I ran sags bot 3 and 4 gear about forever and I hope one will handle 300 HP I am throwing 400+ at mine. LOL The Sag 3 speed was the mainstay for chevy up into the 70s. If you owned a Chevy with a 3 speed it was a sag and many got way more then 300 ponies in front of them. Make sure that the box is tight, get a good shifter and don't miss gears you'll be fine.
There are only two answers to this question. Yes and No. So far we have both. So I would say the subject is covered.
Agree with everyone, Yes if you are somewhat easy on it, No if you used them like I did back in the day, 60's, street racing, 57 Chevy 210 2 door sedan, 348/tricarb, 3 speed, 4:11 posi, street slicks. less than 300 HP but higher torque, broke every piece of drive line several times, replaced with junkyard parts always (my speed shop source) did figure out to weld syncro drum ring on/re-machine, ( 3speed)so it did not pop off speed shifting (had Hurst shifter w/stops) launch @ 3600, shift @ 5000/5200 rpm, pretty good 1/8 mile street racer. Had a 64 Impala SS hardtop, 300/327, 4 speed, 4:56 then 4:88 posi, street slicks, added 30/30 solid cam, headers, different carb combos, maybe 350/360HP, launched @ 5000 rpm power shifted @ 6200/6400 rpm, this big old Heavy Impala was a damn good 1/8 mile street race car, But again, Broke everything in drive line including BW T10s and Muncie 4 speeds, (again had Hurst shifter w/stops) ( was buying rebuilt 4 speeds from reputable source back then, the M22 , don't rember of hearing of it to try, my street racing days ended in 1970. Shifting is Kool/Fun, but if you go to a modified auto you'll have way less breakage, be more consistent as a lot men don't seem to have the coordination necessary, IMO. Merry Christmas to All
My 64 Impala non ss 327 4 speed aluminum intake headders no spare and jack weighted 3480 over the scales less than a GTO. Not so heavy.
Your 2.85 Saginaw can easily take 300hp. The problems come when someone installs a clutch that holds more torque than the transmission can take. Lets say your 327 puts out 400ftlbs or so on a dyno. Install a clutch that holds 650ftlbs behind it, it's possible for the input shaft to see that 650ftlbs even though the engine only makes 400. That's because that clutch has the ability to draw that much additional inertia energy from the rotating assy. Engine rpm loss after a clutch dump is basically the result of inertia energy exiting the rotating assy. If you want to make your Saginaw install trouble-free, either install a clutch with a proper torque capacity in front of it, or install an overkill clutch but add a clutch hit controller to manage that clutch's hit. Grant
Interesting, all these years I thought it was a heavy car(never looked up GVW) many guys back then commented on how quick it was for a big old car.(owned 68/70) I know it twisted up the X-frame a ton on launch, had guys tell me it picked up left front, (no pics). One the many items that failed was the center u joint support for the 2 piece driveshaft, the second time, quite a project to fix. I would win $20/30 from new muscle car guys regularly, just first checked to see their tire deal and most of my/our street racing was 1/8 mile type, Ah, the memories, the Fun/excitement, ( night in pokey, high insurance rates, license revocation, fines, not so much) always spent more on parts/repairs than made, A trend that followed my entire racing hobby (open wheel) and have managed to maintain all through my hobby car deal to this day, would not trade or change anything, Memories, Priceless !
LOL I have never run one with any more clutch than a Zoom. What used to kill tem was one of two things, the driver could not drive and either missed or scraped gears and over shifting one due to a shifter without stops. I used to run them a lot because they were a 15 dollar junkyard transmission. On a good day I actually had a spare in the trunk. LOL
I've broken waay more than my fair share of Saginaws as well, most were slick shifted and faceplated. All my failures were either 1st gear teeth on the cluster or the input shaft teeth, although I did bend a mainshaft once and had to buy a pair of earplugs for the drive home. Never did break a Saginaw that I wasn't able to drive home. Best I ever did with one was 6.516 with a 1.456 60'. Pretty sure I could beat that knowing what I know now, but I long ago gave away all my Saginaw stuff and switched to Ford Toploader. Here's a pic of one of my Saginaw setups, 1st gear had a synchro, 2nd gear was slick shifted, 3rd gear was faceplated, 4th had a synchro... Grant
The "slick shifted" 2nd gear in the pic above has every other spline removed from inside the slider, also every other tooth on the side of the gear that engages with the slider is removed as well. All the teeth are removed from that brass synchro ring, it's only there to help locate the 3 keys that are still there to keep the 1st gear synchro functional. The "faceplated" 3rd gear slider in the pic above has it's internal teeth removed from the 3rd gear side and functionally replaced by a face plate that's welded to it's side. The stock 3rd gear dog teeth on the side of that gear were removed and functionally replaced by a welded on dog ring to engage with the slider's face plate. All the teeth are removed from that brass synchro ring as well, it's only there to help locate the 3 keys that are still there to keep 4th gear synchro functional. The function of both modifications is to widen the engagement window for those gears, making it faster/easier to complete a shift at high rpm. Faceplate engagement is also far more durable than slick shift. Grant
It's not about hp A 283- 315 hp fuelie Corvette at 295 ft lbs of torque I would say yes but a 430- 310 hp Mercury at 460 ft lbs torque No.
"All my failures were either 1st gear teeth on the cluster or the input shaft teeth, ...." That is the kind of failure I think of when drag race type starts are involved. Might be one big hit, or a bunch of lnot-quite-so big ones that ending up fatiguing the same few teeth. The next next step would be case breakage when shrapnel got between gear teeth, etc. Transmitting high horsepower or torque through several gears during a prolonged acceleration run, combined with quick but not abusive shifting is another story. That tests all the teeth's bending fatigue strength, especially gear tooth root design and detailing ( smoothing, deburring, shot-peening) . Other manufacturers' transmission "rating" parameters are tooth face durability (time at max load before spalling or other types of surface distress develop) , gear capacity by means of tooth strength rating, scoring hazard rating, and allowable stress index (whatever that is).
If Saginaws were so bad why did every dirt track super stock and pro stock run them until the rules allowed Berts, Brinns, and Falcons. We still run a dirivitive of a Sag in ours. We're taking Motown and Dart 415-432" block engines makin over 600 hp.
I saw lots of Saginaws in some expensive stock cars. Most were gutted to allow 2 forward gears and a reverse only. They were plentiful when I raced and can't recall a failure on the track.
If you look at the general theme of replys, basically if you want to just cruise and granny shift you will be OK. If you plan to use it vigorously on ocassion, it will last a while but you will always be wondering when it will break.....because it will. Remember, this is not a new transmission that you are starting with. My view is that you have something which has value in its current condition. Once you break it, it has little value and may cost far more to repair than its worth. I'd sell it and put the money into a stronger 5 speed. Then you get a better and stronger transmission. Better acceleration when you want it as well as better gas mileage. No one can see what transmission you have.......just put a plain ball on the shifter. To me having a car thats more enjoyable to drive outweighs bragging about having a nostalgic transmission. Let the Flathead guys have the Saginaws.
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