The Stovebolt Site Forums The Shop Area Driveline sm420 help.

I took the top off the trans. hoping to find what gear it is in and move to neutral . looks like a little rust got there first. I am trying to get the top plate to shift the pattern. nothing seems to want to move. there are notches on the sliders that should line up to move the arms but they are not in that position and dont seem to want to move freely. anyone have a idea where they should be and why they wont move the pic shows the part.

More info. The front slider looks like it should be behind the upper bolt hole and the rear slider forward of th lower bolt hole. in the trans the rear gear set moves with some help, the front doesnot. reverse works easy. turning the trans it looks like no chipped teath. gona let the blaster sinkin tonight. also thinking of putting the top in a vice and the shift arm in and see if i can get some movement.

I agree, put the cover in a vise and take advantage of the long shifter lever...but first soak the sliders with PB Blaster overnight. There are detent balls with springs on each slider that lock then in place so the don't vibrate out of gear when running down the road...you might need to remove them and clean them up.

Mike B

Submerge the whole top cover in a container of Diesel fuel with some cheap automatic transmission fuel mixed with it and walk away for a few days. Fill the trans case about halfway with the same solution. Then walk away for about a week. That shifter and those gears didn't get stiff overnight, and it's not going to free up that way. Once the solvent works its way through the rust you should be able to get things moving properly. Get impatient, and you'll break some e$$$pensive bits and pieces!
Jerry

Thanks. will start soakin in the am. I understand the big hammer idea. always start small and workup. would a little heat be good or burn down the barn?

I'd avoid heat unless you intend to do a complete teardown. That might still be needed if the rust has gotten to the bearings. A SM 420 with square bearing balls sounds approximately the same as a rock crusher when it's turning. Fortunately, Novak sells a small parts kit that includes all the ball and needle bearings, but your bank card might need a little CPR!
Jerry

Thanks I spoke with novak friday. nice people. sending the front bearing cover and some gaskets for now. pb helped get the shift forks moving. now to get the trans gears sliding.

Search for BK108. This is a SM420 rebuild kit. Prices vary amongst suppliers.

Kit does not include syncro rings. Syncro rings are available for later transmissions. Don't know if yours is new enough...

things are freeing up . But trans still is in some gear so the input drives all the way thru. anyway to find the correct position of the sliders to put it in neutral ? found my manual last night and looked quick at the trans info. didnt see anything helpfull.
Gord, looked at your truck. Nice engine.

Did a bit of web searching and supposedly the below pictures shows the positioning of the gears in an SM420 in the "neutral" position.

Check/compare with yours and lets us know please and thanks.

mine are not that way large gear is all the way to the rear. i can move it forward and see what happens Thanks very helpful Tom

Sounds good Tom.

Come back and let us know how things turned out.

Ok! I had played with the top cover last nite and got neutral for 1 2 3 4 but not rev. Moved the rear gear to the position in the picture and spun the input ,holding the output the front turns rear stays free so we have neutral. There is a drag on the gears probably crud from 63 . good soak coming wish i could put a motor on the shaft and spin it to free it up. The ratchet is a little underpowered.

Yahoo!

Finding neutral in the gears and the shifter forks leads to moving things on down the road.

As you mentioned your shifter mechanism was somewhat rusty/crusty, you most likely do have some serious crud to clean out. I'm pretty sure that there have been recent discussions about how to give your transmission an internal bath and then refill with fresh oil to get things running smoother.

Maybe another Bolter can chime in with suggestions/guidance on that topic???

The suggestion I got for the same situation was put diesel fuel to the normal oil level and start it up and let it idle for five minutes or so. Be sure to put the cover back on. Don’t ask how I know that.

I did it once and plan on doing it a second time when I get the clutch and tranny back in. The one time run cleaned a bunch of muck out. Diesel came out black.

Doug

Hot Rod Lincoln's suggestion for cleaning out the crud is here.