Close or wide ratio manual trans?

[kickasswelch69]

ok im lost. What does close or wide ratio describe in a 1967 Camaro transmission?

[Stingr69]

The top gear is 1:1 on both versions but the wide ratio transmission has more multiplication in the first gear ratio. The close ratio tranny has a 2.20 low gear while the wide ratio tranny has maybe 2.56 first gear ratio. 2nd and 3rd are in between.

The close ratio tranny is good for engines that have a high RPM peaky torque curve where you want to stay in the torque peak during shifts (think solid lifter screamers) while the wide ratio tranny is better for a lower RPM torquey type engines with a flatter torque curve (think big blocks or base engine cars) where they can run great over a wider range of RPMs.

-Mark.

[kickasswelch69]

:Sorry Mark, I don't even get what you are saying. I think what I should have asked first was what was gear ratio... woops.

[Stingr69]

Don't feel too bad. I have no idea what the question is.

-Mark.

[kickasswelch69]

well you could have said that. but what i was trying to find out is what is gear ratio? and what does a wide or close ratio transmission do?

[Fightinfire921]

I'll do it for you. Enjoy!

http://en.wikipedia.org/wiki/Gear_ratio

[kickasswelch69]

Ouch, all that work for nothing. Sorry I can't use Wikipedia as a source. This is a school project.

[steveo9043]

close ratio: rev's faster to redline, each gear will have a slower MPH
wide ratio: rev's slower to redline, each gear will have a higher MPH

[kickasswelch69]

Thanks stevo! Much obliged! Now can anyone explain to me what gear ratio is?

[PAUL SS]

Also with a close ratio trans the rpm drop between gear changes will be less.

Gear ratio refers how many times the output shaft turns in relation to the input shaft.

[Stingr69]

The gear ratio in a transmission is the ratio between the rotation of the engine and the roation of the drive shaft. The engine and drive shaft can operate at different speeds because of the "gear ratio". A 2:1 gear ratio (two to one) means that the engine will turn over 2 times for every 1 rotation of the driveshaft. This 2:1 ratio is a mechanical advantage or "multiplication". A 1:1 ratio (one to one) means the engine will rotate at exactly the same speed as the drive shaft and there is no mechanical advantage (no multiplication).

The 2:1 ratio will take the torque put out by the engine and double it. If the ratio was 3:1, the engine torque will be multiplied by a factor of 3. The higher numericaly the gear ratio is, the higher the torque multiplication will be BUT this will also lower the output speed on the driveshaft.

Think about a see-saw. If the see saw fulcrum is in the middle then both sides of the see-saw move at the same rate and there is no "multiplication". Both sides of the see-saw will move at the same rate and have the same lifting ability. This is a 1:1 Ratio. If the fulcrum is not in the middle, one side of the see saw moves up and down less but it allows a tiny person sitting on the long side to lift a very heavy person sitting on the short side. That is mechanical advantage or "multiplication". This is the same as gear ratio in a transmission. The higher numerically the ratio, the more mechanical advantage you get but the less movement on the output side.

I hope this helps.

-Mark.

[midlife]

Close or wide. The bottom line is this. If you want the car to be an everyday driver that you can enjoy, your best is a rear axle ratio of 3:55 to 3:73 with a wide ratio 4 speed. These combo is the same as 4:11 or 4.54 rear end ratios in 1st 2nd 3rd gears. Once in fourth you get the big rev drop off. But for tooling around town with this combo it feels like tall gears. Plus on the highway you can do 60 MPH at less than 3,000 RPMs. In away it was a little like today’s overdrive.
The Close with the 2:20 first gear is the real deal for a ¼ mile beast with 4:11 or 4:56 the problem is you cannot drive the highways due to high revs. If you run this tranny with the 3:55 of 3:73 you will not get the performance in the lower gears.