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help correcting speedo after lift

2K views 15 replies 8 participants last post by  rblprd 
#1 ·
Ok I need help correcting the speedo after a 5.5 lift and going from 30's to 35's
apparently what was thought to be a simple speedo gear swap is turning into a less simple fix alright lets start with what I have now

2006 LJ/TJ unlimited
4.0 straight 6 automatic
dana 30 front, dana 44 rear 3.73 gearing
5.5 RE lift
SYE kit
35x12.5r15's

So the questions
#1 how do I fix the speedometer can I just switch the speedo gear or do I need to use a programmer
#2 should I correct the speedo issue now, or wait till I re-gear to a better gearing 4.10/4.56

thanks in advance
Noah
 
#4 ·
New gears are cheap. I would wait until the regear tho. Keep in mind that the error in your speedo compounds, at 30 mph you might only be 5 mph faster then your current speed, where as 65 mph you might be closer to 10-15 mph faster. Alot of cops don't bite on "it must be the bigger tires sir" anymore, specially with a significant tire size increase. 4wd Hardware has them if you want to order online.
Provelogear thanks are you shure that the 06 LJ still uses the speedo gear to calc the speed because I've had some people say it's off the computer and some off the speedo gear and the shop that I went to tried to swap the speedo like they normally did and either they ordered the wrong speedo twice or theirs a different transfer case in my rig

The Black Sheep

yes I noticed that on the way home after the lift was done I used my Garmin 60csx to check the adjusted speed 25 is the new thirty and 58 is the new 70
 
#3 ·
New gears are cheap. I would wait until the regear tho. Keep in mind that the error in your speedo compounds, at 30 mph you might only be 5 mph faster then your current speed, where as 65 mph you might be closer to 10-15 mph faster. Alot of cops don't bite on "it must be the bigger tires sir" anymore, specially with a significant tire size increase. 4wd Hardware has them if you want to order online.
 
#10 ·
I've got the same exact setup, '06 LJ with 5.5" and 35's, speedo is waaay off.

Here's a chart that might help:
http://www.raingler.com/tech/speedoChart.asp

I went ahead and decided to take the easy route and 'do nothing' until I re-gear, the 4.56 or 4.88 gearing will get things a lot closer and if it still bugs me then it's time for the new speedo gear.

Curious about your 6th gear, does it ever engage anymore after the lift? I've got a manual trans and rarely even get to use mine anymore, only downhill with a tailwind :laughing:
 
#16 ·
I went thru 2 Accuspeeds (first was a return and was fried) 2nd one installed and dialed in easily, and I have a 2nd setting I can use if I get another larger or smaller set of tires and still keep the calibration for my 35s with 4.88s.
 
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