The Stovebolt Site Forums The Shop Area Driveline SM420 pilot bearing question

I'm assembling my transmission after buying a 3rd gear synch ring. Found out that the needle bearings are not all the same (14 one size, 4 slightly biger) but both, less than the 3/4" long that are supposed to be. Also when installing the spacer, the transmission main drive gear synchronizer won't go all the way close to the main drive gear. On the shop manual, there is no mention of this spacer on the disassembly or assembly instructions, just a retainer ring. On the master parts book, the ring is not mentioned or shown in the picture. On the shop manual, though, on the cutaway of the transmission, the spacer and the ring are shown. My tranny doesn't have the retainer ring. Where can I find it, as well as the bearing and the spacer, since it looks like someone worked on the tranny and didn't left things as they were supposed to be. Thanks

There are supposed to be 18 needles, all the same size. If you have four larger ones then
someone got them mixed up. Here is the gear with the needles loaded with the retainer in
place.
http://www.pbase.com/dennygraham/image/137529544
This shows the main shaft assembly and the order that it goes together.
http://www.pbase.com/dennygraham/image/137530309
Here are all of the pictures of my SM420 assembly.
http://www.pbase.com/dennygraham/sm420_rebuild&page=all
Denny Graham
Sandwich, IL

Dear Denny: pictures shurely speak louder than words. Your picture of the retaining ring totally wiped my ignorance regarding the matter away. Hipotetically, I could assemple the rollers without the ring, right? The other question that remains is the spacer. In the assembly picture it's not shown. Did you used it? The specs for the rollers are 3/4" lenght and 7/32 diameter. The "big" rollers (4) I have are a little bit less than that and have a flat surface on the ends. The other 14 are easily 1/16" smaller and have rounded ends, like your pictures. the problem as I desctribed is that the synch ring is not completely close to the gear. On your pictures it appears as if it has some sort of gap between them. Is this normal? If so, how much would it be? Last question. The main shaft bearing (front) according to mpb and timken is a 1209L, mine had a 6209N (skf spec). Is it the same bearing? I noticed the pack you bought has Nachi bearings, am I being to anal trying to fit just Timken or National bearing on the truck? Thanks

Yes, theoretically you can assemble the clutch shaft to the main shaft with out the
"retainer" it just makes it a lot easier because you don't have to worry about the needles
collapsing when you assemble it. I assembled gears and shafts in transmissions many
times using heavy fiber grease and have often had to take several tries at it before I could
get the shaft started with all the needles in place. You can make the needle bearing
retainer from any light gauge metal strip if yours is missing, it gets pushed back into the
recess in the main shaft when you assemble the two.
Once again, I'm assuming that you mean four of your needle bearing are longer but all
are the same diameter, obviously they have to be the same diameter so it appears that
someone has mixed up the needle bearings from two transmissions.
And again, I’m not sure what spacer you are talking about, the blowup illustrations in the
manuals clearly show all of the parts as they should go together.
The companies that made the bearings that were in the transmission a half century ago
have been sold and sold and sold again. With all the acquisitions that take place some of
the names survive many don’t. Bearing manufacturing was probably one of the first of
our (US) products to be moved off shore and China has been making a lot of our bearings
for several decades if not longer. Some of the original names are around but the
companies are a completely different group of people.
Denny Graham
Sandwich, IL

Denny: The spacer I'm talkng about is on the illustration part No. 591436, its also on the specs. Regarding the bearing, after long night, figured out those are the same bearing.

Ok, gp. 4.352 pn. 591436 that spacer acts as a bunper or end stop for the needles and if your haveing trouble with the assembly not going together it may be that it's those four long needle bearings that you said you had. So here goes one more time, if you don't have 18 needle bearings that are the same size, meaning diameter and length then somewhere down the line they got mixed up with another transmission and you're gonna have problems assembling it.

Take a look at the last three pictures in this album, they should answer your questions: http://www.pbase.com/dennygraham/sm420_rebuild&page=all
dg

Denny: The last picture show the spacer I was talking about and it looks like the one I have. Checked with Novak, and it doesn't come with the rebuild kit, offered me some used ones. I think I'll use mine. Thanks for the pictures.

Denny: Just a question regarding your rebuilt kit. What part does the Nachi bearing came with? I'm curious since specs call for a Timken 1209L but this spec on a lot of gear manufacturers is for self aligning two row bearings, even on Timken but matching NTN to BCA bearings it came with either 6209N or 209L. The later with a higer dynamic and static capacity. My transmission had the 6209N installed, the other 3 bearings had no markings on them go figure what they are.

Boy buddy, I can't really help you out with all those numbers. I just used the bearings that came in the kit that I bought from Novak.
Maybe one of the other members know something about bearing cross reference numbers, I don't.
Denny G

Don't worry, I really appreciate the help with the pictures and all. Looked at the parts book and cross referenced to Timken (BCA/Bower), if it helps anybody: The five bearings (including the pilot) are: W1518Q (mainshaft front, rollers) 1209L (maximum capacity or 6209N/209L for standard capacity, main drive gear) M1206EL and 308L front and rear countershaft and 307L mainshaft rear.