[Keith Seymore]

Originally Posted by Shiny

Pulled this off Teufert's web pages. I remember reading something that said the higher ratio first would be stronger than the 3-groove version.

Anyone know if this makes a difference?


# of grooves 1st 2nd 3rd 4th Notes:
0 2.85 2.02 1.35 1.00
1 2.56 1.81 1.37 1.00 Third gear on cluster has 25 teeth
1 2.56 1.81 1.44 1.00 Third gear on cluster has 21 teeth
2 3.11 2.20 1.47 1.00
3 3.50 2.48 1.65 1.00

I didn't know they even had a 3.50 low gear version. Learn sumpin' new every day.

K

[71 Ventura II]

Had a '79' Z28 with a decent 350/Saginaw 4-speed in it we raced on street tires for a couple years without complaint. I'm not sure how it would have held up with sticky tires though. On the flip side, I built a mild 350 making maybe 330HP with a Saginaw 3-speed behind it in a '78' LT Camaro and it blew the crap out of the transmission! The trans locked up tight, when we pulled the inspection cover pieces of gears fell out on the ground.

This thread has me wanting to switch my Ventura to a 4-speed! Maybe later when I get the race bug out! LOL Good Luck... JD

[A.W.Dille]

The stronger transmissions are the ones with the three ring and two ring input shafts. They have the thicker gears and are the stronger transmissions. I started using them in my GTO back in 1990 when I was racing at National Trails just outside of Columbus, Ohio. Just with the change from an M-20 Muncie to a Saginaw with the 3.50 first dropped my times from a best of 14.40 with the Muncie with the factory 3.23 rearend and 28 1/2 inch tall cheater slicks to 13.80's, with no change in the tune-up. Granted I broke a few but the car was consistent with either the 3.50 first or the 3.11 first, and ran in the 13.80's, with a best of a 13.76, and this was with a stock 70 400 big car engine, with small valve 16 heads, Torker intake, 6853 series 650 spreadbore Holley, N, and still ran the points ignition with a total advance or 40 degrees all in by 2800, but it worked. In fact I've lost 2 rearends and both times the Saginaw's have held up. I have no complaints and would not hesitate to run another of the same if needed.

[A.W.Dille]

Okay some of my post got deleted while typing. As far as my engine at the time it was a 70 YD 400 with small valve 16 heads, Torker intake, 6853 series 650 spreadbore Holley, Crane Blueprint RAIV cam, points ignition with a MSD Blaster II coil with a total advance of 40 degrees all in by around 2800, and a set of Hooker Competition headers. Nothing fancy or high dollar, but very reliable and consistent. Same with the present combination, stock 72 400, with a pair of unported 670's, Lunati BMII cam, stock iron intake, 6213 800 spreadbore Holley, HEI, headers of unknown brand, with a 3.11 first gear Saginaw, and 3.08 rear, last time it was raced the only thing different was I was running 3.55 gears. The Saginaw held up to 1.80 60fts on slicks, (better than the motor and trans mounts held up) to run a best of 8.46 in the eighth. In fact the same transmission is in the car today and still working good.

[Shiny]

Sounds like the saginaw in my "someday" pile would not be as sketchy as I thought... it needs a few parts ($$) and after reading so much about how weak they were, I thought it might have to go into the "bad idea" pile. Positive experiences posted here (thanks to all) tell me I should keep it, as I could have a rebuilt 4-spd for a couple hundred less than a used Muncie.

I don't remember the groove count on mine, but my guess is a 3.11 or 3.50 1st with my 3.55 rear would jump right across Keith's intersection. I had a truck like that once - 49 Ford with a 327 Chevy and a 4-spd from a Blazer with a "granny gear". I remember 1st gear was over really fast, but it did get the truck moving.

[1967Tempest]

Yeah, I was a little worried as well. But I've heard more positive stories lately. I have the 2 groove 3.11 first gear. I also have a 70' GTO WF 3.23 rear that I am going to be putting in.

Going from a TH350 with 2.56s I should be seeing a night and day change!!!!!

Thanks!!

[Pontirag]

you can puta saginaw OD behind those 4 speeds I'm told

[nzjkb5]

Originally Posted by Shiny

Pulled this off Teufert's web pages. I remember reading something that said the higher ratio first would be stronger than the 3-groove version.

Anyone know if this makes a difference?


# of grooves 1st 2nd 3rd 4th Notes:
0 2.85 2.02 1.35 1.00
1 2.56 1.81 1.37 1.00 Third gear on cluster has 25 teeth
1 2.56 1.81 1.44 1.00 Third gear on cluster has 21 teeth
2 3.11 2.20 1.47 1.00
3 3.50 2.48 1.65 1.00

Yes, all things equivalent, a higher (lower numerically) first gear will be stronger. It's all about the amount of torque multiplication and the actual size of the gears involved. A higher first gear (lower numerically) has a larger drive gear. For example, the Tremec TKO500 and TKO600 are made of exactly the same materials and are of the same design; the TKO500 has a low first gear (3.27:1) and is rated for 500 lb.-ft., the TKO600 has a higher first gear (2.87:1) and is rated for 600 lb. ft.

[Shiny]

nzjkb5,

Thanks - that's what I did not remember !!

And I think the 3.50 1sts are more plentiful because they were used on a lot of light cars with low-torque engines (Vega ??).. I would guess this is why these tranny's have a reputation for being weak.. with this many versions and wide range of 1st ratios, there will be a wide range in strength.

So this means the 1st gear set would be the weak link. I also think the bearing design for the input shaft seems weak - it is badly worn on mine.

[aldbeir]

didn't pontiac put the dearborn 3 spd in their cars cause they thought they were stronger?

[A.W.Dille]

Believe it or not the Saginaw four speeds to avoid are the ones with the 2.56 first gears, they are the weakest of all Saginaws. Those are the ones used in Vega's.

[1967Tempest]

Originally Posted by A.W.Dille

Believe it or not the Saginaw four speeds to avoid are the ones with the 2.56 first gears, they are the weakest of all Saginaws. Those are the ones used in Vega's.

Going by logic, then I would have the second strongest. As I have the 3.11 First gear. Turning out to be a good purchase.

Dave

[Z Code 400]

Originally Posted by A.W.Dille

Believe it or not the Saginaw four speeds to avoid are the ones with the 2.56 first gears, they are the weakest of all Saginaws. Those are the ones used in Vega's.

Yep...Same unit in the Vega/Astre as in the Novas. I have seen both variants in both vehicles over the years...Robert

[andyg]

Originally Posted by 1967Tempest

Going by logic, then I would have the second strongest. As I have the 3.11 First gear. Turning out to be a good purchase.

Dave

Maybe I shouldn't have tossed my 3.5 first gear sag into the trash. It really only had 1 broken gear.

[1967Tempest]

I see a lot of websites with rebuild kit for all manuals. Wouldn't they strengthen them when you get new gears?? Still cheaper than a Muncie.....

[Z Code 400]

David,

There are a lot of factors that effect gearbox strength. The lower ratios are known to be weaker because of the greater torque multiplication. You can installed the higher gearset ratio in any Saginaw case.

One of the problems that I have seen with the Saginaw is when the snap ring is incorrect or improperly fitted to the tailshaft behind first gear. This is critical and the snap ring in most kits that I have seen is NOT correct in thickness or diameter.

I have seen more than one Saginaw used in an oval track application with this snap ring welded to the mainshaft, in very high horsepower/high rpm applications...Robert

[PonchoV8]

Originally Posted by aldbeir

didn't pontiac put the dearborn 3 spd in their cars cause they thought they were stronger?

I thought it was because of a fire.

[Shiny]

So I am still confused about which versions are weaker. Sounds to me like gear strength should be worse on a 3.5 than on higher ratios, but this may not actually be why they break? If it is true that the 2.56 are the most unreliable, what makes them worse? Is there something else about the 2.56 that would make them weaker than the 3.5?

[A.W.Dille]

The thickness of the gearsets. The transmissions with the thinnest gearsets, mainshaft and cluster assembly are the transmissions with the 2.56 first. Wish I still had one of my old ones that had the 2.56 first and was able to get pictures up so I could show how different the gearsets are. There is a major difference.

[1967Tempest]

This might help someone describe it. The first gear is all the way to the right.

Dave