4.88's vs. 5.29s

[liljlandon]

I want a lower axle gear to tote around my camping/work supplies, but judging by the cost of them it would be cheaper to go with a 5.29 ratio. My problem is I am only running a 31x10.5R15 Trxus and dont know what each would bring me. I found a really good deal on a marlin crawler 4.88 3rd w/ a detroit but It would cost less for me to go 5.29 with lockrights f/r after i regeard to 4.88 in the front. I feel pretty good with my dad setting them up, but the main question I am trying to ask is, Is a 5.29 to low for a stock vehicle? or would fifth finally be usable, and honestly I could live with fifth being about the same as forth.

4th= 1:1
5th= 0.85:1
So would a 15% increase in gear ratio be enough
4.11x1.15=4.73

So in theory of that a 4.88 would actually make 5th gear feel a little lower than 4th.
So what do you guys think?

 

[Jetboy]

I'd say 5.29 is just right for 35's. Way too low for 31's. Plus why not spend the $ on 4:1 t-case gears for the stock case, and drive in 4th on the highway? That way you'll have the low gears you want offroad and about the same highway performance. My opinion is that the transfercase is a better place to get your low gearing for offroad. For the highway I just don't see any benefit of puting it in 5th over 4th.

 

[Hilux]

put some 33's on it if you insist on the 5:29's

Personally I would not lug a truck I drive at all, for the sake of when I do go off roading.


If the 5:29 is more economical to you then its just an,...and a good one at that, excuse to get bigger tires. Then your clearance will be better off road....


still not sure if I understand you post though. See if this helps. Sit down with a pen and paper and you can SEE the RPM's the gears will be giving you at the speed you want.


Lifted v, and your OD ratio is different

mph x final drive x O.D / (divided by) Tire dia x 336


Alright, now some things you need to remember here is 1: you cant put a gear in the calculator you think you running, it'll be inaccurate or wrong. Like I said. I use, .10 per 1" so because you are running a theoretical gear (not the true 4:11) adjust this to work in the equation. And 2: It's an equation for an SAE, its not for a metric tire so heres the formula for that:

tread width/ 25 x aspect : x 2 + wheel dia.

265/70x16

265/ 25 = 10.6 (which incidentally is the tread width in ")
10.6 x 70% = 7.42
7.42 x 2 =14.84
14.84 + 16 = 31.84 (which incidentally is the tires height in ")

see?


Now, "what would be my top speed with 4:88's??????????? 35mph?????"

Is that a trick question?

I'm assuming you mean rpm at 35mph with 4:88's and 33's, If I am correct here goes.

33 x 4:88 x .71 = 114.33 / 33 = 3.46 x 336 = 1,164rpm at 35 mph


And since the OD is most likely not on:

33 x 4:88 = 161.04 / 33 = 4.88 x 336 = 1,639rpm at 35 mph


And since it wont be in either one of those gears (OD or 1:1< 3rd) and I don't have the proper gear ratio's I cannot tell you the answer to that

Well snap,....ask and yee shall,......but I aint doing it!, uh uhh


A440F
Produced January, 1990 through July, 1992 on U.S. spec FJ80s
1st gear: 2.950 to 1
2nd gear: 1.530 to 1
3rd gear: 1.00 to 1
overdrive: .717 to 1

 

[Hilux]

55 x 5.29 x .85 / 31 x 336 = 2,680rpm's at 55mph
70 x 5.29 x .85 / 31 x 336 = 3,411rpm's at 70mph


55 x 4.88 x .85 / 31 x 336 = 2,472rpm's at 55mph
70 x 4.88 x .85 / 31 x 336 = 3,147rpm's at 70mph


55 x 4.11 x .85 / 28 x 336 = 2,305rpm's at 55mph
70 x 4.11 x .85 / 28 x 336 = 2,934rpm's at 70mph



You might not want to take my word for it. learn to do this yourself and you'll always know its right

 

[liljlandon]

well, id rather go dual cases than a 4.7, for many reasons, i would actually have hi, med, and low vs. hi and low.

I am a hardcore weekend wheeler, the truck gets me atleast 30 miles to school and then a 45 mile trek to work and back home a day, along the way I constantly am transfering from interstate to hills, and then riverbottom to stay out of traffic, and about once or twice a week i try to brinbg home loads of metal(reason i want more power). i can get around 23-25 mpgs if i leave it in 4th at 70-75mph. I figure if i can get the better take off and better gear widths then i should be set to go on these treachorus hils and keep the gas mileage by using my pretty much obsolete 5th gear. I have heard tghat the lower the axle gear the less stressful the shock is on the xcase.

And Hilux, i really got confused, wats the 336 for?

 

[Hilux]

i can get around 23-25 mpgs if i leave it in 4th at 70-75mph.

spedo corrrrected?

And Hilux, i really got confused, wats the 336 for?

Heck I don't know, and dont care, all I know is it works

 

[2ndGenToyotaFan]

I use 5th all the time and I'm pushing 33's with 4.10's.... Not up much of a grade, but it's still usable.

also, here's a helpful link:

Calculators from www.4Lo.com

 

[Hilux]

I use 5th all the time and I'm pushing 33's with 4.10's.... Not up much of a grade, but it's still usable.

also, here's a helpful link:

Calculators from www.4Lo.com

Thats all well and fine but FYI you cant have 4:11's with 31's AND... 28's

 

[2ndGenToyotaFan]

Thats all well and fine but FYI you cant have 4:11's with 31's AND... 28's

What's the rest of that thought? Do you mean don't mix tire sizes? That's a rule regardless of sizes and ratios.....

 

[Hilux]

What's the rest of that thought? Do you mean don't mix tire sizes? That's a rule regardless of sizes and ratios.....

I knew this was coming.


Heres my thought, say someone punches in they have factory gears and 31's. Is the answer that calculator is going to give be the same RPM's as with 4.56's?


IDK, but I don't think its right,

see what I'm saying? For example UserX punches in 31's w/ 4.11's b/c he didnt take the overall difference the added tire DECREASED his real gear ratio, didn't factor in "correction". Will the equation be accurate?


I think not

 

[2ndGenToyotaFan]

No, 31's with 4.10's and a 0.85 5th is 2077 rpm.... 4.56 is 2310

Yes, the rpm calculator works......

 

[WarDamnEagle]

No, 31's with 4.10's and a 0.85 5th is 2077 rpm.... 4.56 is 2310..

Which is why I'm buying TRD elockers with 4.56 gears to go with my 31" BFG MT tires.

Note: Jerod's figures above are for 55 mph. At 70 mph it's 2644 rpm with 4.10's and 2941 rpm with 4.56's.

 

[liljlandon]

spedo corrected?

Thats factored in, the odo is off by 33%, so if i drive 20 on the odo im actually driving around 30. So i multiply my trip meter by 1.33 to get my actual mileage and divide by my gallons
usually i get 270-300ish off of 12-13gallons.

Also, once i factor in the difference of my original tire size it says my current axle ratio is 3.70
original 28
new 31
gears 4.10
new axle ratio 3.7032258064516123

Same as above using 4.88 gears
new axle ratio 4.4077419354838705

I actually come out a bit lower, which is what i want.

I dont think that the my tach is right, because according to that i should push 2800 rpm at 75 in 5th (.85) while i actually push more to the 3300 side.
4th (1:1) at 75 is 3332 while my tach says around 3800.
Can my tach be that far off?
Or have my gears been changed by the PO?
Ill check when ever my new seals get here from man-a-fre.

Thanks for all your help

 

[WarDamnEagle]

Thats factored in, the odo is off by 33%, so if i drive 20 on the odo im actually driving around 30. So i multiply my trip meter by 1.33 to get my actual mileage and divide by my gallons
usually i get 270-300ish off of 12-13gallons.

I don't think your odometer is off by 33%. By my calculations it's off by 10.7% so you should multiply your odometer mileage by 1.107 to get your actual mileage.

The above assumes exactly 31" OD tires vs. exactly factory 28" OD tires with no other changes to the vehicle.

Or have you checked your odometer with a GPS and know for a fact that it's 33% off? (Which means that something else has been changed, like gears, or your speedometer doesn't work properly.)

 

[Jetboy]

Thats factored in, the odo is off by 33%, so if i drive 20 on the odo im actually driving around 30. So i multiply my trip meter by 1.33 to get my actual mileage and divide by my gallons
usually i get 270-300ish off of 12-13gallons.

Also, once i factor in the difference of my original tire size it says my current axle ratio is 3.70
original 28
new 31
gears 4.10
new axle ratio 3.7032258064516123

Same as above using 4.88 gears
new axle ratio 4.4077419354838705

I actually come out a bit lower, which is what i want.

I dont think that the my tach is right, because according to that i should push 2800 rpm at 75 in 5th (.85) while i actually push more to the 3300 side.
4th (1:1) at 75 is 3332 while my tach says around 3800.
Can my tach be that far off?
Or have my gears been changed by the PO?
Ill check when ever my new seals get here from man-a-fre.

Thanks for all your help

Doh, WDE beat me to it while i was looking for the color codes.

I'm confused by your math. With 31's, assuming you have a 4x4, you're not off by 1/3 on the spedo. Stock 235/75/15's are 28.9" so figure 29" to make the math easier. So one rotation of a 29" tire is 91". One rotation of a 31" tire is 97.34". So we're talking about a 9.3% difference. When you're spedo says 20, you're going 22mph, not 30. To get that far off you'd need 38.5" tall tires. I think that's why you think you're getting that good of mileage. Borrow a GPS and test it. I'm guessing you'll find your a lot closer to the spedo than you think.

If your engine is healthy, you should not have a problem with 31's.

I don't really care what you do, but I can tell you from experience that 5.29's work great for 35's and will be too low for 31's. That's what I had on my 84 pickup. And that's in Montana at 6,000 feet with mountain passes. I've also had 31's on my 84 stock with 4.10 gears and thought it was about right. I currently have 38's on my Landcruiser and 5.29's and they are actually a little low for highway cruising. It also had 4.11 stock gears.

Also, FYI, if you have stock gears you can check the ration by the color of the marking paint on pinion without pulling the 3rd members.
Table: Ring and Pinion ratios

Color

3.42 Purple
4.10 Pink
4.11 Orange
4.30 . . Blue . . .
4.37 Green
4.56 Yellow
4.88 White

 

[2ndGenToyotaFan]

Yeah, 31's are 10% bigger, not 33%. Which means your mileage isn't as good as you think.....

 

[cokidva]

just read this post... my head hurts

 

[Hilux]

just read this post... my head hurts

x3.14

Thats factored in, the odo is off by 33%, so if i drive 20 on the odo im actually driving around 30. So i multiply my trip meter by 1.33 to get my actual mileage and divide by my gallons
usually i get 270-300ish off of 12-13gallons.

Also, once i factor in the difference of my original tire size it says my current axle ratio is 3.70
original 28
new 31
gears 4.10
new axle ratio 3.7032258064516123

Same as above using 4.88 gears
new axle ratio 4.4077419354838705

I actually come out a bit lower, which is what i want.

I dont think that the my tach is right, because according to that i should push 2800 rpm at 75 in 5th (.85) while i actually push more to the 3300 side.
4th (1:1) at 75 is 3332 while my tach says around 3800.
Can my tach be that far off?
Or have my gears been changed by the PO?
Ill check when ever my new seals get here from man-a-fre.

Thanks for all your help

4.10 x 75 x .85 / 31 x 336 = 2,832rpm's at 75 mph 31's 4.10's

Dang! now I remember.....I used to have the tire size (or was it rpm's??) to miles formula!...It made it real easy to see the difference they made up in ONE mile shocking.


it had pie (3.14) in it and the # feet in a mile IIRC, but its burried in about 100 magazines

 

[WarDamnEagle]

Doh, WDE beat me to it while i was looking for the color codes.

I'm confused by your math. With 31's, assuming you have a 4x4, you're not off by 1/3 on the spedo. Stock 235/75/15's are 28.9" so figure 29" to make the math easier. So one rotation of a 29" tire is 91". One rotation of a 31" tire is 97.34". So we're talking about a 9.3% difference. When you're spedo says 20, you're going 22mph, not 30. To get that far off you'd need 38.5" tall tires. I think that's why you think you're getting that good of mileage. Borrow a GPS and test it. I'm guessing you'll find your a lot closer to the spedo than you think.

That was all good informatiion Jetboy so I don't want to split hairs with you but stock (I think this is on an 84 Hilux) was P225/75R15 which is more like 28.3". OK, maybe I am splitting hairs....

 

[Devil's Slide Doug]

You can buy used factory 3rd members in 4.88 ratio (for cheap) and it will buzz along the highway with 31's or work well with 33"s. I would not bother with 5.29's unless i had a 35" or larger tire.