Need help gaining HP again...

[FlyerFox0]

Hey, I have an 07 Mustang GT with 7000 miles on it. Just recently some f***ing dumba** with a PT Cruiser hit me while trying to make a u-turn into my lane in front of me so my left-front connected with his right-front. Also, my right wheels got run up against the curb. What got fixed was basically the entire front-left (from the fender all the way down to the rails and suspension), three new rims, and a new rear differential to replace the bent one. Now his insurance covered everything and I got it fixed at Mike Raisor Ford; the car looks great again but there is definitely performance issues: My speed seems to be topping off at 140rather than the 150 that it used to top off at (or governed at?). Not to mention it is taking way too long to even get to that 140 and when it does there is a loud whistling sound. I have no idea where to start looking. I have been thinking a lot about this but I'm thinking they may have used the wrong gear ratio for the axle or it is a problem with the tranny and/or engine. Please help me out; this issue has been really driving me nuts...

 

[KreagerM]

My speed seems to be topping off at 140rather than the 150 that it used to top off at (or governed at?). Not to mention it is taking way too long to even get to that 140 and when it does there is a loud whistling sound. ...

At that speed the wind will cause the wistle. A new panel could be set a little off then the way the factory panel was positioned, causing your new wistle.

What gear ratio did you have before the accident? Maybe FORD put in a set of stock gears. That's easy to see, just raise the rear and rotate the tires.

 

[DarkFireGT]

If they put in a higher gear, like 3:31's, then theoretically you'd be able to reach a higher top speed than with say 3:55's or something lower. So I don't think your problem is there. Sounds to me like something is still out of whack. I would check your pinion angle on your driveshaft, and also check your rear differential alignment, as if you were installing an adjustable panhard bar. If you're out of alignment, it could be creating resistance when you're driving, causing you to not reach top speed and slowing acceleration. The other thing to check would be your front end alignment. After that, I'm out of ideas. Good luck.

 

[KreagerM]

If they put in a higher gear, like 3:31's, then theoretically you'd be able to reach a higher top speed than with say 3:55's or something lower. So I don't think your problem is there.

One point he mentioned was that it's taking him longer to get to 140. So if he had 3:55's before the accident and now has 3:31's, the car would feel slower getting to top speed.

As for toping out at 140, now rather then 150. Could be a govern, no clue, sorry.

 

[FlyerFox0]

Thank you guys for all the replies. Before the accident I had 3.55 (by the way does that mean 3.55:1 or 3:55). I just got in touch with Mike Raisor Ford and they said they only replaced the differential housing so the ratio is still the same. As for the allignment could it really affect the max speed by 10mph and the time it takes to even come close?

 

[kooldawg6]

3.55:1 is the same thing as 3.55(easier to say and type). For every 3.55 revolutions your driveshaft makes, the rear axle makes 1.0 revolution, thus the 3.55:1.

Alignment has alot to do with speed and acceleration. If it is out of whack, it will create more rolling resistance be it your camber( tire in // or tire out \\at the top ) or toe( toe in // \\ or toe out \\ // ). Hope that helps.