what is the flaw with a saginaw 4 speed? how are they weaker than a muncie m-21? where are they prone to break? will they with stand a stock daily driven 327/300 sbc? should i just stay away and continue my hunt for a muncie?
Here's my thoughts on it. Muncie moved reverse into the tailshaft housing, making space to keep the gear teeth wide when they added a fourth gear. Saginaw didn't, so it's all jammed into the main case. A well built Saginaw is stronger than it's reputation. As long as you're not hammering it, a Saginaw in a daily driver with 327/300 should work well. Bob
A buddy of mine bought a new '67 El Camino with a 4 bbl 327 (don't remember the hp), 4 speed which was a Saginaw. He drove the car hard at times although he didn't abuse it and he added headers, 4 bbl Holley, and a Z-28 intake. The Saginaw held up fine and never was a problem. Later he built a much more radical 327 and went to a Muncie at that time. I got his Saginaw and put it in my '55 with a 265, 4 bbl Holley, Corvette solid lifter cam, power pack heads, and headers. Granted, the 265 after all of that probably still put out less hp than his stock 327, but I drove the hell out of it and never had a problem with the trans. I agree with Bob that a dailey driver 327/300 will work well. A Saginaw will be a bargain compared to the Muncie, too. Kerry
I bought a new 1971 GMC Sprint..350/270- 4 speed Saginaw. I'm here to tell you that trans took a beating and never missed a beat. Used it as a tow vehicle for my Modified Production wagon and when the race car was down I dragged the GMC. Many 1/4 mile passes and lots of playing on the street,added to being my tow car,and that Saginaw never complained. I am still amazed that it held up. You should be fine with one.
Trans durability is directly linked with how it's used. I have seen Muncie transmissions broken by mildly modified SB street engines. Lots of cars came with Saginaws and had no problems, but they don't have a very good reputation compared to some of the other options. I bought a new '75 Olds Starfire(like a Monza). It had a Saginaw trans and a 231 V-6. Although I drove it hard occasionally(as hard as a stock V-6 will let you), otherwise it was a normally driven street car. With 30,000 miles or so the trans had a major failure. I never took it apart to see what failed. Based on how it acted I believe the mainshaft broke near the front, or the pilot broke off the forward end of the mainshaft.
If you are using an M21,that has a 2.20 first gear-close box. Not too good for the street unless you have deep gears,light car,bunch of torque etc.M20 is wide box-2.54 first. Saginaw had a few gear ratios ranging from 2.54 up to 3.50,and a few in between. I would go with a wide box.
I used a POS vega skaginaw in my old 50 chevy sedan delivery with a fresh hotrod 406 SBC...I chose the vega box because it had the 3.40 [some guys say it's actually a 3.50] first gear. I had a freeway-flyer 2.29 rear gear so the vega box worked great around town and I cruised at about 80 MPH at 1850 RPM...once buzzed the motor up when Montana opened up it's speed limit...speedo went WAYYY past the 100 or 110 peg. The crazy thing would get almost 20 MPG and the car was pretty quick off the light. I HAMMERED that thing every chance I got...never caused any problems except the teeth on the reverse idler wore badly...appeard to actaully be bent! I replace the idler and all was good again. I never broke that damn thing and the guy that bought the car eventually broke the dainty little 7.5" 10 bolt but the tranny lived on.. Flip side of that was the night I was drinking with a buddy from work and he wanted me to test out his big block 66 elcamino becaue he just put a new saginaw in it that afternoon..I did and 2nd gear went away immediately...big crunching noises...told him I didn't wanna drive it.
I had a Saginaw behind my hopped up six (6), triple carbs , headers etc and it eventually gave up. I replaced with a Corvette close ratio Muncie and never had a problem.
i would save my money and use a saginaw.your talking street tires with basically stock sbc.Most of the time its the person doing the driving not the transmissions fault for breaking.I remember an old saying about he could break an anvil with a rubber hammer
I've used Saginaws plenty with no issues. A lot of the issues I see with them is when someone takes a used one and puts it in without even a look see inside, then they're surprised it goes out.
the saginaw is actully a BETTER trans than the muncie for everyday street use-because of its cast iron case-the muncie aluminum case expands way more when warmed up than the sag cast iron case-and that causes leaks/breakage /wear-the muncie gearing and lighter weight is better for racing though-saginaw is a very old GM company that is very respected-they are the ones who probably built the sterring box and componets in your GM vehicle and somtimes other makes
My '57 had a .060 over 283 (292), double hump heads, a Duntov cam and a Carter AFB with a Saginaw behind it. That was 1982. I drove hell out of it and the guy that I sold it to drives it the same way. We have never touched it---
i i had a a 461hp sbc in my old 55 chevy 411 rear and slicks. and a saginaw out of a vega .i had a muncie come unglued on me at the track. i found a saginaw cheap and really abused it.still in the car when i sold it. loved it. shifted smooth and quiet.
The lower first gear is, the less torque a given trans can tolerate in low gear. Muncies weren't available with a low first gear, so that makes them harder to break than they would otherwise be. You can get some feel for a trans by what sort of vehicle the manufacturer puts it in. Of course that doesn't mean some manufacturers(especially GM) haven't tried to save too much money at points in their history.
Go with the saginaw with the set up you have you'll be fine. My only words would be not to use a 3 grove with 3:50 first gear.
Like someone hinted before, it's the idiot behind the steering wheel more than the trans that will ultimately decide how durable a given trans is. Frank
This has as much to do with it as anything. Same story for T-5 trans - the 4 cyl versions have lower first gear ratio and consequently are lower torque rating.
Yes,and the "head " gear ratio....the input shaft gear is much smaller than the gear it drives on the cluster shaft.Less tooth contact.............. Muncie gears are larger diameter and perhaps 50 percent wider than a Saginaw.Saginaw counter shaft has a single set of rollers on each end and the mainshaft is pretty wimpy But as mentioned above a Saginaw in good shape will take abuse.
I have a 3.10 first gear saginaw behind a 468 big block chevy in my model A. with 3.00 rear gears it has plenty of low end but still cruises 70 mph @ 2500 rpm. its like a poor mans overdrive. i have broke a few transmissions in my day, saginaws and muncies, mostly due to very hard launches . for the street it will work just fine
Saginaws had a thrust washer in front of the main drive shaft, backing up the 'pocket bearing'. There was a 'repair kit' some years back, Advance Trans stocked it (L.A.) so did the big automatic trans parts suppliers. It consisted of a Torrington bearing and 2 matching races ("washer-shaped side races") All it required was the removal of .045" (or thereabouts) of material from the 4th gear hub, and reassembly. Big difference. Smoother shifting (obviously) and quieter thru the lower gears...a great update.
I've tore up just about every ratio Saginaw in my OT car, went thru 5 just last year. I found the limit at around 375 to the ground with drag radials. On the 3.50 ratio gearsets, teeth come off of the input shafts first. On the 2.84 gearsets, the stronger input shaft gear would move the failure point to the cluster, the teeth would come off of 1st gear's 15 tooth mate on the back. 3.11 gearsets seemed pretty well balanced, hard to predict what would fail. Sometimes it was 3rd gear. Never twisted an input shaft or mainshaft, but twisted lots of splines in the spicer slip yokes. Lost some front bearings as well, but those happened at the same time along with an input gear failure, so i'm thinking teeth probably went thru the bearing. Mine were all synchro 1st, crash box 2nd, faceplated in 3rd, with lots of street miles. My favorites was the 3.11 gearsets, pretty nice compromise on the gear spreads. I felt the 2.54 1st gearsets were just too high for my 3.73's at the strip, so i didn't try them.
funny this thread should comr back up. im about to put a saginaw in a high horse o.t. nova.after i look inside.
I have hammerd many of them and they held up well. the only weak leaak I see is Rev is casted to a boss on the houseing and snap if you hit it hard in Rev.
mine was 80 bux out of a vega. i wire wheeled a rust spot off a few teeth & beat the crap out of it. the thing is quiet as can be, can't complain.
Yeah, and the reverse idler is engaged in all gears...all power goes through it. I actually wore the teeth off a reverse idler. Replaced it and went on about my bidness.
Nine times out of ten when I hear a "those things are junk, I blew one all to hell" story, this is the real reason why. I have seen a few lunched muncies in cars that are regularly raced with slicks. The countershaft is supported by a hole in the aluminum case, which tends to wallow out or crack, then the countershaft is free to move away from the mainshaft, and its goodbye charlie. A steel bushing in the countershaft hole will prevent this. A friend of mine even lunched a muncie behind a fairly healthy 283, when we pulled it out, the case had cracked from the countershaft hole.
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