axle ratio with 460/c6 auto

[jamesw]

I have a West Coast Cobra 460/c6 auto. I believe the 9'' rear is 4.88. What would be a streetable axle ratio?

[Tom Wells]

jamesw,

I have a 2.88 Jag in my Cobra with the 521. My Zephyr wagon has an 8.8 with a 2.75; it has a 557. Both have C6s.

If your engine is stock you might want to try a little higher number, probably not more than approximately 3.00. Mine can spin street tires at 100 mph with those ratios if I whack the throttle...

Also, I have 1600 rpm stall converters in both cars - about the same stall speed as a stock converter. A "loose" converter with >2000 stall would be a heat and tire smoke generator. It would reduce your mileage too. There's a mud truck converter maker in Deland FL who supplies mine.

Hope this helps,

Tom

[Kenny B]

James:

Top gear is 1.00. What size tires do you have? What rpm do want to run at 70?
I used Powerspec to figure mine.

[jshel1]

Howdy James,

Are you local to Texas?

Welcome to the Texas Forum. I didn't check the Transmission Forum, but if you haven't posted there, I would suggest doing so to get a more robust set of opinions.

Tom has real world experience with two examples of C6 and echos an opinion of taller gears. Your 460 will have significant torque to spare to overcome the loss through a stock automatic. You might wish to investigate outcomes of changing axle ratio with rims/tires in mind.

Here is a link to a gear ratio calculator where you can alter various parameters to see gear/rpm/speed outcomes.

While all of the selectable transmissions in the calculator are manual, I suggest the newly added Quaife ZFQ Transaxle. This option will load with closest gear ratios to match a stock C6. First gear should be a pretty close match, your 2nd will be about half-way between the Quaife's 2nd and 3rd, and your 3rd will be a close match to Quaife's 4th.

Cheers and Welcome to the Texas Forum.

Please find other calculators under the reference tab on my site.

John

[jshel1]

Howdy Ken,

Sorry to walk on your post. We probably started typing at about the same time, but you know how long winded I am. Of course, then I had to edit and spell check.

James - Ken's point of what rpm at 70 is also key.

[Kenny B]

I know, I know John. No problem. All good info.
I have a program I use at work to spec trucks. All I need are the known parameters - top gear ratio of trans, tire size, target rpm, then I play with axle ratios to hit the target.

[Kenny B]

James: I think we met at Birdville in October. You change the interior yet?
Join us in San Marcos in April. More cobras than you can shake a stick at. All makes.

[jms_wagner]

What RPM stall torque-converter are you using?

[LuvDaBlues]

Originally Posted by jshel1

Howdy James,

Are you local to Texas?

Cheers and Welcome to the Texas Forum.


John

John, it's Jim Wagner from the Fort Worth area. His wife is Penny. Dark Green car with an automatic. He's my hero from the California trip who stayed with me when my car broke down and everyone else abandoned me. (Yes, I still remember all of you. Your names are all written on my garage wall......)

Dude, you where the president. You're suppose to know EVERYONE!!!!

[cgsincc]

Originally Posted by jms_wagner

What RPM stall torque-converter are you using?

Originally Posted by LuvDaBlues

John, it's Jim Wagner from the Fort Worth area. His wife is Penny. Dark Green car with an automatic. He's my hero from the California trip who stayed with me when my car broke down and everyone else abandoned me. (Yes, I still remember all of you. Your names are all written on my garage wall......)

Dude, you where the president. You're suppose to know EVERYONE!!!!

Your hero huh?

[Mother]

I have a 740 HP 460. I have a Tremec 600 5 speed with a .82 fifth gear. My 60 mph RPM is 2050, in Fifth. My RPM at 60 mph in forth is 2550. Top speed is limited to 154 mph @ 5500. That is where I have the motor pilled.

[jshel1]

James,
Are you working up an alter ego, or just trying to keep your post count to a minimum? Either way, welcome!!

Steve,
These days I sometimes feel like I know more people than I want to, or maybe I just need more handlers. PS - thanks for sharing the list from your garage wall. My navigator and I will be on the lookout.

[LuvDaBlues]

Originally Posted by cgsincc

Your hero huh?

Yup ...... He stayed in Monterey to find parts and fix car with us while all others headed south. I'd consider that a hero.

John, just text me when you spot one..........