90 gs speedo gear adjustment questions

[RCAmechanic]

So I just bought a 90 eclipse gs and it has a smaller tire than what it had from factory on it. So of course the speedometer is off, are there any sort of speedo gears I can get for this car to make it accurate or is there any way to adjust the speedo to be accurate.

 

[92AWDHX40]

a smaller one any pics mine was the same on my old gs whats wrong with it, check the cable.

 

[RCAmechanic]

Well the speedo reads at 75 when I'm going 65, the cable does make a howling noise at higher speed so I might replace it, where would I get the smaller gear?

 

[92AWDHX40]

I didn't know they made a smaller gear I would call jnz tuning and ask about those parts.

 

[RCAmechanic]

Oh I wasn't sure if they did either .

 

[bryanwheat]

If there is a different gear than you would have to switch the gear inside the transmission also. There isn't much of a solution here other than running the correct diameter tires.

 

[92AWDHX40]

Yeah I just never paid attention to it maybe they do don't know.

 

[RCAmechanic]

Ya I haven't been able to find any others online so they probably don't, thanks for the info, what would the factory diameter be?

 

[1990dsmkid]

Factory size is 205/55 if memory serves me right

 

[RCAmechanic]

Hmmm if so then my speedo may have a different issue cuz I'm running 205/50r16 tires and it seems to make like a 10 mph difference at higher speeds

 

[Paul@RTM]

Just so you know, there aren't different size speedo drive/driven gears to compensate for different tire sizes. You'd need to make custom gears, or get a custom speedometer.

 

[pauleyman]

Well... a 205/55 is not the same diameter as a 205/50. Are you 15 or 16" diameter? Stock is 16.

 

[Mischif]

185/70/r14 would be the stock tire size for a 1g base model, not sure if thats what a gs came with. However since they use the same transmission i would assume it would probably be the same tire for a GS as well. If the driver side door sticker is still intact it will tell you tire size and recommended pressure.

If the speedo is off by that much i would look at the gauge as the suspect. More than likely someone pulled the needle off at one point and didn't put it back on perfect.

 

[RCAmechanic]

Ok good to know about the speedo gears, also I'm running the factory 16 tires but it does seem to be too much of a speed difference cuz at 75 on the speedo its 62 based on the digital sign I checked it with[DOUBLEPOST=1411960167][/DOUBLEPOST]Makes sense the needle does like to vibrate occasionally so that may well be it.

 

[GSLENK]

(1) based on the digital sign I checked it with
(2) Makes sense the needle does like to vibrate occasionally so that may well be it.

(1) IDK why they even put those things on the road. They are TERRIBLY innacurate, ignore it. Download a GPS speedo app on your phone and maintain a constant speed and compare. You shouldn't be too far off.

(2) AFAIK, 1g cars just do that. Mine does. I dont really care. FYI I am on Enkei 17" with a reasonable sidewall, and I am ball park close enough. My car over reads just by a hair, so I like it. I am actually slower that I think helps save me on photo tickets etc...

My friend had a honda with a Euro gauge (only KM/h) He decided to write a speed reference conversion chart and stuck it next to the speedo , you may consider the same. Or buy a husge river speedo from autozone.

 

[RCAmechanic]

I'll have to try the GPS thing and that's good to know that mine isn't the only one that vibrates

 

[pauleyman]

Why would you think you have a different issue? You are not running stock size tires. The diameter is definitely causing a speed difference.

 

[RCAmechanic]

The difference in speed seemed too extreme for the difference in tire size. But I think GSLENK is right about the speed sign not being accurate so it's probably not as far off as I thought