Gear Ratio ID/ Limited Slip?

[Lignum]

Is there a way to tell what gear ratio you have besides spinning the driveshaft and counting how many times the wheel goes around? I didn't see a little tag on the diff or anything like I have seen on other vehicles. I will probably end up doing a regear sometime in the future so I would like to know where I am starting at.

Also, did they put some sort of limited slip diff in the 2000 Sports? I always spin both rear tires when I gun it in the dirt.

 

[brian2sun]

No LSD was ever offered in any of the 3rd gens (no hash, or mushrooms either, haha). And unfortunately, no one makes any aftermarket LSDs for our diffs (and that sucks because a 7.5 for the front would really kick ass).

Many (including myself) have gotten wrong info online regarding diff ratios. Spinning the shaft is really a good way to find out IMO (that's what I did and found out my stock ratio was 4.11 - unlike the online chart that said I had 4.30s based on my door sticker code). But, if you are scared of not being able to tell the difference between 4.11 and 4.30 etc, jack up your rear tires, take out the fill plug on your rear diff, mark a tooth on the ring gear, spin the tires and count the teeth. And, while you're doing that you can also see if your tires spin together which would mean a previous owner installed an Aussie (or similar) locker in there. If the tires go in opposite directions, you have a normal open diff.

 

[Lignum]

When I did the lift I spun the wheel and the other one spun the opposite direction, but somebody told me that's not always an accurate way to tell. I am sure it is stock and if they didn't install LSD in 3rd gens then I'm sure it is open.

 

[Mr. Leary]

No LSD was ever offered in any of the 3rd gens (no hash, or mushrooms either, haha). And unfortunately, no one makes any aftermarket LSDs for our diffs (and that sucks because a 7.5 for the front would really kick ass).

Many (including myself) have gotten wrong info online regarding diff ratios. Spinning the shaft is really a good way to find out IMO (that's what I did and found out my stock ratio was 4.11 - unlike the online chart that said I had 4.30s based on my door sticker code). But, if you are scared of not being able to tell the difference between 4.11 and 4.30 etc, jack up your rear tires, take out the fill plug on your rear diff, mark a tooth on the ring gear, spin the tires and count the teeth. And, while you're doing that you can also see if your tires spin together which would mean a previous owner installed an Aussie (or similar) locker in there. If the tires go in opposite directions, you have a normal open diff.

There is a guy over on ExPo (xcmountain80) who has an LSD up front in his 3rd gen, I think.

If there was even a limited slip carrier in the rear diff the tires should spin in the same direction when in the air. Most likely the rear is an open diff.

 

[notrayray]

More and more it's seeming the best way to find out your axle code is to pull the third and count the teeth yourself.

 

[Lignum]

What are the most common stock gear ratios?

 

[Martinjmpr]

More and more it's seeming the best way to find out your axle code is to pull the third and count the teeth yourself.

True, I think. I went to a couple of different web sites that are supposed to give you the ratio based on the door codes and got 3 or 4 different answers.

QUESTION: Is there enough of a difference in ratios that we would be able to tell by speed/gear combinations? IOW, get your 4runner out on the highway so it goes into 4th gear (OD) (<---obviously the MT guys know exactly what gear they're in but us auto people have to put it on a long stretch of highway to make sure.) Then, take it up to 60mph (or some other set speed) and say "if your rpm is 1800, your ratio is XXX, if your RPM is 2000, your ratio is YYY, if your RPM is 2200, your ratio is ZZZ."

Of course, one thing that would immediately be an issue would be speedometer accuracy or lack thereof, but many of us (if not most) have GPS units that can measure speed pretty accurately.

In fact, might it be possible to do those calculations mathematically beforehand? Full disclosure: I took the absolute minimum amount of mathematics needed to graduate college, so I'm probably not the person to figure this out, but it seems to me it'd be an issue of fairly simple calculations.

Something like this: You'd have to know the diameter of the tires, because then you would calculate the circumference of them. Figure out the RPMs the wheels have to turn in order to go 60mph.

Then figure out the gear ratio of the highest gear on the tranny. then substitute in each of the gear ratios and calculate the approximate RPMs accordingly. Wouldn't that work? It wouldn't be too accurate (since the tach on the 4runner only has tick marks at 500rpm increments) but it would give people a good guess as to their gear ratios.

 

[Lignum]

True, I think. I went to a couple of different web sites that are supposed to give you the ratio based on the door codes and got 3 or 4 different answers.

QUESTION: Is there enough of a difference in ratios that we would be able to tell by speed/gear combinations? IOW, get your 4runner out on the highway so it goes into 4th gear (OD) (<---obviously the MT guys know exactly what gear they're in but us auto people have to put it on a long stretch of highway to make sure.) Then, take it up to 60mph (or some other set speed) and say "if your rpm is 1800, your ratio is XXX, if your RPM is 2000, your ratio is YYY, if your RPM is 2200, your ratio is ZZZ."

Of course, one thing that would immediately be an issue would be speedometer accuracy or lack thereof, but many of us (if not most) have GPS units that can measure speed pretty accurately.

In fact, might it be possible to do those calculations mathematically beforehand? Full disclosure: I took the absolute minimum amount of mathematics needed to graduate college, so I'm probably not the person to figure this out, but it seems to me it'd be an issue of fairly simple calculations.

Something like this: You'd have to know the diameter of the tires, because then you would calculate the circumference of them. Figure out the RPMs the wheels have to turn in order to go 60mph.

Then figure out the gear ratio of the highest gear on the tranny. then substitute in each of the gear ratios and calculate the approximate RPMs accordingly. Wouldn't that work? It wouldn't be too accurate (since the tach on the 4runner only has tick marks at 500rpm increments) but it would give people a good guess as to their gear ratios.

I was thinking that too, but I was assuming you would have to turn the OD off becuase if you didn't the tranny ratio would be like 1:0.75 or something instead of 1:1 like it would be in the final gear minus overdrive.

I once found a site where they tell you how many rotaions make a mile for each tire, I think it was the Nitto site.

 

[Lignum]

I found something interesting, on the yokohama site, I found my exact tire, the Geolander H/T-S in a 265/70R16. It say the tire makes 677 revolutions per mile. So assuming my spedo is correct, if i go exactly 60 and get my engine RPM. I should be able to divide engine rpm by 677 and get the gear ratio. Assuming everything is very accurate. lol.

 

[Toy4ever]

While we are on the topic, does anyone have a good reference where to pick up some 4.88's. I am looking to replace front and rear.

 

[Mr. Leary]

What are the most common stock gear ratios?

Most common gear ratio in the 4wd is 4.11.

Most common for 2wd is 3.909.

Some have 4.30, but I believe this only came in the Limited with the Elocker.

BTW, I tried once to call Toyota USA and confirm gearsets using the VIN... they told me I had 3.909.... pulled it apart... 4.11.... so don't waste your time calling them.

 

[Mr. Leary]

While we are on the topic, does anyone have a good reference where to pick up some 4.88's. I am looking to replace front and rear.

Yukon.

 

[Toy4ever]

I called the 4wd shop this morning and asked them what parts and labor for putting 4.88's in front and rear and they quoted me at 2300.00 parts and labor. lol :gun5:

 

[brian2sun]

Why would you guys pull the whole third when you can see the teeth of the ring gear through the fill hole like I was saying earlier? And the equations and standarized rpm tables you guys are talking about would be way innacurate because there are too many variables. Every engine runs a little differently, the torque converter in the tranny can soak up a few hundred rpms if you're not aware it's engaged, the diameter of your tires gets smaller everyday - way, way overcomplicating a simple process. Just spin the driveshaft, it's VERY accurate and as long as you can count to 5 and are aware that whole numbers can be divided, it's freakin stupid easy.

 

[brian2sun]

I called the 4wd shop this morning and asked them what parts and labor for putting 4.88's in front and rear and they quoted me at 2300.00 parts and labor. lol :gun5:

Shop around, I had mine done for about $1700 P&L for Motive gears (which Motive, Yukon, and many others are all made my Midwest Gear and just re-boxed - just like Moog, Beck-Arnley, Sankei, and 555 parts are). The brand of the gears alomost means nothing, 99% of it is in who does the set-up.

 

[Lignum]

Why would you guys pull the whole third when you can see the teeth of the ring gear through the fill hole like I was saying earlier? And the equations and standarized rpm tables you guys are talking about would be way innacurate because there are too many variables. Every engine runs a little differently, the torque converter in the tranny can soak up a few hundred rpms if you're not aware it's engaged, the diameter of your tires gets smaller everyday - way, way overcomplicating a simple process. Just spin the driveshaft, it's VERY accurate and as long as you can count to 5 and are aware that whole numbers can be divided, it's freakin stupid easy.

That's true. I used to be a nuclear mechanic, so I tend to over complicate things:jump::banana: