The Stovebolt Site Forums The Shop Area Driveline Saginaw 3-speed Overdrive Question

I found one of the hard to find Saginaw 3-speed overdrive transmissions. It is now in my 1950 1/2 ton panel truck, and I took it for a test drive today. I converted my original drive train to the straight drive version of this transmission around 1979, so this was an easy install for me. The adaptor that I made to connect the straight drive transmission to the original cross member fits also the overdrive version. I have the overdrive locked out, so it drives the same, as I expected. A future project will be to change to a differential with a 3.73 gear. Then I will work on the overdrive. I have done no wiring yet.

I have a problem that I have to fix: I cannot shift into reverse when the overdrive is not locked out.

There is a pin that is meant to push the OD shift rod into the lockout position when the transmission is shifted into reverse. That pin looks too small for its hole. When the OD shift lever is in the OD lockout position that shift lever holds the reverse engagement pin it a straight position. I think that is why I can shift to reverse when the OD is locked out. When the OD shift lever is in the OD allowed position that pin droops down. It appears that it is engaged by the cast portion of the shift forks when the transmission is shifted to reverse. I cannot see with the shift fork side cover installed, but the idea of a drooping pin being engaged by a rounded cast surface does not seem logical when compared to how well every other operation is made to happen. I think that droopy pin may be what is preventing me to get reverse gear to engage when I do not have the OD locked out.

I have found a lot of mention of these transmissions on this forum, but I cannot figure out what is wrong with this one.

Has anyone had one of these apart?

Here are the pages that I found to be most helpful. I had never had one of these, or any OD, apart.

http://devestechnet.com/Figures/bwrebuild.pdf

The pin that I question is shown in place in the first 4 photos.

Thanks!

The simple fix would be to put a bushing into the hole so the pin doesn't drop out of position. There's probably one missing. The Borg-Warner overdrive will be more or less the same unit, regardless of which transmission it happens to be mated with. I would strongly suggest finding a more reliable source for your repair information.
Jerry

The simple fact is that the system is designed to prevent the overdrive from being engaged in reverse.
Mainly because it will destroy internal components such as the blocker ring, the ONE WAY roller clutch, and
likely the planetary set. The reference material that is shown on Deve's site is from the Old Burb Website
and is a good reference. Yes I have rebuilt overdrive transmissions for more years than I care to mention.
Fred

Thank you both for your answers. I've been researching for a long time, and I have learned of the reason for locking out reverse. I'm happy that I learned that part by reading, not from experience. I was thinking of making a bushing. I think that I would be able to get one in place by removing only the side cover. Before I started messing with it, which will not be soon, I wanted to ask people who do know what these look like. Besides the instruction that I reference above, I have a copy of the BW repair instruction and a copy of Ford's version. I will look more closely at those to see if I find reference to a bushing. I have also an OD transmission from a 1955 Chevrolet car that I can take apart to look at.

This posting from the 67-72chevytrucks forum shows a drawing from the '68 Owners' Manual. It shows a one piece OD shift rod.

https://67-72chevytrucks.com/vboard...ighlight=saginaw+overdrive+repair+manual

I re-read the instructions in the BW manual and in the Ford manual. Both instructions show a shift rod that looks like the one shown in the above drawing. My shift rod is different and looks like the one shown in the instruction that I linked in my original posting. The middle photo on page 4 of that instruction shows the two piece shift rod. The pin that I think I have a problem with is the one shown in the lower left. I do not find reference to a bushing. Something is different about mine. I'll keep looking.

I took another look at the photos in your original posting. I have not seen a 2 piece rod in any of the OD's I have worked on. Later photos show it protruding through the case as it should. Yours is likely broken and needs to be replaced. I have one in my stock from an earlier unit. I'll take a look at it and see if there is any way they come apart.
Fred

Thank you for having a look. It does not look like it is broken. It does look like the two piece one shown on page 4 of the instruction that I linked. Something about mine, and the one in the instruction, is different.

The earlier ones are a solid shaft without the "bulb" on the forward section. Later R-10 units have the bulb and a recess
machined on the adapter plate. The spare one that I have is of the later type. It looks like a single shaft with the bulb
possibly pressed on. However I don't see how the shaft could be 2 separate pieces unless it was damaged.
I can't see how it would work as two pieces and have never seen a sleeve or anything else to hold it in place.

I found a shaft in an R-10 unit that I previously worked on that was from a Rambler or something. It was too short
and would not engage the reverse lock out cam on the side cover. I subsequently replaced it and everything worked.
Fred

Thank you for checking your parts and again for your further advice. This is the first one that I have had apart. Now that I have it back together and know what to do with it I call the rebuild easy. I do not have any others to look at. A friend has one on his shelf that he plans to put into one of his trucks. He lives in a different state, and it will be a while before I am there again. When I am there I will ask if I can take his side cover off and look for differences there.

For now I am driving the truck with the OD locked out, so I do have reverse. I earlier (1979 or 1980) changed to the straight drive version, so the truck drives no differently.

I have no wiring or OD accessories installed yet. I plan to install all of that when I find a 3.73 differential and am ready to put that in.

Robert,
I just obtained a SM326 Saganaw 3 speed with the R10Q BW OD. I removed the side cover to look at the reverse
lock out rod you were concerned about. It is solid and working normal.
I don't see any way it would work in the condition you described.
Fred

Thank you for checking that, Fred. For now I have the OD tie wired in the lockout position and am driving it just as if I still had the straight drive in place. I have a friend who has one on his shelf, but he lives in a different state. I plan to be nearby this coming May, and I will ask if he will allow me to take his side cover off to look at how his reverse pushes back on that rod.

Did you happen to notice what activates that rod when reverse is engaged? I did not have the side cover off my straight drive and my OD version side by side, but I did not see any provision to make the reverse engagement activate, of push back, that rod.

Again, thank you for your help.

Robert

On the SM-319 the lockout rod is moved by the 1st.-reverse shift fork as it goes into the R position. The rod is spring loaded into the "released" position so it disengages when the transmission comes out of reverse. The Saginaw most likely works in a similar fashion.
Jerry

It operates the same way on the Saganaw, and other applications as well. The plunger releases the sun gear from the
planetary but does not change the manual cable position. Some earlier BW units had an electrical reverse lock out switch
that eliminated the governor. Same principal, just more electrical components to deal with.
Fred

Thank you for your advice. A man on another forum sent a photo of the first/reverse fork on a 4 bolt cover version. SM-318 or SM-319 maybe? I have not yet learned where to learn those numbers. That shift fork shows a tab that works to push the rod to the rear push. I did not see anything more than a cast nub on that fork of my version. SM-326 maybe?

I have a 4-bolt cover version that I can take apart, if I get that motivated. I am most looking forward to being able to look at the one that is like mine that my friend in another state has in a couple of months.

Also, I do not rule out operator error on my part. I trust the man who sold me mine. He used it until he decided to go to an automatic and never had a problem with it.

The actuator part is really not on the 1-R fork, it is really a cam designed into side cover mechanism that holds the fork.
The side covers are substantially different between the SM319 and the SM326 but they both accomplish the
same function. It really doesn't move the shaft very much to disengage the sun gear when reverse is selected.
Fred

Thanks! I saw that cast cam before I put the side cover on. Of course, I cannot see its function with the cover in place. The entire internal parts are precision machined or ground, so it is unexpected to me that a cast and not machined hub is meant to activate the rod. I still hold the guess that the drooping of that rod makes it contact at not the correct part of that cast cam.

A friend in Texas allowed me a look at his OD transmission when I was in Texas. I expected the shifter to have some machined provision for engaging the reverse lockout rod. His shifter does have that provision. The shifter on my OD transmission does not have that machined surface or that shape to add the machined surface. It is the same shifter that my straight drive version has. It is the one shown on the left. I presume the gouge is from years of use sort of engaging that lock out rod. The one on the right is from my straight drive version.

It looks like I may try to find a correct shifter cover.

I did not enter the photo captions correctly. The photo on the left is of the working OD version. The photo on the right shows on the left side what I have on my non working OD version and shows on the right side what I have on my straight drive version.

Robert,
It appears that you found the problem. Likely someone did some work to the transmission that didn't understand
the overdrive operations. You might try Anaheim Gear in Anaheim CA. They may have that lever/cam part or have
a suggestion on where to get one.
I would like to offer a correction to an earlier post regarding the shift rail for the reverse lock out. It is a two section
shift rail as shown in the Old Burb photo. What you have is correct and would operate with the correct side
cover and L/R cam assembly.
Fred

With the right nickel alloy welding rod and a bench grinder, that non-OD shifter could be modified to work properly. Build up the boss with a few layers of metal, and then grind it to the proper contour. It's not like it has to be something that is a precision fit - - - -all that needs to happen is a short push on the lockout lever as Reverse is engaged.
Jerry

Going through the old photos on my phone, I found these. You can see how the lockout rod works to lockout reverse

Thank you all for your further advice. I like the advice given by Hotrod Lincoln about building up the cast nub. I found this option:

https://66impalass427.tripod.com/id34.html

That example mentions welding a tab onto the reverse lever of a 4-speed version. Maybe I can do something similar for my 3-speed version. I will measure and find what I will need to activate the rod.

I cannot tell from the photo of the disassembled parts provided by DoubleDingo what his shift housing looks like. The photos in my previous post do show the one in my friend's working transmission to be different from the straight drive version. That straight drive version looks like the one in my not working transmission, both shown in my 2nd photo.

To clarify the problem of engaging reverse that DoubleDingo notes in his posting just above mine: I have the additional problem of the hole in the casing for the engagement rod being to big (somehow for some reason). All photos in these postings show the rod sticking straight out. My rod droops because of that too big hole in the casing. Instead of pushing the rod into the OD housing to lock out the overdrive, attempting to shift into reverse binds the rod. That binding prevents the rod from going in, and prevents the shift fork to move enough to engage reverse gear. Keeping the OD locked out with the cable lever keeps the rod away from the shift forks, so I do have use of reverse. I plan to fix that problem with a sleeve.

I just recently repaired one of the aforementioned transmissions and obtained another one for my own use. This is the only
one I have dissembled in many years so it was a learning experience as well. The case is drilled as an offset to the centerline
of the shifter rail. The front part of the rod is separate from the shifter assembly. The transmission case is drilled to hold the
shift rod in place. The rod has a raised end portion that fits into a machined counter sunk area in the case. When installed,
the rod is held in place in a straight line to match the reverse cam assembly on the side cover. Clearly your case is damaged.
A new case would be unobtanium so possibly the case can be machined out and have a bushing made to correct the problem.

Note: The rod is completely different from the one used on the SM319 which is one piece and goes through a somewhat larger
hole in the case. They both perform the same function, however.

I'm going to take exception to Shane's post that " reverse does not activate the rod". It most certainly does.
The rod is a two function component. The cable operates a lever that engages and disengages the overdrive
components. The engagement fork also contains a spring loaded slide that disengages the sun gear when reverse
is selected. The cable is still engaged in the overdrive position at that point. The system was designed to employ
all the electrical components for it to function properly. Flipping switches and manipulating the cable is not
part of that system.
I hope this helps, Fred

Thank you, rfs56trk for your further advice.

I cannot get past the fact that it worked fine with the PO, and now it doesn't. Have you tried hooking up the solenoid to a toggle switch to see if it works? Perhaps it is causing some minor binding in the tailhousing, thus, not allowing the rod to move freely? I don't see how it worked fine and now doesn't. Does the lever that engages and disengages overdrive move freely? If it does, then the rod should as well.

I agree with your thought about the PO. I will not return it or ask for my money back, so I ignore that part. I felt that he was trustworthy when I met him. He told me that he used it in a 1955 Dodge truck that he still had. He changed it some years ago for an automatic because he lost the interest in shifting. He appeared to be in his 70's, and he told me that he was selling things that he knew that he would never use. He took the time to draw me a color coded diagram of how he wired it. I sent it out for a rebuild. I learned when he returned it that he had never rebuilt an OD transmission. Something could have happened during that.

The lever that locks it out with the cable works freely.

I have check the operation of the solenoid. I had to clean the terminals, but it does work. I have installed no electrics yet. That will come after I get the mechanicals sorted. I've learned that that solenoid with the 1-1/2 inch long shaft is also an unobtainium part. I have found only the 1 inch long shaft versions reproduced.

I have some progress on this project. My welder friend gave me a pad that I was able to shape to work the reverse lock out rod. I have it back together, and it does work the rod. I call that an improvement, however, something is still amiss. The spring that holds the lockout rod out is much stronger than the spring that holds the shifter forks in place, so I can now shift to reverse without first manually locking out the OD, but I must hold it in reverse. The shifter pops out of reverse the second I let go of it.

I also have a question about the routing of the cable that works the manual lockout lever. The solenoid is directly in the way of the direction of pull.

Every account I read of one of these transmissions in use is very positive. I look forward to getting there myself someday.

Does anyone have advice on my reverse shifting problem or on my cable routing problem?

Thanks!

It sounds like reverse is not getting fully engaged- - - - -maybe your lockout rod is bottoming out before the detent engages? How about increasing the length of the bellcrank on the cable lockout? That will clear the solenoid. The only downside would be a slightly longer pull on the cable knob when you use the manual lockout- - - -which will be seldom if the OD is working properly.
Jerry

The cable is routed under the solenoid and held in place by a half moon shaped bracket
that is attached to the lower solenoid mounting bolt. If you don't have the correct bracket
the cable won't be routed correctly. Send me a PM with your email address and I can send you
a picture of the bracket.
Fred

Thank you both for your further input. I sent a PM to Fred.

I thought the same as Jerry on the engagement. Attached are marked photos that I used to size the shaping of my new pad. I ground the pad to measure near 1/32 more than both measurements with the goal of preventing the pad from preventing reverse to fully engage. I cannot measure a difference between the location of the shift arm with or without the OD locked out. With the OD manually locked out I am confident that reverse does fully engage. When I have reverse engaged then manually unlock the OD, the shifter is immediately knocked out of reverse. That is how I made my stronger spring guess.

Thank you for your photo, Fred. I will look at cobbling up something that will work. I have a 4 bolt side cover OD transmission from 1955 that has a similar bracket. I will look at making that work for me.

Here is a photo of Fred's photo and also of the bracket that I will try to make work for me.

I'll be following here for info, the pictures really help with getting things in order. I recently picked up a complete 319 OD to put in my 67 Chevy, 250-3 ott 3:73 rear, she's happy at 55-60, other drivers..not so much.

I'm working on figuring out how the bracket that I have, similar to the one in Fred's photo above, fits onto the transmission. Does anyone have a photo of this bracket installed?

Thanks!

Robert, Below is a pic I found in a 67-72 Chevy Trucks forum post that looks like the bracket in Fred''s photo installed on a Saginaw 3 speed with OD. Hoping this helps you along a path to success.

It very much does! Thank you! I was trying different positions to get it to fit the lockout arm.

Thank you for posting that. I had no idea there was a bracket that held the cable. I figured my setup was missing something, now I know it was.

Glad it helped you too Shane!

I think that I may have possible information about why my transmission springs/pops out of reverse when the OD is not locked out. The photo below of the reverse shift lever that has a notch in it is of the side cover that came on my OD transmission. That cover looks like the cover that was on the straight drive version that I have had on my truck for many years. I did not notice a difference in the spring that holds tension on the shift forks for either side cover. The photo below of the reverse shift lever that has a pad to operate the lock out rod is on the side cover of my friend's OD transmission. In these photos it looks to me like the spring that holds tension on the two shift forks in the OD version is much heaver than the spring that is on the straight drive version. If true, then that heavier spring must provide enough tension to allow the reverse position to hold the OD lock out rod in place.

My friend and his transmission are in a different state (Texas), so I cannot make a side by side comparison.

Does anyone have information on this spring concerning a possible difference between the straight drive and the overdrive versions?

Thanks!

I connected an external spring to pull the 1st/rev shifter arm toward the upward/reverse position to overpower its being pulled out of reverse when the overdrive is not locked out with the cable. That did not work. On my column shifter any movement done at the transmission does not carry to the shifter box. It only locks then must be unlocked from under the hood.

Still thinking and trying things.

Edit: I put a side cover assembly for this transmission in the 'Wanted to Buy' section.