SM 420 tech Q

[RUSH55]

I just finished tearing down a 420 I have and came across something weird. After pulling all the guts, I fished around the sludge at bottom with a screwdriver and found the remaining pieces of a snap-ring. Now this snap-ring is just your basic run-of-the-mill snap-ring with the two holes, one on either side of the gap, for use with a regular ol' pair of snap-ring pliers. I can't seem to find where it came from. It's I.D. was prolly somewhere between 1 and 1-1/2". It was the kind of ring that you spread apart to remove, as opposed to the squeeze together type. All of the snap rings seemed to be there on all the bearings, and none were this type. Not one other snap-ring had "ears".
Anyone have a clue what this was for?

 

[largenfirm]

I've run into this before...

Transmission demons put them in there, just to drive you nuts!

Kirk
[No, I haven't a clue about SM 420 trannys]

 

[peesalot]

that is wierd. check the schematic on birfield.com.

 

[treerootCO]

http://www.kinzers.com/don/landcruiser/transmissions/sm420/doc/150x150/sm420_3s.jpg

Lots of 'em in there.

 

[RUSH55]

-Not trying to hijack your thread, but it wasn't this ring was it.-

Nope, not that one.

-What holds the reverse idler shaft in place or possibly shift rails?-

According to the schematic, pins hold the reverse idler shaft in place, and there aren't even any snap-rings on that shaft, apparently.
But I'm going thru the top plate and shift rails tonite.

 

[Pin_Head]

The only snap ring about 1.5 inches inside the case is the one that retains the 3-4 synchro hub on to the front of the output shaft, but it doesn't have any "ears" with holes in them. They usually have a stripe of paint to indicate their thickness. Maybe somebody just dropped one in there to mess with your mind.

 

[peesalot]

Hey Rush55 , quick ? , in the pic from 66fj40 you can see the dog teeth on the input and the synchro , look to be no gap between them. I was wondering when you opened your tranny was there a space between these two( the dog teeth and synchro) ? I had like 1/8 in. of a gap and after rebuild still had gap so I opened a spare 420 to check and there was a gap in it too. I was just curious what your's looked like ? gap or no gap ?

 

[RUSH55]

Yeah, mine has a gap. If it's not an 1/8", maybe a tad less.

 

[65swb45]

The short answer is, if you've accounted for all the other parts that belong in there, then it doesn't belong there.


The long answer is I had this exact same experience with an SM420 several years ago. The story will appear in an issue of Toyota trails in 7 or 8 months from now, so I can't say more.

 

[RUSH55]

-The long answer is I had this exact same experience with an SM420 several years ago.-

No kidding?! That's weird! That is unless it was something done in the Muncie factory. Maybe somewhere there's someone who knows all about this apparent mystery. Now I'm gonna go to a scrap yard and find me a couple more 420's, tear em' down and see if broken snap-rings are buried at the bottom of the cases! Ha!

 

[RUSH55]

I just remembered that this tech Q was a two-parter. Have any of you 420 veterans replaced the two little guide pins for the stick at the top of the shift tower? Anyone know where I can get these (tranny shop?) or does anyone have a cheap, hardware store fix for these?

 

[Pin_Head]

You can use "roll pins" that you can get at any hardware store.

 

[66fj40x2]

Spector also sells a repair kit to the Toyota tranny's that I've been told worls on the sm420 too.

 

[RUSH55]

Got another Q. Can someone tell me why the 420's GM TO bearing won't work with this conversion? Is the TO bearing too small? Is the front bearing retainer's nose cylinder too short?

 

[peesalot]

I think it is cause the gm to does not hook to the toyota fork.