4 speed w/granny gear...lets talk...

[72_ventura]

anyone put a late model block(96 vortec 350) in front of one of these?

[Captainfab]

There isn't anything that different about bolting a SM420/465 up to a L31 Vortec engine. You'll just need a flywheel for a one piece rear main. Everything else just bolts up.

Originally Posted by 72_ventura

anyone put a late model block(96 vortec 350) in front of one of these?

[292farmer]

ive got the sm465 in my 72 c25 and i love it though 1st and 2nd are useless around town as i got 5.13s out back, however when cold i use those gears to help speed the motor warming up
heres a vid of me shifting it.

http://www.youtube.com/watch?v=0NNgkr9iGJc

[Shyguy]

Originally Posted by 292farmer

ive got the sm465 in my 72 c25 and i love it though 1st and 2nd are useless around town as i got 5.13s out back, however when cold i use those gears to help speed the motor warming up
heres a vid of me shifting it.
http://www.youtube.com/watch?v=0NNgkr9iGJc

Great Video!

[treveiger]

Anybody ever rebuild one of these 465s?

[Frank71]

What would you say is the best rear end set up for granny? Mine is a 3.08?

[Shaky]

Originally Posted by Frank71

What would you say is the best rear end set up for granny? Mine is a 3.08?

The problem with high gear ratios like that is the spread between the 2-3 shift. You have to wind out 2nd to hit the low end of third. You could probably get away with it if you never haul, and you have an engine that spins (like a 327).

I know that others don't like the Gear Vendors option I showed, but it allows me to keep my 7:1 granny first, then split the remaining gears, and overdrive at .78:1. It's cheaper to put in a 5-speed, but I love that low first and all that cast iron...

[292farmer]

thanks shyguy
their not overly hard to rebuild if u do make sure while your in their i believe 3rd gear needs a snap ring?(cant remember now) that helps the tranny survive if your gonna speed shift in and out of 3rd. though speed shifting these trannys can get tricky no matter how their built. but their strength is great ive seen them behind 800hp bbc in mud trucks and the axles will snap before that tranny even peeps.
as for a rear end i'd look for a 3.2-3.42 if just a driver, and a 3.73 if some towing is seen. you could go higher like a 3.08 but that beggs for alot of low end torque or the need to wind up. i had a truck with a 3.55 and i felt it was a very doable gear, still had gaps but didnt need to get all tricky with the clutch or motor. (btw truck had a 305 w/stroker kit)

oh yeah if your rebuilding the tranny yourself when pulling out of truck USE A JACK!! their heavy never get directly underneath it and dont sit on the seat in cab and try and jiggle it using the shifter cuz when it drops say OUCH goodbye man berries that shifter will pinch you with all 160+lbs of cast iron.(my dad just watched me then tell me after words..what did we learn??...)

[treveiger]

Originally Posted by 292farmer

thanks shyguy
their not overly hard to rebuild if u do make sure while your in their i believe 3rd gear needs a snap ring?(cant remember now) that helps the tranny survive if your gonna speed shift in and out of 3rd. though speed shifting these trannys can get tricky no matter how their built. but their strength is great ive seen them behind 800hp bbc in mud trucks and the axles will snap before that tranny even peeps.
as for a rear end i'd look for a 3.2-3.42 if just a driver, and a 3.73 if some towing is seen. you could go higher like a 3.08 but that beggs for alot of low end torque or the need to wind up. i had a truck with a 3.55 and i felt it was a very doable gear, still had gaps but didnt need to get all tricky with the clutch or motor. (btw truck had a 305 w/stroker kit)

oh yeah if your rebuilding the tranny yourself when pulling out of truck USE A JACK!! their heavy never get directly underneath it and dont sit on the seat in cab and try and jiggle it using the shifter cuz when it drops say OUCH goodbye man berries that shifter will pinch you with all 160+lbs of cast iron.(my dad just watched me then tell me after words..what did we learn??...)

What tools did you all need to do it? What kit did you buy, and how were the directions that came with the kit? Did the snap ring come with the kit im assuming? Im going to pull the motor and tranny out together so i dont have to be under the truck trying to get it loose or hopefull anything like that. Im debating on rebuilding it myself or having a professional do it because ive never built one before or messed with a tranny. I cant imagen having that happen will defenitally make sure i stay away from that one .

[292farmer]

if the tranny is fine now i wouldn't bother with a rebuild, i believe now the snap ring comes with kits as its a popular upgrade hoping someone will chime in and verify its been a couple years. believe you need a special tool for 4wd mainshaft lock nut. you'll need bearing press and a couple other tools i cant remember off hand. my dads a professional mechanic so he helped me with.

[Frank71]

Originally Posted by Shaky

The problem with high gear ratios like that is the spread between the 2-3 shift. You have to wind out 2nd to hit the low end of third. You could probably get away with it if you never haul, and you have an engine that spins (like a 327).

I know that others don't like the Gear Vendors option I showed, but it allows me to keep my 7:1 granny first, then split the remaining gears, and overdrive at .78:1. It's cheaper to put in a 5-speed, but I love that low first and all that cast iron...

The whole deal is behind a 350, and I don't really plan on hauling except my teardrop.

[burnin oil]

Originally Posted by Shaky

The problem with high gear ratios like that is the spread between the 2-3 shift. You have to wind out 2nd to hit the low end of third. You could probably get away with it if you never haul, and you have an engine that spins (like a 327).

I know that others don't like the Gear Vendors option I showed, but it allows me to keep my 7:1 granny first, then split the remaining gears, and overdrive at .78:1. It's cheaper to put in a 5-speed, but I love that low first and all that cast iron...

NV4500 gear ratios are about the same. Once again it is a 3sp trans with an OD and granny gear. Unless you are going for milage you might as well just put a cam in there that runs well at 3-3500 RPM if you have 4.10s or lower. I have no complaint with either the 420/465 transmissions or the nv4500 5spd. I do use granny alot in traffic, even with 4.10 gears.

[Shaky]

Originally Posted by burnin oil

NV4500 gear ratios are about the same. Once again it is a 3sp trans with an OD and granny gear. Unless you are going for milage you might as well just put a cam in there that runs well at 3-3500 RPM if you have 4.10s or lower. I have no complaint with either the 420/465 transmissions or the nv4500 5spd. I do use granny alot in traffic, even with 4.10 gears.

Agreed. I like my SM420.

There's other 5-speeds that have better spreads. I have a Richmond in my '66. First is fairly low and 5th is 1:1. It works pretty good with a 3.08 rear.

[treveiger]

The tranny is starting to leak and show signs of wear. And my truck is 2wd an is a 69, would the tranny be different from the 70s 465?
Thanks.

[292farmer]

i cant imagine their any different,

[GASoline71]

Had a 4 speed granny low (SM465) in my 1979 GMC 3/4 ton. Best manual tranny I ever had. Pullin' and haulin' they can't be beat. Even on the trail.. dump the NP205 into 4 Low, run the tranny in granny... and let the clutch out. It would crawl places a Billy Goat couldn't. You could walk faster than that thing would crawl at idle...

I miss that truck... a lot.

Gary

[Brainchild]

I have driven these 465's so long now I don't even notice. Just gas shift gas shift and smile..lol
They are impossible to tearup, mine has jumped out of 3rd for as long as I've had it and it's still going. Just waiting for me to drop the other one in that I've been saving in case it actually does quit, which I don't see happening.

[Dick's 67]

I see trucks with sm465 transmissions. I bought a 66 c10 chevy. It has been changed from a column 3 spd to a 4sp granny but the numbers on the side are 2c gm 477 , 3901127. It looks like it may have a power take-off on the side. On the top behind the shifter the numbers are D208, 3706. Anyone have or know about one of these transmissions? thanks, Dick

[Captainfab]

If reverse is towards you and down it is a SM420. If reverse is away from you and down it is a SM465. If the top cover is aluminum it is a SM435.

[Shaky]

Originally Posted by Dick's 67

I see trucks with sm465 transmissions. I bought a 66 c10 chevy. It has been changed from a column 3 spd to a 4sp granny but the numbers on the side are 2c gm 477 , 3901127. It looks like it may have a power take-off on the side. On the top behind the shifter the numbers are D208, 3706. Anyone have or know about one of these transmissions? thanks, Dick

This place has some pretty good pictures/info:

http://www.novak-adapt.com/knowledge/sm420.htm

[Dick's 67]

Thanks Captainfab, my reverse is dwn an away so it's a sm465. And Shaky, the 66-67 builds were great, and the road trip in my favorite yr. chevy truck to Alaska, priceless!
Thanks to both, Dick