I'm replacing my wrecked Cobra with a very similar one, only it as 4:10 gears rather than 3:73 (in my old Cobra that is now a parts car).

I drive the car to work most of the time and although gas milage is not my primary concern, I'm purchasing my 2nd modified Cobra afterall, I'm curious how much different it actually is.

Any thoughts?

I'm thinking of swapping the rears when my new car makes it down here. I'll be selling the extra set of gears and I'd like to make this decision soon. Long story, but one of the rears will be going back to stock 3:23 and into my Dodge Dart.

 

I would think the difference between 3.73s and 4.10 would be negligible. 3.55 to 4.10 would be noticeable.

You're going to put an 8.8 ina Dart? What year?

 

about 200rpm cruising speed difference, gas mileage would only me one fraction of a mpg.

 

I have a '67 Dart GT with a 273 V8 and a dying 7-1/4 rear. The cars are the same width and some guys in my car club have done this sort of swap before and found it relatively easy. I was looking at a mopar 8-3/4 for it, but they're hard to come by.

I think I'll drive a few tanks with the 4:10s and see. My recently wrecked Cobra was getting a little over 17 MPG with the 3:73s with nice "normal" driving to and from work. The Cobra I'm buying has a similar set-up but 4:10s. I'll be sure to report! My old Cobra's best dyno was 529.8 at the wheels at 80*. I'll be getting a dyno on the new one ASAP.

 

i get great mpg with 4.10's in my 96. On road trips i get in the 25.7mpg range. although i wasnt pushing 500rwhp. I would say as long as you arent getting into boost very much with the 4.10's while cruising. If you are, i'd probably go back to the 3.73's.

 

I think I'm heading back to the 3:73s.

My agerage MPG for daily driving was 17.5, now it's 15.8. I really think the 4:10s are too much gear for just the S/C and eventually the TB when I get around to installing that. If I were dragging it all the time, it'd probably be worth it. I'd probably want smaller gears, but it's just my fun car that I also drive for work and errands.

I ditched my boost guage (my brother has already given me plenty of crap for this), but I did note before I took it out that I really don't get into boost in regular driving. Only when I'm having fun.