Speedometer issue

[Danabee]

I was transitioning from the 10 to the 30 when a nice Redlands police officer pulled me over for doing 90 MPH, the speedo said 75 (if I was doing 90, then the ole jeep has suprised me one more time). Anyway, anyone know a reputable calibration shop?

[blkTJ]

I'd check out one of those speedo gear charts, then confirm with gps.

[Jerry Bransford]

What size tires are you running and what is your axle ratio? It's a five minute process (just one bolt to remove) to calibrate your own speedometer to dead-nuts on accuracy.

[Danabee]

33's with 3:73's

[cbrazor1]

33's with 3:73's

im preety sure that 32 tooth speedo gear will do the trick you can order it from quadratec online or go to 4 west in colton about 20 bucks

[The-Hurricane]

was the police officer moving or stopped. because if he was moving, their car is supposed to be calibrated once every 30 days, to make their radar and spedo's sync up, got my buddy outta a ticket cause the cop car was like 41 days since last sync

[miguelitojeep97]

yea mine is way outa wack also and I did this gear ratio rpm chart and I really dont think im going this fast on the freeway. http://www.grimmjeeper.com/gears.html
I have a Rubicon transfer case in my TJ with 33 and 48s. I know its super low but im planning on going to 35s. I hate the gears on the fwy but aroun dtown its fun and on the trail its sweeT!

[cbrazor1]

yea i wantto install 4.88 to im running 34s how are they ishould have mine some timein the next week cant wait

[miguelitojeep97]

yea say good bye to speed on the freeway.

also I have had really bad driveline vibes since i got re-geared. I was told that my driveshaft slip yoke has to be re-built. the shaft is like 3yrs old! they want like $200 to fix it. yea right....i bought it all for under $300. I have it disconnet=cted and strapped to my frame for now...looks pretty lame

[cbrazor1]

how does it crawl my jeep aint a daily driver just my toy looking foward to getting them installed

[miguelitojeep97]

it crawls oh so nice and creepy slow. I have a 5 spd with a 4:1 and 48s on 33s and its way low. I can have my foot on the brake and clutch while my hand does the hand throttle and creep up anything. Really fun. Also really nice to have on steep hills when your brakes are not that great.

[Mtbikbob]

I was transitioning from the 10 to the 30 when a nice Redlands police officer pulled me over for doing 90 MPH, the speedo said 75 (if I was doing 90, then the ole jeep has suprised me one more time). Anyway, anyone know a reputable calibration shop?

Here's a link to an earlier discussion. My 2005 has a magnetic pick up for the speedo. Regearing is not the answer for mine. In that thread it tells of the devices you can get to make it right.
Good luck.
BTW, mine speedo runs 33% slower than actual speed.
BobO

http://www.myjeeprocks.com/forums/showthread.php?t=7631

[Mtbikbob]

In the end of that thread 'Polar Bear' makes it all clear..here's what he said.......
Thanks for all the info guys... I wanted to add a little bit of information out there too... I went to the dealer and tried to have the corresponding control unit reprogrammed, unfortunately Jeep didn't think that we would upgrade their wranglers (what where they thinking) and thus you cannot reprogram it for new gear/tire sizes.

So after doing some research, and asking around. I found out that the dakota digital speedo calibrator is not as precise as the SuperLift truespeed. Also, the Superlift module allows you to calibrate your speedo with the turn of a special key instead of DIP switches. Thridly, the Superlift unit has 2 configs you can choose from by simply flicking a switch. This would allow you to run two different sets of tires without having to recalibrate the unit every single time.

Installation takes roughly the same amount of time for both units and the instructions are fairly straight forward (once you pass all the "small print").

As an end result, i purchased the SuperLift true speed and will have it installed by the next wednesday... If anyone is interested i can post my thoughts and opinions of the unit once its done (as in accuracy and the like)

[Jerry Bransford]

33's with 3:73's

You want a 31 tooth speedometer gear (Jeep p/n 52067631) which has been GPS verified as accurate for that tire and gear combination.

Go to http://www.4x4xplor.com/speedo.html for a quick illustrated tutorial on how to install the gear which can be easily done in 5 minutes with nothing more than a 1/2" wrench. The speedometer gear snaps into place so it's an easy job. That webpage also gives a speedometer gear chart that is known accurate. Heaven knows there are many inaccurate speedometer gear charts floating around the internet.

[Danabee]

Thanks to everyone.