6 speed conversion
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Joined: Apr 2015
Posts: 88
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From: Hialeah Florida
T56 in a 69
I've been offered a T56 for my 69, what I've gathered from reading this Thread is that the tranny crossmember needs to be cut and made the removable type, is this correct and can it be done with the body on? Thanks, Tony.
Advanced
Joined: Apr 2015
Posts: 88
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From: Hialeah Florida
Can be done
Found the info needed here, can be done but extremely diffcult, not ready to cut crossmember so will pass on t56 for now.
Drifting
Joined: May 2005
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From: East TN
Pro
Joined: May 2013
Posts: 672
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From: Rapid City South Dakota
Thanks for the post. I thought the Tremac TKO 600 was a lot stronger. I made some quick checks that it looks like you are correct. Damn.
So I have a TKO600. Looks like it is not as strong as I thought. The Tremac T56 you say is rated at 700 ft-lbs. Any comments about 5 or 6 speeds that get you above the 600/700 foot pounds of torque? Maybe I'm mistaken, but I think Tom's Differentials sells C3 differential's that are rated up to about 1000 foot pounds. If this is accurate, transmission torque ratings for performance C3' trannies need to be pretty high....they need to get up to Tom's torque values. Maybe I'm mistaken....comments? Thanks
So I have a TKO600. Looks like it is not as strong as I thought. The Tremac T56 you say is rated at 700 ft-lbs. Any comments about 5 or 6 speeds that get you above the 600/700 foot pounds of torque? Maybe I'm mistaken, but I think Tom's Differentials sells C3 differential's that are rated up to about 1000 foot pounds. If this is accurate, transmission torque ratings for performance C3' trannies need to be pretty high....they need to get up to Tom's torque values. Maybe I'm mistaken....comments? Thanks
I think the best stuff (strongest) Tom sells can take about 1200 hp.
Racer
Joined: Aug 2013
Posts: 264
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From: Virginia
T56 crossmember
You may want to call Jeff Kauffman, he has offered discounts in the past. Nice guy, knowledgeable, he can help you make up your mind and they have EVERYTHING (shifter, driveshaft, bellhousing, crossmember, etc.) you will need to make it fit just right. They also have payment options. My kit will be paid off and ship next month.
Jeff's contact info 865.609.8187 and jeff@shiftsst.com. Be sure to Mention you are a forum member.
Good luck
Advanced
Joined: Apr 2015
Posts: 88
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From: Hialeah Florida
Thanks for the help
I'm able to get the T56 for a good price, might just buy it and let it sit until I'm ready for the conversion, now the car has other priorities, a/c, electric headlights, paint, etc.
With 4:11 gears the car is no fun on the highway but I do have a set of 3:08 gears I might put in to make the car more all around driveable.
With 4:11 gears the car is no fun on the highway but I do have a set of 3:08 gears I might put in to make the car more all around driveable.
Melting Slicks
Joined: Jun 2011
Posts: 3,114
Likes: 592
I find this interesting why people think 4:11s with a t56 is great.
First gear becomes useless, and if 1st gear is a 2.66 and then its only marginal.
Is it based on "tire spinning" and 2 sec acceleration feel ?
Factory cars with T56 transmission are mostly 3.42 rear Ratios (C6 Corvette's etc ) so I would think 3:36 or 3:55 would be a much better choice.
The only time I have seen C6 corvette's change the rear ratio is for Drag Racing.
First gear becomes useless, and if 1st gear is a 2.66 and then its only marginal.
Is it based on "tire spinning" and 2 sec acceleration feel ?
Factory cars with T56 transmission are mostly 3.42 rear Ratios (C6 Corvette's etc ) so I would think 3:36 or 3:55 would be a much better choice.
The only time I have seen C6 corvette's change the rear ratio is for Drag Racing.
Last edited by cagotzmann; Mar 22, 2016 at 10:26 AM.
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Race Director
Joined: Nov 2006
Posts: 19,445
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From: Athens GA
St. Jude Donor '12-'13, '15- '16-'17-'18-'19, '21
I find this interesting why people think 4:11s with a t56 is great.
First gear becomes useless, and if 1st gear is a 2.66 and then its only marginal.
Is it based on "tire spinning" and 2 sec acceleration feel ?
Factory cars with T56 transmission are mostly 3.42 Ratios (C6 Corvette's etc ) so I would think 3:36 or 3:55 would be a much better choice.
The only time I have seen C6 corvette's change the rear ratio is for Drag Racing.
First gear becomes useless, and if 1st gear is a 2.66 and then its only marginal.
Is it based on "tire spinning" and 2 sec acceleration feel ?
Factory cars with T56 transmission are mostly 3.42 Ratios (C6 Corvette's etc ) so I would think 3:36 or 3:55 would be a much better choice.
The only time I have seen C6 corvette's change the rear ratio is for Drag Racing.
The T-56 with a first gear ratio of 2.66 and a rear ratio of 4.11 = 10.93 final drive ratio
Yet the gears you propose 3.42 x 3.36 or 3.55 = 11.49 and 12.14 final drive ratios.
Those would be WORSE if amount of time in 1st gear and tire spinning are the main concern.
Now a 3.08 rear gear with a 3.42 first gear T-56, would give a lower ratio than the 4.11 and 2.66 T-56.
Just a thought.....
Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
1st is anything but useless..maybe a 3.27 first like you see in some trannies. Contrary to popular belief youre not shifting every 10 ft unless youre motor is dead by 4-5k then a taller gear may work well.
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
Interesting conclusion on your part....
The T-56 with a first gear ratio of 2.66 and a rear ratio of 4.11 = 10.93 final drive ratio
Yet the gears you propose 3.42 x 3.36 or 3.55 = 11.49 and 12.14 final drive ratios.
Those would be WORSE if amount of time in 1st gear and tire spinning are the main concern.
Now a 3.08 rear gear with a 3.42 first gear T-56, would give a lower ratio than the 4.11 and 2.66 T-56.
Just a thought.....
The T-56 with a first gear ratio of 2.66 and a rear ratio of 4.11 = 10.93 final drive ratio
Yet the gears you propose 3.42 x 3.36 or 3.55 = 11.49 and 12.14 final drive ratios.
Those would be WORSE if amount of time in 1st gear and tire spinning are the main concern.
Now a 3.08 rear gear with a 3.42 first gear T-56, would give a lower ratio than the 4.11 and 2.66 T-56.
Just a thought.....
Melting Slicks
Joined: Jun 2011
Posts: 3,114
Likes: 592
Interesting conclusion on your part....
The T-56 with a first gear ratio of 2.66 and a rear ratio of 4.11 = 10.93 final drive ratio
Yet the gears you propose 3.42 x 3.36 or 3.55 = 11.49 and 12.14 final drive ratios.
Those would be WORSE if amount of time in 1st gear and tire spinning are the main concern.
Now a 3.08 rear gear with a 3.42 first gear T-56, would give a lower ratio than the 4.11 and 2.66 T-56.
Just a thought.....
The T-56 with a first gear ratio of 2.66 and a rear ratio of 4.11 = 10.93 final drive ratio
Yet the gears you propose 3.42 x 3.36 or 3.55 = 11.49 and 12.14 final drive ratios.
Those would be WORSE if amount of time in 1st gear and tire spinning are the main concern.
Now a 3.08 rear gear with a 3.42 first gear T-56, would give a lower ratio than the 4.11 and 2.66 T-56.
Just a thought.....
2.66 x 3.36 = 8.94
2.66 x 3.55 = 9.44
2.66 x 3.42 = 9.1
seems you thought first gear is 3.42. T56 first gear is 2.66(close ratio) or 2.97 C6 corvettes first gear is 2.66 with a 3.42 rear ratio.
Melting Slicks
Joined: Jun 2011
Posts: 3,114
Likes: 592
Yes, I have the T56 with the 2.66 first gear, and I need to ride the clutch slightly from a standing start with 3.55 rear gears. The .5 overdrive can only be used at a minimum of 70 to keep from lugging the motor, tho it has plenty of torque to do it. This trans was set up for 4.11 rear gears, any thing lower than the 3.55 will be difficult to drive.
Final drive is 0.63 for me. Love the highway cruising to the track in 6th @ 1800 RPM.
Last edited by cagotzmann; Mar 22, 2016 at 07:21 PM.
Race Director
Joined: Nov 2006
Posts: 19,445
Likes: 349
From: Athens GA
St. Jude Donor '12-'13, '15- '16-'17-'18-'19, '21
Misread your post.
Thought you meant that the T-56 in a C6 has a 3.42 First gear.
Ideal overall gearing from my understanding is as close to 10-1 as possible.
Which is why my setup will be a T-56 with the 2.66 first gear and 4.11 rear gear.
Back in the good old days (1969) my 67 Camaro had the new Super T-10 with the 2.54 first gear. It was the early aftermarket trans that had just come out. Had 4.10 gear in the rear and it screamed at the track. And shifting out of first was not necessary until almost 60mph.
So...put me down as partial to a 4.11 especially with the double overdrive.
Bman
Melting Slicks
Joined: Mar 2008
Posts: 2,989
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From: Meriden CT
Melting Slicks
Joined: Jun 2011
Posts: 3,114
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2.66,1.78,1.3,1,0.8,0.63 (tremec website)
What rear gears do you have for 80MPH 0.63 with a 2.73 = 84 MPH
0.63 with 3.08 = 75 MPH ?
Safety Car
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Melting Slicks
Joined: Mar 2008
Posts: 2,989
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From: Meriden CT
Instructor
Joined: Apr 2007
Posts: 142
Likes: 6
From: Indianapolis, Indiana
I love a little deeper gear.
I'm running a T-56 Magnum (2.66 first) coupled with 4.56 rear gears and 30 inch tires, it works very well with my engine combo (see sig below). The motor peaks about 6500 and pulls hard to 7k+ rpm. It launches hard and I have plenty of power in the upper rpm range to utilize the lower gears. The 6th gear ratio is .63, which translates to a 70 mph cruise rpm at a little over 2200 rpm. The best of both worlds.
The lower overall 1st gear makes it drive easier on the street, IMO. Easier to get things moving, especially if you have a big lumpy cam, larger heads, big intake and carb. Yes it will very easily overpower the tires, but pretty much any combo making decent power will lose traction "on the street". I've used regular street radials, M/T Drag radials and Hoosier QT Pros on the street and they all spin easily. You are not going to have real good traction until you get on a well prepped track with drag or DOT slicks.
I'm running a T-56 Magnum (2.66 first) coupled with 4.56 rear gears and 30 inch tires, it works very well with my engine combo (see sig below). The motor peaks about 6500 and pulls hard to 7k+ rpm. It launches hard and I have plenty of power in the upper rpm range to utilize the lower gears. The 6th gear ratio is .63, which translates to a 70 mph cruise rpm at a little over 2200 rpm. The best of both worlds.
The lower overall 1st gear makes it drive easier on the street, IMO. Easier to get things moving, especially if you have a big lumpy cam, larger heads, big intake and carb. Yes it will very easily overpower the tires, but pretty much any combo making decent power will lose traction "on the street". I've used regular street radials, M/T Drag radials and Hoosier QT Pros on the street and they all spin easily. You are not going to have real good traction until you get on a well prepped track with drag or DOT slicks.
Last edited by 71454Chevelle; Mar 23, 2016 at 07:39 AM.