Pumba

At this past January's North American International Auto Show GM had a cutaway model of the TREMEC 6070 7-speed transmission. I took several pictures of the cutaway model, including two where I used a measuring tape to document the overall length of the case and extension housing and the extension housing on its own:









In July of this year I was contacted by an Editor of GM High Tech Performance magazine who had noted my pictures. He asked for permission to use them in an article he was writing.

http://www.gmhightechperformance.com/tech/transmission/1307_first_look_tr6070_transmission/


Also, later in the summer when I was down at RPM Transmissions in Anderson, Indiana having a 4.10:1 C6 differential installed in my Z, we took a look at the underside and tunnel area of my car. Our opinion is, seeing that the 6070 trans is 45 mm longer than the T56 or TR6060 transmissions, that there is enough room to put the TREMEC 6070 7-speed trans in a C5 or C6.

My plan is to try the conversion next spring. The following are a list of items that need to be obtained or changed:

• Shorten the torque tube by 45 mm.
• Shorten the shift rod by 45 mm
• Purchase a 45 mm shorter carbon-fiber driveshaft from the Driveshaft Shop
• Purchase a 6070 Reverse Lockout
• Purchasing a 6070 extension housing
• Purchasing a 6070 main-shaft
• Purchasing a 6070 0.48:1 7th gear set
• Purchasing a 6070 7th gear-Reverse gear synchronizer
• Purchasing a 6070 Reverse gear

In addition to those parts, there is one issue that needs to be resolved:


- What are the electrical system differences between the C5-C6 reverse lockout and the 6070's reverse lockout?

When the conversion is completed I will have a 7-speed transmission with the following gear set:


1st --------- 2.26:1 - I changed this in the spring of 2017.

2nd -------- 1.78:1

3rd --------- 1.30:1

4th --------- 1.00:1

5th --------- 0.79:1

6th --------- 0.63:1

7th --------- 0.48:1


With my 4.10:1 final drive ratio I will be turning the following RPMs in 7th gear:

70 mph ----- 1,800 rpm

75 mph ----- 1,900 rpm

80 mph ----- 2,000 rpm


Wish me luck.

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Wulverine

Interesting project, I just don't see the need or benefit of another gear.

WhiteDiamond

It will make for a great article and I am sure others with means will have to follow, but I just don't see the need for another gear. I rarely use my 6th as is now.

Unreal

Going to 4.10s and doing this would be awesome, adding a 7th gear with stock gears, not so much.

Hopefully it works out.

Too-Fast

Pumba

That's probably because you lose 33.5% of your engine RPMs when you shift from your .74:1 5th gear to your .50:1 6th gear.

If a C6 Z06 owner were to install the gear set I am planning to install in my Z, along with a 4.10:1 final drive gear he will end up with a 19.8% increase in rear wheel torque in 1st through 6th gear. And 7th gear gives you a highway cruising gear to recover your fuel economy.

Image doing those two changes and watching ZR1 or a new Viper GTS disappear in your side-view mirror.

Your don't have to do any engine modifications. You don't give up any drivability.

Also, because you have the 6060 version of the TREMEC six-speed, you can change out individual gears. You can change 5th gear to a .80 and 6th gear to .63 for only a 20.1% rpm loss between shifts. Your acceleration improves in the higher gears and your top speed will probably increase.

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Wulverine

If only someone made a 4.10 gear that fit in a C6Z pumpkin.

Pumba

NO! Unfortunately, no vender has stepped forward and paid to have a 4.10:1 gear set manufactured that will fit the C6 Z06 or ZR1 diff case.

I worked with a vendor about a year ago on this very project for about six months. Unfortunately, the vendor was not able to proceed due to other financial commitments.


What would need to happen for a C6 Z06 or ZR1 owner to use a 4.10:1 gear set would be for them to have someone like RPM Transmissions convert their differential to a C6 Base case.

Wulverine

Curious why you like blue font?

Pumba

It is something I have used and prefer since I first started using the Internet.

Brandon619

Pumba I can't wait until you attempt this swap. Keep us posted.

glenB

After reading the December 2013 Vette magazine, I was wondering about the same thing. The article states the overall length grew by 42mm. They also shorten the torque tube by same amount. They did mention that the output shaft changed but doest state exactly what.

Bad_AX

Pumba, if I understand you correctly, you will retain your existing gear case and add to that the extension housing, main shaft, and some gears from the 6070? Of course I understand you have to shorten the drive shaft, torque tube and shifter rod.

pkincy

What is your speed/rpm in gears with the 4.10?

I have 4.10s in my ZF6 in my C4. And it is a perfect combination. I can start in 1st or 2nd either and actually get to use 6th some.

I bought my car in Austin and drove it to SD but that is the only time it has ever been in 6th gear. 4.10s and the gear is somewhat useful again.

JwT

Have you looked at the C7 torque tube to see if the unit will fit without modifying the C6 unit?

JoesC5

Since the wheelbase on the C7 is an inch longer than the C6's, probably not. Besides, the C7's torque tube is made of steel and weighs more than the C6's aluminum unit.

Pumba

Bad AX,

You are correct in your assumption. I will install the 6070 mainshaft in my case, add their 7th gear and Reverse, and the 6070 extension housing.

Pumba

Using a 7,000 rpm shift point and my 325/25R20 rear tires, which are 26.4 inches in diameter, I calculate the following speeds in each of the first six gears:

1st -- 2.66 -- 59.3 mph

2nd -- 1.78 -- 75.3 mph

3rd -- 1.30 -- 103.1 mph

4th -- 1.00 -- 134.1 mph

5th -- 0.79 -- 169.7 mph

6th -- 0.63 -- 213.5 mph


In 7th gear I will be turning the following RPMs while cruising:

70 mph = 1,754 rpm

75 mph = 1,879 rpm

80 mph = 2,005 rpm

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FNBADAZ06

sub'd

SIK02SS

This is 4 years old...is it even still ongoing?