Gear/speedo Question

[white venom]

I JUST GOT MY 4.10 GEARS INSTALLED AT THE DEALER, NOW WHAT IS THE PROCEDURE ON GETTING THE SPEEDOMETER ACCURATE??

[Mike Kievit]

Either have the computer adjusted(best way). Or get a speedometer calibrater.

A tuning shop can usually adjust the computer to your gears and tires. They may also be able to squeeze some extra HP out of the engine for a few dollars more.

Mike

[white venom]

cool, thanks for the info

[Skip Miner]

Or for a few dollars more you can go ahead and get a Superchip or Diablochip or some other performance chip and kill two birds with one stone -- fix your speedo and tune your car for more performance. If you plan to add a blower later, you can cut out the cost of the chip.

[Mike Kievit]

OK Skip,

That's a good idea too.
I just put my spare pumpkin in today with 3.73's. And now I want the 5pt. harness. Why did you send me those pics.lol
I'm also trying to figure out how to make a six point.

Oh well, it's a good sickness.

MK

[99_Venom]

I just added a Dallas Mustang Speedcal. That way you don't have to mess with the computer.

[Ken 01-Cobra]

Since I already had a Diablo chip in mine, I just had them burn a new program that compensated for the gears. It took Diablo 3 times to get it right, but they are pretty darn close now. If I had it to do over again, I would add the speedcal instead. It's about a wash in cost, but the speedcal has some other benefits. ;)

[Lumpydogs]

Uh 3.73 or 4.10, maybe 4.30 ???????

My NA 01 cobra coupe is looking for gear suggestions. Want to
keep her a daily driver but improve off the line.

What RPM do the different gears turn at 80 mph with the OEM
5 speed?

Suggestions please.

***dumb question of the day****

Will different gear ratios affect Dyno results from the
Rear Wheels?

[Ken 01-Cobra]

Originally posted by Lumpydogs
Uh 3.73 or 4.10, maybe 4.30 ???????

My NA 01 cobra coupe is looking for gear suggestions. Want to
keep her a daily driver but improve off the line.

What RPM do the different gears turn at 80 mph with the OEM
5 speed?

Suggestions please.
I am partial to 4.30's. ;) You can play with the numbers at:
http://www.prestage.com/carmath/calc_gears.asp
click "solve for rpm"
type in the rear ratio you want to see
add .67 for tranny ratio (5th in the 3560)
add 26" for tire height
add 80 for MPH...click solve...

For one persons view of the 4.30's, try this thread: http://www.svtoa-atlanta.org/phpBB2/upload/showthread.php?&threadid=27



***dumb question of the day****

Will different gear ratios affect Dyno results from the
Rear Wheels?
Yes. There is a thread on here somewhere with a link to an article by DynoJet that explains why, but I'll let you do your own search. ;)

[bower]

With stock trans and rear gear ratios, at 80 you are going:

3rd: 4553
4th: 3425
5th: 2294

For any other gear, just divide the ratios to get the % change. For example, a 3.73 rear gear is 1-(3.73/3.27), or about 14% shorter. So multiply the above RPMs by 14% (e.g. 5th is now 2294 + (2294*.14), or 2615 rpm).

Note that a 14% increase in rpm also means that you have increased torque to the halfshafts by that same % at any engine rpm or any gear you are in.

I put 3.73s in my Cobra - and while on occasion a steeper gear would be nice, this is a good compromise for me as this is my daily driver (and occasional track event).

-Dave
'01 Cobra coupe

edit: Forgot to add: Normally the dyno numbers would not be different, but really low gears (like 4.30) do present additional drag and the large ring gear takes more power to spin up. But I don't think it's more than a few hp.

[Lumpydogs]

You guys have all the answers.

THANKS :D :bna :tmb: :beer:

[Ken 01-Cobra]

Originally posted by Lumpydogs
You guys have all the answers.

THANKS :D :bna :tmb: :beer:
Nah...we just went through it earlier than you! ;)

You're welcome though...

[Ken 01-Cobra]

Originally posted by bower
edit: Forgot to add: Normally the dyno numbers would not be different, but really low gears (like 4.30) do present additional drag and the large ring gear takes more power to spin up. But I don't think it's more than a few hp.
According to the DynoJet article, you lose 3-5% ON THE READING with the steeper gears. e.g. if you read 300, odds are you actually have 309-315. Since I read 304, odds are I have around 310 to 316 actual. It works for me! ;)