Help me choose the correct gear!

BigFudge

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Hey guys, I've got a 2012 Mustang GT. I race it at all my local 1/8th mile tracks but never take it to a 1/4. I'm thinking I could benefit from a gear change but not sure what gear to go with. It has the 6R80 transmission and here is my setup....stock 3.15 gear, boss intake manifold, BBK long tubes, off road X, flowmaster outlaw axle back, Circle D 5C converter, BMR tubular K member, lightweight radiator support, BMR upper/lower control arms, panhard bar, relocation bracket. The car shifts at 7700 rpm. The personal best for the car is a 1.6 60' and 7.57 @ 93 mph in 90+ degree weather with over 3500 DA. I run 15x3.75 front runners and 15x10 rear wheels with 275/50/15 Mickey Thompson ET streets (26" tall). I've been pondering going up to a 3.31 gear. I keep getting told to go to a 28" tall tire but I feel that would negate any gains that I picked up with a gear change. Please and thank you for the help! It's hard figuring out gearing on these A6 Coyotes. Here's a video of my second best pass...if you listen to the car it seems like it rolls through the traps at too low an RPM in 3rd gear....

https://m.youtube.com/watch?v=UTLr1Q5HfWc
 

drive_55_not

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No doubt the Boss intake is hurting you off the line so a gear change and some aggressive tuning would help.

Aaron Lail, a local tuner to me, runs 3.73 for mostly 1/8 mile and has the quickest NA stock intake Coyote around here ... headers, 5C converter and a tune were his only mods IIRC, he was still running the stock air box.

His cars the reason I wanna 6R in my junk .. Still waiting for Baumann to release their controller.

https://www.youtube.com/watch?v=O0lD7olmg00


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BigFudge

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No doubt the Boss intake is hurting you off the line so a gear change and some aggressive tuning would help.

Aaron Lail, a local tuner to me, runs 3.73 for mostly 1/8 mile and has the quickest NA stock intake Coyote around here ... headers, 5C converter and a tune were his only mods IIRC, he was still running the stock air box.

His cars the reason I wanna 6R in my junk .. Still waiting for Baumann to release their controller.

https://www.youtube.com/watch?v=O0lD7olmg00

Haha it's a small world. I live in Hickory, NC. He's the one who tuned my car and advised me to go with the boss intake/5C converter.
 

drive_55_not

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Haha it's a small world. I live in Hickory, NC. He's the one who tuned my car and advised me to go with the boss intake/5C converter.


I thought that was Wilkesboro, I live over behind Maiden ..

Aron knows more about tuning these cars than I do but personally, I'd went with the CJ setup myself.

There was a guy with a CJ intake running 6.80's NA at Piedmont last time I was there .. Don't know what all he had done other than serious weight loss but that car was crazy fast ..

Best thing to do is get with Aron and see if can get you sorted out.


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skaarlaj

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I'd rather run the deeper 3.31's on a 28 tire, just to have more grip that a taller tire has over a shorter tire of the same width. I look at it like this wider tire equals wider contact patch, taller tire = longer contact patch. As far as crossing the stripe in the correct gear, I say screw that, and just gear for the best 60' possible, especially in an auto car that NEVER has slack in the drivetrain like a clutch car between shifts wether they are granny shifts, or power shifts, there is momentarily Zero hp going to the road when your clutch is in, not the case for auto's.
 

Marble

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I'm not well versed on the in and outs of coyote motors and gearing. Butt I'll share my.02 on what I would look into.

I would want the most tire on they ground as possible. That means a 28.5x10 tire our a 28.5x10w with a stiff sidewall and tube.

A convertor they has a stall 500-700 below peak torque. Or call circle d and ask.

Or, don't reinvent the wheel and go find someone with a very similar set up and copy the shit out of them.
 

Five Oh Brian

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I'm a big fan of 4.10's in the Coyote/6R80, especially combined with a big stall and NA like the OP's car. Also like the longer contact patch of a 28" tall tire.
 

skaarlaj

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Because of my DA aka "lack of hp", I'm barely shifting into 3rd going through the traps in the eighth, so I'm either gonna raise my shift points to stay in 2nd, or gear down
 
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Marble

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I'm not sure of your power level or your future plans, but if you are all NA and will be staying that way in theory you want to be crossing the beams at the top of your gear.

If you plan on increasing power substantially with something like a TVS I would hold off and again, find someone with a similar set up.

Having a taller gear and a high stall converter can be great. Especially with good PD blower. Depends a lot on the tranny, RPM ETC.

So really I have no specific advice for you lol...I've screwed around with my car enough to know now to play copy cat with someone who is successful.
 

skaarlaj

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Another thing to note about these automatics, is when paired with the right converter, traction, they all seam to run pretty damn good, and a gear change can probably make the car feel alot different, but if tuned properly, you probably won't see much difference at the track imo. There's people that think that so and so's geared too low, and so, and so went faster with factory gears. I really think Five Oh Brian should swap in some factory 3.15's or 3.31s, make some hits at his local track, run the same number and put this to rest, hahaha!
 

Unreal

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Ran 3.15, 3.55 and now 3.31s. 28" tire, 4C convertor. The 3.31s have been the best setup for my car.
 

skaarlaj

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Ran 3.15, 3.55 and now 3.31s. 28" tire, 4C convertor. The 3.31s have been the best setup for my car.
How much ET and 60' difference between the three, if no other mods?
 

skaarlaj

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Went 12.2s on 3.15, 12.3s on 3.55s and 11.9s on 3.31s. All on a 28" tire.
Well then it does seam kind of magical then hahaha. I might have to install the 3.31's I took outa my manual car??? Did you pick up trap spped too or just 60' the best? If you don't mind me askin. I run in the eighth alot more than full quarter so 60' improvements benefit me much more than gaining trap speed.
 
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BigFudge

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I guess most of you missed where I said in my original post that the car has a Circle D 5C converter in it, recommended to me by anyone and everyone I asked with a fast N/A car. I believe I'm going to go with a 3.31 gear and run that with the 26" tall tires to see how the car does. If needed, I'll go up to a 28" tall tire. I'm not having traction issues as of now.

Well then it does seam kind of magical then hahaha. I might have to install the 3.31's I took outa my manual car??? Did you pick up trap spped too or just 60' the best? If you don't mind me askin. I run in the eighth alot more than full quarter so 60' improvements benefit me much more than gaining trap speed.

1/8th is all I run also. I hope the 3.31 picks my car up.
 
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