Changing from 2.76 to 2.94 gear help city MPG?

[YY1]

My Satellite has a 7 1/4 2.76 rear.

I have a super clean 2.94 742 SG setup from a trailer package car.

I was planning to swap a 3.73 R&P into it and use it in my 66, but...

I also have an E body 8 3/4 housing, and now I'm thinking about putting those two together and putting it in my Satellite.

I LOVE limited slip, and I'm sure the slight step up in ratio will help "seat of the pants" performance, but...

Do you think I'll see any "city driving" MPG improvement? (especially without hurting HWY MPG)

On the highway it seems pretty effortless to "wind out", so to speak.

- - - Updated - - -

...and I might add that all of my previous "20 MPG" average 318 cars were 66/67 Coronets, presumably with 2.94 rears.

My 73 sat is getting 14.5, and I've done pretty much all I can do tuning wise.

Not that I'm all about MPG, but I like to have a nice balance of added power and useable torque with decent mileage in a street car.

 

[RustyRatRod]

I honestly don't think you'll see much difference. That's not much of a change. Nothin wrong with tryin to improve mileage a little. I usually say somethin stupid like "go buy a Toyota" but gas approachin 4 bucks a gallon, that ain't funny anymore.

 

[WP29440SE]

i have a 291 gear in my duster and honestly i cant tell the difference between that and a 276. its really not enough of a jump in my opinion.

 

[RustyRatRod]

Yam some 4.86s back there. You'll know sumffin's up then.

 

[Meep-Meep]

That's only about a 6% change and I'll agree you won't get much out of that swap for your labor. Now if you find the A999 tranny that has the 2.77:1 first gear, that is a 13% change and you are likely to feel that. Put that with the 2.94 and you may have a hole shot monster! Also a tighter converter may help too.

 

[YY1]

2.77 you say...Hmmmm (clenches and rubs hands together, while slightly drooling).


But then 2.94 to 3.23 is "not that much" and neither is 3.23 to 3.55.......

 

[kb67mopar]

That's only about a 6% change and I'll agree you won't get much out of that swap for your labor. Now if you find the A999 tranny that has the 2.77:1 first gear, that is a 13% change and you are likely to feel that. Put that with the 2.94 and you may have a hole shot monster! Also a tighter converter may help too.

Hmm wonder how my 4.02 first gear will be then...

 

[Meep-Meep]

Hmm wonder how my 4.02 first gear will be then...

Probably climb a tree.

- - - Updated - - -

2.77 you say...Hmmmm (clenches and rubs hands together, while slightly drooling).


But then 2.94 to 3.23 is "not that much" and neither is 3.23 to 3.55.......

3.23 - 3.55 - 3.91 - 4.30 are all about a 10% difference. 2.77's and 2.94 will be about 22% lower than 2.45 and 2.71. But that's only in first. A wide gear spread like that would probably like a nice wide torque band.

 

[RustyRatRod]

Get a 200R4 and 4.30s. Best of all three worlds. Come outta hole like a mofo, cruise like a mofo and you don't have to hack up the mofokin flo to get the transmission in.

 

[YY1]

Probably climb a tree.

- - - Updated - - -




3.23 - 3.55 - 3.91 - 4.30 are all about a 10% difference. 2.77's and 2.94 will be about 22% lower than 2.45 and 2.71. But that's only in first. A wide gear spread like that would probably like a nice wide torque band.

OK, 2.76-2.94-3.23-3.55 and 3.91-4.10, I agree with, but 3.55-3.91 is not.

Those pesky 3.77's are missing.

Thanks for everone's input.

Guess I'll just try it.

 

[wedgie]

Meep meep is right on. Best of both worlds. Think about it. Good outta the hole and low cruising RPM. No cutting floor pans either. There'a also low gear sets available that will fit the 904 and 727 transmissions.

 

[YY1]

Here's meeps post from a different thread, and my reply ---

Originally Posted by Meep-Meep
I'm running around with 4.30's in my 66 440 powered Belvedere and it could care less. And on the freeway I make no effort to go 60! Around here it's keep up with traffic at 70+ or get run over, so needless to say my tach is well into the 4K RPM range. I don't drive it much and not on long trips, but a half hour ride is no big deal. For a car that you want to spend some time in I'd recommend no lower than 3.23 for the long trips. I'm setting my 69 RR up with a 3.70 Dana, and with the Passon OD gear set, I will end up with something like 2.96 final. If you spend nearly half your time at the track then 3.55 or lower depending on your engine power band.
/end meep

I like that answer.

I don't want to be in the slow lane doing 60 in a car that looks like it should be doing 100.

(but I don't want v6 mustangs beating me off the line, either)

I think the 3.7x with o/d 2.9x final is probably the ultmate compromise.

Is that Passon 5 speed on the market, yet?

 

[Meep-Meep]

Get a 200R4 and 4.30s. Best of all three worlds. Come outta hole like a mofo, cruise like a mofo and you don't have to hack up the mofokin flo to get the transmission in.

No ****? Hmmmmmmm....... I have another car that may benefit from this. I think by now one can build a 200R4 to hold up to something more than an anemic V6.

- - - Updated - - -

OK, 2.76-2.94-3.23-3.55 and 3.91-4.10, I agree with, but 3.55-3.91 is not.

Those pesky 3.77's are missing.

Thanks for everone's input.


Guess I'll just try it.

I'm no math genius, and could very well be missing something, but if I take and add 10% to 3.55 I get 3.905. Adding 5% to 3.55 = 3.7275. I went from 4.30 to 4.10 in my Bel and it made an ever so slight difference on the top end but not as much as I would have guessed because the difference going down was only 4.5%.

 

[RustyRatRod]

The 200s are already strong enough to hold up behind a stock to mild 440. They are beefier in every way than the 700s the chebbie boys get hard ons for. Remember, Buick chose the 200 OVER the 700 for the Grand National and GNX cars, WHILE the 700 was also being made. They are beefier and have a much closer set of ratios than the 700. And yes, upgrades can be made to them to make them stand up to pretty much anything.

 

[Cranky]

that's only about a 6% change and i'll agree you won't get much out of that swap for your labor. Now if you find the a999 tranny that has the 2.77:1 first gear, that is a 13% change and you are likely to feel that. Put that with the 2.94 and you may have a hole shot monster! Also a tighter converter may help too.

6.5% :icon_winkle:

 

[Dennis H]

Passon 5 speed is missing in action.