which gears

[Dukes69]

I love my 4.88's offroad with my Auto, but on the freeway SUCKS!!! 4.56's would probably do better. You have to take into account what size tire you will stop at. 35's? 37's? There are calculators online that will tell you what your final speed/RPM will be. Find something that works good for you.

Edit: Found one http://www.quiknet.com/~ke6vut/rpmcalc.html

[igofshn]

Those calculators don't work for autos.

[Dukes69]

Originally posted by igofshn
Those calculators don't work for autos.

Prove it

[Trailbst]

IGOFSHN, I already asked you once why not. I have friends with autos that will tell you otherwise for the Freeway.

PROVE IT

When the torque converter isn't slipping on the highway and your tranny is 1:1 or .75:1, and the transfer case is 1:1, different gearing in the axles will make a difference and the calculators can show you different RPMs.

PROVE IT

Erik

[igofshn]

Put your 5 speed in 4th and do 70. Tell me what the rpm's are. My 3 speed at 70 with 35's and 4.10's turns 3000. The calculator says I turn 2700. My speedo is dead on. That's your proof.....

[Dukes69]

Originally posted by igofshn
Put your 5 speed in 4th and do 70. Tell me what the rpm's are. My 3 speed at 70 with 35's and 4.10's turns 3000. The calculator says I turn 2700. My speedo is dead on. That's your proof.....

My Torque converter locks up creating a 1:1 ratio, my trannys 3rd gear is a 1:1 ratio. 1:1 = 1:1. So basically you are saying that your torque converter is effed up, and not locking up? Thus slipping and giving you higher RPMs. At 65 w/ 33's and 4.88's I spin a little over 3k. The calculator says 3232 rpm.

[Trailbst]

So, you're also saying that you're gonna quibble about 300 RPM, and that makes the calculators inaccurate for alll Automatics. That is lame. 300 RPM is nothing, that's a 10% tolerance. Heck, at 55 MPH posted speed limit, you get a guarnateed 10% fudge for speeding.

WHATEVER!!

[igofshn]

This is straight off www.4lo.com , so they are full of it also. They aslo say your rpm's for a 3 speed auto will be higher.

The below table can be used to get a rough idea on gear ratios. The colors represent ideal RPM's at highway speeds (65). For highway cruising and best fuel economy stay towards the yellow (2600 rpm), around town daily driving is color coded green (2800 rpm), and for better towing power or just more 4-low power use the ratios near the red (3100 rpm). These calculations are assuming a manual transmission with a 1:1 ratio. If you drive an automatic your RPMs will be higher, and the opposite is true if you have overdrive (your RPMs will be lower).

Better Gas Mileage Close to Factory Ratio More Power


Gear Ratio
T
i
r
e


D
i
a
m
e
t
e
r
3.31 3.42 3.55 3.73 3.91 4.11 4.27 4.56 4.88 5.13 5.29 5.38 5.71 6.17 7.17

27" 2677 2766 2872 3017 3163 3325 3454 3689 3947 4150 4279 4352 4619 4991 5800
28" 2582 2668 2769 2909 3050 3206 3331 3557 3806 4001 4126 4196 4454 4813 5593
29" 2493 2576 2674 2809 2945 3095 3216 3434 3675 3863 3984 4052 4300 4647 5400
30" 2410 2490 2584 2715 2846 2992 3109 3320 3553 3735 3851 3917 4157 4492 5220
31" 2332 2409 2501 2628 2755 2896 3008 3213 3838 3614 3727 3790 4023 4347 5051
32" 2259 2334 2423 2546 2696 2805 2914 3112 3331 3501 3610 3672 3897 4211 4894
33" 2191 2263 2349 2469 2588 2720 2826 3018 3230 3395 3501 3561 3779 4093 4745
34" 2126 2197 2280 2396 2512 2640 2743 2929 3135 3295 3398 3456 3668 3963 4606
35" 2065 2134 2215 2328 2440 2565 2664 2845 3045 3201 3301 3357 3563 3850 4474
36" 2008 2075 2154 2263 2372 2493 2590 2766 2961 3112 3209 3264 3464 3743 4350
37" 1954 2019 2095 2203 2308 2426 2520 2692 2881 3028 3123 3176 3370 3642 4243
38" 1902 1966 2040 2144 2247 2362 2454 2621 2805 2948 3040 3092 3282 3546 4121
39" 1854 1915 1988 2089 2190 2302 2391 2554 2733 2873 2962 3013 3198 3455 4015
40" 1807 1867 1938 2037 2135 2244 2331 2490 2664 2801 2888 2937 3118 3369 3915
41" 1763 1822 1891 1987 2083 2189 2275 2429 2599 2733 2818 2866 3042 3287 3819
42" 1721 1778 1846 1940 2033 2137 2220 2371 2538 2668 2751 2798 2969 3208 3728
43" 1681 1737 1803 1894 1986 2087 2169 2316 2479 2606 2687 2733 2900 3134 3642
44" 1643 1698 1762 1851 1941 2040 2119 2263 2422 2546 2626 2670 2834 3063 3559

[igofshn]

Originally posted by Trailbst
So, you're also saying that you're gonna quibble about 300 RPM, and that makes the calculators inaccurate for alll Automatics. That is lame. 300 RPM is nothing, that's a 10% tolerance. Heck, at 55 MPH posted speed limit, you get a guarnateed 10% fudge for speeding.

WHATEVER!!

I'm saying they aren't accurate. 300 rpm's is more than one tire size.... The difference between 33's and 35's. You also have said that the auto doesn't give you almost twice the crawl ratio. The torque converter does a lot that the manual isn't capable of. That is one reason a lot of auto drivers don't use the 4-1 tcase. The 2 in combo can sometimes make gears too low.

[Trailbst]

You're ability to read fails you! This is what I posted earlier in this thread, aimed directly at you:

Ok, so we've had this conversation before. I am converted about Autos offroad, and the ability to use the torque converter for limited amounts of time to provide infinite:1 Final gearing.

Ok, there, have a piece of that cake and shut up for a while. It is infinite:1, when you bleed the brakes and buildup RPM in the torque converter, it's not 2:1, and it is for as long as your brakes can take it. I was recently taught by a friend who wheels a BIG cherokee with the AW4. THANKS!

As for the page, I guess you need to quote it some where. I didn't see anywhere that it says it didn't work for the Autos, as a matter of fact, check out this part of the website you linked to:
Transmission ratios

Holy Sh1t!!!! Check that out, he lists the AUTOMATIC transmission in there to use in his calculator.

Next point. Why can't Cops give you a ticket for going 5 MPH over the speed limit?? Do you know?? It's that tolerance factor. They have to give 5 MPH because the factories don't always put out 100% accurate speedometers.

Next, how do you know yours is dead on. Did you put it on a Dyno?? How did you prove that??

Finally, all we did was suggest that a online calculator be used to give a ballpark of what gear he should go to. We never said it was the HOLY BIBLE for figuring it out. Truthfully, unless he goes to a Tranny shop, he won't know. I had a converter built for my speedo on my XJ, he had a cable with a counter that screwed into the speedo gear spot on the transfer case, I drove a mile, and based on the number on the counter, he built a adapter for the gears that I had with the tires that I had. I think it was close but won't say dead on. SH!T, I didn't think of this till just now, WHY do they change the tires on NASCAR so often, YEP they wear, they also get smaller and affect the overall diameter, and thus the speed of the car. MAYBE, your speedo isn't dead on anymore, like you think it is. HMMMM, are your tires brand new, or in the same condition as when you changed the speedo gear, HMMMM.

Lots of variable HUH???

So like we said, if he wants an estimate of what gear to use, try one of the online calculators.


Erik

[igofshn]

We know the ratio is 1-1. Never argued that point. I also said my speedo was dead on, unless my gps is off. I said that it didn't work for autos because it wasn't accurate. Like I said before the difference can be more than one tire size. That's a lot. That's not ballpark. And yes, cops can give you a ticket for going 5 over, but that is part of our discussion.

[Trailbst]

Check this out.

My 3 speed at 70 with 35's and 4.10's turns 3000. The calculator says I turn 2700. My speedo is dead on. That's your proof.....

Ok, check this out from Drivetrain Direct:

With an automatic transmission your rpms will be higher due to slippage in the transmission and the torque converter.

Drivetrain Direct.com
It is in the paragraph under the scale. Last sentence.

There is proof that it will work for Autos.

No, cops can't, that is one that you can fight and win every time, because of the reason I posted!! It is part of the discussion. It shows a tolerance.

[Trailbst]

They do work as an estimate!

[igofshn]

Originally posted by Trailbst
Check this out.



Ok, check this out from Drivetrain Direct:

Drivetrain Direct.com
It is in the paragraph under the scale. Last sentence.

There is proof that it will work for Autos.

No, cops can't, that is one that you can fight and win every time, because of the reason I posted!! It is part of the discussion. It shows a tolerance.

Note that the scale above is based on 65 MPH and a 1 to 1 gear ratio with a manual transmission in 4th gear. With an automatic transmission your rpms will be higher due to slippage in the transmission and the torque converter.

Where does it say it works for autos??????

It says exactly what I have been arguing.

With an automatic transmission your rpms will be higher due to slippage in the transmission and the torque converter.


Don't come to Ca. They do give tickets for 5 over.

[Trailbst]

HMMM, it still doesn't say that it DOES NOT work for Autos, as you originally stated. It says with an auto they will be higher, so it does work. SH!T, what happens, you go over 40, and you can't read?? Last I looked you still had a 1:1 in your auto tranny. It still works for an estimate, which is what Chris and I have been screaming all along. It will just be higher, doesn't say how much higher, but higher. So if YOUR torque converter is slipping more than Chris', then it will be higher than the chart.

I could still fight the ticket in CA and win. Most people are uninformed and therefore just pay the ticket.

Estimate!!!!! That's all! Crimeny, all this casue you think you have to be right, and be 100% correct. Estimate!!!! That's all he needs to get him near where he should be. Estimate!!!!!!

I'm done. Post what you want in response, but I'M DONE. TonkaDave, use a calculator to get an estimate. Then decide where you want to be.

Erik