Gear Ratio

[DKz Garage]

Looking for some advice a on gear selection: LSA motor, T-56 /close ration trans, 26.91 rear tire diameter. I know the LSA makes a lot of torque at low RPM, I'll do a lot of street driving, some auto cross. 3.70 and 3.89 ratios seem to be a popular choice. Any input would be appreciated.

[Motobrewmaster]

I have a similar combo and run the 3.89. It has been great for spirited street driving. I did one track day with that gear ratio with my old engine and it worked good for the road course I was on (Club Motorsports).

[DKz Garage]

I have a similar combo and run the 3.89. It has been great for spirited street driving. I did one track day with that gear ratio with my old engine and it worked good for the road course I was on (Club Motorsports).

Thanks for your input!

[Schwartz Performance]

With your tire size & trans I usually go with the 3.89, but supercharged applications I usually dim it back a little and would do a 3.50 or 3.70. It's minimal difference.. but a torquey LSA doesn't need as much torque multiplication.

For what it's worth, an LSA ZL1 camaro had a 3.73 gear and 28.4" tire with the same close-ratio trans.

-Dale

[GoodysGotaCuda]

I don't have a torque problem, but I just put 3.73s in my car with a 28.5" rear tire. I had to setup a new diff and changed from 3.91.

[icemanrd19]

Do a gear ratio calculator in tremec website and see where you would like rpms to be while cruising in 6th gear in the highway, 2nd gear low rpms to max rpm speed limit while autocross and find a happy medium. T56 magnum, ls3, 315/30/18 rear tire here. I had 4.10 and it was fun but ran out of 2nd gear for my likings in autocross and cruising at 70 on the highway the rpms were a couple hundred high for my liking not to mention 1st gear. I went to a 3.70 and I’m much much happier. 2nd gear from 3k to 7k for autocross is great and 72 mph on the highway keeps me st 2200 rpms. 4th gear pulls going 70 mph to 140 pulls hard as well

[John McIntire]

For what it's worth, I plan on running a 3.90 with a 26.68 tall tire and a T56 Magnum.

Same gearing as the latest Z28's Chevy made.

I also will have an LS7, so torque will not be a problem down low.

Like was mentioned before, play around on Tremecs website with their gear calculator and plug in a few different RPM's all the way up to redline to get an idea of how it'll perform.

[DKz Garage]

With your tire size & trans I usually go with the 3.89, but supercharged applications I usually dim it back a little and would do a 3.50 or 3.70. It's minimal difference.. but a torquey LSA doesn't need as much torque multiplication.

For what it's worth, an LSA ZL1 camaro had a 3.73 gear and 28.4" tire with the same close-ratio trans.

-Dale

Thanks Dale.... I'm thinking the 3.70 would be a good choice.

- - - Updated - - -


For what it's worth, I plan on running a 3.90 with a 26.68 tall tire and a T56 Magnum.

Same gearing as the latest Z28's Chevy made.

I also will have an LS7, so torque will not be a problem down low.

Like was mentioned before, play around on Tremecs website with their gear calculator and plug in a few different RPM's all the way up to redline to get an idea of how it'll perform.

Thanks for the input!

[DKz Garage]

I have a similar combo and run the 3.89. It has been great for spirited street driving. I did one track day with that gear ratio with my old engine and it worked good for the road course I was on (Club Motorsports).

Thanks for the input...... I'm running a 3.90 in my 69, LS408 w/T56 close ratio. It's real responsive for sure.

[DKz Garage]

I appreciate all of the input...... Just ordered all my parts except the gears. Any advice on the best set of 9 inch gears? Is there a set that is both strong and "less noisy" ??

[nicks67camaro]

I debated this for a while. I went with the close ratio t56 but opted for a 3.43 rear gear. To me having more street car orientated set up and more highway low rpm cruising was more important to me. I think Stielow on his last build used a t56 mag close ratio (with a 6th gear change to .50) and a 3.50 rear gear. I think a 9.5 to 1 first gear is ideal but other factors lead me to a 9.12 to 1.

My LSA is somewhat built so 1,2,3 are probably useless anyway....HA!