Thread: Final drive ratio question

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  1. #1 Final drive ratio question 
    SE Level Member 07CrimsonGT's Avatar
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    From what I have seen and read, our GP's came with a 2.93 gearset in the tranny, or a 3.29 ratio as an option.

    I would have thought that the GP GT would come with the lower ratio, but my paperwork states 2.93.

    What is the 411 on this??

    Tnx in advance.............Don
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  2. #2 Re: Final drive ratio question 
    The mod from over yonder TheOtherNick's Avatar
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    Your 07 gt is supercharged right? I can't remember when they dropped the GTP badge. The supercharged cars came with the 2.93's and the n/a's came with 3.29's.
    01 gtp-big cam e85 dd 78dodge- guzzling fuel 05 cummins- rollin coal
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  3. #3 Re: Final drive ratio question 
    SE Level Member 07CrimsonGT's Avatar
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    01:

    Yes, my GT is supercharged. IIRC, the GTP went away in 04 and the GT which was previously not SC became so.

    I had a chance to drive a GXP when I was shopping, but did not since it was 3 hours away and I was kind of afraid I would have to have it.

    Don
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  4. #4 Re: Final drive ratio question 
    The mod from over yonder TheOtherNick's Avatar
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    04 and 05 still had GTP's and the comp g package, so I think they might have dropped it in 06.
    01 gtp-big cam e85 dd 78dodge- guzzling fuel 05 cummins- rollin coal
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  5. #5 Re: Final drive ratio question 
    GXP Level Member Iron Indian's Avatar
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    06 was the first year for the "GT Supercharged", yes...
    Shawn W. Larsen

    2005 Pontiac GTO 6.0 LS2/A4... Stalled/Cam Only: 406 RWHP , 370 RWTQ

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  6. #6 Re: Final drive ratio question 
    SE Level Member 07CrimsonGT's Avatar
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    II:

    As my memory breaks off the crust and cobb webs, I think you have it correct. I have seen 04 and newer GPs that are GTs with the "2" VIN code which was the N/A 3.8.

    After reading more last night, I am thinking that the gearset itself is a 3.29 ratio, and that the 2.93 is the effective ratio when in OD.

    Don
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  7. #7 Re: Final drive ratio question 
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    what kind of difference does the gear change make on cruising on the highway. I'm talking about 3 ratios, 2.93, 3.29, and 3.69.
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  8. #8 Re: Final drive ratio question 
    GTP Level Member Scimmia's Avatar
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    Quote Originally Posted by 07CrimsonGT View Post
    II:

    After reading more last night, I am thinking that the gearset itself is a 3.29 ratio, and that the 2.93 is the effective ratio when in OD.
    Very close. The differential (final drive) on all of the GPs is 3.29:1. The difference in on the input side, where the drive chain is overdriven with the supercharged engine; the NA trans use sprockets with 35 teeth on both, where the supercharged trans uses 33 on one and 37 on the other, giving it an effective 2.93 overall ratio. The individual gear ratios work from that, so the effective ratio in OD would be 2.93 * .71 = 2.08
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  9. #9 Re: Final drive ratio question 
    GrandPrix Junkie Sabrewings's Avatar
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    GTP Comp G's were the only supercharged 3800s to receive 3.29 final drive gears. All other supercharged 3800s were 2.93.
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  10. #10 Re: Final drive ratio question 
    GT Level Member BoostedComp's Avatar
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    Quote Originally Posted by Sabrewings View Post
    GTP Comp G's were the only supercharged 3800s to receive 3.29 final drive gears. All other supercharged 3800s were 2.93.
    ding ding ding theres the winner
    and yes all n/a gp's were 3.29 also
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  11. #11 Re: Final drive ratio question 
    GTP Level Member Scimmia's Avatar
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    *sigh* I'm really getting tired of this site. Once again, ALL 97-07 L36/L26/L67/L32 Grand Prixs had a 3.29:1 final drive, i.e. differential. The difference was on the input side.
    2001 Buick Regal LS - Almost Stock
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  12. #12 Re: Final drive ratio question 
    Donating Users blowfishRus6's Avatar
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    Quote Originally Posted by Scimmia View Post
    *sigh* I'm really getting tired of this site. Once again, ALL 97-07 L36/L26/L67/L32 Grand Prixs had a 3.29:1 final drive, i.e. differential. The difference was on the input side.
    dont get frustrated. thats good info. so in medifor, to change the relistaic ratio of the trans, you would change out the sprocket??? thats good to know.
    white 04 comg G gtp. wizair, pacesetters, slp 1.8 rr
    its slow.
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  13. #13 Re: Final drive ratio question 
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    Quote Originally Posted by blowfishRus6 View Post
    dont get frustrated. thats good info. so in medifor, to change the relistaic ratio of the trans, you would change out the sprocket??? thats good to know.
    If you had a GT, then changing the sprockets will only get you a worse gear ratio. Also, if you had a GT, you had the best gearing you could get shy of doing 3.69 gears. I'm not sure what was involved in making that work.

    Also, with a standard 4t65e, you could swap the diff to change the gear ratio. 3400 powered w-body cars got a 2.86 FDR, 3800 Impalas usually came with a 3.05/6 FDR and the GPs and MC SS got the 3.29 FDR.
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  14. #14 Re: Final drive ratio question 
    GTP Level Member Scimmia's Avatar
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    Quote Originally Posted by blowfishRus6 View Post
    dont get frustrated. thats good info. so in medifor, to change the relistaic ratio of the trans, you would change out the sprocket??? thats good to know.
    Yes, to change from 2.93 overall to 3.29 overall, you would swap the input chain sprockets for ones with the same number of teeth, most commonly found in the non-HD trans. AFAIK, the HD diff only came in 3.29, so there's no choices on that end, I'm afraid. Well, I don't know that anyone's tried swapping the sun gear/planetary gears from a non-HD diff into an HD diff, so it could be possible, and I think was mentioned on this site at one point, but who knows.
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  15. #15 Re: Final drive ratio question 
    SE Level Member 07CrimsonGT's Avatar
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    Guys:

    Tnx for the many comments. It does make some sense to me that the N/A would have a shorter set due to less overall grunt on tap.

    In any case, these fwd drivelines are nothing like the older rwd cars some of us had in the 70's where you swapped out the rear gear, and really woke things up.

    I was just curious to know what the spec was. There is not much difference between 2.93 and 3.29 anyway. That is about like swapping a Ford 3.27 to a 3.55, or a Dodge 3.55 to a 3.92.

    Don
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  16. #16 Re: Final drive ratio question 
    Donating Users blowfishRus6's Avatar
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    no its not a huge diffrence, but a diffrence either way.
    white 04 comg G gtp. wizair, pacesetters, slp 1.8 rr
    its slow.
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  17. #17 Re: Final drive ratio question 
    The Blue One blueguy's Avatar
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    Don...let me tell you about swapping to 3.29's and how F'ING AWESOME they are. I went from chirping the tires at 30mph with my 2.93's to blowing them the f**k off through 2nd gear Oh...and that is in a Triple Edge Performance Race Transmission
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  18. #18 Re: Final drive ratio question 
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    Quote Originally Posted by bluegtp91 View Post
    Don...let me tell you about swapping to 3.29's and how F'ING AWESOME they are. I went from chirping the tires at 30mph with my 2.93's to blowing them the f**k off through 2nd gear Oh...and that is in a Triple Edge Performance Race Transmission
    It's the truth. I can chirp them in my Monte SS at 30 if I go WOT. And that's with Eagle F1 GSD3s.
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