NFRTurboTerror

I just picked my car up today from the transmission shop and I have a few questions. First, I was told that my speedo would be off. But I now have to shift out of second about 62 or so where I had been shifting out about 65. Also in 6th gear I'm not running 6k rpms until almost 120mph where it was doing 6k around 110mph before. I was told the 2% higher 6th gear only makes 100rpm worth of difference but it seems to make almost 1000 rpm worth of difference. I was also told that the 5th gear was lower but I was never able to do 140 in 5th only around about 130 or maybe a little bit faster. Also when I have swapped engine/trans I never had to have the speedometer recalibrated. I know with a rear diff swap you have to get it recalibrated but I've never heard of it with just a transmission swap. Lower speed in 2nd and higher speed in 6th tells me that the speedometer seems to be right on, but maybe someone could explain all of this too me.

Other than those questions I have NO COMPLAINTS, and I am EXTREAMLY happy with the swap. The new transmission is SO QUIET. It puts out ZERO of the buzzing or gear noise that my other one so LOUDLY pronounced, and the car just feels quicker too. I would recommend this swap to EVERYONE.

cdelena

I think you need a yellow box...

xviper

Take a look at the "gear" calculator and plug in the numbers for comparison:
http://www.turnzero.com/technical_resource...gear_calculator

You will see that the first 4 gear ratios are exactly the same from AP1 to AP2 trannies. It is the 2ndary reduction gear that changed and they changed 5th and 6th gear ratios to compensate in order to maintain the same (or better) highway cruising rpms.

If you are comparing your tach with your speedo, you may not be using a valid reference as your speedo signal is still reading as before. They are still on the same reference plain as before. You need to have a "Yellow Box" to recalibrate the speed signal so that it reflects a more accurate MPH.

By the calculator, at 120 mph in 6th .........................
AP1 tranny should read about 6400 rpm on the tach.
AP2 tranny should read about 6300 rpm on the tach.
So what you heard is correct.

If you swapped engine and tranny with the same type before, you didn't need any re-cal. But this time, you've put in a tranny with different ratios and where the speedo sensor pick up is, this can affect the signal.

6th at 6K rpm should see about 113 mph. This should have been about the same before.

5th gear now should be about 138 mph. Same before. So I'm a bit

Running at high speeds may not be very accurate anyway. Whether or not a Yellow Box is necessary and at what correction is hard to confirm at this time. You should do various speed comparisons with another car that has a typical stock configuration. Pace at 30 mph, 60 mph and maybe 90 mph and record the difference. Do each one in the appropriate gear for that speed. Perhaps in any given gear, try to different speed comparisons. One at about 3000 rpm and another at about 5500 rpm. No need to beat your car up just to compare speedos. Then you can work out the percentages and determine what the YB correction needs to be.

pdexta

Anyone - Does the yellow box allow you to calibrate different correction factors for different gears?

RedAP1S2k - Can you tell any significant difference in acceleration through the lower gears? If you don't mind me asking, how much did the transmission and installation cost you?

Wildncrazy

xviper you are saying that 1-4 are the same on both trannies?

How come everything I've read since '04 say 1-4 are lower and 6th is higher?

That's been part of the issues with the newer cars. I know people who have had both and they have said that when you couple lower rev limits and lower tranny gearing you have to shift too much on an autocross course, which gives slower times.

OR are you saying that the secondary reduction is what gives the lower final gear ratios?

Elistan

Here's a handy chart:

00-03 transmission: 1.160 secondary reduction gear
1st - 3.133 (3.634 with secondary)
2nd - 2.045 (2.372 with secondary)
3rd - 1.481 (1.718 with...)
4th - 1.161 (1.347...)
5th - 0.970 (1.125)
6th - 0.810 (0.940)

04-06 transmission: 1.208 secondary reduction gear
1st - 3.133 (same, but it's a shorter 3.785 with secondary)
2nd - 2.045 (again same, but shorter 2.470 with secondary)
3rd - 1.481 (same, but shorter 1.789 w/ secondar)
4th - 1.161 (same, shorter 1.402 w/ secondary)
5th - 0.942 (taller, but still 1% shorter 1.138 w/ secondary)
6th - 0.763 (taller, and taller still 0.922 w/ secondary)

So gears 1 though 4 are the same, 5th and 6th are taller, and the secondary reduction gear is shorter.

Elistan

Oh, and from 1.160 to 1.208 is a 4% change. So I expect that you're going 4% slower than your speedo indicates. (Ie, 4mph off when you're going 100mph.)

xviper

Yes, gears 1 to 4 one both trannies have the exact same ratios.

They are "lower" because of the secondary reduction gear. To make up for this, gears 5 and 6 changed, so they are higher when combined with the 2ndary, but only marginally.

Your "OR" is correct.

NFRTurboTerror

[QUOTE=scottrunsxc,Mar 23 2006, 12:24 PM] RedAP1S2k - Can you tell any significant difference in acceleration through the lower gears?

Billman250

The fact that 1-4 are the same doesn't matter. the secondary reduction must be figured in.

So, out the back of the trans on the 04 tranny, 1-5 is lower. 6th is taller.

Your speedo is off, amounting to the difference of the reduction ratio.

It is turning faster, so you'll get less tickets