Need help with diff. ratio.
Registered User
Joined: Aug 2013
Posts: 12,804
From: Evansville, IN
Hi, welcome to Classic Oldsmobile.
To help you, we will need more information. What car, what year, what engine, and what your application and wants are.
There is no 200r4 transmission. There is a TH-200-4R and a TH-700-R4 and those letters are easy to screw up. The 700-R4 is a stronger transmission, so if you want to put down some beef, you'll want it, but you'll need to tell us the engine and the plan first.
For ratio, both transmissions have a OD that is close, .067 and .70. That would make that rear act like a 3.18 or so, which would be great for highway with normal tires, and probably ok with taller tires as well to an extent.
For first gear stack up you have 2.74 or 3.06 times your 4.55 rear. The 700 has a much bigger jump between first and second than the 200. I think a 200 can be built up for most needs, but I am not a transmission builder.
For drag racing, if you have a hypothetical strong 455, I think that is too much rear to use with these OD transmissions and you'll be losing traction in first gear.
To help you, we will need more information. What car, what year, what engine, and what your application and wants are.
There is no 200r4 transmission. There is a TH-200-4R and a TH-700-R4 and those letters are easy to screw up. The 700-R4 is a stronger transmission, so if you want to put down some beef, you'll want it, but you'll need to tell us the engine and the plan first.
For ratio, both transmissions have a OD that is close, .067 and .70. That would make that rear act like a 3.18 or so, which would be great for highway with normal tires, and probably ok with taller tires as well to an extent.
For first gear stack up you have 2.74 or 3.06 times your 4.55 rear. The 700 has a much bigger jump between first and second than the 200. I think a 200 can be built up for most needs, but I am not a transmission builder.
For drag racing, if you have a hypothetical strong 455, I think that is too much rear to use with these OD transmissions and you'll be losing traction in first gear.
CH3NO2 LEARN IT BURN IT
Joined: Jul 2010
Posts: 5,636
From: Land of Taxes
Will it work? Yes So will a 256:1 and a 500:1
Odd ratio. Do you mean 456:1 Define "work?" What are your intentions? What is your setup? Tire size, engine et al...456:1 is a track-only gear...not street with any trans.
Odd ratio. Do you mean 456:1 Define "work?" What are your intentions? What is your setup? Tire size, engine et al...456:1 is a track-only gear...not street with any trans.
Out of Line, Everytime😉
Joined: Dec 2006
Posts: 10,109
From: Melville, Saskatchewan
You want at least a 3.42 gear. Even with a short tire you will be under 2000 rpm at 60 mph. Here is a very accurate calculator. It assumes a lock up torque converter and already has the .67 OD ratio built in. Of course you know these transmissions need upgrades to live behind a 455 but have the best gear ratios of any 4 spd auto.http://tech.oldsgmail.com/ch_axle.php
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