Jump to content

New Gear Ratio's - Advice For Autox


polyol

Recommended Posts

I would like to put some lower gears in my 2010 Z06 (10,000mi).  Did a search, but didnt find what I was looking for.  Appolgies if this has been beaten to death.

 

For starters im not a fan of the huge gears in the Z06.  Just not my thing.  I road race occasionally but I mostly Autox.  The stock gears for Autox are not what I would consider "optimal" by any stretch.  In many courses I am stuck in 1st gear and it is far too "snappy".  I would much rather leave it in 2nd gear 90% of the time.  I drove in a grand sport and I liked the gears in that much better.  I would like 2nd gear to top out at 70-80mph range...80 max max. 75 would be ideal.

 

Can you tell me what the current rear diff gear ratio is?  What ratio do you think would be optimal for my needs.  If I could top out second gear at 80mph that would be sweet. 

 

What shops should I consider, mind you I will also get the heads replaced (due to the valve drop issue) and probably some performance mods/tune to boot.  Would be nice if it was full service build and tune.  I live in the east valley (Gilbert) so some place semi nearby would be nice but would be open to another shop further if they are the best.  I am not cheap, I want a god honest shop, that are experts that do not cut corners.

 

Thank you so much for any info you can provide.  Ask any questions you would like and please excuse my ignorance if some of these are stupid questions.  Paul

IMG_1870.JPG

20161210_140401.jpg

Link to comment
Share on other sites

old yeller

Contact Joe Cordes at CPR in Mesa. He will answer all of your questions and is a full service shop. He normally has a set of heads in stock for your Vette.

Link to comment
Share on other sites

GS manual has 2.97, 2.07, 1.43, 1.00, .74, .50 for a total of 3.42.

 

Z06 manual has 2.66, 1.78, 1.30, 1.00, .74, .50 for total of 3.42.

 

Maybe drop a GS gear pack.

Link to comment
Share on other sites

My advice would be to contact RPM for a built unit with a 3.90 or 4.10 gear set. I found there aren't many places who can swap gears as the set up is very specialized. Keep your original diff in case you ever sell the car.

Link to comment
Share on other sites

http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php

On the gear calculator chart, plug in 75 mph, your tire diameter, and the RPM you want to be at 75 MPH. Take the result and divide it by 1.78 (your second gear ratio) and the answer will be the rear gear ratio to accomplish your goal.

As an example, if you use 75 MPH, a 26" tire, and 7100 RPM, the result is 7.33. Divide 7.33 by 1.78 and the rear gear would be  4.12.

Play around with the numbers until you find the speed, tire size, and RPM you can live with.

  • Upvote 1
Link to comment
Share on other sites

9 hours ago, Ted Y said:

My advice would be to contact RPM for a built unit with a 3.90 or 4.10 gear set. I found there aren't many places who can swap gears as the set up is very specialized. Keep your original diff in case you ever sell the car.

 

Are they local?  Only place I found looks to be out of state.

Link to comment
Share on other sites

joe@cpr.com

We can easily set you up and go over your goals. I sell rpm units and they do a core exchange so downtime is no longer than it takes to swap the diff or trans. I do have core heads that we do an exchange program on as well. Feel free to look at what we do, I specialize at this and have lots of cars out there to vouch on our work. 

Www.facebook.com/CordesPerformanceracing 

Even if you don't have Facebook it pulls up like a site. 

  • Upvote 1
Link to comment
Share on other sites

14 hours ago, HOXXOH said:

http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php

On the gear calculator chart, plug in 75 mph, your tire diameter, and the RPM you want to be at 75 MPH. Take the result and divide it by 1.78 (your second gear ratio) and the answer will be the rear gear ratio to accomplish your goal.

As an example, if you use 75 MPH, a 26" tire, and 7100 RPM, the result is 7.33. Divide 7.33 by 1.78 and the rear gear would be  4.12.

Play around with the numbers until you find the speed, tire size, and RPM you can live with.

Toms advice is the direction I would be looking,a simple change in tire diameter may get you to your goal with out tearing into the cars drivability for daily duties.

 

As an aside do you have any links to places to find autocross events?

 

This is something I was thinking of looking into with maybe a little less conventional vehicle purely for the fun factor.

 

Link to comment
Share on other sites

7 hours ago, joe@cpr.com said:

We can easily set you up and go over your goals. I sell rpm units and they do a core exchange so downtime is no longer than it takes to swap the diff or trans. I do have core heads that we do an exchange program on as well. Feel free to look at what we do, I specialize at this and have lots of cars out there to vouch on our work. 

Www.facebook.com/CordesPerformanceracing 

Even if you don't have Facebook it pulls up like a site. 

 

I do, following your page.  You are really close to my work so this may be ideal.

Link to comment
Share on other sites

Just a quick peek on the site I mentioned, brings up your 80 mph peak at 7100 rpm using 26.25" tires with a 3.90 rear gear.

Of course swapping to the Z51/GS gearbox the same 80 mph and 7100 rpm needs 26.8" tires and you stay with the 3.42 gear.

You can't change tire sizes enough to reach your max 80 mph @ 7100 rpm goal, so the choices are either trans gears or rear gears.

It's just simple math.

Link to comment
Share on other sites

But my understanding is the GS gearbox is not as strong?  I do plan on putting on full bolt ons and tune...think the GS would handle that run after run?  I think 80mph would be fine for a top speed for autox...a little higher than I would like but not bad.

 

I am going to go see Joe today and get his advise.   I was thinking 3.90 since it would still make it a bit more trip worthy.  4.10's would probably compromise that a little

Link to comment
Share on other sites

joe@cpr.com
4 hours ago, polyol said:

But my understanding is the GS gearbox is not as strong?  I do plan on putting on full bolt ons and tune...think the GS would handle that run after run?  I think 80mph would be fine for a top speed for autox...a little higher than I would like but not bad.

 

I am going to go see Joe today and get his advise.   I was thinking 3.90 since it would still make it a bit more trip worthy.  4.10's would probably compromise that a little

 

A grandsport has the same TR6060 trans as you, I push those well over 1k rwhp often. 

Link to comment
Share on other sites

Went with 3.90's...done deal.  Ill let you guys know how it works out.  Should make it fun on the street....

Link to comment
Share on other sites

  • 1 month later...

Well I did it.  Car dynoed 475whp at 105F ambient.  I love the gears exactly what I wanted.  Second gear rips.  This should be fun at autox.

Vette Dyno 063117.jpg

Link to comment
Share on other sites

insatiableOne

awesome, should be fun on the street as well

 

good luck on the Auto-X

 

was that Joe@cpr that hooked you up?

Link to comment
Share on other sites

joe@cpr.com

Thank you for letting us do your car Paul! We did wcch heads so he won't go kaboom and did an rpm diff with 3.90 gears. That thing is a lot of fun for so little done to it. 

  • Upvote 1
Link to comment
Share on other sites

Thank you Joe, my only regret is the 500-mile break in process.  500-miles of driving like a grandma till I can flush the diff oil out again.  Oh I really like the short shifter.

 

:)

Link to comment
Share on other sites

I'm waiting for the 3.90 gear set that's supposedly coming out late in the summer for the Z06 rear end, but the 3.90 rear gear is what I want :)

I bet it's a lot of fun ripping thru those gears now.....congrats !!!!

Link to comment
Share on other sites

joe@cpr.com
31 minutes ago, FNBADAZ06 said:

I'm waiting for the 3.90 gear set that's supposedly coming out late in the summer for the Z06 rear end, but the 3.90 rear gear is what I want :)

I bet it's a lot of fun ripping thru those gears now.....congrats !!!!

He still has a Z diff btw :)

Link to comment
Share on other sites

1 hour ago, joe@cpr.com said:

He still has a Z diff btw :)

Really ???? You've already got the 3.90 gear for the C6 Z06 rear end ?

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...