firstgear

I have several options available

Rear end ratios
3.55
3.79
4.11

Tranny ratios (T-56)
1ST 2ND 3RD 4TH 5TH 6TH
2.98 1.99 1.35 1-1 .86 .73 Transmission 1
2.71 1.79 1.30 1-1 .89 .75
2.62 1.60 1.21 1-1 .85 .76
2.29 1.60 1.21 1-1 .85 .76 Transmission 2

Rear tire diameter of 27.0"

I have played around with some programs that give you RPM with different combination's of gears.

Here is their output.

Transmission One
6600 RPM Redline
Gear
Ratio Max MPH
1st Gear 46.92MPH
2nd Gear 70.27MPH
3rd Gear 103.58MPH
4th Gear 139.83MPH
5th Gear 162.6MPH
6th Gear 191.55MPH
Final Drive 3.79:1

Transmission Two
6600 RPM Redline
Gear
Ratio Max MPH
1st Gear 61.06MPH
2nd Gear 87.4MPH
3rd Gear 115.56MPH
4th Gear 139.83MPH
5th Gear 164.51MPH
6th Gear 183.99MPH
Final Drive 3.79:1


now changing the final drive gear to 4.11

Transmission One
6600 RPM Redline
Gear
Ratio Max MPH
1st Gear 43.27MPH
2nd Gear 64.8MPH
3rd Gear 95.51MPH
4th Gear 128.95MPH
5th Gear 149.94MPH
6th Gear 176.64MPH
Final Drive 4.11



Transmission Two

6600 RPM Redline
Gear
Ratio Max MPH
1st Gear 56.31MPH
2nd Gear 80.59MPH
3rd Gear 106.57MPH
4th Gear 128.95MPH
5th Gear 151.7MPH
6th Gear 169.66MPH
Final Drive 4.11

I like the combination of 3.79 and Transmission 2, third gear becomes a great combination for a "pass now" gear (drop into third and pass anything on the road!)

The T56 I am looking at is a Rockland T-56 Son of Tranzilla good for up to 800HP.

Am I missing something in the evaluation of the gear ratios for both the tranny and final drive ratio?

I would appreciate comments here because I am probably missing something or don't see other issues.

regards, Herb

GCD1962

What engine?

firstgear

either LS7 or LS3 with a far different intake set up

Sky65

I'm not sure max speed in gears is the way to look it this. Wouldn't rpms at specific speeds be more relevant? Where does the engine make it's power? Where is it happy?

GCD1962

Any way to mate the C-6 rear and A6 trans? I have the A6 paddle shift in the '09 and it's a blast with great gearing.

6t5silver

I just changed my rear gear from 3.08 to 3.70 . What a blast !! My cam comes in to its power range very quickly. The cam is very happy and so is the owner
I'm using a super t10 nod iron case 904, with 3.42 first gear, 327 about 350hp.

It changed the complete driving feel of the car. It now feels like a Vette. No more tree stump pulling for me.

Black_Magic

Herb,

I added your 2 transmissions examples to my gear calc. Perhap this will help a little.

====>> Gear Calc

George

BTW.........Do you have the Reverse Ratio for those 2 boxes?

firstgear

Here are two more ratios available for the T56 Rockland
1ST 2ND 3RD 4TH 5TH 6TH
2.98 1.99 1.35 1-1 .86 .73
2.71 1.79 1.30 1-1 .89 .75
2.62 1.6 1.21 1-1 .85 .76

I will have to post later the reverse gear ratio as I called and the tech line was busy,.....

thanks, Herb

Black_Magic

2 more that looks like 3 to me

No problem added (2) and when you get reverse(s) let me know

George

GTR1999

Is that a typo on the 3.79 ratio? Could be 3.70 or 3.73, I never built one with a 3.79, if correct who is the mfg?

Nick D.

I think it depends on your driving style and what the car will be used for. I have a 66 coupe with a T56 6 speed from a Camaro, it has a 2.66 first and .74 5th and .50 6th. It is behind an LS1 with a 3.73 rear. The rear tire is 26.7" dia (275/40/18) and the car weighs 2950 lbs. This combo works extremely well for overall driving conditions, great off the line with excellent fuel economy. It will overpower the tires just about any time you like and it gets 25-30 mpg on the hiway and 17-20 around town. It fits my driving habits very well. I would consider 4.11's but am really happy with the 3.73's.

The .73-.76 6th gear will cost you in fuel economy and revs. If you look at the MPH charts that Black_Magic provides, my rpm in the 70-90 crusing speeds is 1644-2114. Using the .75 6th gear with your tire and 3.73 rear, your rpm would be 2439-3136. Can you get the Rockland tranny with a .5-.6 6th gear?

Nick

firstgear

that is Herb not knowing what the heck he is talking about....I just remember it was 3.7something!

firstgear

I didn't see it noted any where. I have given up on Rockland, they have a nice web page and what looks to be a good product. But if you call and need technical help you have to leave a voicemail. I never got a call back. I figure if I can't get a call back now, what happens during install and I need help.

I was referred to D&D Performance also out of Michigan and I will call them on Monday and see what kind of advice they can give. D&D is a premium Tremec dealer and they can build up the T56 to support Viper kind of horsepower for a Chevy.