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jeepfourlow

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speedo gear
« on: November 16, 2005, 05:36:50 PM »
so i swapped out the 41 tooth gear in my yj today in favor of a 33 tooth gear to make up for the 33" tires i have. got this info from a calculator at http://www.jeeptech.com/javaAps/Speedo.html now i want to know if anyone else with 33" tires has swapped out the gear because im not too sure if it is accurate, seems a little too fast...oh yeah and i think this would be good for FAQ Jeffy
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Offline Jeffy

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speedo gear
« Reply #1 on: November 16, 2005, 06:08:51 PM »
It already is there.  It's under NVG231 since it's a part of the transfer case.

http://www.4bangerjp.com/forums/viewtopic.php?t=447
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jeepfourlow

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speedo gear
« Reply #2 on: November 16, 2005, 06:19:27 PM »
hey but the calculator is different from your chart! which one do i use? 33 or 36?
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Offline Jeffy

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speedo gear
« Reply #3 on: November 16, 2005, 06:22:44 PM »
Well, it sorta depend on the actual height of your tires.  AT's or MT's. PSI and overall weight.

I used the jeeptech chart but it's off a bit when I used it.  I'm using a 35T for my 35's and 4.56's.  It's as much as 4mph off at speeds above 65mph.  I think to go with a 36T or 37T to correct it.
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jeepfourlow

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speedo gear
« Reply #4 on: November 16, 2005, 06:33:20 PM »
well i measured my tires and their actually a stunning 31.5 inches! supposed to be 33.......
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Offline Jeffy

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speedo gear
« Reply #5 on: November 16, 2005, 06:37:02 PM »
Most 33's start off at 32.3-5" or 32.5-6".  This is dependant on AT or MT.  If you can get the speedo to be accurate to about 1-2mph, then you're doing pretty good.
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Offline Jeffy

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speedo gear
« Reply #6 on: November 17, 2005, 01:35:46 PM »
Forgot to ask, what gears do you have?
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jeepfourlow

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speedo gear
« Reply #7 on: November 17, 2005, 07:18:57 PM »
stock gearing, i ordered a 36 tooth gear
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Gearhead2.5

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speedo gear
« Reply #8 on: November 23, 2005, 09:48:32 PM »
Anyone know what speedo drive gear would be appropriate for 33" tires w 4.56 gears ( my 88YJ ) ,   or ........ 33" tires  w/ 4.88 gears( my 94 YJ ) ?

The charts and calculators I've seen are showing different results , I'd like to go buy a couple of drive gears ,  and do this one time only .
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Offline Jeffy

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speedo gear
« Reply #9 on: November 23, 2005, 09:57:40 PM »
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Gearhead2.5

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speedo gear
« Reply #10 on: November 23, 2005, 10:12:37 PM »
Great article , valuable information and good suggestions for upgrade possibilities. The chart shown suggest's I need a 39 tooth and a 41 tooth , however , ........ when using the calculator @ jeeptech.com  , that produces a 37 tooth count and a 40 tooth.

Confirmation of what is going to be best would be nice ,  so I  can arrive at the most accurate results.
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Offline Jeffy

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speedo gear
« Reply #11 on: November 23, 2005, 10:24:14 PM »
Well, if it was me, I'd go with the chart.  Although the Java calc is as accurate as the data you enter.  I've got 35's and 4.56's with a 35T.  It's a bit slow at higher speeds.  Below 60, it's only off by 1-3mph.  At over 70 it's off by 4mph.  It's progessive and not an exact 4 over the whole range.  I should have went with a 37T I think.  My stock is a 41T though.
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Gearhead2.5

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speedo gear
« Reply #12 on: November 23, 2005, 10:46:53 PM »
What I should have done  , .......... Duh ............. I put slip yoke eliminators in both Jeep's this year ,  did I count the gear teeth when I had the drive gears out ? , nope !  . It won't take long to pull them and get a tooth count .

The 88  had 3.54 gears ,  last month I swapped in a pair of Dana 44 axles from an 87 Grand Wagoneer , rebuilt them through out , brake overhaul , 4.56 gears , Detroit locker out back and a Detroit tru trac in the front w / new Warn hubs.  The rims are now six bolt , the old rims w/ 33" tires went on the 94 YJ , which got rebuilt from end to end ( long story , to be discussed later ) . The larger tires kinda killed the power , so.......... I pulled the 4.10's out and the open rear diff , installed a tru trac and 4.88's , front and rear.

I'd like to know what  speedo drive gears I have now ,  I'll check in the next few days , once I know , I'll decide what gears I will buy , maybe one of the gears I already have is the correct tooth count , e.g.  the stock drive gear for the 94 would work in  the 88 , we'll  see , .............
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