what's the best gear ratio for interstate driving

[gymratt30]

After logging 4500 miles on our route 66 trip, I've come to realize the 3:54 gears in our Superbird turns alot more RPM than I'd like.
what's the best ratio 2:91 or 3:23. ( not worried if the car won't launch .....just want better hwy speeds without the RPMs.

[Ghoste]

3:23 will be easier to find and might be best compromise so you still have some around town but obviously the other one will be better on the highway and the 440 certainly has the torque to carry it.

[hemi68charger]

GearVendor with 3.23 !!!!     Varrooomm, Varrooomm..............

[Aero426]

2.76 is nice on the highway with 15" wheels.    With my automatic, I can run it in 2nd around town.    

I had 3.23 in for a while.  I still preferred the 2.76 on the interstate for distance driving. 

[gymratt30]

GearVendor with 3.23 !!!!     Varrooomm, Varrooomm..............

Tell me more Troy....
Also PM me about the cost if you don't mind

[gymratt30]

So far the 276 or 291 seem to be what I'm looking for

[62 Max]

So far the 276 or 291 seem to be what I'm looking for

Unless your car is a 4 spd with Dana,then you're limited to ratio.

[Mike DC]

        
You have to get way down into 2.76 territory before it gets tall like modern overdriven cars.  

An automatic puts a limit on tall you can get because the torque converter will be slipping too badly below a certain cruising engine RPM.  


I would probably shoot for 2.94s in your shoes.  3.23 is workable but it still feels low compared to modern vehicles.

[billssuperbird]

4speed 354 gears in mine. 

[ODZKing]

Depends somewhat on the engine as well.
In my 67 - 383 I have 2.94's.  At about 65 it is around 2200 RPM, give or take. I get about 18 MPG with that.
My 73 - 400 has 2.71's and it is about 2500 RPM at 65, give or take.  Our Carlisle trip this year we saw 16 MPG with that.
Neither car I bought because I was looking for fuel economy or mileage.  But I have no interest in taking it to the track either, so these are fine with me.
2:76's or 2.91's will probably be the easiest to find and since many don't want them, very affordable as well.

[moparfan]

GearVendor with 3.55 when on drops it to 2.77 that's what I got and it works great.

[Mike DC]

  
One more thing worth mentioning on this topic - 3.54 is the tallest gear that fits in the Dana 60 case.  It really is a truck axle.  

[62 Max]

 
One more thing worth mentioning on this topic - 3.54 is the tallest gear that fits in the Dana 60 case.  It really is a truck axle.  

Incorrect, ratios 3.31:1 through 7.71 were available from Dana Spicer,carrier break is at 4.56 for the lower ratio.

[HPP]

I was doing some calculations once for using a Gearvendors. Very nice unit that is very strong and will cost a bit to get into service. They are going for around $3000 now days. By comparison, you can probably get a peg leg 2:91 unit out of the salvage yard for $100.

First column of the gear ratio is the original gear set. Next column is the over driven ratio using a 26" tall tire. As mentioned by Mike, ou torque convertor choice can impact whether these ratios will work for you.

gears/OD   2.76   2.21   2.94   2.32   3.23   2.55   3:54   2.79   3.73   2.94   3.91   3.08   4.11   3.24
26"                                          
speed                                          
55   2073   1660   2208   1742   2426   1915   2658   2095   2801   2208   2936   2313   3086   2433
65   2450   1961   2609   2059   2867   2263   3142   2476   3310   2609   3470   2734   3648   2876
75   2826   2263   3011   2376   3308   2611   3625   2857   3820   3011   4004   3154   4209   3318
85   3203   2565   3412   2693   3749   2959   4108   3238   4329   3412   4538   3575   4770   3760

[flyinlow]

I like my 3.55 with a 518 transmission. ( .69 OD , 28" tires) Gives you a 2.45 axle. 2100rpm at 70 mph.

A 2.76 is a good freeway gear.  Took lots of summer vacations when I was a kid in the Plymouth stationwagon with a 2.76 axle. I am sure we strained my parents patience with endless "are we there yets" but with that gear the 383 was not straining at 70 mph.

[69charger2002]

2.76 is a perfect highway gear. If you have $3000 to spend get a gear vendors overdrive and 3.55's. best of both worlds.

[Troy]

What size rear tires? I ran 2.76 rear gears in one of my Chargers (440 auto) and it was pretty great on the highway. Taking off was fairly weak with 28" tall rear tires. I have 3.23 rear gears (also 28" rear tires) in my Challenger but it has a 4-speed. The clutch did NOT like the 2.76 gears when taking off so 3.23 is a compromise. I can drive reasonably fast (71-73 mph) without opening up the secondaries. The 2.90 something gears were a bit difficult to find (I thought) but they would be my choice if I had tall rear tires. With the stock sized tire I'd use 2.76 gears. You don't want the rpm to be so low that the engine is bogging or out of the power band. Again, performance off the line will be fairly pathetic for a 440.

Troy

[gymratt30]

Thanks for all the good info guys.

[Mike DC]

           

Incorrect, ratios 3.31:1 through 7.71 were available from Dana Spicer,carrier break is at 4.56 for the lower ratio.

My understanding is that Dana 60-series ratios under 3.54 exist, but they require a D61 housing with the pinion farther offset (and 3.5" axle tubes).
 

[62 Max]

           

Incorrect, ratios 3.31:1 through 7.71 were available from Dana Spicer,carrier break is at 4.56 for the lower ratio.

My understanding is that Dana 60-series ratios under 3.54 exist, but they require a D61 housing with the pinion farther offset (and 3.5" axle tubes).
 

I could be wrong (I have been before) but I think it is the other way around,4.56 and higher.The Dana 60 in my 62 Savoy wagon has a ring gear dated 4 .10.66 and is 3.31 ratio and same housing as the 60 that is in my Superbird.

[tan top]

 have 2:94 gears with a sure grip in a 742 centre section , with 27 inch tall tires . would not mind trying a 2:76    ,  

would like to try these rear gears  with a four speed  

[pettybird]

I could be wrong (I have been before) but I think it is the other way around,4.56 and higher.The Dana 60 in my 62 Savoy wagon has a ring gear dated 4 .10.66 and is 3.31 ratio and same housing as the 60 that is in my Superbird.

could you get a dana in a '62 Savoy?  my knowledge drops off SHARPLY pre-1966...

[Ghoste]

No, you couldn't.

[AKcharger]

I have 2:76's in the '70, great for highway

[62 Max]

No, you couldn't.

But you could put it there !