4:11 positraction

[Wally A.]

Looking for someone to change out my 4:11 posi. to a 3:36 in central Florida, fuel is killing me.
anyone recommend a good person or shop in this area? thanks for your input... unit is out.

[Mark E.]

Re: 4:11 positraction

I haven't done business with them but C&S Corvette is a large shop in Sarasota. I enjoy their YouTube videos.

https://www.corvettepartscenter.com

[Bob J.]

Re: 4:11 positraction

Looking for someone to change out my 4:11 posi. to a 3:36 in central Florida, fuel is killing me.
anyone recommend a good person or shop in this area? thanks for your input... unit is out.

Advanced Driveline on Carder RD, Orlando has been doing them for 33 years.

[Wally A.]

Re: 4:11 positraction

thanks for your input, Bairs does great work, shipping will set you back.. sure one of these shops can handle what i need.
thanks again

[Thomas S.]

Re: 4:11 positraction

[Mark E.]

Re: 4:11 positraction

I don't have any data to answer the question. But why are you asking? How much do you spend per year on fuel romping around town in your Corvette? Probably rounding error compared to the other costs of this hobby. And how much would you save if you spent big money to change the rear axle ratio? A fraction of your annual fuel cost.

IMHO, if you "drive mostly local", enjoy the responsiveness of 4.11 gears. 4.11 only becomes annoying if you use it for road trips.

BTW, for comparison and grins, my 1993 6-speed travels almost exactly 100 mph at 2,000 rpm.

[Thomas S.]

Re: 4:11 positraction

Mark, it was not a question intended to 2nd guess the original post so I apologize if i came across that way. The combination of engine, trans and gearing and its affect on mileage was the question and this example was just a opportunity to use for someone with more knowledge and expertise to comment.

I use racing Sunoco fuel (ethanol - free) to compensate for hot start issues in the summer months. It's a know issue on some engines including FI motors. I was using 95 octane pump gas station prior to that. I don't keep track of MPG because I don't put that many miles on the car and it is only driven in late spring to early fall, no rain, no salt on the road (NJ).

I also have 4 other classics and a C8 all of which get driven in that short year period. So maybe 1,000 miles per year on the 63 and 2-3 fill-ups per year when I was using pump gas. I went through 40-gallons of racing fuel last year. These are rough numbers and and I would guess that my mileage is somewhere in the 15MPG range. Florida drivers can enjoy the car year-around plus temperatures are higher than up north so I can see why a lowering of the ratio could be desirable but perhaps in the end not really making much of a difference under certain driving conditions.

So, back to my question which was again intended to be answered by someone with deeper (than me) engineering/combustion engines background. My thinking was that in a non-highway situation, a numerically low rear ratio would require you to be in a lower trans gear to prevent lugging, and thus the actual engine RPM's might not be any different than the 4:11 in a higher trans gear.

In other words, changing the rear ratio may not give you the desire results and that was that was underlying question.

[Owen L.]

Re: 4:11 positraction

So, back to my question which was again intended to be answered by someone with deeper (than me) engineering/combustion engines background. My thinking was that in a non-highway situation, a numerically low rear ratio would require you to be in a lower trans gear to prevent lugging, and thus the actual engine RPM's might not be any different than the 4:11 in a higher trans gear.

[Mark E.]

Re: 4:11 positraction

You can do that with lots of torque.

Thomas has a good question- would he save gas with a higher rear end gear ratio while driving around town in his solid lifter small block? If this causes him to drive it in a lower gear to keep the engine speed about the same, probably not. But he certainly would not save enough gas to justify the cost of switching rear ends.