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Gear Ratio Change

well 3,29's will definatley accelerate faster, but i mean , these cars already do have good low end power...
 


Thats why im unsure on which ones i want. My cousins gxp has 2.93s and with 255s it spun pretty good. i have 245s and with the mods i plan on doing im sure ill have quite a bit more power
 
my stock gtp with brand new brideston potenza grids spin way too easy on dry pavement. havent got the car back on the road yet after the headers and 3.4 setup



edit- realized the wording makes this a little exagerated. it's not ALOT of spinning but definatley enough to send you sideways if your not careful
 
most of the high power build guys do go 3.29's though so if you dont care alot of driveabilty go fro the 3.29's they will be faster
 
Well my tranny isn't completely shot so after i finish the swap ill see how bad the spin is with 3.29s if anything ill stick with racing from a roll
 


Ready....set.. here's how it works.

In an HD transmission the drive and driven sprockets aka gears are 37/33 this gives you a 1.21 ratio on them. Couple that with a 3.29 HD diff (only size made) and you get 2.93 overall.

In a nonHD trans (aka almost the same as the HD trans) the drive to driven are 35/35 aka 1.00 ratio. Add that to any diff and you get an overall ratio that is equal to the diff. (really the diff being bigger and the ratio of drive to driven are the main changes from HD to non)

If you take the Non-HD trans drive/driven gears and put them in a trans with an HD (3.29) diff, you get 3.29 ratio. Program your pcm and you are all set.

To make the change of gears, it's the same basic procedure as how to swap out the 4th clutch hub. Search on my screen name and "easy", you'll find the procedure for pulling the trans, which bolts to take out to do the swap of 4th hub/gears and the way to change the gear ratio in HPT and DHP.
 
JoRoW99 said:
Bill would it not be easier to just get the on HD trans and put in an HD differential?
Click to expand...

It would already have an HD diff. If you picked up an HD trans, then you'd want to get NA drive/driven gears and put them in, likely with a new 4th hub shaft, new EPC and some fresh drive chains.

Acid.. how?
 
BillBoost37 said:
It would already have an HD diff. If you picked up an HD trans, then you'd want to get NA drive/driven gears and put them in, likely with a new 4th hub shaft, new EPC and some fresh drive chains.

Acid.. how?
Click to expand...

Read through it, you participated in it lol. Just general statements that could help not much facts. That's why I said it might help
:rolleyes:
 


If i swap the gears in a hd tranny would i have to get a tune since my car originally came with 3.29s and im just swapping the same gears into an HD trans? Also i search easy and didnt find anything on the 4th hub/gear change.
 
You've probable already said this somewhere but just to be sure all i have to do is swap the chains? And since my car is a gt that comes with 3.29s i wont need to tune it when i put the 3.29s in the HD trans.
 
Actually I let those things slide.

You need to swap over
Drive and driven gears aka the ones with the chain on them.
You won't need to do any programming because you'll keep the same ratio
You will need the passenger axle from the donor car. The NA axle is longer than the SC (HD)
If the trans is pre 04, I would have an EPC and hardened 4th hub shaft on hand as well.
 


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