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Discussion Starter #1
After my GT2871 Turbo and AEM Water/Meth system was installed by DDM last year, my "way to short" final drive ratio of 3.73 needs help. I'm looking at the 3.42 GEN 1 CTS-V ring & pinion (GM 89058650) gear set. With 400 whp, 1st and 2nd gear are very short in comparison with my prior 944 Turbo's. It had a 3.42 final drive ratio which made things much more manageable on the track as well as in the twisties.

Has anyone else considered or done this? My current, as well as new, calculated speeds in gear at 6700 rpm are as follows:

Current speed in gears with 3.73 Final Drive
-----------ratio--------MPH
2nd gear--2.26------ 63.158
3rd gear-- 1.51------ 94.528
4th gear-- 1.00------ 142.737
5th gear-- 0.73------ 195.531

Calculated speed in gears with 3.42 Final Drive
------------ratio-------MPH
1st gear- 3.75------ 42.753
2nd gear--2.26------ 70.939
3rd gear-- 1.51------ 106.174
4th gear-- 1,00------ 160.323
5th gear-- 0.73------ 219.620

I'm still running the factory clutch and realize this will hasten my SPEC3+ upgrade due to the additional torque this will place on the transmission and clutch.

Any comments would be welcomed.
 

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I say do it. You could even go to a numerically lower gear set if available like 3.27. With just an E47 tune I was thinking the same thing. Plenty of power in 5th at 65-70. I was thinking a 6th gear was needed. If you can hardly use first/2d then gears will fix that cheaper than a new tranny. My G8GT has 2.92 gears stock and just a touch more HP and weight.
 

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Discussion Starter #3
Thanks for the moral support. I feel like this will get me closer to letting "The Genie out of the bottle". With our slight weight advantage, I feel like it will put me in the C6 Z06 Realm as it's already stronger than the C5 Z06. The guy in the C5 that I "educated" really thought I'd stuffed an LS in my Coupe. He just refused to believe a 2.0 liter was showing him it's license plate. I had to pop the hood before he believed it.

Off topic but yesterday I saw the most awesome Black G8 I've seen to date. It must of had an aftermarket ground effects kit as I'd never seen a factory car that had wheel well lips and many other niceties. Wished I could have gotten a photo. As a former GM supplier, I've been to the Holden, Australia plant but never saw anything this appealing going down the production line. The Aussie's take their V8's very serious. Walking through the employee parking lot was like going back in time to the early 70's in the U.S. It was great and once again, I was without a camera.
 

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Pretty sure you've seen the comments here, they probably aren't adding anything to what you already know:

Update on rear end ratio change to 3.42 [Archive] - Cadillac forums : Cadillac Owners Forum

Sounds like a reasonable idea given you'd like to be in gear a little longer, especially in 1st/2nd, and you have plenty of power to pull it off....

Bill, why don't I see you listed in our Coupe registry thread? I scanned it 2x's and didn't see you. Your choice of course but I'd be happy to update it.
 

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Discussion Starter #5
Taller Final Drive Ratio

Thanks for the reply and you're exactly right on the 1st/2nd gear issue. I had DDM set my rev limiter at 6800 to keep me from blowing the monster up. There are actually two options from the CTS/STS V Cars. The original STS-V had a 3.23 but I calculated that with my "Speed in Gear Spreadsheet" and the 3.23 wasn't an option. A) The torque that the trans and drive shaft would have to endure would break something. B) as I remember at 70 mph I'd be turning less than 2200 rpm and that's a little below the LNF Optimum Torque curve. The 3.42 was great in my money pit 944 Turbo's which had similar gears from 1st to 5th. I didn't matter if I was on the track, in the twisties or just cruising on the interstate, It always had the correct gear to choose from.

As far as the Coupe list, I thought I'd properly submitted my info. It was one of the 1st 100+, non-sequential VIN's, 1G2MG25X09Y106109. As a pre-production car, it got a lot of special attention. I knew the entire crew that dealt with it as prior to and during my cancer issue. I was the quality manager for one of GM's tier 1 electronic powertrain components. With several other customers, I would never have considered a pre-production evaluation vehicle. GM is years beyond other car manufacturers as far as what is done with the pre-production vehicles. There is nothing left hanging as it relates to potential problems. I know this first hand as, more than once, I've been on the hot seat for a pre-pro quality issue and every single issue is addressed, corrected, and monitored under a microscope. Many even have an instrumented ECM which gives the Hardware and Software guys logging at 100x faster speed than anything you'd ever get over the OBD II port.

Please drop me a PM if there's anything additional I need to do regarding the Coupe list. I'll take this car to my grave as $ for $, there's nothing on the market that, when done properly, gives you a bigger bang for the buck with aftermarket upgrades. I'm already planning on upgrading the HARD parts, rods, pistons, valve springs with ported and polished head this fall. I can then coax another 75-100 wheel hp over the 400 I already have without worry of scattering the engine.
 

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Thanks for the reply and you're exactly right on the 1st/2nd gear issue. I had DDM set my rev limiter at 6800 to keep me from blowing the monster up. There are actually two options from the CTS/STS V Cars. The original STS-V had a 3.23 but I calculated that with my "Speed in Gear Spreadsheet" and the 3.23 wasn't an option. A) The torque that the trans and drive shaft would have to endure would break something. B) as I remember at 70 mph I'd be turning less than 2200 rpm and that's a little below the LNF Optimum Torque curve. The 3.42 was great in my money pit 944 Turbo's which had similar gears from 1st to 5th. I didn't matter if I was on the track, in the twisties or just cruising on the interstate, It always had the correct gear to choose from.

As far as the Coupe list, I thought I'd properly submitted my info. It was one of the 1st 100+, non-sequential VIN's, 1G2MG25X09Y106109. As a pre-production car, it got a lot of special attention. I knew the entire crew that dealt with it as prior to and during my cancer issue. I was the quality manager for one of GM's tier 1 electronic powertrain components. With several other customers, I would never have considered a pre-production evaluation vehicle. GM is years beyond other car manufacturers as far as what is done with the pre-production vehicles. There is nothing left hanging as it relates to potential problems. I know this first hand as, more than once, I've been on the hot seat for a pre-pro quality issue and every single issue is addressed, corrected, and monitored under a microscope. Many even have an instrumented ECM which gives the Hardware and Software guys logging at 100x faster speed than anything you'd ever get over the OBD II port.

Please drop me a PM if there's anything additional I need to do regarding the Coupe list. I'll take this car to my grave as $ for $, there's nothing on the market that, when done properly, gives you a bigger bang for the buck with aftermarket upgrades. I'm already planning on upgrading the HARD parts, rods, pistons, valve springs with ported and polished head this fall. I can then coax another 75-100 wheel hp over the 400 I already have without worry of scattering the engine.
Bill, send me a PM with your data as requested on the coupe list and I'll add you. Go here and you'll see in the preproduction/non-sequential you aren't listed.

http://www.solsticeforum.com/forum/f114/newest-solstice-coupe-list-here-74384/index6.html

Back to your thread questions, in bold the latter comment I couldn't agree more, this little 2.0 sewing machine easily made 300/340 pretty stock, and a little more serious can easily get you in that 400hp range, incredible. While still getting great MPG's if you can possibly keep your foot out of it. The motor is one of the main things that interested us in the purchase. To add to your love comments, we are still a new owner of this car from purchase last August, and it still pisses me off reading some the reviews of the car, and TOTALLY missing the point IMO. They always knock the interior cheapness, and overall performance, and ergonomics, and yet never give it cudos for being the one, along with perhaps the mazda miata, being the least expensive in what they are testing. I love the simplicity of the interior, perhaps a bit cheap when you look at it, but it works. Ergonomics I have a few gripes that don't make sense (the drivers side window controls mainly), and those crap plastic wheelwell liners, but overall, for the price, the car is fantastic. As people have mentioned before, it's really too bad these reviewers never picked up a GMPP-Tune equipped one, or even that plus the zok or DDM handling upgrades.....

Your torque comment now makes me wonder.....these larger aftermarket turbos are supposed to be slower spooling up aren't they? You talk about stock torque curve, but I'm sure you are a little higher up in the curve now with your setup? What's your response like now right off the line and for the first couple thousand RPM, because it will be slower once you do this? The tradeoff will be that you will be more dominant mid to top RPM.
 

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I ran a 3.42 rear end in my Buick. It was hands down the best all around driving set up that I ever had in any car. The perfect mix of launching torque, but yet comfortable revs at highway speeds.
 

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I ran a 3.42 rear end in my Buick. It was hands down the best all around driving set up that I ever had in any car. The perfect mix of launching torque, but yet comfortable revs at highway speeds.
yea but GS, what Buick? What year, weight, motor, tranny? It was a match for YOUR application.

Speaking of which WillF, I also note that your tires are a 275/30/20, how does that compare to stockers height-wise? I'll have to go put them into an online calculator. It should have added weight, but again with your added power that should not bother you.
 

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Agreed on the application comment. However, I made said comment assuming similar torque to weight vehicles. Of which I have driven many. Believe me, I have been all over the spectrum with this: from lanky highway geared to nut busting 1/4 mile cars that would almost blow up from the revs at the end. :lol:

The reason for my comment was because power to rate ratio was very similar:

Buick 4000 lbs at 510 pounds of torque. = 7.8
(Keep in mind that these are sea level numbers, and the N/A big block takes a big hit on power at altitude, so the true power to rate ratio was actually worse than the Sky at my altitude)

Sky 2900 lbs at 340 pounds of torque (GMPP tune). = 8.5

And gearing ratios for the Sky Redline are actually lower:

Buick (M22W):
1st-2.559, 2nd-1.752, 3rd-1.366, 4th-1.0

Sky: (Asian MM5-taller 3rd for Turbo Car)
1st-3.416 2nd-1.950 3rd-1.510 4th-0.971

In fact this is the main reason that I actually loved the Sky Redline the first time I drove it: It was one of the very few cars that delivered the same (actually better usable) torque as my GS.

In my opinion: A non-tuned Sky performs pretty darn well as designed. However, a tuned Sky runs out of 1st gear so fricken quick that it is a little silly. So I feel taking that rear end down to 3.42, from 3.73 may be a good move. And the change isn't that much anyway. Of course you do need to take my comments in context. I have been known to take a 2.73 highway geared car all the way down to 4.11.
(again, it was a torque monster; so I could get away with it :lol:)
 
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