sm465 trouble

[82chevyk10]

My truck has a 4 speed muncie sm465. It seems to be a great transmission that won't die no matter how hard I abuse it, but age seems to be taking over. Since I bought the truck 1st has always been difficult to get into, though gently letting off on the clutch while pushing it into gear seems to make it easier. Last year it started jumping out of 3rd unless I manually hold it. It only really does this at higher rpm's right before shifting to 4th. Other than that the transmission seems to be strong with no problem catching gears while driving.

 

[crazy4offroad]

1st (granny low) is non-syncronized so you have to be completely stopped. Letting out slightly on the clutch helps too, just like reverse. Mine was falling out of 3rd (not really "popping out") and I put a new shift fork in it per someone's advice years ago. It didn't help. Hopefully someone else can chime in and we both can get our 3rd gear fixed.

 

[bucket]

I remember reading something about the 3rd gear trouble, I think it involved tearing it down and rebuilding it. It was a few years ago.

 

[82chevyk10]

Overall I love this transmission because it's so rugged. 1st isn't a horrible issue having ease of the clutch when getting it into gear because it's only used I'm hill climbing or pulling extremly heavy loads. The 3rd gear issue is really only a real incovienence when in traffic thats just about too fast for 3rd, but too slow for 4th. If only they would've built this transmission with slightly different ratio in 3rd and 4th and added a overdrive, and still keep the overall duribillity.

 

[crazy4offroad]

Yeah I've beat the immortal hell outta mine too lol I better not brag on it too much though, usually when I do **** like that it fails on me next time out.

 

[HotRodPC]

C4 is correct on Granny 1st. By you lifting up the clutch a little, you are actually just starting to engage the clutch and manually synchoronizing the gear so it falls into place.

As far as your 3rd gear, if its popping out, your sychros have gone bad on the gear. Synchros are brass rings that ride on the shaft just before the gear. They are triangle shapped so as you shift over them, they help the shift fork assembly slide over the gear instead of like hitting a flat wall surface. Basic same principle as a turd being tapered so it can get out of your ass. Could you imagine if it were just cut off flat and squared off. But, the synchors serve another purpose also. They do hold a gear in place. When the synchro wears, you will have the issue you describe, and C4, right again, clutch fork replacement will not help that issue. If you like the trans, a rebuild kit should include your seals and gaskets, bearings and your brass parts wich are synchro's. If your gears are all good, then with new bearings, seals, gaskets and brass, its as good as a brand new transmission.

 

[Irishman999]

There are two issues with the SM465, shifter slop and third gear popping out. I wish I could remember what the fix was for it but it required tearing it down. I was hoping by now I could have done a rebuild on mine so I could have pictures or a write up on it but check out..... http://www.novak-adapt.com/ They have numerous kits on ebay also.

 

[82chevyk10]

Thanks, I'm sure complete rebuild kit couldn't hurt anything. I've vever done trans work before, so I'll most diffenently have to get a book about it.

 

[89Suburban]

Basic same principle as a turd being tapered so it can get out of your ass. Could you imagine if it were just cut off flat and squared off.

 

[HotRodPC]

Just trying to make sure you comprehend it 89S. I bet you get it now huh?

 

[89Suburban]

Just trying to make sure you comprehend it 89S. I bet you get it now huh?

If I don;t take my daily fiber rations that's EXACTLY how it feels coming out, cut off and square with a burr edge.

 

[HotRodPC]

If I don;t take my daily fiber rations that's EXACTLY how it feels coming out, cut off and square with a burr edge.

That must hurt on both ends. I assume that means your ******* slams shut too if you don't have fiber?

 

[GreaseDog]

Yeah I've beat the immortal hell outta mine too lol I better not brag on it too much though, usually when I do **** like that it fails on me next time out.

South Bend Clutch, SM465, NP205... been trying to break it for years... poor quadrajet knows 2 positions, idle, and WOT. i love my 465.

 

[GreaseDog]

the fix for the sloppy shifter for future searches, and potentially the OP:
http://pirate4x4.com/tech/billavista/sm465/index.html

 

[crazy4offroad]

the fix for the sloppy shifter for future searches, and potentially the OP:
http://pirate4x4.com/tech/billavista/sm465/index.html

Bookmarked!!