11' GT A6 -- Went from 3.15s to 4.10s.. Better times, but theres a catch..

coyoteugly5.0

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So first, My mods..

Power wise is Airaid CAI, UPR O/R X Pipe, GT500 Axlebacks, and a Mike Rousch tune. I run 19x8.5s on the front in a 255/45/19 and the rear is 19x10s w/ 275/40/19. I've got Tokico Spec D adjustable shocks in all 4 corners, and steed lowering springs 1 in the front and 2 in the back I believe.

My rear for some reason was basically toast, so I had to get it rebuilt and replace wheel bearings, so while I was at it we put some 4.10s in the rear to replace the factory 3.15s. I haven't been too fascinated about the 4.10s. I normally go to a local drag strip that's 1/8 mile, and haven't went to that track since I installed the o/r x pipe and the gears at the same time.

Before the gears and o/r x pipe at an 1/8 mile track:

1.99 60 ft and 7.99 1/8 was my best times.

After (But at a really good hooking 1/4 mile track, that's nothing like the 1/8 track)

1.85 60 ft and 7.68 1/8 and 11.88 1/4 at 119.

I'm doing all this on michellin pss street/summer tires.

My problem, is at the 1/8 mile track it didn't hook for shit, even with the 3.15s, so I'm wondering if my car is actually faster or slower with the 4.10s. I'm wondering if I would've went to the same 1/4 mile track that was hooking on the 4.10s with the 3.15s if I would've ran the same if not better times.


That 1/4 mile track (SGMP) in Valdosta is sticky, and I was able to just mat it at the pony wars. On the street, and any where else, I break loose about 1/2 way thru 1st, and went it hits 2nd it spins so hard it prematurely shifts into 3rd and is bogged down.. I'm wondering if I went to a 3.31 gear if I would still get that little extra jump, but manage better times..

Should I do the 3.31s? Should I just keep the 4.10s and work on UCA LCA and doing a good suspension setup? Ive been running the shocks all the way soft in the front and hard in the back..
 
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twistedneck

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1.88 60' on a street tire? I'm totally depressed now. that's my best 60' on Hoosier drag radials but then again I have a manual and have not been slipping the clutch at all - just coming out burning.

Nice times man, that car flies for the mods.
 

scotmach

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A converter will make a significant difference. Have you even considered one?

It sounds like you answered your own question when you say the track with the 4.10's that you ran had much better prep.

Ask Mike about his testing he personally did between the 3.15's and the 4.10's.
 
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coyoteugly5.0

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Yeah, I thought it was pretty good, but then again, that track was amazing.. If anyone has the chance to race in Adel, GA at SGMP, DO IT. I'm just confused if I did have the 3.15s, if it would've cut THAT good of a 60ft/ and 1/4 mile. I plan on going with a 100 shot in the near future, and I'm thinking 4.10s would be definitely too much at that point. But then again, look at American Muscles car, they had 4.10s and a 150 shot ripping 10.4s I believe..


I did talk to Mike, and he did recommend a stall. We didn't talk how big of a stall to go with tho, as this is my daily driver. He also said with the 1 and 2 ratios in the a6 that the 4.10s were too much. He had a lot of good advise, but he didn't knock the 4.10s at the same time, but he could've been just being polite.

I think I will save up and buy the 3.31 gears and converter. I want to get the best NA times without spending a ton of money before adding nitrous. I'm only doing the 100 shot, so I want to be able to still dip into the 10s range and 6's in the 1/8 using it. so maybe 7.20-7.40s on motor would give me a 6 second pass on a 100 shot.
 

4VFTW

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hard to make an apples to apples comparison when you have the addition of an x-pipe combined with 2 different tracks...were you spinning the tires at the 1/8 track?
 

768MPH

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Should I do the 3.31s? Should I just keep the 4.10s and work on UCA LCA and doing a good suspension setup? Ive been running the shocks all the way soft in the front and hard in the back..

You need to run full soft in the back and hard in front. You need to squat on take off. Try that and see how you do.
 

blackbeast12

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4:10s are better in every respect except gas mileage...I've had 3:31's, 3:90's and now 4:10's i have a tremec manual, and I'm in the process of building a brand new 8.8 with a detroit locker true trac, strange axels with c-clip eliminators and a brand new ford racing housing with ford racing 4:10's...my current rear broke..i also have 305/35/19 mt dr's on all the time...lol!
 

scotmach

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How is it any different if both cars are hooking? 4:10's will be bettter then 3:15's auto or manual! Its not that complicated!
On an auto no. Sorry but you're way off base here. Time and time again the 4.10's have proven to be no faster than the 3.15's.
 

Scott8583

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On an auto no. Sorry but you're way off base here. Time and time again the 4.10's have proven to be no faster than the 3.15's.

I find that hard to believe on a NA automatic... The auto needs it worse then the stick. Mine was weak as hell with 3.15's when it was NA
 

scotmach

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zinc03svt

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I would say a converter with the stock 3.15's has already been proven to work very well with a sticky tire. Why did your rear end need rebuild...?
 

466roller

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I've got 3.15's in my car as well and with street tires it will spin and shift up into 3rd the same way you describe. Personally I'd never put 4.10's in MY car. I'd say decide what your going to do to the car as far as power/bolt-ons etc. That will give you an idea of what kind of power the car should make. Then determine the tire you want to run as this will effect overall gear ratio and THEN decide what gear to run to best suite your needs. I doubt it will be 4.10's. Just curious what gear and RPM are you going through the traps at with the 4.10's vs 3.15's?
 

2012GT

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I have the same shifting problem. 1-2-3-2 shift at wot. Blows the tires off into second gear , bogs into 3rd and drops back down to 2nd. There are tuners out there that address this particular issue with the Auto cars.
 

Scott8583

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Lidio at Alternative auto had 4.10 gears in his 2011 when he was NA... I remember him saying it took some time to get the shifts right. I put 3.55's in mine at the same time I installed the TVS, so I can't really compare.
 

Holovacko

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You're correct about Bama running 10's with 4.10's and nitrous with stock converter...Casper also ran 10's N/A with 4.10's and aftermarket converter. It's just a matter of your preference in set-up and how you want car to feel on the street. Both 3.31 and 4.10's will work. Unfortunately, it's expensive to go fast N/A.
 

kona 199

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GET SOME REAL TIRES and u will be very happy with the 4.10 gears .maybe a hoosier dr 275/60/15.
 

blackbeast12

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If your car spins like crazy with the tires you have steeper gears wont help, auto or manual. The point I'm making is when the car is hooking. 4:10 will be quicker. Auto or manual. The reason why I'm upgrading my rear is for some reason the pinion bearing race got overheated and expanded causing the pinion to become unstable and under a heavy load it failed and sheered 6 teeth off the ring...
Still dont know why it happened, maybe the bearing failed, all i know is with a failed bearing race the housing has to be replaced, and with that i'm taking the opportunity to fill it with top notch parts.
 

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