Which gears in my rear end?

[hat_man]

As I have said before I am not a "car guy". Just a guy trying to get the most out of what I have and improve when I can afford.

That being said, how can I tell what gears are in my rear-end? (I know I am leaving myself wide open for "rear end" jokes, but I'm willing to take the risk.) Is it listed somewhere? Something to look for in physical design? I am at a loss. I had read a few places on the net that some people were seeing good to better MPG with 3.08 (?) gears in their Ford Rangers. Mine is a 2.3L with a 5-speed manual w/OD. Is there any truth in there? Maybe that's what I have now, I don't know. I see great mileage, but there is always room for improvement. My little Ranger see about 80% highway and the only real in-town driving is short trips to run errands.

Thanks for the help.

[rmay635703]

I have 2.8's in my diesel suburban but thats an 8 banger, not a ranger.

Generally speaking higher gears give higher FE, but only if you keep your foot out of it ESPECIALLY in 5th, you need to downshift to conserve FE if you actually end up overgeared but a ginger driver can take advantage of gears higher than the vehicle can realistically tolerate by not overloading the motor at low RPMs.

Good Luck
Ryan

[Big Dave]

Usually, US axles have a little sheetmetal tag held on by ine of the cover screws. But these often are gone on older vehicles.

[rmay635703]

Originally Posted by Big Dave

Usually, US axles have a little sheetmetal tag held on by ine of the cover screws. But these often are gone on older vehicles.

Ah yes re-reading GM vehicles have codes inside the glove box that you can have your dealer look up, the serial and whatnot can get your dodge dealer to give you a build sheet. Now ford, I have absolutely no idea, never did one.

I will say that if you turn the propshaft with the wheels in the air you can count place a timing mark on both and count out the gear ratio, not fun but doable

Cheers
Ryan

[Olympiadis]

Ford Ranger Axles - The Ranger Station

I think most of the 4-cylinders got the 4.10:1 ratio, 3.73:1, or 3.55:1 ratio rear gears, but it's always best to check.

You can usually determine it by using the conversion formula for engine speed vs vehicle speed in your 1:1 gear.

RPM = ((MPH * (rear ratio * 336)) / (tire diameter in inches)

[Fubeca]

One way to check is to use a friend and a piece of chalk.

On a flat straight surface like a parking lot or driveway mark the rear tire at the ground and put a mark on the rear driveshaft and axle housing where the driveshaft attaches.

Then drive slowly forward or backward and have your helper count the number of times the driveshaft rotates during one revolution of the tire.

[Phantom]

Use the site that Olympiadis listed or check Ranger & B-Series - Ford Truck Enthusiasts Forums almost all cars you can search for the RPO codes online to get all the info on what was included on the car.

RPO Codes.com- GM option codes,GM rpo codes,Regular Production Options

OptionCodes.com- Ford, Chrysler option codes lists

[hat_man]

Thank you all for the advice. I am going to try the chalk method this weekend. (Thanks Fubeca)

I do drive pretty light footed especially on the highway. Usually only giving it just enough right foot to keep moving at 55. In town I don't even use 4th gear. 1st thru 3rd to get up to 30-35 then 5th (O/D) to maintain it.

Rmay- This may sound silly but, can you explain what you meant by "a ginger driver can take advantage of gears higher than the vehicle can realistically tolerate by not overloading the motor at low RPMs." Does this mean I might have a more difficult time driving in-town at lower speeds/rpms? Without a tach I can only guess what kind of rpm's I am turning at 55mph but I would think around 1600-1800. That's just a guess though. In-town at 35mph in 5th gear I wouldn't have a clue.

After checking the great link from Olympiadis (Thanks) it seems I have an open 7.5" rear end with 3.73 gears. There are two other gearings listed lower than mine. (3.45 and 3.08) I wonder if either of these two would be beneficial to me. Any thoughts?

Thanks again for all the advice.

[comptiger5000]

What he means is that getting on it too hard at low rpms is just as bad as having higher rpms. There's a balance between gearing, engine and driver to be struck.

[hat_man]

I think I see what you mean. I'm pretty lightfooted in-town also. It's pretty evident from the annoyed looks from the drivers behind me. 30-35 mph in-town in 5th gear when everyone else is in such a hurry. I love pulling up to them at the stoplights after they go roaring past.