Sack Rat TT

I went to 21st Century Musclecars for a bullet-proof transmission rebuild of my MN-6. My factory tranny has been great for 41K miles and I was geting nervous about its lifespan. During the rebuild I replaced the main gear-set and added a LPE hardened, micropolished main shaft, etc. The gear-set retains the factory MN-6 1st thru 4th ratios but changes 5th from 0:74 to 0:80 and 6th from 0:50 to 0:70. For a street driven car this makes 6th gear a more usable ratio as you can see in my before and after comparison. I made notes before the changes and on my way home noted the RPM vs. speed differences from stock. I run stock 3:42 rear gears and the speeds were read off of my speedometer so they are approximate but close.

RPM 5th Stock 5th :80 Ratio 6th Stock 6th :70 Ratio
2000 63 MPH 57 MPH 94 MPH 67 MPH
2500 78 MPH 71 MPH - 83 MPH
3000 93 MPH 83 MPH - 98 MPH

I did not test stock 6th at 2500 or 3000 RPM as there was too much traffic but we all know it is up there. Also, the lower 6th gear at 6000 RPM gives approximately 196 MPH. So far I am very happy with the gearing and I will get the cobwebs out of the 6th gear slot in the shifter gate.

DDSLT5

Sounds great - but your fuel economy will suffer. Now you'll be up late tonight losing sleep about that!


Keep us posted on how it feels at highway speeds, hammering it in 6th!

Sack Rat TT

[QUOTE=DDSLT5]Sounds great - but your fuel economy will suffer. Now you'll be up late tonight losing sleep about that!

You are correct, fuel economy was paramount when I did the TT mod. Ha Ha. Both 5th and 6th have an all new personality that was never there before at normal freeway speeds. Still can break the tires loose in 4th. But, 5th feels like 4th except more SOTP acceleration than before the changes. Like taking an A-4 car and adding a 3:42 rear and torque converter giving new SOTP personality.

3XBlack6spd

The M12 Needs help with the Shift from 3rd to 4th...any suggestions?

Sack Rat TT

The only thing I know of is to rebuild tranny with the MN-6 gear cluster ratios. Drive a MN-6 first to see if it suits you. Good Luck

GR8-LIFE

Hey Rick,

Hows you car doing?

Sack Rat TT

No issues!! Runing like day one. The 5th-6th tranny thing is awesome. As someone said this is the way the factory should have done the ratios. However, they, the factory, have mileage/emmissions/compliance issues to deal with concerning EPA/DOT certification that we as individuals do not have to adhere to.

towercontroller

Hi Rick! Glad to hear you got your transmission in and sounds great so far. Car looks great

GO

performancemetal

If you want to see some pictures of the gears click on the link below. The quality of these gears is amazing. They also look to be much stronger than the factory gear set. My company did the micropolishing. I have done quite a few transmissions for Rodney and some ring and pinions. The pictures really don't do justice to the finish on these gears. They look like they were chrome plated. We actually micropolished everything in the transmission.

www.performancemetal.net/gforce

Todd

Sack Rat TT

My company did the micropolishing. I have done quite a few transmissions for Rodney and some ring and pinions. The pictures really don't do justice to the finish on these gears. They look like they were chrome plated. We actually micropolished everything in the transmission.
Todd

Todd, thanks for the pic's. It is really impressive seeing the parts look like that. You guys do a good job. You are correct, all the internal parts were micropolished. All I could see before the install were the micropolished input/output shafts of the tranny. They made factory shafts look shabby. The micropolish is well worth it especially on the FI powered cars. I like to say it can only help and not hurt.

0rodney@rpmtransmissions

3XBlack6spd

I had a MN6 in My '98 Vert, but It is a whole different beast than a Blown Z06!