Pumba

I recently purchased a new C6 ZR1 MH3 Tremec T6060 six-speed manual transmission. As many of you are aware, GM upgraded to this transmission due to the higher torque and horsepower that the LS9 supercharged 6.2L engine delivers.

GM also chose a 2.29:1 first gear for the transmission in order to be able to achieve 62 mph - 100 kph in first gear without losing the 0.2 of a seconds that is required for a one-two shift before reaching the LS9's 6,500 rpm rev limit.

What will follow next is a pictorial display of the improvments that I had Liberty's Gears make to the transmission:

1. Change the 1st gear ratio from 2.29:1 to 2.423:1 - The new 1st gear gives the same RPM drop as the one-two shift of the MN6 trans used in the C6 Z06 - It is also more suitable for street use and for engines that can achieve 7,000 rpms
2. Install Carbon-Fiber tripe-cone synchronizer system
3. Install Bronze shift fork pads
4. Install a Billet shift interlock
5. Install Grade 8 interlock bolts
6. Cryogenically treat all components
7. Cut stainless-steel wire peen all components
8. Surface enhance - polish - all components
9. Precision assemble the transmission with proper clearances and preloads

Here are some pictures of the case and internal components as delivered:


It seems everyone in the Tremec plant wanted to write on the case.








The T6060 mainshaft - 30 splines versus the T5600's 26 spline





The input shaft which contains 4th gear




The original cluster gear and the 2.29:1 1st gear set




The T6060 uses a ball bearing to hold the shift fork assembly - This assembly has a tendency to have some of these small ***** fall out.







Liberty upgraded and assembled the entire transmission:


Liberty cleaned up the case.








This picture shows the much thicker T6060 gears versus the older T5600 gears. These thicker gears are what makes the T6060 able to handle higher horsepower and torque.






This is the revised cluster gear. The 2.29:1 1st gear was cut of the shaft and a new 2.423:1 1st gear was pressed and then welded on. Note the weld. After the gear was welded on the cluster gear and the new 1st gear was cut, the two gears were honed for quiet operation.





Here are two pictures of an actual failure of the ball bearing assembly









Here is the bronze bushing that Liberty manufactures to replace the failure prone ball bearing assembly.





This picture shows the powdered metal OEM shift interlock and Liberty's billet interlock. The OEM part fails in Road Racing and Drag Racing usage.




This picture shows one OEM shift interlock bolt and two of Liberty's Grade 8 shift interlock bolts - $45 each. The OEM bolts shear off.




Here is the billet shift interlock on the shifter assembly





The 1st/2nd - 3rd/4th - 5th/6th and Reverse plastic shift fork pads were replaced with bronze pieces.




These are examples of the Carbon-Fiber synchros that replaced the OEM bronze syncros.




Main shaft, Cluster gear, and shifter components during assembly. Note the high polished gears.





LocTite 518 Gasket Eliminator is used through out the trans during assembly.






The finished transmission - Just under 125 lbs. without fluid.





This chart shows the RPM loss of my custom MH3 trans versus the MN6, MN12, and the custom MN6 transmission it will replace. The MH3 shows the lowest RPM loss of any of these transmissions.







Now it's onto RPM Transmissions where Rodney, TJ, and company will mate the trans with a new C6 ZR1 differential that includes a Quaife center section and a micro-polished GETRAG 3.42:1 ring and pinion. My aluminum driveshaft will be replaced by a Pfadt Racing carbon-fiber driveshaft.


-

SouthernSon

I understand from one of the driveline engineers that the validation process includes running the ZR1 up to 4K RPM and drop the clutch. Sorta explains the beefiness.

Eric D

Nice set of photos! What makes up the rest of the drivetrain? Engine, clutch, slave, tires, etc.. Will any changes to the torque tube be included?

Pumba

As the final comment states, I will be traveling down to RPM Transmissions' facility in Indiana later this month. They will install the following:

• C6 Rear Crossmember
• Pfadt Racing offset rear crossmember to differential mounts
• C6 ZR1 differential, with a Quaife center section and micro-polished Getrag 3.42:1 ring and pinion
• Pfadt Racing carbon-fiber driveshaft and Titanium couplers

The car already has a modifed DTE trans-dif girdle, a Fidanza dual-disc clutch and aluminum flywheel, and GM slave cylinder.

On track days I install Hoosier A6 285/30R18 front and 335/30R18 rear tires.

Over the winter of 2010 -2011 I will be having a 440 cubic inch LS7-based engine built.

Eric D

I did catch everything in your first post, when I asked about your torque tube I ment the torque tube, not the propshaft. Are you making any changes to it? Going to the C6 crossmember is a good move as I'm sure you already know. Hope it all goes well.

Pumba

Sorry!

No, I am not making any changes to the torque tube.


-

Jaymz

Nice writeup but can I ask why you are sticking with a 3:42 rear gear? Modifing the 5-6 gears like you did will almost be worthless with a 3.42.

2K3Z06

Man, if your gonna do all that, should have called LG and got the sequential shift race transmission. beefier and you never miss a shift. probably not much more than you already spent...................

Pumba

The T5600 trans that I presently have in my Z06 has all stock ratios, except for 6th gear, which has been changed from 0.50:1 to 0.563:1. I matched this trans with a 4.10:1 RPM Transmissions built Quaife differential.

My new package with the modified 1st gear T6060 transmission will have the stock 5th gear ratio of 0.81:1 and the stock 6th gear ratio of 0.67:1. My overall gear ratio in 6th gear with the C6 ZR1 3.42:1 differential will be almost the same as my existing package - 2.291:1 versus 2.308:1.

In addition to road race track days, I also use my Z06 for Open Road races such as the Big Bend Open Road Race and the Sandhills Open Road Challenge.


-

Pumba

A new C6 ZR1 trans can be purchased for less than $4,000.

The 1st gear change cost $1,970.

The durability modifications cost $1,620.

That's a total of $7,600.

The L.G. Motorsports Corvette Sequential Transmission is $27,595, and because of its straight cut gears it will be very noisy to drive on the street.

I'll keep the other $20,000 and use it as partial payment for the new engine next winter.

-

2000BSME

awesome work, but as with anything something can go wrong, and I'm betting the syncros will be the weak link in this trans as well as most well built transmissions. One bad clutch foot while shifting gears and then the dreaded 'grrrrr' when making shifts from then on. Too bad they weren't easier to change.

Pumba

Thanks.

You are correct. When TREMEC redesigned the gears, making them wider, the place where they got the additional width was by making the syncros narrower.


-

AU N EGL

4.10 Diff ? think you will run out of gear ?

3.42 or 3.73 for road racing.

4.10 or 3.90 for very very tight street circuits.

and I liked the 2.29 1st gear

Pumba

Tom,

The course that I get to use most frequently in my area is Waterford. It is very tight. With my present package I hit about 125 mph at the end of the back straight in 4th gear.

With my new package, I will be able to achieve approximately 150 mph in 4th gear.



The 2.29:1 1st gear is great for a dedicated track car, but it is too shallow for a 90% street - 10% track car.


-

AU N EGL

Good Deal Pumba. Every track is different.


yup 2.29 is not a great choice for street use.

but standing starts races, Oh YAH . . .. . .

Eric D

Pumba,

Just curious, but do you know anyone else running the combination of components you plan too, or are you the alpha tester?

Pumba

TJ at RPM Transmission tells me that they have done two or three other conversions of a C5 drive train to the C6 ZR1 drive train.


-

2000BSME

those guys are great. I went to their shop a few years back, about a nine hour drive. they did a trans install and a rear diff for me. The original trans install I did myself, but there was a problem with a component within the trans. I didn't feel like doing it all over again, so I just spent $300 in diesel an towed my vette to them in 9 hours and had them correct the problem. It was a cool road trip. I went to lunch with all of them at the local greasy burger joint in Indiana.

snow everywhere, made the trip a little icy.

Good times. I'm sure I'll see them again if I keep road coursing this a4 transmission.

C6RAPTOR

I was thinking about a track trans change this winter and I was looking for more info on someone who has made the changes for track & street.
I know that RPM is tops. Has anyone used RS Gear?
I received this quote from them:
WE BUILD A TRANZILLA MAGNUM STYLE
RATED AT 850FTLBS
RACE READY WITH CARBON RINGS 1-4 BLUE PRINTED THIS TRANS HAS MAJOR UPGRADES FROM THE T56 (NO SYNCHRO KEYS) WIDER GEAR TRAIN, LARGER INPUT AND CLUSTER BEARINGS, LARGER 3/4 SYNCHRO
2.66 1.78 1.30 1.00 .74 .50 OR .80 .63
2.97 2.07 1.43 1.00 .74 .50 OR .80 .63
THESE COST 3495.00 R/R OR EXCHANGE
CLOSE RATIO
2.29 1.60 1.21 1.00 .84 .67
COST 3995.00 R/R OR EXCHANGE

Jaymz

Rockland Standard is the best tranny shop around. I have a RS gear Tranzilla in my racecar and have had zero issues with it. It is bullet proof, something that I can not say from the other vendor you enquired about. Customer service is top notch too. Any issues call George up there and he will get it taken care of. You can order one thru Danny @ RAFT Motorsports.