Swapping the SM465 for a Car style 4 speed

[mcarlo86]

Put in a nv3500, then you got overdrive too boot. No matter what combination you end up with youre milage is gonna still suck. It is what it is.

There is a whole different set of things to think about going with a NV3500 like hydraulic clutch, electric speedometer and then with an OD transmission, 3.08 gears are too tall. I like the Saginaw idea better for what you are looking to do.

NV3500 are smooth shifting, had one in a '90 1/2 ton back in the day and liked it.

 

[idahovette]

Yeah, Saginaws are NOT the toughest transmission around , but I ran one in a 68 Nova for a couple of years at Firebird Raceway in Boise and never tore it up. Wasn't the quickest, fastest car around but it did get into the 13s. Had 12 bolt posi 4.56 gear set and NO headers. But sooner or later you will probably waste it. I still say it will be streetable with whatever gears you have and fun!!

 

[DoubleDingo]

Also the. Saginaws had grooves cut in the main shaft to identify 1st gear ratio not all had the same 1st gear.If you dump the clutch on that Saginaw very often you will need another Saginaw.

4 different 1st gear ratios available. No groove is like 2.5 first 1 groove like 2.85 first 2 groove like 3.11 1st 3 groove was like 3.5 first low horsepower junk I used to look for 2 grooves I don't remember this ratios for sure but I know I'm close

It falls back to, if you can find one of those coveted grooved input-shafted transmissions. I only see them without grooves, so those are for the low gear rear end vehicles, such as 4.57 or 4.10 or 3.90. I bet 3.90 gears are a blast for twisty roads.

 

[WFO]

I've got a 3 groove sittin on my shop floor. It was in my 69 Chevelle SS396 when I bought it, and worked fine. But I found a fresh Super T-10 for $150 and jumped on it.
Been saving the Saginaw for a C10 if I find the right one.

 

[DoubleDingo]

I've got a 3 groove sittin on my shop floor. It was in my 69 Chevelle SS396 when I bought it, and worked fine. But I found a fresh Super T-10 for $150 and jumped on it.
Been saving the Saginaw for a C10 if I find the right one.

All of mine are no-grooves, both 3 speeds and the M21.

 

[HotRodPC]

Don't forget, you'll need a shifter to make it real fun. Like a Hurst Competition Plus. I had a Muncie M21 and then a Muncie M22 in my 3/4 ton pick up with a Dana 60 and 4.56's with a LSD unit. That truck was so much fun. Of course the speed limits back then was 55 and the engine was screaming to do that 55.

 

[75Monza]

I ran a 3 grove Saginaw in a '71 C10 longbed with a rumpity 350 and 3:43's. It was really fun while it lasted, smoke the tires everywhere....but got in sand once and hopped the rear and split the case instantly, lol. Swapped in a super T-10, that held up till I got rid of the truck. The weight of the full size truck is pretty much a killer on Saginaw's when you apply torque AND get traction at the same time, lol.
My current '71 C1500 longbed is getting changed back to 4 speed from auto, put a 3:73 with a tru trax in the back and 295/60/15's for traction, still not sure if I want to do another Super T10 or mod a Tremec TR6060 in.

 

[794spdcustom]

I had a ‘69 Torino Cobra (428 CJ engine) and with the 2.32 low 4 speed and F70-14 tires (about 26” diameter) they recommended 3.91 gears for the street. With the 351 engine in the GT they used the 2.78 low gear 4 speed to improve off the line performance.

Based on that very small data point, you will need lower gears if you want snappy performance on the street with a car 4 speed in your truck. And you would want a Saginaw with a low 1st gear ( some apparently go as low as 3.50) if you can find one.

Bruce

 

[794spdcustom]

Yes I believe this has the 3.50 (3 grooves on the input shaft) I know they are limited as to how much power can be put through them, i,m going to build a simple 300 ish hp smallblock for it.

 

[794spdcustom]

Don't forget, you'll need a shifter to make it real fun. Like a Hurst Competition Plus. I had a Muncie M21 and then a Muncie M22 in my 3/4 ton pick up with a Dana 60 and 4.56's with a LSD unit. That truck was so much fun. Of course the speed limits back then was 55 and the engine was screaming to do that 55.

I seen a really cool shifter in a you tube vid yesterday, would be perfect for the truck I think

 

[794spdcustom]

I ran a 3 grove Saginaw in a '71 C10 longbed with a rumpity 350 and 3:43's. It was really fun while it lasted, smoke the tires everywhere....but got in sand once and hopped the rear and split the case instantly, lol. Swapped in a super T-10, that held up till I got rid of the truck. The weight of the full size truck is pretty much a killer on Saginaw's when you apply torque AND get traction at the same time, lol.
My current '71 C1500 longbed is getting changed back to 4 speed from auto, put a 3:73 with a tru trax in the back and 295/60/15's for traction, still not sure if I want to do another Super T10 or mod a Tremec TR6060 in.

The three groove is the one I have found, I believe I have 3.08 gears in the back but have yet to confirm. Sounds like you had that combo dialed in. I know these Saginaws dont like too much power but the muncies and t-10s were like 3 times the price!

 

[794spdcustom]

Also the. Saginaws had grooves cut in the main shaft to identify 1st gear ratio not all had the same 1st gear.If you dump the clutch on that Saginaw very often you will need another Saginaw.

4 different 1st gear ratios available. No groove is like 2.5 first 1 groove like 2.85 first 2 groove like 3.11 1st 3 groove was like 3.5 first low horsepower junk I used to look for 2 grooves I don't remember this ratios for sure but I know I'm close

Honestly I have heard different stories from various people, but the consensus is you dont want to throw a bunch more than 300 hp through them. Other than that they are fairly reliable minus a bunch of clutch dumps. I know the three groove is a 3.50 first and believe you are close on the other numbers

 

[794spdcustom]

....if you can find one...that is the kicker.

Honestly I have heard different stories from various people, but the consensus is you dont want to throw a bunch more than 300 hp through them. Other than that they are fairly reliable minus a bunch of clutch dumps. I know the three groove is a 3.50 first and believe you are close on the other numbers

The high tunnel. the drive shaft, and shifter placement will be the biggest points, I think. The crossmember will need to be relocated, but this isn't gonna be rocket science for any of this??

Your right, it wont require rocket science, just wanted to ensure I was missing something that others have, exactly why I am relying on some of your expertise to avoid issues when I do the job

 

[DoubleDingo]

Well swap that sucker in and share the progress and fun driving after the fact

 

[794spdcustom]

Thanks for all of your replies fellas. I do have a bellhousing from the Muncie we put in my sons Nova so that is all good. Seems to me the biggest issues may be the crossmember, finding a yolk for the Saginaw, perhaps driveshaft fitment and replacing the tunnel. I have heard that these are replaceable and some are bolted in??