the side cover of the old transmission to see what was involved. It looks like I need to have the forks straddling the gears. Does anyone have any special things I need to know before I swap them? I know this probably transmission 101, but I want to do it correctly.
Thank you.

Just make sure the shift forks reside in a proper location before installing.

Ed

What is that location please?

The U-shaped shift collar at the rear straddles the low-reverse sliding gear. The front shifter with the narrow slot engages the raised ring on the 2-3 synchronizer. With the transmission in neutral and the shifter lockout on the side cover in the middle position, it should be very obvious where those parts fit, unless your name is Stevie Wonder or Ray Charles! The forward shifter with the narrow slot is notorious for getting worn, so be sure the slot isn't V-shaped.
Jerry

Knew I could count on you Jerry! I sure wanted to get that done today, so I appreciate the assistance.

Took the step van for a test drive today with the overdrive. I left it in direct drive and heard a clatter that made me worry. I got about 4 pints of gear oil in her before I left. I read as much as 7 could be used. I don't see how as it was running out the overdrive fill hole at 4.

I went 62 mph on a test drive, quite exciting.

Make sure the brakes and steering are up to the challenge of keeping up with traffic! Negotiating an unexpected sharp turn at speed in a glorified saltine box can increase your pucker factor, also. Have fun, but be careful!
Jerry

The gears are grinding a bit, especially from second to third. I've adjusted the clutch a bit, but still grinding. I swapped out the side cover from a truck transmission to the overdrive car transmission. I've read that the synchro might be worn. Anyone have any idea on other things to check? Thanks

You installed a used overdrive transmission and you have clattering and grinding. It's been my experience, having rebuilt 9 of them last year and 5 this year that they are generally well worn. You likely have bad bearings and worn syncros. There can be problems lurking in the overdrive component as well.
You cannot get more speed out of an overdrive transmission with the overdrive locked out, it would still be 1:1 which is the same as the transmission you took out.
The capacity is slightly less than 4 pints.
Fred

OK, I'm going to say it. I have no intention of hurting anyone's feelings.
If someone gave me a complete R10 overdrive transmission, I would not install it in my truck. Parts are hard to find, and ones in good condition are hard to find as well.
Another reason not to go that way is, since you will be going away from stock, why not go with a far superior option of a T-5. They are the ultimate upgrade for a Stovebolt engine. Another bonus with the T-5 is getting away from the problematic 3 on the tree shifter.
Those R10 transmissions are somewhat in demand, so if someone gave me one, I could easily sell it for more than what a junkyard T-5 goes for.
Carl