I have a stock 2.73 set of gears in my diff and I would like to change to something with a bit more pull. I use my car as a daily driver and still would like to get decent fuel economy. I would like to know what RPMS you guys are seeing with both of these gear ratios at 65 MPH lets say. I turn about 1200 RPMs at 65.

 

I would definitely say go w/ 3.73. I turn I think around 2200 at 65, I am not exactly sure, I will check later if someone on here doesn't already know for sure. You want see that much of fuel change but you will have a big gain going from 2.73 to 3.73. I went from 3.23 to 3.73 and holy crap I loved it.

 

2:73 to 3:73 is like a night and day difference. you'll love every minute of it

 

3.73's hands down!

I did the switch from 2.73's to 3.73's. and let me tell you, it makes the feel like a muscle car should feel. they are very streetable as long as your not a chump about getting great gas milage. The 3.73's make the car respond so much better.

Dont forget to have the pcm reprogrammed for the gears asap.

Mike

 

To check RPM with different gears see www.f-body.org/gears/

 

Thank you that was exactly what I was looking for.

 

Well I have 3.73's sittin next to me waiting to be installed right now as I type this, so my pick is 3.73's.

 

I put 3.73's in my car last year (they whined, I whined, 2.73's are back in.................long story ) but ANYWAY.....

.....my fuel mileage hardly suffered at all. I normally average around ~350 kms per tank (~220 miles) but can get as high as ~450 kms (~280 miles) and even 500 kms (although, that only happened once). Even with the 3.73's, I was still getting between 350 - 400 kms, and I didn't change my driving habits at all (still did some highway cruises, and my car is a daily-driver).

On the highway, to do 75 - 80 mph, the RPM's were a little high (between 2700 - 3000 RPM). Off the line grunt was absolutely neck snapping though! Even with the stock stall converter. I ran at the track and pulled the exact same time as in my sig though, because I lost a ton of traction. DR's or E/T Streets definitely would have helped out there.

My complaint with the gears (besides the fact that they were screwed from day 1 and whined like an ambulance siren ) was that they put the transmission downshift points in really wierd places, and from pretty much any speed, the transmission would only ever drop 1 gear. I didn't like that, and I actually prefer my 2.73's for where the downshifts occur, and for the fact that the tranny can drop 2 or even 3 gears depending on the speed!

For a daily driver, I might actually recommend 3.42's. My friend put them in his '96 T/A and is really happy with them. Good luck with whatever you decide.

 

I plan on going to 3.73's in my '93 Formula but no one can seem to tell me what speedometer gear I need to install to make my speedometer read correctly. I would think SOMEONE on this board has done a 2.73 to 3.73 swap and figured out what part number the speedo gear is. Any help here would be appreciated, SLP no longer stocks gears OR the calibration box

 

The 93's still use a gear drive type speedo cable?? I thought that all the 4L60E's used an electronic signal to the computer, thus no more "gears" for re-calibrating the speedometer? Maybe 93's were different though?

Well, I know when I had my '81 Z28 and I changed the gears in the diff, I had to change the gears in the tranny to re-cal the speedo. It was something like a 37 tooth gear upto a 44 tooth (don't quote me, just saying for example). Anyway, 3.73's are 36.6% more gear than 2.73's are, so let's say "hypothetically" that the speedo drive gear has 37 teeth, then to slow your speedometer back down, you need the final speedo drive to be 36.6% slower. You might need something like a 44 tooth driven gear (giving you 18% slower) and a drive gear with 24 teeth instead of 30 (for an additional 18% slower).

**I am making these numbers up**...........BUT, I know that I went into the GM dealership at the time, and one of the guys spent a few minutes with me figuring out the gear ratio I had, the speedo gears that I had, and what combination of speedo drive gears I'd need to compensate for the change I did with the rear gears.

I hope I haven't confused you on this, but it's what you might have to do if your transmission doesn't use an electronic signal for the speedometer.

 

Yeah, 93's still have the 700R4 trans with gears. It almost makes me hate getting a 93 model. I'll keep looking, SOMEONE here has to have done the research already.

 

I just put 3.42's in my car, and like Capn Pete said, My tranny will still DOWN shift into 2nd from 60mph. You still get that nice kick and go.....I dont think 3.73's will go to 2nd from that speed. My 3.42 were a nice compromise between 3.23 and 3.73, not to much rpm at freeway speeds and still a nice improvement over my 3.23's from a roll.

 

Is there a way to reset the detent cable and get your shift points back I thought on the 700R4 it was all about the RPMs as far as shifting went. On the trucks we would push a button on the bottom and reset the cable to WOT and it would basically be set.

 

anyone here has a 3.73 w/ a 2800 stall converter? How is your traction? Right now I have a 2800 stall and considering to purchase a 3.42 or 3.73 gear. I know I will lose traction no matter which gear I have but I don't want to lose to much. Right now I have 2 new 285 35 18 Michilen Sport tire rear and 255 18 35 in the front...

 

With stock Cam.. I'd goto a set of 3.42's instead of 3.73's.