So, i've had this problem since i bought the truck. The speedometer is 10mph fast.
When i'm doing 35 it says its at 45mph on the speedo.
How do i go about adjusting the speedo?
It's not broken, just, i'm so used to it that when i get into any other vehicle i'm doing 10 over the speed limit.

 

Umm how do you know its off?

 

speed checkers, or a GPS most likely

 

You can also check your speedo on the freeway. Use a watch with second hands, put the car on cruise at 60. You should be able to make it from milepost to milepost in 1 min. If your doing 65, it should be 55 second.

The lower the seconds is takes to reach the mile markers is how much faster your going. The more seconds the slower.

At least that's how my gpa taught me to do it.

 

Did you put different sized tires on it? That's the only way that I can think of, for it to be wrong. I don't think that there's a way to fix it.

 

Your truck came stock with 225/75/15's now you are running 30" Cooper Discoveries?
hmmmmm. Rolliing diameter changed....


try checking your speedo using this link: http://www.4lo.com/calc/gearspeedo.htm

 

just rotate the speedo counter clockwise about 10 degrees. that should line the numbers right up again.

what size tires are you running? i believe stock is P225s. modify tire = modify speed reading. 225/70s are a little smaller circumference than 225/75s, so that could be it right there.

the hard way to recalibrate a speedo if you really want to do it -- is to pull the gauges, separate the clear plastic so you can get to the needle, pry the needle off with a fork, then just barely put it back on. reinstall, test drive and move the needle as necessary, then press back on tightly. it's a beyotch so i don't recommend it. i just did this with my motorcycle, but i was also blacking out the back of the gauge face to eliminate a glare that was irritating me for years.

 

Speedo's off by 10, because i'm 10mph slower than traffic. Plus, when i stop my gauge reads 10mph.
So, at 0, my guage reads 10.
i understand the tire size change in speedo accuracy, but it would only be off by 3-5mph.. and the rate would change. At slower speeds it would be off by less, while at higher speeds off by more.
This thing is off a full 10mph at any speed.

 

pop the needle off and put it on alligning to zero, that simple if it starts off at ten over, sounds like someone tried doing there own speedo work before and didnt align it right

 

that's it?
o.0
no crazy job involving some impossible to find tool from the jungles of south america that calibrates a speedometer?

 

not at all. ive actually done all my own cluster work, that involves complety disassembling it, mine works just fine now, i got it set a little high on purpose though, i got it so it says im doing 65, but actually im doing 60, cause i have a bad case of speeding five over all the time, so it says im doing 70 and actually doing the speed limit, the cops near me are usually right on with speedlimit.

 

https://www.yotatech.com/forums/f116...ite-up-190118/ heres my backlight write up in case you do something like i did, or if you have any questions just ask me.

 

sweet thanks. if i do i'll be sure to PM you.

 

no problem, i like to share the knowledge i actually do know,

 

"Speedo's off by 10, because i'm 10mph slower than traffic. Plus, when i stop my gauge reads 10mph.
So, at 0, my guage reads 10.
i understand the tire size change in speedo accuracy, but it would only be off by 3-5mph.. and the rate would change. At slower speeds it would be off by less, while at higher speeds off by more.
This thing is off a full 10mph at any speed. "

Thats what I was getting at first of all, glad it will not be anything major for you!

 

yeah..
this fix is on the backburner for a while though, i'm burned out on working on this thing and more focused on my CJ2A...
still waiting on that jeep floorpan -.-

 

do you still have a DLX cluster? if so, it may make more sense to swap out for one of those SR5 versions now, than tearing yours open. patrol fleabay for a while or hit up one of our yt'ers for a good deal maybe?

 

i'd love to snag an SR5 gauge, but like i said, my truck is on the backburner atm.