Speedometer is still fast after changing speedo gear

[Gasman1979]

I bought the correct gear for my 32” tires with 4.56 gears and dropped it in last night. My Speedo is still 10mph fast. did I miss something? I used the chart posted here on the forum to get the size.

 

[hear]

Everybody is different, but personally, I would have shared with us which speedo gear you used and how you clocked it.

 

[mrblaine]

Everybody is different, but personally, I would have shared with us which speedo gear you used and how you clocked it.

Clocking it in any direction won't change the speed, that only changes whether it spins the sender gear, not how fast it spins it.

 

[mrblaine]

I bought the correct gear for my 32” tires with 4.56 gears and dropped it in last night. My Speedo is still 10mph fast. did I miss something? I used the chart posted here on the forum to get the size.

If the gear was correct, the speedo would be. It isn't so it wasn't.

 

[Gasman1979]

Well that was amazingly helpful !

If the gear was correct, the speedo would be. It isn't so it wasn't.

 

[Gasman1979]

I used the 37 gear. That’s what the chart shared here on the forum recommended for 32” with 4.56. Actual tire size 31.80”

 

[mrblaine]

Well that was amazingly helpful !

Well, it's not like there hasn't been a bazillion threads about this and about how to correctly and simply use the gear calculator to determine your actual tire size. You just need a MPH at a given RPM along with your gearing in the axles. Plug in those numbers and then change the tire size until what you have on the calculator matches what you see on the dash. It won't be 31.8" tires.

 

[mrblaine]

I used the 37 gear. That’s what the chart shared here on the forum recommended for 32” with 4.56. Actual tire size 31.80”

Actual is likely going to be closer about 30.8".

 

[Gasman1979]

Forgive me all knowing

Actual is likely going to be closer about 30.8".

jeep man. I have owned a jeep for all of a month and have never owned a vehicle that’s this old so there’s a distinct learning curve for me here. Give me a scanner and something after 2010 and I’ll tell you anything you wanna know. Really not a need to be a jackass when someone comes on a forum asking for help and trying to gain knowledge. I suppose you came out dry and a jeep expert tho.

I actually measured my tire. Not an educated guess. And I used the chart provided to come to the gear conclusion I did. I was simply asking if there was something i was missing here. I’m sure I’ll figure it out. I always do.

 

[Rubiconned]

I don't change my speedo for nobody!

I thought a little humor might ease tensions.

 

[Apparition]

View attachment 543751

I don't change my speedo for nobody!

I thought a little humor might ease tensions.

And now we know what you look like. Nobody needed to see that.

 

[hear]

Forgive me all knowing


jeep man. I have owned a jeep for all of a month and have never owned a vehicle that’s this old so there’s a distinct learning curve for me here. Give me a scanner and something after 2010 and I’ll tell you anything you wanna know. Really not a need to be a jackass when someone comes on a forum asking for help and trying to gain knowledge. I suppose you came out dry and a jeep expert tho.

I actually measured my tire. Not an educated guess. And I used the chart provided to come to the gear conclusion I did. I was simply asking if there was something i was missing here. I’m sure I’ll figure it out. I always do.

It's just what you get here sometimes.

But to his point, if you put a gear in and you didn't get the correct result, then it stands to reason that the gear is wrong. Read some old threads. He was actually pretty restrained here. ¯\_(ツ)_/¯

But verify the RPM & road speed and back into the tire size using the Grimm Jeeper calculator, and use that to determine what gear you need. I've also that measuring from the ground to the center of the hub and doubling it is a good proxy, but I've never tried it.

 

[TheBoogieman]

I used the 37 gear. That’s what the chart shared here on the forum recommended for 32” with 4.56. Actual tire size 31.80”

You're welcome.

 

[LONGJP2]

Actual tire size 31.80”

How did you come up with that?
A good way to measure is from the center of wheel down to the ground.

 

[mrblaine]

Forgive me all knowing


jeep man. I have owned a jeep for all of a month and have never owned a vehicle that’s this old so there’s a distinct learning curve for me here. Give me a scanner and something after 2010 and I’ll tell you anything you wanna know. Really not a need to be a jackass when someone comes on a forum asking for help and trying to gain knowledge. I suppose you came out dry and a jeep expert tho.

I actually measured my tire. Not an educated guess. And I used the chart provided to come to the gear conclusion I did. I was simply asking if there was something i was missing here. I’m sure I’ll figure it out. I always do.

Well, then that is how you start your post. I don't know shit about Jeep TJs, I fucked this up somehow by not understanding effective tire size and how that affects my speedometer. I used some dumbass chart that I find while searching and failed to search far enough to find the correct way to understand tire size and why my tape measure lied to me.

 

[mrblaine]

It's just what you get here sometimes.

But to his point, if you put a gear in and you didn't get the correct result, then it stands to reason that the gear is wrong. Read some old threads. He was actually pretty restrained here. ¯\_(ツ)_/¯

But verify the RPM & road speed and back into the tire size using the Grimm Jeeper calculator, and use that to determine what gear you need. I've also that measuring from the ground to the center of the hub and doubling it is a good proxy, but I've never tried it.

You just said the exact things I've said, is he going to be grumpy with you too?

 

[Gasman1979]

Well, then that is how you start your post. I don't know shit about Jeep TJs, I fucked this up somehow by not understanding effective tire size and how that affects my speedometer. I used some dumbass chart that I find while searching and failed to search far enough to find the correct way to understand tire size and why my tape measure lied to me.

Lmmfao.

Well, then that is how you start your post. I don't know shit about Jeep TJs, I fucked this up somehow by not understanding effective tire size and how that affects my speedometer. I used some dumbass chart that I find while searching and failed to search far enough to find the correct way to understand tire size and why my tape measure lied to me.

so because I “don’t know shit about keep TJ’s” you feel the need to act like a super douche ? lol. Lookie Sally , just cause I don’t know much about antiquated stone age technology like yourself doesn’t make you superior. It just means you’ve worked on more old shit than me. Bravo. I came here to learn about this old bullshit because I like to tinker and the jeep was cheap. If you can’t add value to the conversation or simply want to have a dick measuring contest hit another thread and leave me the fuck alone. I asked a simple question. “Is there something I’m overlooking”. Sorry you felt the need to make yourself feel special and be an ass. Now bless your heart and have the day you deserve.

 

[Gasman1979]

Well, then that is how you start your post. I don't know shit about Jeep TJs, I fucked this up somehow by not understanding effective tire size and how that affects my speedometer. I used some dumbass chart that I find while searching and failed to search far enough to find the correct way to understand tire size and why my tape measure lied to me.

Lmmfao.

You're welcome.
View attachment 543808

Looks like I miffed and got off on the 4.10 ratio , looks like you pointed out what I was overlooking and without being an asshole. Thank you good sir.

 

[DuckNut]

I bought the correct gear for my 32” tires with 4.56 gears and dropped it in last night. My Speedo is still 10mph fast. did I miss something? I used the chart posted here on the forum to get the size.

I'm not a rocket surgeon but according to Boogiemans chart, you have the wrong gear for 32's. The right gear for 35's. That would explain the 10% provided I am reading the chart correctly.

 

[mrblaine]

Lmmfao.


so because I “don’t know shit about keep TJ’s” you feel the need to act like a super douche ? lol. Lookie Sally , just cause I don’t know much about antiquated stone age technology like yourself doesn’t make you superior. It just means you’ve worked on more old shit than me. Bravo. I came here to learn about this old bullshit because I like to tinker and the jeep was cheap. If you can’t add value to the conversation or simply want to have a dick measuring contest hit another thread and leave me the fuck alone. I asked a simple question. “Is there something I’m overlooking”. Sorry you felt the need to make yourself feel special and be an ass. Now bless your heart and have the day you deserve.

Go read your first post again. You said you bought the correct gear, you didn't. You thought you knew what your tire size is, you don't. That's what you're missing and you are overlooking the actual help to discover how to fix both of those things.