The tranny in my bird is a Saginaw 4 speed and I was wondering whether it would be worth the effort to swap it for a Muncie. The gear ratios ave very different so it might go better with the 400 v8 that is presently in the car. I understand the Saginaw came with the 6 cyl engine which was in my car from the factory.
In looking at the gear ratios I see that my 2nd gear is the same as the 1st gear in the close ratio Muncie. At this ratio it seems I could forget using 1st gear....or am I missing something??
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
They came with the Saginaw 4 speed too. Here's a link in the FAQs; https://firstgenfirebird.org/FAQ/trans_clutch/trans.html I would do some extensive road tests first to see if there is a need to change it. Carefully decide whether you need the trans ratio to change or a rear gear change. The rear gear change would be less costly....
According to my service manual: 3 speed Dearborn was used as the standard transmission for full size Pontiac and as heavy duty transmission on Tempest and Firebird. Fully synchronized. Gear ratio 1st...2.42:1, 2nd...1.61:1, 3rd....1.00:1.
3 speed Saginaw was the standard transmission on Tempest and Firebird (except 400ci V8 engine). (Not synchronized). Gear ratio 6 cyl 1st....2.85:1, 2nd....1.68:1, 3rd....3.00:1 V8 (all but 400) 1st....2.54:1, 2nd....1.50:1, 3rd....1.00:1
4 speed Saginaw was used on ALL 4 speed Tempest and Firebird 6 cyl. engines. Fully synchronizes. Gear ratio (Firebirds) 1st....3.11:1, 2nd....2.20:1, 3rd....1.47:1, 4th 1.00:1. (Tempest ratios slightly lower.
4 speed Muncie is used with all v8 engines in full size Pontiacs, Tempests and Firebirds. Fully synchronized. Both Std and close ratios available. Gear ratios (std) 1st....2.52:1, 2nd....1.88:1, 3rd....1.46:1, 4th....1.00:1. (close ratio) 1st....2.20:1, 2nd....1.64:1, 3rd....1.28:1, 4th....1.00:1.
With this said, it is the low 1st gear on my Saginaw 4 speed that is realy too low (3.11:1 compared to the Muncie 2.52:1, or 2.20:1) I can really get off the line fast, but there is a huge gap going into 2nd gear.
Any sugestions?
Last edited by Richman; 01/21/0807:11 PM. Reason: Emphasis correction
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
It would also depend on the amount of power you are putting through the tranny and your driving tendancies!!! The Muncies were called rock crushers for a reason!!!
The OHC's had more RPM (6500)than the V8's hence the longer legs in your Saginaw.
Also your ratio in the rear end would be the other major factor!
I requested a quote for either a 5 speed or 6 speed from this company, but money is always an issue.
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
Fuhrmann, the "Rockcrusher" was the M-22 close ratio Muncie. It was called that because the gears on it were a different angle than the M-20/21 Muncies. They made more noise than the M20/21's Alot of people think they have "Rockcrushers" but have an M-21 instead. They are actually pretty rare. If your rear gear ratio was 3.55 & higher, you had an M-20, anything lower had an M-21/22.
BTW, I would strongly recommend replacing the Saginaw, it is a weak transmission & will break easily behind a 400. What is your rear gear ratio?
According to my service manual: 3 speed Dearborn was used as the standard transmission for full size Pontiac and as heavy duty transmission on Tempest and Firebird. Fully synchronized. Gear ratio 1st...2.42:1, 2nd...1.61:1, 3rd....1.00:1.
3 speed Saginaw was the standard transmission on Tempest and Firebird (except 400ci V8 engine). (Not synchronized). Gear ratio 6 cyl 1st....2.85:1, 2nd....1.68:1, 3rd....3.00:1 V8 (all but 400) 1st....2.54:1, 2nd....1.50:1, 3rd....1.00:1
4 speed Saginaw was used on ALL 4 speed Tempest and Firebird 6 cyl. engines. Fully synchronizes. Gear ratio (Firebirds) 1st....3.11:1, 2nd....2.20:1, 3rd....1.47:1, 4th 1.00:1. (Tempest ratios slightly lower.
4 speed Muncie is used with all v8 engines in full size Pontiacs, Tempests and Firebirds. Fully synchronized. Both Std and close ratios available. Gear ratios (std) 1st....2.52:1, 2nd....1.88:1, 3rd....1.46:1, 4th....1.00:1. (close ratio) 1st....2.20:1, 2nd....1.64:1, 3rd....1.28:1, 4th....1.00:1.
With this said, it is the low 1st gear on my Saginaw 4 speed that is realy too low (3.11:1 compared to the Muncie 2.52:1, or 2.20:1) I can really get off the line fast, but there is a huge gap going into 2nd gear.
Based on that chart my OHC has a 2.85:1 1st 3 speed. I think I'll go with the 2.52 M-20 and maybe a 3:36 or 3:55 rear gear when I put the Sprint 6 in it.
Seems odd to have a 2.85 1st 3 speed and a whopping 3.11 1st (truck gears)4 speed. I run out of first as it is, can't imagine what the 3.11 is like.
Wanting a Custom fit in an off the rack world.
I don't have time for a job, I just need the money.
My car had an M21 when I bought it in 2000. In 2004 I pulled it out because it wouldn't stay in 4th gear (kept popping out). When I pulled it, my buddy game me what I thought was a T-10 and it's been in there ever since. It has a REALLY low first gear.
Today I went to a friends house and we looked it over, as I now have a brand new M21 blue printed and ready to go in the car. I had a buyer for the T-10. As it turns out, I have a Saginaw 4 speed and not a T-10. The guy was suprized that I have been running it for the last 4 years especially the way I like to beat my car (when it runs right) that is.
Anyway, that Saginaw doesn't seem to be too bad IMO. Although I am looking forward to getting the new M21 back in the car...
you can find a good muncie in the 6-700$ range all day long!!! depends on your driving style and needs. if your going to beat it go for the better trans otherwise cant justify the cost!! the sag would get you around without laying into it because you'll break it if you do!! otherwise consider upgrading to at least a muncie!!
Andy
due to budget cutbacks, the light at the end of the tunnel has been disconnected for non payment.
My cammer has a 3.55 rear and it's a nice balance with the trans (3spd Sag) ratios. It does top out quicker in final drive than I'd like. But I still get 20 MPG on the highway, so it's a nice compromise.
My car had an M21 when I bought it in 2000. In 2004 I pulled it out because it wouldn't stay in 4th gear (kept popping out). When I pulled it, my buddy game me what I thought was a T-10 and it's been in there ever since. It has a REALLY low first gear.
Today I went to a friends house and we looked it over, as I now have a brand new M21 blue printed and ready to go in the car. I had a buyer for the T-10. As it turns out, I have a Saginaw 4 speed and not a T-10. The guy was suprized that I have been running it for the last 4 years especially the way I like to beat my car (when it runs right) that is.
Anyway, that Saginaw doesn't seem to be too bad IMO. Although I am looking forward to getting the new M21 back in the car...
the sinchronizers need replaced!!! they are too worn to hold the gear in place thus it popping out all the time!!! few hundred at a trans shop would fix this problem!!!
Andy
due to budget cutbacks, the light at the end of the tunnel has been disconnected for non payment.
Well, I did buy the kit, took it to a shop and the guy told me I was better off buying a new M21 as my gears were also chewed up etc. Ultimately that is what I did. I do still have my old m21 although I may trade it off to the guy who has my new one for labor to install.
the old one can be sold on ebay. also the gears are sold as NEW now. you can convert an m-19 to an m-22 with all new parts. there may be some differences in the case but i dont know of any. maybe others do!!
Andy
due to budget cutbacks, the light at the end of the tunnel has been disconnected for non payment.
there is some math to do in regards to the rear end. Multiply the rear end gear by the first gear. You want to be over 9 and under 10 IDEALLY.
example:
Rear end: 3:23 ratio TIMES First gear on tranny 2.85
EQUALS
9.21
That gets you off the line correctly.
If you have 2.90 gears or something in the rear end and put a M-22 (2.52 first gear)in, you will not be happy getting off the line as the math comes out to 7.31. A so-called "close ratio M-22 would have an even higher first gear at 2.20, so that would be very bad off the line...This is why you would see that transmission with a 4:11 rear end oftentimes, where you get the total gear value at 9.04.
You want to be over a "nine" so just do your math, when going with a 4 speed
If it is too high, you will be gear bound. So do some homework upon switching it up, and change the gears somewhere, either in the tranny or in the rear end if need be.
Good luck.
1969 Firebird 350 Coupe, Rust free Texas body, formerly brown, now a TA clone with quality spoiler, latching hood and TA wheel; 1969 GTO Convertible Expresso Brown/Parchment(currently painted red). Both numbers matching. My first love was a Cameo White 67 326 Coupe, bought back in 1983, at the age of 17, for $1,200. Been hooked since on PONTIAC! Working on a 67 400 ragtop for customization-Gulf Turquoise/Parchment/400/4 spd! My winter project!
there is some math to do in regards to the rear end. Multiply the rear end gear by the first gear. You want to be over 9 and under 10 IDEALLY.
example:
Rear end: 3:23 ratio TIMES First gear on tranny 2.85
EQUALS
9.21
That gets you off the line correctly.
If you have 2.90 gears or something in the rear end and put a M-22 (2.52 first gear)in, you will not be happy getting off the line as the math comes out to 7.31. A so-called "close ratio M-22 would have an even higher first gear at 2.20, so that would be very bad off the line...This is why you would see that transmission with a 4:11 rear end oftentimes, where you get the total gear value at 9.04.
You want to be over a "nine" so just do your math, when going with a 4 speed
If it is too high, you will be gear bound. So do some homework upon switching it up, and change the gears somewhere, either in the tranny or in the rear end if need be.
Good luck.
I like math and nice, tidy equations like this(above). I'm going to put this math to the test in the spring. I recently bought an unfinished project car that will do it. It has all new drive train components. The engine is an aluminum head Pontiac mill that is built close to RA IV specs. The trans is a 2.20 M-21. The rear gears are 3:23. (2.20 x 3.23 = 7.106) With the above mentioned equation, I should have very little power off the line. Since the builder of this car had a lot of experience, I'm thinking it will be just fine for cruising. We will see when the rubber hits the road.....
Uncle Sam, you run that candy shop over by Home Depot? I was drooling over your brown 69 you had out for sale in front of the store. There's a few of us first gen birders around in Schenectady.
In my opinion, Jim, the M-21 sucks unless you have a high number rear end, then you rev too fast at highway speeds. My M-20 with 3:23 gears (with little tires) is OK off the line and still revs high at highway speeds.
Uncle Sam, you run that candy shop over by Home Depot? I was drooling over your brown 69 you had out for sale in front of the store. There's a few of us first gen birders around in Schenectady.
In my opinion, Jim, the M-21 sucks unless you have a high number rear end, then you rev too fast at highway speeds. My M-20 with 3:23 gears (with little tires) is OK off the line and still revs high at highway speeds.
I've had m-21's before. They are excellent transmissions. The ones I've had always were with 3.73 rear gears. They scream off the line and high rev on the e-way. This one should be good on the e-way due to it's ability for high revs. We will see how it is off the line. The guy who planned and built it was not a rooky. He had built many cars in his life and this was his best...just before he passed away unexpectedly. I can't imagine him building a 'dud'. I have reciepts for all the parts used on the car and he was a 'build master'.
I was only opinionating on the gear ratios, not the quality of the trans. My experience with an M-21 was in my 66 Impala with a 396 and a 12-bolt with "highway gears" when I was a kid. It was a horrible combination. At the time I had no clue why first gear was so steep. I though a "Corvette close ratio Muncie" had to be good. I remember I paid $50 for it, with a Hurst shifter. Looking back, it was probably hot.
Jim, I doubt that you'll have "very little power off the line". You'll have about the same overall torque off the line as a Chev 350 in a Camaro with 3.73 gears. You will have to either slip the clutch more or spin the tires more with a close ratio. I vote for the tires.
The numbers are "rule of thumb" that slants the numbers toward street racing rather than cruising. They also assume, as usual, that you're running a Chev 350 in a Camaro (ratio of engine size to car size - barges need more engine). A 400 or 455 in a Firebird would obviously need less gear to light the tires up.
I usually use 8.5 to 9 as my highest number and frequently end up with less than 8 because I tend to travel more than a 1/4 mile at a time. I spend a lot more time above 30 mph than below but that's me.
Decide what is more important to you and adjust the numbers to suit.
Jim, I doubt that you'll have "very little power off the line". You'll have about the same overall torque off the line as a Chev 350 in a Camaro with 3.73 gears. You will have to either slip the clutch more or spin the tires more with a close ratio. I vote for the tires.
The numbers are "rule of thumb" that slants the numbers toward street racing rather that cruising. They also assume, as usual, that you're running a Chev 350 in a Camaro (ratio of engine size to car size - barges need more engine). A 400 or 455 in a Firebird would obviously need less gear to light the tires up.
I usually use 8.5 to 9 as my highest number and frequently end up with less than 8 because I tend to travel more than a 1/4 mile at a time. I spend a lot more time above 30 mph than below but that's me.
Decide what is more important to you and adjust the numbers to suit.
I recently owned a 69 Z28 with 350/302 and 3:73. It had more than enough torque off the line.
Bob, I'm not sure why your Chevy combo was such a dog. Some of those 396's weren't all that great.
And a heavy car. Probably felt like you were starting in second!
350/302?
I had the 350 and also the 302 later.
The 2.20 M21 trans and 3:23 gears combination with a high output Pontiac engine in a first gen will be a fun test. I'll be happy to post the results just as soon as I get the car done and the salt leaves the county. Probably both happening around the same time.
Just came back from a cruise night. I have so say, this saginaw in my car has certainly taken a beating over the last 4 years. Especially since you guys all say they don't typically hold up that well. I guess I have been lucky with this one. It shifts fine and everything. Oh well, I am looking forward the new M21, I spoke to the guy who built since reading this topic and he says my new M21 has a 2:52 first gear. I am running 3:55 rear gears...
Math comes out to 8.946 close enough or not? Hmmm, guess we'll see. Although I beleive that is what this saginaw I am using now has for a first gear as well...
Ok, I checked with the guy who built my new Muncie, he used a 2.56 first gear and with my 3.55 the math comes out to 9.088. He used the 2.56 first gear to match what I have now with the Saginaw as I told him I did not want to loose the low first gear. The guy is also shocked that I have gotten away with this Saginaw for so long. He said I better get the new Muncie installed soon now that my car is running correct as I just can not keep my foot out of the gas now!
Interesting... That's an M20 then? Did he use all the gears common to a 20 or did he mix and match them from M20 and M21?(per your reference that it was a 21) The reason I ask is if my new set-up(M21) bogs in first I may want to just swap out the first gear....
It's an M20. My original was an M21. When I pulled it and installed the Saginaw (which at the time I was told was a T-10) I absolutely LOVED the low first gear. SO based on that, this guy told me I would want the M20 set up.
This guy's garage is nuts! He has Muncies lined up by year, all taged with dates etc. He goes so far as to put a clear cover on the side so you can see everything inside is new, and everything works etc. The guy is a perfectionist. When he sells one he gives you an entire card with all the specs. etc.
Thanks. I hear what you are saying about trying it out. I'm eager to try mine too. I need to see if that equation 'holds true'. Mine works out to just over 7 when I multiply(2.2x3.23). Maybe I will use the clutch like a stall convertor!
