Close ratio VS. Wide ratio 4-speed tranny...Pros/Cons...

30 years ago I owned a '69 Z/28 with a close ratio Muncie 4-speed. I also owned a '67 Nova with a cast iron Saginaw wide ratio 4-speed. I really don't recall there being a whole lot of difference in the two cars performance.

What are the benefits of using close ratio over wide ratio? The reason I ask is that one costs about $800 more than the other, and I just don't see a great benefit of using one over the other in a 2500lb hot rod that wouldn't be thrashed on at the drags....your thoughts...

 

Close ratio is good for racing to minimize RPM drop between gears to keep engine in optimium hp range. For street, the wide ratio, with a lower first gear gets you moving faster, than a cose ratio with same rear ratio or can allow a higher rear ratio for better fuel economy, if using the same effective first gear ratio.

 

I agree with Algoma56. I have a close-ratio Muncie in my Camaro, with 3.42 gears, and I'd like to go to a wide-ratio to get a better launch. I think from the factory you couldn't get a close-ratio four-speed with gears above a certain ratio.

-Dave

 

I just switched from an M20 to a close ratio M21 in my 68 camaro. Still sucks on the highway. The close ratio has the same final ratio I believe but the rest of the gears are closer together which is good for racing because it keeps the motor at a higher rpm where the motor makes more power. I am now installing a T56 6 speed. best of both worlds.

 

Fourth gear is still 1:1; but first gear has less multiplication so you don't have as big a drop 1-2.

-Dave

 

Further to my comment above,

A wide ratio Muncie(2.52) with 3.42 rear would have an effective first gear of 8.6, the same rear with a close ratio Muncie first gear(2.20) would be 7.5. The higher effective first gear gives you better torque multiplication to get moving. On the same thought, to get the same 8.6 effective ratio with the 2.2 first gear of a close ratio, you would have to put in 3.91 in the rear. So, by using the wide Muncie box, you could better gas mileage with the 3.42's. For example, only.

 

The close ratio also has higher torque capacity. Less multiplication means it can handle more input. On the Fords, 390 or larger engines only came with the close ratio 3 and 4 speeds.

 

I've used both in my '55 Chevy. The close ratio seemed to work better on the drag strip with the tunnel ram and slicks, but the wide ratio seemed better when it was in street trim.

 

To me, wide ratio is the only way to go. I have a wide ratio with the same straight cut gears as the M22 Rock Crusher and it is awesome. Close ratio is for road racing.

I've got 29.5" diameter tires and a 3.90 rear. I needed the steeper first gear.

I can run 100 in second at 7000 rpm. It is the shit

 

I have both in various cars. Agree with most here - close ratio is best for road racing - wide ratio best for anything else. But, 5 or 6 speed even better, and about the same price as a good Muncie these days !

 

are you sure about that gear ratio in a muncie

 

Sorry to confuse: That gear ratio is in the 10-bolt behind the Muncie.

-Dave

 

putting a close ratio behind say a 230 six with 3.08 gears and you will have trouble climbing steep driveways.

 

My '69 Z had the M-21 and the '69 SS had the M-22 grinder....

 

Regardless of the engine, the wide ratio (M-20) will have a slight advantage over the M-21.

 

I have a 2.78 1st gear Liberty geared top loader in my SEGA super stock wagon. I just changed from a 5.29 gear to a 6.00 gear so I can really use 4th gear in the 1/8 th mile. We have a spec 29 x 7 Hoosier slick.
One of my competitors runs a similar engine combo in a Falcon and runs a 2.43 1st gear G Force close ratio with a 6.50 gear. His rational is it is less violent on the hit but makes it up on the big end.

 

I’ve always gone by anything with 3.70’s or stiffer , use a close ratio trans. With a numerically lower gear (like 3.08) use a wide ratio trans.

 

I miss Larry.

 

I have played the trans. ratio game in many cars. Bowie is right on. A base line for the factory cars was exactly as he said. 3.70 and lower - close ratio. 3.55 and up - wide ratio. But you could order any combination. I found this rule to be very effective.

 

I now have a wide ratio Muncie with a 3.42 rear , it does move out faster but can't hit 70 in low gear like i could with the close ratio T-10 .

 

Someone help me out here, a wide ratio has larger rpm changes between gears. If so, why would running a lower numerically geared rearend be better and vice-versa?

Or is it assumed with the 3.08 rear and wide ratio transmission, your running a big block with more lower/mid range grunt?

I can see keeping a higher winding engine in its power band with a close ratio.

 

That's it! End of story.

 

Nice to see one of his old threads

 

Nobody has mentioned the clutch. The wide is easier on it with a street gear.