3.42 Gears for the GT?

[Blackdevil77]

I was playing around with the RPM/Speed calculator in the 1/4 section and Just plugged in different final drive ratio's with the stock transmission gearing. I plugged in the 3.42 gears (like what the Corvette ZR1 has) and what I found seems to be very good. First gear would end at about 39 mph, as opposed to 44 with the stock gears. 6th gear at highway cruising would be at 2000 rpms at 66 mph. Again, thats not so bad. Also with the given trap speed I have, I would be going through the traps in 4th gear at a little over 6000 rpms, which again, seems very good, right at the end of the explosion of torque when the line starts to simmer down :)

What do you guys think about putting these gears in our cars? Too much? Not enough? Any reason why or why not? Just looking for input/opinions. I haven't looked much at gears.

[vic2186]

Hey Mario since we last spoke I traded 18s painted them black install a hsrk and magnaflow muffs..just to let you kno

[Crazy Paul]

Available ZF G8 diff gear ratios are:

2.92
3.27
3.45
3.70

[Devilish34]

Available ZF G8 diff gear ratios are:

$2.92
$3.27
$3.45
$3.70

Fixed
BlackBerry8330/4.5.0.77 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105

[Andy@SquashPerformance]

Available ZF G8 diff gear ratios are:

2.92
3.27
3.45
3.70

Are we still looking at $2k to do this swap? Can you get just the ring and pinion?

Andy

[Crazy Paul]

Are we still looking at $2k to do this swap?
Can you get just the ring and pinion?
Andy

Looks like US$1800 for a crate diff at your door, but not from me.
Yes gear sets are available, again not from me.

Sent you a PM

[SpeedRacerX]

I love the idea of lower gears for this heavy, highway-geared car.

Anyone have any idea on "theoretical" quarter mile improvements from the gear/rear swap? Time reduction or trap speed increases??

2.92 to 3.27
2.92 to 3.45
2.92 to 3.70
2.92 to 3.90 (rare or one-off but it's out there)

I know traction becomes an increasing problem but I'd like to get a rough idea.

It's confusing when one person puts in a 3.27 and gains .40 and another person puts in a 3.45 and gains .10 - how could that be?

[GeorgeInNePa]

I love the idea of lower gears for this heavy, highway-geared car.

Anyone have any idea on "theoretical" quarter mile improvements from the gear/rear swap? Time reduction or trap speed increases??

2.92 to 3.27
2.92 to 3.45
2.92 to 3.70
2.92 to 3.90 (rare or one-off but it's out there)

I know traction becomes an increasing problem but I'd like to get a rough idea.

It's confusing when one person puts in a 3.27 and gains .40 and another person puts in a 3.45 and gains .10 - how could that be?

Pay attention to the DA on the before and after runs.

[Devilish34]

Originally Posted by SpeedRacerX View Post
I love the idea of lower gears for this heavy, highway-geared car.

Anyone have any idea on "theoretical" quarter mile improvements from the gear/rear swap? Time reduction or trap speed increases??

2.92 to 3.27
2.92 to 3.45
2.92 to 3.70
2.92 to 3.90 (rare or one-off but it's out there)

I know traction becomes an increasing problem but I'd like to get a rough idea.

It's confusing when one person puts in a 3.27 and gains .40 and another person puts in a 3.45 and gains .10 - how could that be?



Pay attention to the DA on the before and after runs.

Exactly and thats why I think we need to add a spot for DA.

[GRRRR8]

I agree with George and John on the DA issue.

Some go to the track and dont realize their loss/gain is DA. Cold air is great. A cold track is not so great.

[familycaronROIDS!]

I love the idea of lower gears for this heavy, highway-geared car.

Anyone have any idea on "theoretical" quarter mile improvements from the gear/rear swap? Time reduction or trap speed increases??

2.92 to 3.27
2.92 to 3.45
2.92 to 3.70
2.92 to 3.90 (rare or one-off but it's out there)

I know traction becomes an increasing problem but I'd like to get a rough idea.

It's confusing when one person puts in a 3.27 and gains .40 and another person puts in a 3.45 and gains .10 - how could that be?

Here are some G8 GT's to compare - all runs were on the sameday sametrack...

(DA 3050 - 90 degrees & windy in So Cal) racing into the wind sucks.

I ran a 13.2 with mods on my sig at 105mph.

Al & Eds ran 13.2 with CAI, tune and 3.45 gears at 105mph. (not 100% sure on the mph).

others with CAI & tune (13.4-13.7) same day at 105-106mph.

3.45 gears well worth it - if you ask me..Just pricey.

[Devilish34]

I agree with George and John on the DA issue.

Some go to the track and dont realize their loss/gain is DA. Cold air is great. A cold track is not so great.

Exactly I had the best and worst the last time I ran. Awesome DA with a cold track I cannot wait to run again and compare. Did I pick up .3 bc of the air but loose a .1 or .2 bc of the track?? I know when I first put my LTs on I could break my previous best of 12.994. But the DA on the 12.994 was 275-300 but my first run with LTs was over 3000.

[jimmytt6]

Sorry to be a bonehead..but what does DA mean again??

[Devilish34]

Sorry to be a bonehead..but what does DA mean again??

Density Altitude it's calculated based on elevation,air temp, humidity, and Barometric Pressure.

http://www.dragtimes.com/da-density-altitude-calculator.php

[Blackdevil77]

do you think there is any noticeable difference what so ever between the 3.42 and the 3.45?

[jimmytt6]

Density Altitude it's calculated based on elevation,air temp, humidity, and Barometric Pressure.

http://www.dragtimes.com/da-density-altitude-calculator.php

Cool thanks!!

[Devilish34]

do you think there is any noticeable difference what so ever between the 3.42 and the 3.45?

No

[GRRRR8]

do you think there is any noticeable difference what so ever between the 3.42 and the 3.45?


Not that you will ever notice. Put the 3.45 ratio into the same equation and you will see little to no difference.

[Blackdevil77]

yup just tried it. Difference is about .3 mph LOL!

[Devilish34]

http://www.dragtracker.com/main.php


Another site for DA


Or you can buy one of these
http://www.dragtimes.com/parts-viewer.php?itemID=400051444067


Very tempting

[edmanet]

On a highly modified car I haven't seen any real difference between the stock 2.92 and the 3.27 diff I had installed. While the car feels stronger it hasn't shown it at the track.

[Devilish34]

On a highly modified car I haven't seen any real difference between the stock 2.92 and the 3.27 diff I had installed. While the car feels stronger it hasn't shown it at the track.

If I get new gears I'll be looking into 3.45s.

[Jackalope]

Also don't forget that every time the trans shifts you lose some time. If you have enough hp and tq sometimes highway gears are faster cause the trans doesn't need to shift as often.

[MGM GT]

I agree with George and John on the DA issue.

Some go to the track and dont realize their loss/gain is DA. Cold air is great. A cold track is not so great.

We have a jet engine for that... love it when they use this on the track. They spray fresh VHT and heat it up! If you cant hook with that you never will.

http://www.wsdot.wa.gov/NR/rdonlyres/B837385B-11ED-425D-A46D-0BC4866CE012/0/PavementDryer1WEB.jpg

[Devilish34]

We have a jet engine for that... love it when they use this on the track. They spray fresh VHT and heat it up! If you cant hook with that you never will.

http://www.wsdot.wa.gov/NR/rdonlyres/B837385B-11ED-425D-A46D-0BC4866CE012/0/PavementDryer1WEB.jpg


Cecil has one too. They ran it the day I broke and sprayed (half track not full like they were supposed to) The track was just shit that day and I could only walk it out of the hole.

[edmanet]

Also don't forget that every time the trans shifts you lose some time. If you have enough hp and tq sometimes highway gears are faster cause the trans doesn't need to shift as often.

I don't believe its a factor here. With the stock gears I ran through the traps in 4th gear. With the 3.27s I go through the traps in 4th also.

[Devilish34]

Also don't forget that every time the trans shifts you lose some time. If you have enough hp and tq sometimes highway gears are faster cause the trans doesn't need to shift as often.

I go through in 4th and I believe Georges new best was in 4th

[MGM GT]

I don't believe its a factor here. With the stock gears I ran through the traps in 4th gear. With the 3.27s I go through the traps in 4th also.

You had your new converter before or after the new gears? Wondering if that had anything to do with it.

[edmanet]

You had your new converter before or after the new gears? Wondering if that had anything to do with it.

Took out triple disc and installed new converter[single disc supposedly same stall] and diff at the same time.

[GeorgeInNePa]

I go through in 4th and I believe Georges new best was in 4th

Yes, I believe that's the source of the amazing MPH.

I need to start a thread admitting to not "holding 3rd" anymore.

lol

[MGM GT]

Yes, I believe that's the source of the amazing MPH.

I need to start a thread admitting to not "holding 3rd" anymore.

lol

haha yepp... I gained .3 by doing what everyone said not to do.

[GeorgeInNePa]

haha yepp... I gained .3 by doing what everyone said not to do.

With my old tune I needed to hold third, otherwise I was slower.

[jetmechinnc@yahoo.com]

By changing the read diff to say 3.45, do you need to correct the speedo? Is it done with a cog change or is it computer controlled and the car would need a tune to fix it? Had a friend who put 3.73 in a 2004 mustang and boy did it come alive. But he had zero traction. would only run 9.4 in the 1/8th mile. My 3.0i Z3 would run 9.0 all day and the only mod I had was a muffler and a reprogrammer, I'd just never spin the tires really.

[GRRRR8]

Gear change corrections are done in the tune. Shift points must be adjusted as well.

[jetmechinnc@yahoo.com]

Ok, thanks, guess I have to get a shop to do it then since I have no way of tuning it myself unless I get a mail order tune.

[SS DAVE]

for the auto 3.27 is the best ,cars over here that run low 12's didnt run any faster goin from 2.92 to 3.45 ,what they gained at the 60 ft they lost with the extra gear shift.if your not running a cam the 3.45's are great,ive just done the swap,really hits the tyres harder and is better coming out of corners,i do how ever have 22 inch tyres that are 125mm greater rolling diameter than the 18's so im proably around 3.3 now.
the cheapest way to do it is to buy a complete diff,the manuals come with the 3.45 standard and most of them swap to 3.7 and sell there 3.45 diff ,i got mine for $800 with 6000 klm on it ,i have seen them for $500,not sure what the freight would cost you guys they weigh 30 kg.