Gear ratio with T56

[touronhold72]

I am curious to hear what gear ratio people are running in combination with a T56. I am currently setting up a 12 bolt for a 1972 Chevelle and need to order the gears. I am using a Truetrac and the car will see very little track use and will be more of a weekend terror.



The default suggestion I get from most people is a 4.10 gear. I would love to hear some other suggestions on gear selection.

Thanks.

[Hotwire]

You need to factor in tire height and trans model as that affects the final gear ratio.

I'm running a TUET2066 T56 out of an 05 GTO, 0.56:1 6th, 3.73s, 26" tall tires, results in 2000 RPM @ 70mph.

T56 models
https://en.m.wikipedia.org/wiki/Borg...6_transmission

Greatest calculator I've found to compare gear ratios and tire sizes
https://www.blocklayer.com/rpm-gear

[SoloC4]

I am curious to hear what gear ratio people are running in combination with a T56. I am currently setting up a 12 bolt for a 1972 Chevelle and need to order the gears. I am using a Truetrac and the car will see very little track use and will be more of a weekend terror.

The default suggestion I get from most people is a 4.10 gear. I would love to hear some other suggestions on gear selection.

Thanks.

This may depend on which ratio you have in your transmission and the torque of the engine. Most standard T56 are wide ratio with a 3.07 first gear which work best with a common factory rear gear in the 3.08 to 3.23 range, whereas the close ratio has a 2.73 first gear and is more suited for the 3.73 to 4.11 range like what you are looking at. This is particularly important if you have a BB or stroker SB that puts out a lot of torque. I hope this helps.

[Lonnies Performance]

It helps to know your HP, cam selection, RPM range, tire height & the particular gear ratios the trans is equipped with.

Typically it works out between 3.42 & 4.10's, but the above info will make the difference.

[touronhold72]

I guess I need to crawl under the car and figure out which T56 it is. If I remember correctly it came out of an '02 Camaro. The car is an older project do it has a 6.0L with a GM hot cam so maybe 400 rwhp and probably somewhere near that with torque. Car had a 26.6" tall tire but I need to double check the model of trans for the ratio.

[Hotwire]

Click on the Wikipedia link then identification, that'll show you applications and gear ratios. If you trans still has the build tag bolted to the rear housing you can verify the tag ID #.

[Mkelcy]

This may depend on which ratio you have in your transmission and the torque of the engine. Most standard T56 are wide ratio with a 3.07 first gear which work best with a common factory rear gear in the 3.08 to 3.23 range, whereas the close ratio has a 2.73 first gear and is more suited for the 3.73 to 4.11 range like what you are looking at. This is particularly important if you have a BB or stroker SB that puts out a lot of torque. I hope this helps.

Virtually none of this is true. There are no T56's with a 3.07 first gear, much less being standard. There are also no T56's with a 2.73 first gear. Most common is 2.66, with 2.97 second.

I've found that it's most helpful to figure out what speed you want to be able to cruise at in sixth gear (which depends on the sixth gear ratio in the T56 and the engine) and then back into the final drive ratio, adjusting as needed for ordinary driving. Most fuel injected LSx's are pretty happy cruising at 1,500 to 1,700 RPM; most SBC's and BBC's want to be in the low 2,000's or above. My hot cammed LS3 (0.5:1 sixth, 3.70 final drive) happily cruises at 70 at about 1,650 RPM.

[SoloC4]

Virtually none of this is true. There are no T56's with a 3.07 first gear, much less being standard. There are also no T56's with a 2.73 first gear. Most common is 2.66, with 2.97 second.

I've found that it's most helpful to figure out what speed you want to be able to cruise at in sixth gear (which depends on the sixth gear ratio in the T56 and the engine) and then back into the final drive ratio, adjusting as needed for ordinary driving. Most fuel injected LSx's are pretty happy cruising at 1,500 to 1,700 RPM; most SBC's and BBC's want to be in the low 2,000's or above. My hot cammed LS3 (0.5:1 sixth, 3.70 final drive) happily cruises at 70 at about 1,650 RPM.

I’m not sure why you think this is “virtual nonsense” The ‘92 T56 had a 3.06 1st gear, ‘93-‘97 Camaro had two T56’s available, a wide ratio with a 2.97 1st gear and a close ratio with a 2.66 1st gear, ‘98-02 Camaro came with a 2.66 1st gear only. The exception was the GTO T56 which had a 2.97 1st gear. All of them had a 1:1 forth gear making it a moot point and two 6th gear ratio .62 for the 2.97 WR, .50 for the 2.66 CR. My first post was intentional short for informational purposes only so as not to complicate things. The OP stated that this was for mainly street driving and wanted to use 4.11 gears which is why I mentioned the two transmissions most commonly used. With a heavy car and conservative torque a 2.97 1st gear would due fine, but a lighter car with excessive power will make 1st gear useless, we’re the 2.66 1st gear is at least livable on the street. This statement comes from first hand experience with a 3100 lb. Camaro with 580 ft/lb torque engine and 3.73 rear gears. I replaced the wide ratio with a close ratio transmission for better street driving and autocross. Strictly drag racing changes everything, but tat was not the topic at hand when the OP posed the question. This ended up being way too long, which is what I was trying to avoid from the start.

[Astro Blue]

I went with 3.89 for LS3 and 2.66 first gear. no clue how it rides the car isnt finished yet.

[thedugan]

I am running a 3.73 in one car and a 3.90 in another. Very happy with the off-the-line, around-town, and highway cruising. The calculators above will show you the speed at the different RPM's. 4.10 to me would be a lot. You would be shifting out of first right off the line.

[Chad-1stGen]

Virtually none of this is true. There are no T56's with a 3.07 first gear, much less being standard. There are also no T56's with a 2.73 first gear. Most common is 2.66, with 2.97 second.

I've found that it's most helpful to figure out what speed you want to be able to cruise at in sixth gear (which depends on the sixth gear ratio in the T56 and the engine) and then back into the final drive ratio, adjusting as needed for ordinary driving. Most fuel injected LSx's are pretty happy cruising at 1,500 to 1,700 RPM; most SBC's and BBC's want to be in the low 2,000's or above. My hot cammed LS3 (0.5:1 sixth, 3.70 final drive) happily cruises at 70 at about 1,650 RPM.

/\/\ This right here.

For a mostly street car I'd carefully consider your 6th gear cruise speed. The only thing I'd add to what Mkelcy wrote is that most T56 based transmissions have either a .5 or .62 6th gear. I'm a fan of 3.70's or 3.73's for a .5 rear gear car if it's LS powered or mild SBC. I don't personally like the 4.10 or 4.11's because of how short it makes 1st gear and how high cruising RPM is in 6th with a .62 ratio. This is also based on common 18" tire sizes. If you are going to run a lot taller tire on a 19 or 20 then it could change things a little.

[Hotwire]

I guess I need to crawl under the car and figure out which T56 it is. If I remember correctly it came out of an '02 Camaro. The car is an older project do it has a 6.0L with a GM hot cam so maybe 400 rwhp and probably somewhere near that with torque. Car had a 26.6" tall tire but I need to double check the model of trans for the ratio.

Any update?

[streetk14]

The F-body T56 is a 2.66 1st with a .50 6th. I ran this trans with a 400 whp LS6 and 4.10 gears years ago, and I really liked it.

Like others have said, it really depends on the trans gearing, how much power you’re making, and what you plan to do with the car. For me it’s always trying to find the balance of comfortable highway cruising (being low enough to be quiet’ish, but high enough the engine is happy), a short enough first for good driveability around town (depends on cam choice, etc.) , and enough gear to finish the quarter mile without shifting into 5th. At least those are my priorities.

My current car has a 2.66/.63 T56 Magnum with 3.89 gears. It revs a little higher on the freeway than I’d like (2400-2500 at 75-80 mph), but everything else is great. The stop and go driveability is much better than when I had 3.50 gears in the car, but I feel like the 3.50s were the sweet spot for freeway driving. I’ve considered swapping out my overdrives for the .74/.50 setup, but it’s probably not worth the effort and cost.

Bottom line is use the gear calculators and do your homework, but there’s pretty much always some kind of compromise when setting up gearing in these things.

[andrewb70]

I prefer being around 1800rpm at 75MPH, so I base all of my hearing decisions based on that. The other important factor to consider is driveshaft speed. This is solely impacted by the choice of ring and pinion ratio. While 4.10 hears are fun, they raise the driveshaft speed dramatically.

If you look at new cars, you'll see a trend towards higher ring and pinion ratios and deep gears in the transmissions.

Andrew

[streetk14]

I agree, Andrew. I wish Tremec made a close ratio Magnum with shorter gears. I guess that would require 4th being shorter than 1:1, but that would be nice. They didn’t even offer the close ratio version with the 0.50 6th last I checked, which is why I ended up with the .80/.63 version.