The Stovebolt Site Forums The Shop Area Driveline OD trans for 55 chevy series 1

Newby here. I have done a lot of reading and want to verify if I am correct. I have a 55 chevy series 1 3100 with 3 on the tree all original down to the 6 volt. Once I get it back from the body shop I want to upgrade the drivetrain. Looks like the best bolt right in trans with OD is the SM319. It sounds like this will bolt right in with no modifications. I will be looking for one.

Does anyone know what year vehicles this trans was used?

Will I need to upgrade the voltage to 12 to power the OD solenoid?

I hope to get a trans that will bolt right in. I assume there are markings on the side of the trans indicating SM319

There are no casting numbers or markings on the transmission that specifically designate the SM319 OD. It will have an R10 H or K designator on the OD unit however. They were used from 1955 through 1965 in both cars and trucks. The differences are the side cover and lower mount holes threaded on trucks. This trans uses basically the same case and internal gears as your current SM318 with a BW R-10 overdrive replacing the tail shaft portion. There are 6 volt solenoids available as other manufacturers used od's in 6 volt vehicles prior to 55. You would also need a 6 volt relay for it to operate if this is your plan. It would probably be better to convert to 12 volts.
There is lots of information on this site regarding overdrives including pictures and wiring diagrams.
Fred

thanks. I have seen a lot of info including the wiring diagrams. first measure is to find one of these that will fit the 55-1 I would think the 55-2 had basically the same driveline.

Also, Fred can tell you anything about them. Hes the resident expert. Very thankful for the help he has given in the past. Finding one is hard these days. I have two (one for parts) and would never pass up a deal to get a third. Keep looking and you will succeed. All of the manuals for it are available here:

http://devestechnet.com/Home/HowTo#driveline

It really is a nice improvement to the drivetrain. I really do like the way they work and improve things for today's driving.

They appear on eBay quite regularly. Most of them are pick up only. Right now there is one on eBay that the guy is willing to ship. I have bought several on eBay and was pleased with them. I drove a Y-Block with an OD for many years. They use the same OD but have a BW main box which is much tougher than the Muncie, but I managed to tear them up back in the 60's. Once I got married, I never tore one up. An OD with 3.90 gears is a real sweet driver. If you have the 55 1st, it should already have the 3.90 open gears. Use the shift cover from your current transmission. Wire her up like the instructions tell you, and you should have a very roadable machine with very little work and about $500 spent. Note that I didn't use the word invested. Money put into projects is money spent, not invested.

I guess I will have to refine my search on EBay to saginaw transmission with overdrive. The BW is not getting any hits. thanks for the heads up on that.

I have a friend who is getting on the older side. He was taught by his uncle to flip a switch on the dash to put it in overdrive. This isnt the normal way to connect an overdrive. Fords have a switch on the accelerator pedal. Chevys have a bracket on the carb actuating when the accelerator linkage hits the switch. Normally anyway.

So my friend has this problem. He forgets to flip the switch! No big deal you say? When you put it in reverse with the switch activated, it ruins the transmission! I hope Fred or someone can explain what happens. Its a very expensive fix. So, please hook it up using the correct wiring diagram or you will be at the trans shop more than driving the vehicle! I call him about once every few months offering to fix that. He says I will be there, then a few trans fixes later, I call again.

Do your search for Chevrolet overdrive. Most sellers don't know that the OD part of the transmission is BW and the main ox is Muncie. A BW search will usually only turn up Ford stuff because Ford's OD transmissions had BW front boxes with the BW OD unit behind them. Saginaw was only used for a year or two in the late 60's and they are very rare. I stumbled across one at a swap meet a few years ago and the guy didn't know what he had.

Deve, I always had manual switches on my Y-Blocks and ran them in reverse OD. You just had to make sure you put it in OD while standing still and leave it there until you stopped. I got a ticket for doing 40 in a 30 on our Main St. going backwards a few weeks before this picture was taken.

https://plus.google.com/photos/1081...1431006034&oid=108197707187186692269

A few months earlier, I got a ticket for going 120 on Main street, but I was going forwards. You sure have to hold the steering wheel straight at 40 in reverse. Its like driving a forklift.

I did find two transmissions on ebay. according to the sellers one was originally from a 61 impala 283 and the other was originally bolted to a SB 265 c.i.d. Will either of these bolt onto a 1955 235. I am guessing that chevy driveline did not change between the series 1 and 2 in the style change mid year. It is times like this when I really miss Dad. He knew this stuff inside out.

Deve,
You have to be extremely careful and pay attention if you are going to use the toggle switch method which is directly connected to the solenoid. This is not to be confused with the kick down switch which is a component of the original configuration. A good thing to remember is that with the overdrive engaged - lever pushed in - the car will roll in 1st, 2nd, or 3rd gear when parked. It will not move in reverse. There is a plunger that prevents the OD engagement in reverse but it's possible to override it if the solenoid is engaged in the pawl electrically. If you forget to disengage the switch and attempt to back up, nothing but bad things happen, it can break the pawl, blocker ring, or other expensive and hard to get internal components.
Eric,
Go back and re-read my original post. It doesn't matter if the unit came from a V-8 or 6, car or truck in those years they are all the same except as noted.
I seriously doubt that most ebay sellers know if their OD transmissions are any good or not. Most have some sort of disclaimer like they don't know anything about it or it came from a friend, or found in a barn. It essentially means that you are on your own and it likely needs to be gone through before it can be used. I buy them at swap meets and Craigs List all the time and most are well worn.
If it has a 4 bolt side cover it is a Muncie/BW (55-65), if it has a 7 bolt side cover it a full syncro Saganaw/BW (66-69).
Fred

Just recently my transmission was damaged by me putting it in reverse with OD engaged. I didn't realize it but the governor was grounding with the truck stopped. This caused the solenoid to stay engaged when I stopped. I stupidly forced it into reverse. It was an expensive mistake. $250 for a used planetary gear assembly plus labor.

I wired mine with a dpdt toggle switch in place of the floor or carb switch.

Yes, I felt it worth mentioning about the reverse issue because those ARE hard to find parts and whats more... those can be the ones you buy off ebay! You just never know. My new build has the Chevrolet style kickdown off the carb and will be wired in accordance with the official wiring diagram. I think then I should be okay.

The planetary in a OD works much like the 2 speed Eaton. Once it has made the shift, it doesn't care if it goes forward or backward. I tore up a lot of input shafts and cluster gears, but I never tore up an OD section. I still have a lot of spare parts on hand.

https://plus.google.com/u/0/photos/...9755236946&oid=112636930370126476644

https://plus.google.com/u/0/1126369...1763522338&oid=112636930370126476644

GM and Ford solenoids are a little different. NOS GM go for big bucks on eBay because they fit Corvette.

https://plus.google.com/u/0/1126369...5530771442&oid=112636930370126476644

I even keep complete spare transmissions.

https://plus.google.com/u/0/1081977...2464951986&oid=108197707187186692269

The part where the solenoid mounts is what makes the difference between a Ford OD and a GM OD. It adapts the rear section to the front section.

There is nothing wrong with wiring them according to factory. One of my 56 Fords is completely stock and the OD is factory wired.