The Stovebolt Site Forums The Shop Area Engine Shop my truck became a lawn orniment!

I was taking the Dubl-Duti for a jaunt around the yard a few days ago and wanted to see if I could get the SM420 to shift from 2nd gear into 3rd (which it didn't like doing previously). I succeeded but to my dismay, the trans will not shift out of 3rd now no matter if the engine is on or off. With or without the clutch!

I took the cover off to inspect it and see if that was the culprit. The forks were fine and the shift lever works just great thru all 4 gears and goes into reverse too. I did notice that the shift rod for 3rd/4th gear had been modified. It looked as though the ball and spring combo for that rod had been lost at some point in time. They spun the rod over so the notches were on top and welded a bead down into the center notch. Then they pulled the pin that holds the shift fork to the rod so it could still move forward and backward. Basically, I could put it into 3rd or 4th with the motor off but it wouldn't give the telltale 'click' to let you know that it was indeed in gear.

Anyway, the cover worked enough to make me think it was the gears that had went bad somewhere. Sure enough! I found a tooth missing off of one of the gears closest to the motor. I have not been able to get the trans into Neutral even after pulling the driveshaft. I found a repair manual for the Muncie transmissions and all it specifies to do is to 'put the transmission into 2 gears at once' to get it to lock up. I may have mistakenly done so but now I can't get it out of gear!! I just got it running again for the year and now it sits in the middle of the yard.

I plan on pulling it to an area I can work on it but pulling the trans is going to be a pain in the butt considering I have to take the bell housing with it and I'll have to do it from inside of the truck! The Dubl-Duti is an aluminum bodied bread truck style vehicle by the way. I don't have a hood. I have a door about the size of an old gas pedal to be able to check my coolant.

I'm looking at putting a t-5 in it anyway tot help make it road worthy so I guess now would be a good time to do so. There's a yard down the street with sm420's and t-5's. If they're close to the same price, I'll do a t-5, get a different clutch disc and an aluminum spacer. Any recommendations on the aluminum spacers and particular clutch discs?

I don't know how you would put a transmission into two gears at once. That's a trick that I didn't think a shift lever would do. Well, it looks like you've got a tranny rebuild or replacement on your hands.

If you replace it, you're going to have to do something with the driveshaft. I haven't gone down that road yet. But considering how long the new driveshaft has to be, I'd suggest upgrading to a good 3" diameter driveshaft maybe.

You know, I'll bet your straight 6 has enough torque to get the truck going in third gear, even if it has to lurch and slip the clutch a lot. You could maybe get her in a better location to work on it.

the manual I have specifies to put the gear stack in two gears at once but not by using the shift lever, you would somehow do this with the top cover off.

luckily for me, the driveshaft has a carrier bearing so I'd only need to modify half of it at this point. Eventually the rear end will get swapped out so I'll need to do the other half at that point. I just want the thing mobile so I can move it without a chain and another truck.

I tried to get it to move while it was in 3rd and it just wouldn't budge.. I think that missing tooth found it's way to a place that it really shouldn't be. I'm tempted to put the cover back on it and try to run it without the drive shaft just to see what happens but I don't want to do any more damage than what has already been done..