Author Topic: Changing final drive ratio (Read 26029 times)

snaponbob · « **on:** August 22, 2011, 12:31:53 PM »

Taking the lazy route, I'll ask before I search. Anybody know of a lower (numerical) ration that can be swapped into the LNF's diff? Cadillac, for instance.

DrJones · « **Reply #1 on:** August 22, 2011, 01:24:31 PM »

Quote from: snaponbob on August 22, 2011, 12:31:53 PM

Taking the lazy route, I'll ask before I search. Anybody know of a lower (numerical) ration that can be swapped into the LNF's diff? Cadillac, for instance.

A fraternity brother of mine works for Getrag at the facility that makes it.

I asked this question a couple years ago and the answer is... No.

All the other gear ratios are higher than the 3.73s in the GXP.

Anyways, "we" can't change the gear ratio in BSP because the GXP/RL never came with any other ratio.

Gentleman Jack · « **Reply #2 on:** August 22, 2011, 01:52:08 PM »

What about changing tire size?

snaponbob · « **Reply #3 on:** August 22, 2011, 01:55:16 PM »

Quote from: DrJones on August 22, 2011, 01:24:31 PM

A fraternity brother of mine works for Getrag at the facility that makes it.

I asked this question a couple years ago and the answer is... No.

All the other gear ratios are higher than the 3.73s in the GXP.

Anyways, "we" can't change the gear ratio in BSP because the GXP/RL never came with any other ratio.

AH !!!!! But you assume BSP, grasshopper !!!!!!!!!!!!! Was looking at the 3.42 ring and pinion from the Cadillac Getrag diff. You know, the one that had leaks, grinds, and seizures ................. just like the Kappa diffs !!!

Hey, you got your car down 2650 yet? I installed a new exhaust made from anti-grav unobtainium. Took a long time to get it because UPS had a hard time handling it. Seems to have about -300 pounds on the scales.

Gotta get a looser helmet.

Now, back to our regularly scheduled electro shock therapy.

snaponbob · « **Reply #4 on:** August 22, 2011, 01:56:01 PM »

Quote from: Gentleman Jack on August 22, 2011, 01:52:08 PM

What about changing tire size?

Ummmmm ............... no. Not an option.

Arabas · « **Reply #5 on:** August 23, 2011, 02:36:55 AM »

SOB do u want higher max speed? i thought that in auto-x you would need quicker accelerations and that u would be looking for a 4.00 diff..

kennysabarese · « **Reply #6 on:** August 23, 2011, 06:39:31 AM »

Kelu and I were looking into 4 and 4.11 diffs a while ago. The Camaro guys who get them say it brings the car to life. I am not sure if they will work on our cars, but since the Camaro is similar to the CTS I thought they would work.

Arabas · « **Reply #7 on:** August 23, 2011, 06:45:41 AM »

kenny, the non-GXP diff (the entire carrier) - 3.91- is a plug and play. just have the one with the torque arm on it. u can find them used for about 350-400 $
i would have bought one to use, but shipping cost for these to Greece is just crazy!!

Dave@DDMworks · « **Reply #8 on:** August 23, 2011, 08:14:21 AM »

Quote from: Arabas on August 23, 2011, 02:36:55 AM

SOB do u want higher max speed? i thought that in auto-x you would need quicker accelerations and that u would be looking for a 4.00 diff..

I think he wants the taller gear to save a shift or two during the course.

We have never actually swapped the gears from the caddy 3.42 into the solstice carrier, but I have heard several times that the ring and pinion will swap over.

snaponbob · « **Reply #9 on:** August 23, 2011, 08:27:47 AM »

Quote from: Dave@DDMworks on August 23, 2011, 08:14:21 AM

I think he wants the taller gear to save a shift or two during the course.

We have never actually swapped the gears from the caddy 3.42 into the solstice carrier, but I have heard several times that the ring and pinion will swap over.

Yup, looking for a longer second gear. Currently, power is the least of my worries. As Alex will attest, once properly tuned traction can be an issue which means that power is abundant. I may switch class next year which would allow a turbo mod or change, and since 7000 rpm comes up in a huge hurry now I am looking at a longer second gear to avoid shifting as it consumes time up and down and gets busy when one left foot brakes.

Dave, do you know where/how I might confirm this?

Dave@DDMworks · « **Reply #10 on:** August 23, 2011, 08:41:38 AM »

Quote from: snaponbob on August 23, 2011, 08:27:47 AM

Yup, looking for a longer second gear. Currently, power is the least of my worries. As Alex will attest, once properly tuned traction can be an issue which means that power is abundant. I may switch class next year which would allow a turbo mod or change, and since 7000 rpm comes up in a huge hurry now I am looking at a longer second gear to avoid shifting as it consumes time up and down and gets busy when one left foot brakes.

Dave, do you know where/how I might confirm this?

Unfortunately I do not know anyone that has actually done it. I know you can get the CTS 3.42 differentials from Schram for around $200 shipped though, so if it does not work out, you are not out that much.

snaponbob · « **Reply #11 on:** August 23, 2011, 08:43:41 AM »

Schram? Hoo dat?

DaveOC · « **Reply #12 on:** August 23, 2011, 10:04:51 AM »

Quote from: snaponbob on August 23, 2011, 08:43:41 AM

Schram? Hoo dat?

Schram is an auto parts recycler. GM uses them to recycle pre-production mules and other test vehicles. They are a very reputable company.
http://www.schramauto.com/

Critterman · « **Reply #13 on:** August 23, 2011, 10:35:57 AM »

Talk to Wade at Wade's Garage in WV. He puts that rear (3.42) in his Solbras.

snaponbob · « **Reply #14 on:** August 23, 2011, 11:37:19 AM »

Quote from: Critterman on August 23, 2011, 10:35:57 AM

Talk to Wade at Wade's Garage in WV. He puts that rear (3.42) in his Solbras.

COOLNESS !!!!!!!!!!!!! Will do it.

DrJones · « **Reply #15 on:** August 23, 2011, 01:04:57 PM »

Quote from: snaponbob on August 23, 2011, 08:27:47 AM

Yup, looking for a longer second gear. Currently, power is the least of my worries. As Alex will attest, once properly tuned traction can be an issue which means that power is abundant. I may switch class next year which would allow a turbo mod or change, and since 7000 rpm comes up in a huge hurry now I am looking at a longer second gear to avoid shifting as it consumes time up and down and gets busy when one left foot brakes.

Dave, do you know where/how I might confirm this?

So are you looking at FP or SSM?
I am *building for FP

*a spread sheet of what i would do and lots of calculations.
I've secretly wanted to build an F-Prepared car since I've owned the GXP.

snaponbob · « **Reply #16 on:** August 23, 2011, 03:50:06 PM »

Quote from: DrJones on August 23, 2011, 01:04:57 PM

So are you looking at FP or SSM?
I am *building for FP

*a spread sheet of what i would do and lots of calculations.
I've secretly wanted to build an F-Prepared car since I've owned the GXP.

Might go SSM. Isn't FP not very turbo friendly?

cdnite · « **Reply #17 on:** August 23, 2011, 09:29:41 PM »

Quote from: DrJones on August 22, 2011, 01:24:31 PM

A fraternity brother of mine works for Getrag at the facility that makes it.

I asked this question a couple years ago and the answer is... No.

All the other gear ratios are higher than the 3.73s in the GXP.

Anyways, "we" can't change the gear ratio in BSP because the GXP/RL never came with any other ratio.

You have been lied to, by your friend...

Just saying...

Straight from Getrag the spec on the Gretrag 645 Differential.
http://getrag.de/en/259

--Christian

numbbers · « **Reply #18 on:** August 23, 2011, 10:37:44 PM »

I have the 3:42 gears from the STS-V in the Mallett. It is just a bolt in. Same basic housing.

snaponbob · « **Reply #19 on:** August 23, 2011, 10:40:20 PM »

Quote from: numbbers on August 23, 2011, 10:37:44 PM

I have the 3:42 gears from the STS-V in the Mallett. It is just a bolt in. Same basic housing.

So it seems. Thanks. Alex ----- you getting this ???? Could help in FP, especially with less weight.

DrJones · « **Reply #20 on:** August 24, 2011, 01:22:03 PM »

Quote from: cdnite on August 23, 2011, 09:29:41 PM

You have been lied to, by your friend...

Just saying...

Straight from Getrag the spec on the Gretrag 645 Differential.
http://getrag.de/en/259

--Christian

I'm sure I was lied to by my friend. Not like he was one of my fraternity brothers for 4 years or anything. He's probably an ass-hole, you know what they're like... "Just saying'"

Eitherway, the info I got was from when I asked him about it a few years ago. Just emailed to ask him if there was any updates and he sent this.

"I.D. of ring is common for all 645 project. Therefore diff should fit all sub products(v, sts, cts) . Ratios available...273,323,342,373,391"

Hope this helps...

Critterman · « **Reply #21 on:** August 24, 2011, 01:28:28 PM »

273's good for what 30 to 90 or so and 45mpg cruising

So now tha your asshole fraternity brother has quit telling you unthruths, which one you going with. 273 might be a bit much for low end grunt.

DrJones · « **Reply #22 on:** August 24, 2011, 01:32:28 PM »

Quote from: Critterman on August 24, 2011, 01:28:28 PM

273's good for what 30 to 90 or so and 45mpg cruising

So now tha your asshole fraternity brother has quit telling you unthruths, which one you going with. 273 might be a bit much for low end grunt.

yeah, 2.73's might be a bit too low

snaponbob · « **Reply #23 on:** August 24, 2011, 02:38:23 PM »

Quote from: DrJones on August 24, 2011, 01:32:28 PM

yeah, 2.73's might be a bit too low

Come on Alex, think outside of the box. Bonneville. No .......... not another Pontiac.

Oh, chose your friends better.

DeepBlueGXP · « **Reply #24 on:** August 24, 2011, 03:47:58 PM »

Which one is best for gas mileage and which is best for drag racing?

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Author Topic: Changing final drive ratio (Read 26029 times)