any body here ever use 4:10 gears with a 700R4 tranny?how does the car react to every day driving?is 4th gear low enough for highway cruizing?how much worse is MPG?

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1991 banditt2 firebird #130of#600

 

if highway and good mileage is your concern>>>>>>>>forget about it. Stay w/ the 3.73's if anything.

 

Also, you may never get a speedo drive/driven gear combo that will work with the 700R4. There are only 2 drive gears available for the 700R4 (15 tooth gray and 17 tooth red) and driven gears only come from 35 to 45.

With 4.10s you'd need either a 49 driven/15 drive gear combo or a 45 driven/14 drive gear combo. I am not aware of any driven gears larger than 45 or any drive gears less than 15 for the 700R4.

So you'd either have to install very large tires to compensate (which reduces your overall gear ratio and probably not fit) or live with a speed that is out by approximately 10% if you keep your tire size around 255/16/50s and use the 45 driven/15 drive gear combo (the closest you'd get for 4.10s).

 

There is also a 16 tooth drive gear, which doesn't help in this case anyway.

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1984 Camaro Z28 Astral Silver w/ 2 1/2" cowl induction hood
Engine: Decked 383 cid 4 bolt w/ oil cooler, 9.6:1 compression, ARP fasteners, 600 cfm Performer carburetor, Torker II intake, Performer RPM Heads, XE268H cam, Magnum roller tip rockers, MSD6AL ignition, Blaster2 coil, recurved HEI distributor
Exhaust: Terminator headers, Custom 3" TIG welded stainless exhaust, Twister muffler
Transmission: 4L60 w/ Corvette servo, .500 boost valve, TransGo 7-CS clutch springs, 700 PKH pump rings, 700-2 reprogramming kit, Borg-Warner High-Energy frictions & bands, 2400 RPM lockup torque converter
Drivetrain: 2.73:1 limited-slip Dana 44 w/ disc brakes
Tires: Front P225/50VR15 Rear P265/50VR15 Eagles

 

Here is a place that can help you with speedometer calibration when changing gears. http://www.speedometershop.com/ratio.html#TEST
Another shop is: http://www.specmo.com/
I know specmo deals with electronic correction as you would need for your year car.
You MUST re-calibrate after changing the gears due to the vehicle speed sensor(VSS)On my 86 Z-28 which doesn't have the electric speedo I'm having a ratio box made for the transmission to correct the speedo. As stated before, I needed to do this due to the(VSS). Any car using a VSS, especially the fully electronic controlled trans. cars(4L60E) need to have the speed being read by the VSS be acurate. Also, go to Richmondgear.com and use their calculators for ref. You'll see that in OD with 3.73's at 60MPH with a 26.1 diameter tire you'd be reving 2132RPM,(with an OD ratio of .74) still very highway driveable. Hope this helped.

 

If it is indeed for a 1991 car (or one with the eletronic speedo), there are electronic boxes (Cyberdyne) that allow you to splice into the wires from the VSS leading to the ECM and electronically compensate for the speed.

Supposedly easier to install.

 

Highway mileage difference between 3.73 and 4.11 gears won't be taht bad. You should change your PROM's spark curve to get more spark advance at highway RPM and MAP levels, though. This will drastically reduce the negative effect on mileage. You should really have to change your entire spark/fuel curves to maximize for geras like that.

I use 4.11's in almost every vehicle I have for myself or I build for someone. Yeah, regular cross-country trips are not gonna be easy with those gears but that's not why I build these cars/trucks. If you have 4.11 posi and some GOOD tires and a moderate chassis, you will be a happy camper and will be using your rear-view-mirror to see the guy you just beat. Just make sure your engine is efficient in the rpm range you plan to run the most.

 

Good point Fastbroker. You should have your PROM changed to reflect the different gearing. I am just boning up on PROM burning and I have noticed that many tables as you have mentioned that are affected by the speed of the engine, especially the locking of the TCC.

With the change to lower gears (higher numerically), you would want your TCC to lock at lower speeds than the stock calibration. While others (the turning off the electric fans with A/C) you may wish to remain the same or even stay on longer.

Since no thirdgen F-body had the electronic tranny 4L60E stock, that is not an issue, other than factors dealing with the TCC.