[PlatinumZJ]

Over the Easter weekend, instead of going to Moab, I installed a Superlift Truespeed to correct the speedometer, transmission shift points, and odometer due to ovrsize tires. While its true I only have 31's that are only a few % bigger than stock, I could really tell that the larger tires messed up the shift points. Installing the Truespeed fixed that problem.

First I remived the center consol: Snap loose the shifter plate that surrounds the shifter and dissconnect the light bulb on its bottom (1/4 twist and pull). Then remove the 4 phillips screws, then open the center storage box and remove the 2 phillips screws there. Gently lift the consol up from the rear and remove the light bulb for the transfer case lever (1/4 turn and pull). Lift the consol up and finangle the shifter plate through the hole and set the consol aside. You then have this.



the Airbag sensor is next to the parking brake handle here Don't mess with it



I then remove the plastic chair that the shift plate was screwed to it has four 8mm sheet metal screws I used a nut driver. I fed the green and yellow wire from my chosen installation point to the shifter area and drilled a 1/4 inch hole about 1-inch inboard to the head of the sheet metal screw head here.



I had already crawled underneath and found a location to drill the hole and feed the wire thru that wouldn't cause any problems. I wrapped the wires with electrical tape and put sealant on the hole after feeding them thru.

Underneath I found the speed sender on the transfer case (TC) - the white with orange stripe WT/OR.



and I put the yellow and green wires in a spiral sleeve for their own protection. Undo the tape and pull back the sleeve around the wires to the TC and seperate the WT/OR wire. One then cuts the WH/OR wire a couple of inches from the plug and connects the green wire to the plug side and the yellow wire to the harness side



After heat shrinking some tubing and wrapping with electrical tape and several zip ties to keep all the wire from dangling, put the consol back together. I then hooked the black wire to ground on the sheet metal in front of the passenger side floor and hooked the red power wire to the switched power at the 10 amp radio fuse in the fuse center in the passenger floor area (fuse 1) with the supplied connector.


After following the directions for programming the unit the Jeep shift much better.

[Nick ZJ]

Looks good. I wish I had some money to do that. How much did that cost you?

[PlatinumZJ]

I found the truespeed for about $187 delivered (new) and about 3-hrs install time.

http://www.4wheelerssupply.com/catalog/product_info.php?ref=860&products_id=1762&affiliat e_banner_id=1&gclid=CM-Ls863t4QCFTaWJAodvnnUCw

[J's02Overland]

Nice write up!!! Good idea too. I will have to consider that when I finally get to get bigger!!

[dpierson]

Something about this post seems sticky...

Hunter? Woody? Bueller?

Nice little write up!

[SteelBlue_WJ]

I figured out that most MPG estimates are throw off from speedo inconsistancies

[dpierson]

Related question that I don't know the answer to:

Would a new speedo gear not accomplish the same thing? Or does that occur only on certain years of the ZJ?

[anticrombie]

Originally Posted by dpierson

Related question that I don't know the answer to:

Would a new speedo gear not accomplish the same thing? Or does that occur only on certain years of the ZJ?

That's what I wanna know. They're really cheap at the dealership, and you can get one for the exact setup you have.

[Reswob]

Originally Posted by anticrombie

That's what I wanna know. They're really cheap at the dealership, and you can get one for the exact setup you have.

I don't think that would correct the shift points though, just the speedo and odometer?

[anticrombie]

Originally Posted by Reswob

I don't think that would correct the shift points though, just the speedo and odometer?

But the speedo gear is what calibrates the shift points. What do you think this box that goes in between the computer and the speedo gear does?

[PlatinumZJ]

True, a new speedo gear would accomplish the same thing. If I could figure out which one to get.

The "31s" i have arn't exactly 31 the published size is about 30.4 but what does it actually measure. The OEM tires are 225/70 R16, which calculates to 28.4 but what is it actually? So far, I've measured tires (but its hard to figure out what the actual diameter is - I haven't been able to measure the diameter twice and get the same answer) and programmed the truspeed.

The first try was off by about 2.5 mph when compared to GPS speed on a straight level road over about a mile (actual speed slower than dash reading). Reprogramming the truspeed takes about two minutes. After reprogramming again, I'm off by 1.5 mph - I should be able to zero in on the next try.

At least it shifts better.

[Texas ZJ1]

I took care of it.


It is in the Faqs.


Hunter

[JamesEric]

I have 31's on my '94 ZJ and the speedo is off by 3mph at highway speeds compared to my GPS with the the speedo gear for 31's installed. TruSpeed seems like a better way to go. Great write-up.

[Colorado 5.9]

First of all It's a great writeup!!!!! If I had a WJ I would be all over it.

Now for being negative. I can't see doing this on a ZJ. A big waist of money IMO. $12 V's $189. There are plenty of speedo gear calculators on the internet that work just fine. I've alway used the one on JU & never had any problems. My shift points have never been a problem either. If you want to adjust the shift point just adjust the kick down cable.

http://www.jcj.net/dodgeram/trans_adjustment.htm

[Virmagicus]

very nice writeup I beleive this mod will get you more precise shifts versus the speedo with your setup.