Ok heres the problem. I went to the track a couple weeks ago with ok results for stock tires. Then I had frpp 4.10s installed. Went through the 500 mile break in and visted the track this past weekend. I was always told that I would feel A difference between the stock 3.55 and the 4.10. I really didnt feel any difference other than going from around 1700 to 2100 rpm at 60. But the track confirmed that!
2.1520 2.0953 60FT
5.8472 5.8165 330FT
8.3125 8.2911 ET at 594FT
8.8593 8.8385 1/8 ET
82.30 82.21 1/8 MPH
13.5653 13.5674 1/4 ET
104.84 104.95 1/4 MPH

Before After

I should mention that as i do not have any gear whine I do have a vibration. It is noticable at 60 and really bad at 100. I thought maybe the shop turned my driveshaft but after looking at it it seems to be in the correct spot. Any help would be great. Should I not expect more from gears?

 

I would expect better times when going from the 3.55 gear to the 4.10 gear set.....cant remember how much time it should shave but I get the feeling that the NVH from the DS has something to do with those times...

 

Was the DA the same for both runs?
Were there any headwinds during the 4.10 run?
Did you reload the tune after arriving at the track(if applicable) for both runs?
Did you allow the engine to cool down for both runs?

 

Same day or different days with different weather conditions...
That could be the difference.
Track surface conditions change also from week to week.

 

^ What they all said. Kind of like comparing dyno runs on different days.

About the driveshaft...What makes you think it was not rotated? Did you or the shop mark it?

 

Drive Shaft was the same both runs. Track days were done 2 weeks apart. It was a little cooler out with the gears. The wind was blowing with me both times at the track.

I marked the driveshaft to trasmission flange when i changed the shifter. I verified that to be in the same plce. Also it looks like the shop marked the other side with a yellow marker that is lined up now.

I tried both my 91 race tune and 93 race. Both had similiar results. Could something actually be binding causeing me to be slower? Or would that make more noise. I hd no vibrations all the way to 140+ before the gear install. Do you think it is something in the install? Should I call the shop?

 

I would loosen all the drive shaft bolts at the pinion flange and then retighten to 41 ft lbs. I'm sure the shop over tightened them. If the vibration is still there then i'd rotate the drive shaft at the pinion until it goes away.

I imagine you need to shift to 4th now and didn't need to with the 3.55 gears or are you an auto?

Even with the extra shift, you'd be trapping higher i'd think. If the Engine was heat soaked on the 4.10 run and not on the 3.55 run, then it would make sense.

 

I thought the driveshaft to trasmission flange was 41 ft/pounds and the pionion flange was 70 something? Anyway yes I have to shift into 4th now. I dont claim to be the fastest shifter but I think I do alright, thats why I accepted what I got before the gears, but I feel no difference. I thought actually that my 60 foot time would go up because of less traction but it doesnt spin any more with the gears than before.

Both runs were actually later in the day with around 5 runs already on the car. I do give it 15-20 min cool down, but im sure its still warm. Would letting it sit longer help?

I will try and retorque the driveshaft. Hope thats whats causing the vibrations.

 

That 4th gear shift could definitely be impacting your 1/4.

 

Transmission to drive shaft is 76, pinion to drive shaft is 41.

Are you sure they installed 4.10's? You should have felt a noticeable difference in 3rd, 4th and 5th gears.