Changing Gear Ratio

[stevel]

I have a 69 step-side with 3 speed on the column and a 6cyl. Want to change my gear ratio so as not to be at such hi RPMs at hi-way speed.
Can anyone tell me the most cost effective and simplest way to accomplish this? At such speeds my fuel millage is horrible.

[my67c20]

Need more info. What rear gears do you currently have? What RPM's are you at at 55 or 65mph? What size tires? How much are you willing to spend? What type of rear axle do you have? Can you post pictures so we might be able to identify the axle? Did you already search for similiar situations (had to throw that in). Cheapest would be to change the size of tires, then the third member or rear gears (if you have an eaton), then axle for a decrease in RPM's. What kind of fuel mileage are you currently getting? When was the last time you did a compete tune-up? Points or HEI? Chrome or dull engine parts? How far do you drive? Loaded or unloaded? Manual or automatic choke? Answer some of these and we should be able to at least make you feel the desperation that most of us feel by chasing the elusive mpgs. And on a side note i only get 10mpg

[Billett]

About 10 here too... I usually just drive slower on the highway, closer to 55-60. People pass me, and some get mad because I'm holding up a bit of traffic but it doesn't bother me any. Some things I did to get some more mileage: change the oil, check the tire pressures, and grease everything!

[cdowns]

lots of guys have gone to "hiway gears" to get increases in gas milage only to find out that with the around town driving the the effort it takes to get to "cruisin" speed they actually killed thier gas milage and got worse in the long run/// tires suspension routine maintenence can do alot to improve what you have

[Billett]

Also, if you're not looking at mpg's, only to lower your RPM's at cruising, you'll have to change transmissions for that... you could do a different rear end, but I doubt it would help much.

[davepl]

Sticking a later model overdrive transmission like a TH200 or TH700 in it would help. The overdrive is about 0.7 so cuts your overall gear ratio substantially. Done correctly you can also get a lockup converter for the highway which will also help.

All that work might take you from 12 to 14 mpg though. No matter how efficient your powertrain, these are still big, heavy, brick-shaped trucks.

In my Range Rover, which is only slightly more aerodynamic, I see a huge difference in mileage between 55mph and 75mph (like 4-5 mpg). Unless you're doing a ton of highway driving frequently with it I'd leave 10 minutes early, keep the speed down a little, which will keep the RPMs down and improve the mileage.

[Billett]

And its a more relaxing drive
Posted via Mobile Device

[GASoline71]

Originally Posted by davepl

All that work might take you from 12 to 14 mpg though. No matter how efficient your powertrain, these are still big, heavy, brick-shaped trucks.

Couldn't agree more...

Gary