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.pdfThe pin that I question is shown in place in the first 4 photos.
Thanks!
