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3.73 Gears installed... car running slower in 1/4

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3.73 Gears installed... car running slower in 1/4 - 4/30/2008 8:33:51 PM   
gburke1

 

Posts: 54
Joined: 4/19/2007
Status: offline
Hello everyone.

The other day I had some 3.73 Gears installed in my car. I drove it for 2 or 3 days & now today I took it out to the track. I ran several times... the best I could get was a 13.7 and most runs were in the 13.9 or 14.0 range... I am certain I was running these 13.9 or 14.0 range when I was stock... and the car seems to FEEL faster than before the 3.73s

I have an Intake, 3.73 Gears, and of course a Tune. Before the gears were in I ran a best of a 13.453 which I lost the time slip for... so I will show a different comparison of some runs before and after.

Before:
R/T .565
60' 2.117
330' 5.814
1/8 8.820 @ 81.84 MPH
1000 11.405
1/4 13.586 @ 103.03 MPH

After:
R/T .094
60' 2.127
330' 5.824
1/8 8.872 @ 80.81 MPH
1000 11.497
1/4 13.734 @ 100.56 MPH

I have come up with a few possibilities of what might have gone wrong...
1) Track timing/clocking equipment was messed up or really bad track conditions (a couple people were saying they were running slower... others said they didn't notice anything... I saw a couple cars that should have ran faster... gto ran 14.4 and 350z ran a 14). This may be most likely as last time I went it was reporting a trap speed that couldn't have been right... like 80 mph
2) Wrong tune was installed by shop. If so I re-installed it when I got home. (lesson learned to bring tuner to track...)
3) Doug gave me a bad tune?
4) Something not right with gear install


Opinions?



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13.453 @ 103.89 MPH
'06 Legend Lime GT Auto (91 B@ma Race Tune, JLT Intake)
New: Installed 3.73 gears.. track times to come!
Post #: 1
RE: 3.73 Gears installed... car running slower in 1/4 - 4/30/2008 8:36:53 PM   
soon2bboosted06

 

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Joined: 8/28/2007
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could be any of the above. i was told about .3 to .4 off 1/4 times. i would reload the tune and try again

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06 vista blue GT auto
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(in reply to gburke1)
Post #: 2
RE: 3.73 Gears installed... car running slower in 1/4 - 4/30/2008 8:39:09 PM   
gburke1

 

Posts: 54
Joined: 4/19/2007
Status: offline
Yeah I reloaded the tune and I am going to go back on Friday and see what happens... also going to try contacting Doug & have him check out the tune.

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13.453 @ 103.89 MPH
'06 Legend Lime GT Auto (91 B@ma Race Tune, JLT Intake)
New: Installed 3.73 gears.. track times to come!

(in reply to soon2bboosted06)
Post #: 3
RE: 3.73 Gears installed... car running slower in 1/4 - 4/30/2008 8:43:42 PM   
Bluestar



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Joined: 2/24/2007
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Did you have your shift points changed for the 3.73's ?????

I think that's the problem.

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RE: 3.73 Gears installed... car running slower in 1/4 - 4/30/2008 8:45:56 PM   
gburke1

 

Posts: 54
Joined: 4/19/2007
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I ordered a new tune from Doug and put on there that I had 3.73 gears and JLTII Intake... would he have done the shift points already?

If not what do I need to do?


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13.453 @ 103.89 MPH
'06 Legend Lime GT Auto (91 B@ma Race Tune, JLT Intake)
New: Installed 3.73 gears.. track times to come!

(in reply to Bluestar)
Post #: 5
RE: 3.73 Gears installed... car running slower in 1/4 - 4/30/2008 10:46:47 PM   
Rock36


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Joined: 2/21/2006
Status: offline
quote:

ORIGINAL: Bluestar

Did you have your shift points changed for the 3.73's ?????

I think that's the problem.


That is a good call, I didn't notice he had an auto.

Your trap speeds dropped significantly too, I'm thinking a bad DA might have had something to do with it too

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2005 Mustang GT

JLT II CAI, Kooks LTs w/ catted X, FRPP CMCV deletes, FRPP 4.10 gears, Steeda UDPs, FRPP Axle backs, BMR LCAs, BMR Rear Sway Bar, BMR Panhard Bar, Panhard Bar Brace, CHE K member brace, Xcal2, Hurst Shifter, Steeda STB.

(in reply to Bluestar)
Post #: 6
RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 1:25:34 AM   
SilvrStang


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From: Las Vegas
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What are the shift points with 3.73s suppose to be?

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Mods: JLT Intake,Diablo Predator,UPR 70MM TB/Plenum,Nitto Drag Radias, Eibach Pro Kit, MAC O/R H Pipe/Magnapacks



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Post #: 7
RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 1:50:10 AM   
67mustang302

 

Posts: 5016
Joined: 4/21/2007
Status: offline
What was the weather like on the different days? Higher temps and humidity can have a pretty big impact on track times.

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Who cares how much horsepower it has, all that matters is how fast it goes!

Best run 13.23 at 106.97mph with a 2.183 60'
Times from before tune and driver mod.

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Post #: 8
RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 2:54:50 AM   
Stkjock


Posts: 2743
Joined: 1/18/2007
Status: online
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quote:

ORIGINAL: SilvrStang

What are the shift points with 3.73s suppose to be?


they would need o be adjusted due the gear ratio change.  i believe that the rpm points would remain the same - the computur would have to be told that the gears were changed


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You can never have too much power, just not enough traction.
12.33 @ 112.3 - 1.71 60"

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RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 7:06:43 AM   
Wally39


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Could be weather and track conditions. Seems to me maybe you were spinning off the line more.

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RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 7:16:54 AM   
cacimar


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Joined: 3/20/2007
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it could that u need to brake in those gears a little bit more, 2-3 days not enough

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RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 7:24:14 AM   
gburke1

 

Posts: 54
Joined: 4/19/2007
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Maybe... but I was rading & seems there was a lot of disagreement on that subject. These things are quiet... can't hear them at all.

I don't think it was the weather because I was running these times when I was stock, in 90 degree weather and it was only 70s today.


< Message edited by gburke1 -- 5/1/2008 7:26:24 AM >


_____________________________


13.453 @ 103.89 MPH
'06 Legend Lime GT Auto (91 B@ma Race Tune, JLT Intake)
New: Installed 3.73 gears.. track times to come!

(in reply to cacimar)
Post #: 12
RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 7:31:30 AM   
AmericanSpeed

 

Posts: 401
Joined: 3/16/2007
From: Orlando, FL
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I'm thinking a worse DA.  Make sure your tune is correct and go again and see what happens.

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05 redfire gt premium 5 spd: K&N CAI, XCAL2, 93 Octane Tune from VMP, full suspension
DynoJet--> 287 RWHP & 307.5 ft-lbs RWTQ
CAI + tune only--12.877 @ 106.79 w/ 1.819
CAI + tune + suspension--12.783 @ 108.05 w/ 1.841
(both on stock tires)

(in reply to gburke1)
Post #: 13
RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 7:36:25 AM   
gburke1

 

Posts: 54
Joined: 4/19/2007
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I calculated DA and it was around 2500... the track is at 800 feet but weather would have made the DA higher. But, that still doesn't explain such a large difference..

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13.453 @ 103.89 MPH
'06 Legend Lime GT Auto (91 B@ma Race Tune, JLT Intake)
New: Installed 3.73 gears.. track times to come!

(in reply to AmericanSpeed)
Post #: 14
RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 9:10:34 AM   
wolfpup


Posts: 309
Joined: 2/6/2008
From: LONG BEACH, CA
Status: offline
im no expert but dont u need 500 miles to break in the gears ???

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RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 12:05:52 PM   
njdanmustang


Posts: 263
Joined: 11/9/2007
Status: offline
^ thats what is recommended.   Yea 2-3 days uh... your gonna be hearing some noise in a while.

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99 flows, bbk intake

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RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 12:17:19 PM   
Projectquick


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Joined: 8/22/2007
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Like others have said the weather and track conditions play a huge part in ETs.

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RE: 3.73 Gears installed... car running slower in 1/4 - 5/1/2008 12:45:10 PM   
gburke1

 

Posts: 54
Joined: 4/19/2007
Status: offline
Hmm well thanks for the advice... maybe ill take it easy then.

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13.453 @ 103.89 MPH
'06 Legend Lime GT Auto (91 B@ma Race Tune, JLT Intake)
New: Installed 3.73 gears.. track times to come!

(in reply to Projectquick)
Post #: 18
RE: 3.73 Gears installed... car running slower in 1/4 - 5/2/2008 6:49:00 PM   
gburke1

 

Posts: 54
Joined: 4/19/2007
Status: offline
Well think I figured out the problem.

Seems to be a bad tune. I tried flashing back to the tune I had before the gears and now I am running back around 13.5 . Did a few back to back runs and each time the old tune ran better. I did go into my tuner when flashing the car and selected 3.73 ratio.

I am at the track now so far best 13.465.

_____________________________


13.453 @ 103.89 MPH
'06 Legend Lime GT Auto (91 B@ma Race Tune, JLT Intake)
New: Installed 3.73 gears.. track times to come!

(in reply to gburke1)
Post #: 19
RE: 3.73 Gears installed... car running slower in 1/4 - 5/3/2008 8:17:18 AM   
njdanmustang


Posts: 263
Joined: 11/9/2007
Status: offline
Get some stickies, shift kit and a stall and you can maybe dip into 12s

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99 flows, bbk intake

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