This RPM right for 2.73's???
Thread Starter
Teching In
Joined: Jun 2006
Posts: 33
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This RPM right for 2.73's??? I have axle code GU2 in the glovebox, which equates to 2.73 gears in the rear. Previous owner said they were never changed. Car turns about 2400 rpm at 70mph in OD, and about 2800 rpm at 80mph in OD. From other cars Ive had, this seems a bit high for 2.73 gears. What do you guys with 2.73s turn at 70 and 80? Any input appreciated TIA
that is way too high. are you sure its shifting into overdrive? for some reference, at 70 mph i am at 2100 rpm with 3.23 and 23 inch diameter tires (smaller than f body tires). your running just a little bit under what i run if i drop it into 3rd
TECH Senior Member
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Joined: Oct 2006
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From: Decatur, TN (N-W of Athens)
I don't know about anyone else, but in OD my 3.23s run around 2K @ 70... And I know the 700R4 has the same gearing as the 4L60E since it's the same damn thing (save being electronic).
But yes, that sounds like you're in D (3rd on our console).
But yes, that sounds like you're in D (3rd on our console).
Just another oppinion....my car ran 2000 rpm @80 mph. with the 2.73's. Now I have 3.42's and I've been messing with tuner cats to tune my car b/c I have been bouncing off the rev limiter between shifts and last week with 3.42's at 80 I was at 2700 rpm did some adjustments and now at 3000 at 75 ????? so I need to do some adjusting on mine, but just my .02 I'd take the rear diff. cover off and count the gears on the ring and pinnion and divide the big # by the smaller one to find out for sure. Alot of times I've heard people getting the 3.23 rearends and putting them in their cars so that they have the series 3 carrier...maybe someone had plans to change the gears and wanted the series 3 carrier??? Good luck man!
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Teching In
Joined: Apr 2007
Posts: 1
Likes: 0
From: NEW YORK
I got a 96 Camaro SS which is supposed to have stock 3.23 Gears in it with the 4L60E A4. I don't know for sure what gears it has in it now but its at 2K when I'm crusin at 59MPH. I'm thinkin whoever had the car before me must have changed the gears because it seems to rev pretty high for 3.23's... Do you guys agree with me? What do you think I have in it? 3.73's???
Originally Posted by nomoneyz
That sounds about where mine is at. My sisters z has 3.23s and at 80 is almost 3000
the only thing that would really make it be that far off is if it wasnt shifting into OD. the converter not locking is only a couple hundred rpms at most, and if the tranny was slipping that bad at cruising throttle, you wouldnt make it for 1 mile before it was gone
Just to add to my post the other day I finally got my tuning issues straightened out today. It seems that when switching to bigger gears other than factory specs(2.73/3.23 for auto) you have to take the old rearend gear size and divide it by the new gear size and use the # which is .xxxx??? and add it to the tables in your pcm. There is alot of math involved but my friend got it straightened out now. And now @ 82 mph I'm at 2500 rpm instead of 70 ish at 3000 rpm. And now my converter is locking up again, we had it disabled somehow by messing with other stuff in the pcm. but anyways I'm happy about that so just wanted to share that with you guys. I tell you 1 thing, I never thought it would've been such a PITA to tune it with Tunercats.
Originally Posted by LT1Formula007
Just to add to my post the other day I finally got my tuning issues straightened out today. It seems that when switching to bigger gears other than factory specs(2.73/3.23 for auto) you have to take the old rearend gear size and divide it by the new gear size and use the # which is .xxxx??? and add it to the tables in your pcm. There is alot of math involved but my friend got it straightened out now. And now @ 82 mph I'm at 2500 rpm instead of 70 ish at 3000 rpm. And now my converter is locking up again, we had it disabled somehow by messing with other stuff in the pcm. but anyways I'm happy about that so just wanted to share that with you guys. I tell you 1 thing, I never thought it would've been such a PITA to tune it with Tunercats.
