Happy New Year to all, Besides the shop manual, does any one have a good detailed link on the disassembly/ assembly of the sm420 transmission? I've seen some in the past but can't find one now. I found a spare/parts tranny, mainly for the front bearing retainer that I had asked about earlier, but also as practice unit for tearing down/building up, so as not to screw up my good one when I go through it. As a bonus, it's a few years newer, it has the open drive end cover w/yoke that I'll put aside in case I ever want go to a different driveline set-up. The best part it was only $30. So, anyways any links would be much appreciated. Thanks, Terry
sm420 Not sure this will help a lot. The view is rather small.... http://www.garagemotorsports.com/muncie.htm
Important Most important thing to remember.......work out down the gym for a few months prior to rebuild and reinstall. Damn they are heavy SOB's
Muncie Repairs You'll have a serious OH , SH*T ! moment when you remove the front bearing retainer and withdraw the input shaft and hear all the (worn out) roller bearings tinkling their way into the tranny's sump..... Not to worry about it tho' , just count how many it's supposed to have and then set about finding all of them , use grease to hold them in place when you're re assembling the gearbox . DO take the time to measure all the parts from both trannys and use the best gears and so on . I hope you know how to support a gear by a bit of coat hanger and rap it to check for cracks , it should ring like a bell ~ if not , try again and again , if still no joy , wipe it clean & dry with fresh clean rags then run a plumber's propane torch over & around it ,inside too as any hairline crack will instantly ooze out a bit of oil , displaying the formerly invisible crack , I hope you know to never , EVER use a cracked gear or casting . Look closely at the cluster shaft's inner shaft too as they often get very pretty symmetrical wear on them ,this is a bad thing and means it's scrap . Take your time and no worries , tranny over haul is fun work , fairly easy too . Remember to work over a LARGE old beach towel to this tiny bits don't go !POING! off into the 27th dimension . Also , do not trust the parts haus to give you the correct roller bearings , I've gotten the wrong ones in the right bags more than once , match them up to the old parts .
Oh Yeah ~ Did anyone caution you about how HEAVY these darn thing are . Seriously , if it gets away from you , even just a little bit let it go on over , nothing will be damaged , especially not you . I like to use extra tranny to bellhousing bolts with the heads cut off as alignment pins , this works out really well .
one bearing out I bought a used rebuilt sm420 and always check inside on the bottom of the case is a habit not to lose. I found one bearing roller on the bottom of the case. What damage could this of done if left in there, anyway I called the yard I got it from and they said " oh no it won't hurt a thing as long as you found it" smooth move ex-lax, put it in and it jumps out of second under a heavy load. won't hurt a thing is a excellent way of lunching the second gear, and comtaminating the case with metal particles.
Um ; Not to P on your parade but , it's either used or rebuilt , cannot be both . That sux , they have -you- doing the heavy leg work to test an unknown tranny.....
