The Stovebolt Site Forums The Shop Area Driveline Borg Warner Tranny problems

Hopefully someone else here has had this issue. I have a 1950 Chevy 3100 with a 261ci and a Borg Warner OD transmission. The Tranny sometimes will not shift when the OD is engaged and it will just free spin as if it is in neutral. I just have to keep messing with the shifter and the gas pedal to make it engage, and this can be dangerous if I am pulling out on a busy Highway. I was taking a look at the tranny and noticed it is covered in oil. It looked like it might be coming from the area where the speedo cable hooks up to the tranny. Could low oil level cause the problem with getting the tranny to engage? Or is this and internal gear issue? Also is that a likely place to leak oil from?

That transmission will free wheel when the overdrive is engaged if you let up off the gas. There are two areas that must be filled with oil. The overdrive fill plug is to the rear . Make sure that the speedometer gear is seated inside the transmission fully then tighten the cable. If the oil level is low like any transmission it will not shift properly. I took my overdrive out and put my regular transmission back in because I did not like the freewheeling with the drum brakes on the freeway. Gook luck with thr repair.

It does not always have to freewheel.

Ed

No need to remove the OD tranny, just pull the lockout cable and it's a regular 3sp.

Yup. I cant wait to put mine in! Its sitting on the garage floor next to the truck. As for the freewheeling issue....... from all the research ive done i would say you could be having a issue with the Freewheeling clutch inside. Thats what freewheels one way and grabs the other way. Ive read the wrong oil can also cause issues with them.

All BW overdrives will free wheel at under 30mph unless locked out. That is the speed the governor breaks the circuit that activates the solenoid. Ignore this if the system has been botched up with toggle switches.

Thanks for all the responses. Does anyone know the correct oil weight for these transmissions? I assumed it was 90 weight gear oil.

As Evan stated, all overdrives will freewheel under 30mph. If freewheeling occurs over 30mph it could be either a internal mechanical issue or possibly an electrical issue. However when the power is applied normal operation should resume. It has been my experience that most overdrive problems are electrical. What you have is unusual as you state that it disengages under power.
That seems more mechanical to me.
The main mechanical components of an overdrive system consist of the planetary set, free-wheeling cam assembly and the blocker ring components. Any or all of the aforementioned components could cause the overdrive to malfunction.
Check the oil level, insure the cable is installed correctly and properly operates the lever, all electrical contacts are clean and tight, and all electrical components are working.
If all that checks out, the unit likely has to come out for a tear down and repair.
Fred

Having re-read your original post, the fact that you have to keep shifting the transmission is an entirely different problem. What you refer to as freewheeling is actually an age old problem with the Muncie SM318/319 transmissions. They literally "pop out of gear" into neutral. This is caused by worn components in the transmission. That transmission uses a syncro "drum" that contains brass rings that engage 2nd and 3rd gear. The rings wear and can also disengage from the syncro assembly. Other related wear components are the shift fork, the engagement ring on the syncro assembly, and the small spring type engagement rings on the gears themselves. Some items that can cause additional problems are loose motor mounts, incorrect placement of motor mounts in modified vehicles, bad u-joints, incorrect driveshaft angle, and worn/sloppy shift levers and arms.

The 55 shop manual I have recommends 90W mineral oil. It is usually not stocked at most parts stores but can be ordered. There are better and more reasonably priced modern products available in my opinion. Don't use any synthetic products.

Fred

I would get rid of that transmission and look for a S-10 T-5 transmission with .72 overdrive. Pretty easy swap. The 92 and earlier transmissions have the same mount pattern as the early muncie 318. There is no shift linkage cause its inside the trans. You will have to shorten your driveshaft as they are about 3 inches longer. There are two types , World class and Non World class. I'm putting a 92 Non World Class in my 56 3100 currently.

I almost went that route myself but I really wanted to keep the 3 on the column. I enjoy driving it too much to move it to the floor. The BW overdrive trannys do work VERY well when set up properly. So well in fact that the truck I borrowed on my wedding day had one and after giving it back to the owner he asked me to take a look at it for him because he said the overdrive wasn’t working........i said yea it actually is. It works so good you can barely even tell it shifts. After showing him he was amazed he couldn’t feel it but just barely hear it when the rpms dropped.