Rear Axle Gear Ratio Question
I have a 1989 automatic with GM1 (2.59) rear axle gear ratio.
What can i change this to? 3.54? is that the highest for the automatic? What is the G92 "Rear axle performance ratio"? Below are the codes that I pulled from another thread..... G44 Rear axle 3,07 ratio G92 Rear axle performance ratio GH0 Rear axle 3,54 ratio GM1 Rear axle 2,59 ratio GM3 Rear axle 3,45 ratio GT7 Rear axle 3,33 ratio GU2 Rear axle 2,73 ratio GW4 Rear axle 3,31 ratio HE3 Rear axle 3,07 ratio Any ideas on cost - both do it yourself and from a shop? |
ratios
As far as I know.....you can change to a 2.73 or a 3.07 by changing the diff itself.....because you have a 2.59 in yours the gear carrier itself limits your selection in aftermarket ratios ,there may be a 3.4X or 3.5X available and I know that there is a 3.75 that will fit your carrier......some other ratios require that you start with a 3.07 carrier :cheers:
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I have a 2.59 and it sucks compared to the 3.07 I had in another vette , so now I just bought 3.75 to put in, but I am doing my intake. and probably heads, and cam later! good luck!
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3.07 is optimum for TPI unless you a doing engine mods to gain more revs=intake / heads / cam
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Originally Posted by rodj
(Post 1567295601)
3.07 is optimum for TPI unless you a doing engine mods to gain more revs=intake / heads / cam
-Beppe- |
I recently took out the 2.59 and rplaced it with a 3.07. It makes a huge difference. I race at a 1/8th mile track and it took 1/2 second off my times. Went from low 9's to mid 8 seconds. I paid about $300 for the complete chunk and it took about 5 hours to swap it out.
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3.07 is as much as you want in an L98. However the difference might not be worth the expense.
For now I'd go with a higher stall TC, and after driving that for six months decide if you want to go in and change the gearing. C409: With GM parts, the 2-series (2.59/2.73) case is different from the 3-series case, so you'd have to change that, IF you were using GM parts. However, many companies make the lower gear ratios (3.54s, 3.73s...) with proper ring gears for the 2-series case. |
Originally Posted by pologreen1
(Post 1567293878)
I have a 2.59 and it sucks compared to the 3.07 I had in another vette , so now I just bought 3.75 to put in, but I am doing my intake. and probably heads, and cam later! good luck!
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:iagree:
Originally Posted by conv90
(Post 1567297022)
:iagree:
-Beppe- |
Originally Posted by myturn89
(Post 1567292859)
I have a 1989 automatic with GM1 (2.59) rear axle gear ratio.
What can i change this to? 3.54? is that the highest for the automatic? What is the G92 "Rear axle performance ratio"? Below are the codes that I pulled from another thread..... G44 Rear axle 3,07 ratio G92 Rear axle performance ratio GH0 Rear axle 3,54 ratio GM1 Rear axle 2,59 ratio GM3 Rear axle 3,45 ratio GT7 Rear axle 3,33 ratio GU2 Rear axle 2,73 ratio GW4 Rear axle 3,31 ratio HE3 Rear axle 3,07 ratio Any ideas on cost - both do it yourself and from a shop? |
I can get a 3.75 ratio but what else do I need to do immediately? Do i need to do anything to the ecm, will shifting get all whacked? I understand that it will not be "optimum" at first but other mods are going to be down the road. since i am changing i was thinking of just doing the full upgrade while i am in there......any thoughts ideas??
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Originally Posted by Kool88vette
(Post 1567298878)
:iagree:
I switched my 2.73 to a 3.07. 2.59s are great for highway gas mileage but they suck around town. i also got a Vigilante TC. thanks |
Originally Posted by myturn89
(Post 1567303174)
what else do I need to do immediately? Do i need to do anything to the ecm, will shifting get all whacked?
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Originally Posted by UNCLEBILL
(Post 1567303768)
Quick question...did you find a noticable difference going from 2.73 to 3.07? I have a 1990 Vert with the 2.73 and have been contemplating a gear swap but not too severe....Im curious about the 3.07's ..need your imput.
thanks I guess the 2.73s and OD are good for mileage while crusing at speeds above 70 mph. I hardly used OD with the 2.73s because the freeways here are too congested and it's always stop and go traffic. At 65 mph in OD the engine would lug up hills. I think I probably lost some freeway mileage but I really haven't noticed anything. I'm glad I did the swap. I picked up a used 3.07 pumpkin in the C4 parts for sale/wanted section and I had it rebuild before I installed it. I had to change my speedo gear. That part was about $11.00 and takes 10 minutes to change. |
I would DEFINATLY stick with the stock stall converter if it's going to be a driver for you.
If you're "ALL ABOUT THE STRIP" then different story... Problem is that you'll "always" be under the lock up for normal driving... P.S. I have the 3.07's and they work very well !!! :D |
Originally Posted by Kool88vette
(Post 1567306843)
I noticed a major improvement in acceleration around town. I have to be careful now or I'll spin the wheels real easy. That's the way I like it.
I guess the 2.73s and OD are good for mileage while crusing at speeds above 70 mph. I hardly used OD with the 2.73s because the freeways here are too congested and it's always stop and go traffic. At 65 mph in OD the engine would lug up hills. I think I probably lost some freeway mileage but I really haven't noticed anything. I'm glad I did the swap. I picked up a used 3.07 pumpkin in the C4 parts for sale/wanted section and I had it rebuild before I installed it. I had to change my speedo gear. That part was about $11.00 and takes 10 minutes to change. |
Originally Posted by Kool88vette
(Post 1567306843)
I noticed a major improvement in acceleration around town. I have to be careful now or I'll spin the wheels real easy. That's the way I like it
I'd imagine the 2.59s are a real dog in LT1 cars, but truthfully they're really not that bad in a L98. I noticed a much bigger improvement in my car (91 A4) when changing to a 2500 stall converter than I did when I changed to a 3.07. |
i am thinking of just going to a 3.54 upgrade - i am getting conflicting responses? I have an 89 automatic convertible, is this a total waste of time or will i know a substantial improvement in performance off the line?
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Originally Posted by myturn89
(Post 1567356893)
i am thinking of just going to a 3.54 upgrade - i am getting conflicting responses? I have an 89 automatic convertible, is this a total waste of time or will i know a substantial improvement in performance off the line?
P.S. If I had stick I would get 4.11's but thats me and I can be excessive! |
Originally Posted by myturn89
(Post 1567356893)
i am thinking of just going to a 3.54 upgrade - i am getting conflicting responses? I have an 89 automatic convertible, is this a total waste of time or will i know a substantial improvement in performance off the line?
I've had a 2.59, a 3.07 and a 3.33 in my car and I regret going to the 3.33. The 3.07 was the best all around performer, at least in terms of 1/4 mile. |
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