3:58 gears in 99' 3rz 5 spd standard cab

So I checked my gears and apparently I have 3:58s...never heard of them. What are they good for??

I bought the truck with 33x12.5s and was "told" it was geared for 33s...thing is 1st gear is like nothing, and I top out about 70mph on the hwy. I have power, I can hold 4th/5th on hills, just don't go that fast. It's a 99' 3rz 2.7L with 5 spd, pace setter header, magna flow exhaust, marlin HD clutch, manual hubs...

On a sidenote, I'm averaging 24.5 MPG on hwy at the same time.

If a guy wanted to switch gears, what would you run and how much, if any will it effect my milage?

I want to go faster then 65-70 on hwy, but I don't want to sacrifice any MPGS at same time.

 

I don't have a tach either so no idea on RPMS but I'm not that crazy on it, it has 285K...I like to think I'm fairly easy on it.

 

Wish I could give you a good answer but I know if you call ECGS (east coast gear supply) they can square you away

 

Have or had 3.58?

 

Cool rig you have there. I run 4.56 on my 33x12.5 and get about 20-23mpg. I can get up to 85 gps before I hit my rev limiter in 5th.

 

My taco has 4.30 gears and I push 32s easily. I actually hit 90 the other day haha. That's a sweet flatbed though. Did you build it yourself?

 

I have 3:58s...I know the kid I bought it from didn't regear shit, among few other things he weasled me out of...

I might just stick with them gears until they break or need replaced then. Good thing is, I can't ever really get any speeding tickets this way haha. And I don't want to screw 24 MPGs up.

Flatbed came with the truck, it's not too bad. Tool box is sunk down, spare bolts down, I welded the brackets for the wood racks for hauling my dog around, since she won't stay on a flatbed.

 

3.58 are best for really small tires. I am having a hard time understanding how you can be topped out at 70mph with road gears like that and big tires. Just for reference most of the 1st gen Tacomas that came with 31" tires came with 4.10 gears and even some 4.30 I think.

 

If you're still stock this is a good link to figure out your gearing based on your vin #
http://www.brian894x4.com/Gearratiosanddiffs.html

If you think they might of changed... Rotate your tire one full rotation while counting how many times your drive shaft rotates. That should get you close.

also, there is a group buy getting together for gears from ECGS
https://www.tacomaworld.com/threads/ecgs-gears-install-kits-and-locker-group-buy.382427/

 

Based on the information you've given you do not have 3.58 gears. If you have a jack you can easily find out. Just put the truck in neutral, jack up one tire, spin it 2 full revolution, and count how many times the rear shaft spins.

If you actually do have 3:58 gears in your diffs the only other explanation that would fit your story is your transmission has different gearing but that is highly unlikely provided it is the stock tranny.

As for what gears you should have for 33" tires, 4.56 or 4.88 are the most common. If top speed is your main concern lower is better. The restricting factor is how much power your truck has to actually spin the tires at high speeds. I run 4.56:1 in my v6 Tacoma and it easily pushed 32's. So much so that I'm going to bump up my tire size for my next set. I also ran 33's on a 2nd gen pickup with 4.88's and it was about right for the power of the truck (22RE).

 

Have you checked the door jam axle code?

 

↑↑this.... something seems weird...should be able to do 115 with that ratio and big tires.

 

If you have 3.58 gears, the truck probably shipped with 225/75/15s on there. This means that when your speedometer says 70mph, you are actually going about 81mph with those 33s. Try checking your speed using gps - you can download gps speedometer apps to your phone.

3.58s are best for getting good mileage on the highway, not great for power with larger tires. They should allow the highest speeds of any Tacoma gears without over revving the engine.

 

Check yo digits here: https://www.marlincrawler.com/differential/ring-pinion

 

According to my door, it says B02A. That chart would make them 3:73s...the chart I looked at and saw the other day said 3:58s

I do have that speedo app, when I'm actually going 70mph, my speedo says 90...my speedo always reads faster then what I'm doing, never slower.

 

The above chart is in first gen Tacoma sticky section, OEM gearing...that says 3:58s

 

If you have oversized tires and your speedo reads higher than your actual speed, then either your gears have been swapped already or your speed sensor gear has been changed.

I recommend you use the instructions posted by Clay up above and see what your actual gear ratio is, then go from there. Maxing out at 70mph sounds like you have a really high gear ratio.

A high gear ratio would also explain your perceived 24mpg. I'll bet if you check your mpg using gps to track the mileage instead of the odometer, you will get a number more in the 18-19mpg range, which is about what I would expect from a 3rz running 33s. My 3rz with 31s and b02a gears gets about 20-21 on summer gas.

 

The door sticker/code charts are historically not always correct. Best bet is to check what you have using the method Clay_916 mentioned in post #10.

 

It might help to run a scan gauge or OBDII bluetooth reader and a smartphone app to check your RPMs too.