Fierysun

Gas prices is going up for no good (crude is at $37 per barrel) reason, and i'm considering changing out to taller gearing to improve my mileage. I have a 87 2wd longbed. I read somewhere that certain 2wd had really tall gearing (3.**). Which years are those? Also is there any aftermarket companies making tall gears?

On a side note: with crude at $37 pb. Gas should be around $1.30 (87), $1.40 (89), $1.50 (91), and not $2.17, $2.27, and $2.37 today's price at the pump. What the heck is going on?

Plumbrbob

!!!!!!TAXES!!!!!!!!

eich75

we got used to payin 3.70+ for a gallon, 2.17 seems cheap now ha ha at least to me

stormin94

Yep. And they want to tax CA's gas 2X more than they already do.

abecedarian

Didn't we have this same discussion when crude was at 60-70-90 dollars a barrel?

yeah, you're realizing pump prices aren't the same as they were when oil prices were similar a few years ago. So now you now that pump prices went up more as we got closer to Bush leaving office and then suddenly dropped so that another Republican wouldn't be voted in... and then jumped up as soon as someone who would not affect oil prices took office.

welcome to the fray. what you see is not what it is.

Matt16

I don't think tall gearing works with tiny engines that need the gearing to stay in their their torque band. Stock probably works best.

stormin94

Not exactly. A larger tire, has a larger rotating mass, and it also weighs more than a stock tire with taller gears. The taller tire will hurt performance, as well as economy, whereas the taller gearing would hurt performance by a smaller degree, but could possibly improve the mileage by a small degree if done within reason, and if your driving style permits it. If you could drop highway RPMs by 300-500, and if your truck still had adequate power, you could possibly see a SMALL increase in economy on the highway. I think a more effective solution is to make sure your tires are properly inflated, and to keep excess weight out of your truck as much as possible.

91Toyota

My 2wd has 4.10s. I don't think those gears are common. lol

Dirt Driver

I am embarrassed to say that I never verified what gears are in my '94. My truck is totally stock save for some 205 tires and a shell and I can wring out 31mpg and change on the highway doing 65-70. Taller gears might improve that slightly, but I found that having a good O2 sensor and the engine in good tune helps noticeably.

Gears are a double-edged sword. Taller gears are better for highway economy, but a steeper ratio will often help economy in city driving.

Corruption, greed, and gouging. Global business as usual.

abecedarian

The best mileage occurs when the engine revs as low as possible with the least amount of pedal applied. No matter which way you look at it- more pedal applied equals more fuel burned.
If you have to floor it to keep 2800 rpm's (say tall tires and gearing) then you should regear so you can take some pedal out. You may end up loosing top speed (running out of gears) but small price to pay for economy.
Short shift whenever possible (don't rev the engine out just cause the yugo behind you is honking their horn ), be light on the pedal and downshift as appropriate- anticipate gear changes and don't wait until you have to shift... keep the engine near at or below the peak of the torque band and in the correct gear and you'll be getting the best mileage possible with whatever setup you have.

a4runnerfreak

Good post, Abe. And since when did yugo come equiped with horns?

Bobzombie

Only standard in certaint models like this one

abecedarian

uhh... uh huh..huh....
Need I say more?

Flash319

I think the stock 5 speed needs another gear. 3 grand at 65-70 is to high and I know the engine will pull lower in the rpm. When you hit a hill is a different story. The more gears you have the better you can manage the rpm/power requirements. To bad no one makes a bolt on over drive like the Saturn Overdrive for Heeps.

abecedarian

hmm... maybe contact GearVendors out here in Rialto, California. If you want an O/D unit, they can make it... costs money though. They could even make a unit to go between the trans and the transfer case so you don't have to worry about splitting gears front to rear....
Yeah, I've looked into what they can and are willing to do and it really is a 'cost is no object' proposition working with them.

desconhecido

Shifting from fourth to fifth gear increases drive shaft rotation by almost 18%. That, it seems to me, is a pretty effective overdrive right there. Also, I don't think that 3000rpm at 70 or so is excessive. I've had a lot of 4 cylinder cars and trucks and 3000 rpm at that speed seems pretty reasonable to me. But, if you went from a 4.10 rear end to 3.90, you'd reduce that by about 5% which may increase fuel economy a bit without affecting the ability of the truck to maintain highway speeds in fifth gear.

As far as bigger, heavier tires not being the equivalent of changing the gears, if you increase tire size by 6% or so, you will increase the amount of angular momentum that the tires have at any particular speed and you will increase the weight of the vehicle slightly. If you're concerned about the extra weight, I'd suggest that going on a diet would probably compensate. Or, wear lighter shoes. If you're concerned about the angular momentum question, well. angular momentum is conserved. Just reduce the weight of the flywheel by the proper amount (or clean the crap off your drive shaft or remove the rear brake drums or get lighter wheels or get bigger and lighter wheels with the same sized tire, or get narrower rims and higher aspect ratio tires) to compensate if the added tire weight and resulting increased angular momentum concerns you. Probably a bigger factor in economy (compared to tire angular momentum) is rolling resistance and I doubt that the increase by going to a bit bigger tire of the same design would change it much.

Probably the way to inexpensively (assuming you're buying tires anyway) decrease engine speed and realize a slight increase in gas mileage is to get slightly bigger than stock highway tires and gas them up to 35-40 psi. Or, get load range c highway tires and gas them to 50 - 60 psi.

abecedarian

blasphemer- reduce the weight of the flywheel to increase mileage?

How about the fact that a reduction of flywheel weight makes the transfer of torque from the engine to the transmission difficult? nothing like depressing the clutch at 3500 rpms and finding the engine is at 800 and your trans wants 2200. can you say "conservation of momentum"?

considering the diameter(s) of the driveshafts, angular momentum is negligible at best... talking about grams... sheesh.

mikepr55

going with 3.90s mite as well go with taller tires but narrow tires less rotateing mass I mean less with the width. Or am i wrong?

riceburner

The mid-80's standard bed base-model 2wd's (carbed) had 3.017 gears w/ a 4-speed trans.

See http://toyotareference.com/

desconhecido

I wasn't really suggesting that anyone remove weight from a flywheel or that cleaning the drive shaft would have a discernible affect. My point is that as far as steady speed highway driving and angular momentum, flywheels and heavier tires are not so different. Of course, lightening the flywheel is going to have all sorts of affects that would need to be compensated for. All you have to do is only depress the clutch at stops. Once you're moving, you don't need it.

I'm not really suggesting that anybody routinely shift without using the clutch. Or remove brake drums. Just being a smart ass.