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Discussion Starter · #1 ·
Ok so I am not sure if I have 4.10 gears or 3.91.

The info on the door sticker is

RZN171L - CRMDKAB
C/TR 3K4/FC10
A/TM B033/W59

The B033 leads me to believe that the gears are 4.10, also my tuck is a TRD and I thought that all TRD's came with 4.10, but there is this part of the gear codes tec section that says:

"some '98-00 models have shown a BO code of "???" on the door plate; so far this turns out to be a 3.91 gear ratio, at least for the 5sp. RZN171L-CRPDKAB with factory 31s/265s should be 4.56 with the AT"

My truck is a manual 5sp, when I bought it the truck had 33x12:50 BF AT's. I have FC-II by Dick Cepek that are 33x12.50 (fairly new). The truck has always been underpowered and I am starting to look into re-gearing it because currently I can only increase my speed in 5th if I am going down hill.

I would like to know what gears it came with, if it was the 3.91 (which I kinda doubt) then I think the previous owner must have re-geared it. Since the last digit in the gear code list isn't a letter I am not sure what to think. Right now at 65 in 4th I have about 2900 rpms.

I have read and done a good bit of searching and it seems like either 4.56 or 4.88 gears are recommended for my engine/ tire size.

Also the sticker inside the door said that the original tires size was P225/74/15 (which seems small to me for a TRD?). I don’t think I will move up to 35” tires but I guess if I ever want to I should go with the 4.88 gears (right?). I read something about jacking the truck up and turning the wheel to see how many revolutions the drive shaft does to figure out the exact gearing, how does this work and how exactly do you do it?

Sorry for the long post but I figured that I would include as much info as possible so I didn’t have to answer 21 questions before I got responses.
 

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Discussion Starter · #3 ·
Got Cope, that doesn't really answer anything, my code is B033. I know what the code says, and I know that B03 = 4.10, but the A part means = 2 Pinion, Open, As you can see from my post I don't have an A, I have a 3, and I still don't know what that means.
 

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Discussion Starter · #4 ·
Can anyone help me figure this out?
 

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you got 4.10 unless the previous owner regeared which is doubtful.

The BO with the ??? doenst apply to you. Like on my truck where the gear code should be all I have is ??? marks. But the RZN171L-CRPDKAB applies to me since I have 4.56's from the factory.

But yes you will want to get a set of 4.56's or 4.88's to go with the 33's
 

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man, i would be surprised if you have been able to run those tires with 3.58 gears. Can't even imagine the lack of power.

You have a manual tranny, with that tire size, going to 4.88's will be almost an overkill IMO, unless your truck is a trail rig only. Of course, you'll love the extra power at the low end. Going with 4.56's and that tire size will bring you closer to stock.
 

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Discussion Starter · #9 ·
OK, thanks for the Ideas; I will do the "spin and count" method today after work. I have the TRD E-locker in the rear so does this mean I have to jack both wheels up?

So is the common opinion that 4.88's with a 2.7 M/T and 33's is overkill, I'd like more power but this is also my DD. The low end in 4 low is great right now it’s mostly the highway that kills me (lots of Mountains here). I don't think I will make the jump to 35's so what is the best gearing that everyone recommends for 33's on my truck?

Thanks a lot for the help guys!
 

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I used the term overkill in terms of highway use. Your RPM's will be significantly higher if you go with 4.88's.

to be honest with you, i'm looking forward to get 33" tires myself to get a little better response with the 4.56 gears I'm running.

It would be different with an auto tranny.
 

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OK, thanks for the Ideas; I will do the "spin and count" method today after work. I have the TRD E-locker in the rear so does this mean I have to jack both wheels up?

You can leave the locker disengaged and treat it as you would an open diff.
If you engage the locker, you will have to jack both rear wheels up.

Doing both allows you to visualize and quantify the differences.
 

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Discussion Starter · #12 ·
GrillMasterP, what do you mean by visualize and quantify the differences, how will this be different from just one wheel in the air unlocked?
 

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GrillMasterP, what do you mean by visualize and quantify the differences, how will this be different from just one wheel in the air unlocked?
What I meant to compare is
Locked both wheels in air vs.
open both wheels in air

It will differ by a factor of 2
 

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Discussion Starter · #14 ·
OK, thanks, would it be better to do one over the other?
 

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lol, nah not really -
 

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living in the mountains you'll want the 4.88's yea you'll have revs a little high but you DO have 5th so it wont be bad, 3RZ's are bullet proof,
 

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Discussion Starter · #17 ·
What kinda rpms am I looking at in 5th and 4th around 75 to 80 mph?
 

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What kinda rpms am I looking at in 5th and 4th around 75 to 80 mph?
ok if your speedometer is reading 65 at 2900 your probably actually going 72 ish

this is really low rpm for that speed in 4th gear

if you change to 4.88's you will have much more power , your speedo will be closer to perfect AND
at 70 in 4th gear you'll be at around 3500 rpm, putting you in a sweet spot in the torque of the 3RZ, you could tow a trailer much easier

if changed to 5th at 70 you would be at about 3000 rpm, what you do now at 65 but will still have torque available,
 

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Discussion Starter · #19 ·
Actually my Speed odometer is dead on, had it checked, guess the guy that did the body lift and 33's had the Speedo recalibrated (I think he was a drug sales rep cause I found lots of Viagra notepads and the truck was spotless underneath, not even a scratch). Anyway, any ideas what effect 4.88’s will have on my MPG?

Thanks a lot for the info 79 Coyote, are you running 4.88’s in a 3RZ right now? If so how do you like it and what tires are you running?
 

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Ok so I am not sure if I have 4.10 gears or 3.91.

The info on the door sticker is

RZN171L - CRMDKAB
C/TR 3K4/FC10
A/TM B033/W59

The B033 leads me to believe that the gears are 4.10, also my tuck is a TRD and I thought that all TRD's came with 4.10, but there is this part of the gear codes tec section that says:

"some '98-00 models have shown a BO code of "???" on the door plate; so far this turns out to be a 3.91 gear ratio, at least for the 5sp. RZN171L-CRPDKAB with factory 31s/265s should be 4.56 with the AT"

My truck is a manual 5sp, when I bought it the truck had 33x12:50 BF AT's. I have FC-II by Dick Cepek that are 33x12.50 (fairly new). The truck has always been underpowered and I am starting to look into re-gearing it because currently I can only increase my speed in 5th if I am going down hill.

I would like to know what gears it came with, if it was the 3.91 (which I kinda doubt) then I think the previous owner must have re-geared it. Since the last digit in the gear code list isn't a letter I am not sure what to think. Right now at 65 in 4th I have about 2900 rpms.

I have read and done a good bit of searching and it seems like either 4.56 or 4.88 gears are recommended for my engine/ tire size.

Also the sticker inside the door said that the original tires size was P225/74/15 (which seems small to me for a TRD?). I don’t think I will move up to 35” tires but I guess if I ever want to I should go with the 4.88 gears (right?). I read something about jacking the truck up and turning the wheel to see how many revolutions the drive shaft does to figure out the exact gearing, how does this work and how exactly do you do it?

Sorry for the long post but I figured that I would include as much info as possible so I didn’t have to answer 21 questions before I got responses.
you have 4.10s

I started out with OE 4.30s with my '00 5sp
went to 33s
changed gears to 4.56s
changed again to 4.88s

there is not a huge difference on the road between the 4.56s and 4.88s but there sure is on the trail in low range ;)

rpms @70 are about 3k with 4.88s/33s (assuming the average 33" tire @
32.6") ...with 4.56s, around [email protected]

If you have a lot of mt roads and/or do a lot of towing/hauling go with 4.88s.
your in-town mileage will be better with them but hwy mileage will drop if you keep it over 65.
hwy mileage w/4.56s was better than the 4.88s when I drove 75 or so compared to the 88s which dropped to around 16 at that speed. In-town mileage with 4.56s wasn't as good as with 88s.

35s really suck the power :rolleyes:
5.29s go in in a few weeks...sigh...
 
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