3.73 Gears installed... car running slower in 1/4 (Full Version)

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

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

soon2bboosted06 -> RE: 3.73 Gears installed... car running slower in 1/4 (4/30/2008 8:36:53 PM)
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

gburke1 -> RE: 3.73 Gears installed... car running slower in 1/4 (4/30/2008 8:39:09 PM)
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.

Bluestar -> RE: 3.73 Gears installed... car running slower in 1/4 (4/30/2008 8:43:42 PM)
Did you have your shift points changed for the 3.73's ????? I think that's the problem.

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

Rock36 -> RE: 3.73 Gears installed... car running slower in 1/4 (4/30/2008 10:46:47 PM)
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

SilvrStang -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 1:25:34 AM)
What are the shift points with 3.73s suppose to be?

67mustang302 -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 1:50:10 AM)
What was the weather like on the different days? Higher temps and humidity can have a pretty big impact on track times.

Stkjock -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 2:54:50 AM)
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

Wally39 -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 7:06:43 AM)
Could be weather and track conditions. Seems to me maybe you were spinning off the line more.

cacimar -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 7:16:54 AM)
it could that u need to brake in those gears a little bit more, 2-3 days not enough

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

AmericanSpeed -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 7:31:30 AM)
I'm thinking a worse DA. Make sure your tune is correct and go again and see what happens.

gburke1 -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 7:36:25 AM)
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..

wolfpup -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 9:10:34 AM)
im no expert but dont u need 500 miles to break in the gears ???

njdanmustang -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 12:05:52 PM)
^ thats what is recommended. Yea 2-3 days uh... your gonna be hearing some noise in a while.

Projectquick -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 12:17:19 PM)
Like others have said the weather and track conditions play a huge part in ETs.

gburke1 -> RE: 3.73 Gears installed... car running slower in 1/4 (5/1/2008 12:45:10 PM)
Hmm well thanks for the advice... maybe ill take it easy then.

gburke1 -> RE: 3.73 Gears installed... car running slower in 1/4 (5/2/2008 6:49:00 PM)
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.

njdanmustang -> RE: 3.73 Gears installed... car running slower in 1/4 (5/3/2008 8:17:18 AM)
Get some stickies, shift kit and a stall and you can maybe dip into 12s

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