2008 Mustang GT Shift Pressure Questions - Ford Mustang Forum
 
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post #1 of 6 (permalink) Old 06-18-2010 Thread Starter
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2008 Mustang GT Shift Pressure Questions

Hey gang,

I am just curious since we have a lot of self-tweakers on this forum, some with automatics:

In your experience, does increasing your shift pressure via tuner INCREASE or DECREASE your 0-60MPH and 1/4 mile times?

I am asking because I am trying to rule that out as what is slowing me down, as recently I've done a 0-60MPH run set (3 total) and NOT been able to get UNDER 7 seconds, but the videos I've took in the past, I have gotten as low as 6.5 seconds 0-60MPH. And to top it off, I'm running on like 1/8 of a tank of gas right now, so the car is practically never going to be lighter than it is right now. Do you think this could be the cause, or should I be looking elsewhere?

Also, should I be concerned about increasing times, or could it be something as simple as the air filter needing cleaning, or the oil needing a change (I am due for my next oil change/fluid check next month, so it very well could be)?

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post #2 of 6 (permalink) Old 06-18-2010
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Originally Posted by GreenGT84 View Post

In your experience, does increasing your shift pressure via tuner INCREASE or DECREASE your 0-60MPH and 1/4 mile times?
Increase. Not a ton but every little bit helps, right?

When NA on my stock Pirellis, I increased pressure in gears 1&2 by 20% and 3&4 by 30%. Any higher pressure in the lower gears just got me sideways under hard acceleration.

Your shift pressure would not be the cause of your car slowing down, FYI. Something else would be causing that.


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post #3 of 6 (permalink) Old 06-18-2010
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You didn't mention if you had heated the tires prior to the run. Traction could be your problem. With firmer shifts you'll find that your tires will break lose during gear changes when at WOT. So, yes it can slow your times down. I've spun mine on every gear change while going down the track before. It was time for new tires with a better compound. That could be what you need; stickier tires to fix the traction problem. Do that and your time should drop again. The firmer shifts should lower you 60ft or 0-60 time. The firm shift is like when we used to install a shift kit in the older auto trans. Your fluids shouldn't really be an issue unless it comes out in clumps. Todays fluids are really advanced, even the non-synth is good compaired to a decade ago.

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RWHP/RWTQ is adequate
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post #4 of 6 (permalink) Old 06-20-2010 Thread Starter
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Well I only have my 1st-to-2nd and 2nd-to-3rd shift pressure increased, and only by 5%, and that's plenty rough for me, makes the speedo jump from 42 to around 48MPH when shifting from 1st to 2nd, which I like.

So you're saying increasing the pressure would indeed increase my 0-60MPH time? Cuz we're not talking about a huge difference, around .4 seconds at most.

It was in cold weather on cold tires, so I imagine that was partially responsible.

How big of a difference does warm/cold on the engine make on times? It isn't really significant on 0-60MPH, is it?

OH and Hubkap, 20% eh? That seems insane to me... but then again I haven't tried it so I wouldn't know for sure, right? LOL Just seems to me that if I'm already screeching tires a bit at 5%, 20 would be nuts.
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post #5 of 6 (permalink) Old 06-20-2010
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Colder air = denser air (intake charge) = more horsepower.
Colder tire = less traction than warm tires (usually)

A warm engine doesn't necessarily reduce your hp, as your lubes ideally need to be up to temp, but the cooler your intake air the better. Easiest way to do this is to run in cool air.

Increasing pressure by 20% in the 1-2 shift wasn't bad for me at all. The tires barked but only for a split second so it was the max I could go. Anything higher and I just got sideways from TOO much of a loss of traction, which of course hurt times. I played with it for a while so it's just a matter of playing with it to find the right balance

Like redruder said, it's just like when we installed shift kits in the older transmissions, only now thanks to computers we have more control over the firmess of the shifts.

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post #6 of 6 (permalink) Old 06-22-2010 Thread Starter
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See with mine, 5% does a bit of a tire screech, and the MPH jumps a few MPH... so I guess I should fool around with it a bit, see if I can take a liking to a higher pressure or if 5% is the max I can handle.

I just don't want my car to be scary for others to drive in case of emergency lol

Thanks for the response, I'll have to test out some different settings for sure.
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