I'm working on a overdrive transmission for my 50 merc and have found quite a few laying around. What I'm wondering is how do I tell if any are good without installing them and finding out they are junk? Any help on this would be fantastic! I need to get my car back on the road!!!
Are we talking about a 3 speed with overdrive? First thing to do is turn on KBUT and tune in to the Lonesome Bob Show 2-4 on Friday afternoons. This will put you in the trans working mood.
I will start with the simplest tests to help get thread rolling. You probably already know to, select neutral, (which should be both shift arms in center position), spin input shaft, feeling for odd bearing feel or anything, then hold output shaft while spinning input, to feel anything unusual. Next, shift one arm into gear, spin input, feeling for bearing drag or problems. Hold output shaft for resistance, as you turn input, to feel any irregularities in that gear set. You should feel any broken gears or teeth. It will be obvious if you have selected reverse. Move that shift arm back to neutral, then to the other position, check the gears in that combination, then move it back to neutral and start the same procedure on the other shift arm. You may want to make notes about which shift arm selection is needed to reach each gear. Low gear will require more turns of input shaft. High will be near 1:1. The solenoid pulls another gear, which overrides high gear (some trans will overdrive other gears, also)(second gear overdrive is very cool in the mountains) so solenoid operation will have to be checked. I will get out an old Motor Manual on that check and get back to you on how to do it. Some of these trans have a cable to pull and a switch to operate solenoid. NOTE: Some of these transmissions are designed to coast down a grade when in overdrive. I am hoping any HAMBers with experience on these trans will jump in. We have got to get this car ready for summer and the 4th of July Parade. I would suggest not to be afraid of popping the side cover off to do an inspection, because they are pretty simple. Just take care of any gaskets and watch where shift arms slide into gear sets. You may not know, that Lonesome Bob Brazell used to run a garage there back in the day, before he became a famous photographer. Bet he could answer a few questions for you. Rockin Rob-CB-'72 to '76.
That is very helpful!!!! Also very interested in the overdrive info though. The one overdrive I found seems to spin freely and shifts when the arm is pulled, but not sure if that is just freewheel and not freewheel. I'm hoping to drive it out to moab in 2 weeks, so gonna try to get something pulled together. I'll post progress. Cheers!
After checking teeth and bearings, turn input shaft in direction of engine rotation while in gear to check that rotation does not try to push shift lever out of gear. I believe that is one of the things that happens when syncros are bad. Kool Merc. I hope we see you on the Ski Area road someday.
The overdrive is near impossible to check without removing the tailshaft . Common failures are planetary gears / sun gear . If the rear overdrive section has gear oil in the overdrive unit I would look at the oil and look for any metal in it .
Dos anyone know if you can just take the overdrive unit off without opening up the rest of the transmission? Looks like 4-bolts..... Sorry to ask I should just go take some **** apart!
Some good, non-hamb, but informative links. http://www.cl***ictruckshop.com/clubs/earlyburbs/projects/t85n/rebuild.htm http://www.ocmafc.org/techarticles/Tom%20Endy's%20Special%20Topics/Borg%20Warner%20Overdrive.pdf http://www.fordification.com/tech/overdrive.htm and parts... http://www.vanpeltsales.com/FH_web/trans-partsprices-BW-ODparts.htm Hope that helps.
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