310HPS2k

I know somebody else has this problem too!

I have a97 ek hatch, i have an SI cluster from a 00 that i put it in. its a direct plug and play.

But i have notice that the speedometer is off, it shows that its like 5-10 miles over what im going!

one time i had to pull my hatch wit my other car, and while it was reading like 55 on the other car, the hatch showed 45-50.

is this common or something? anything to fix this?

thanks

Targa250R

5mph difference at 55mph is normal. 10mph is not. The Si speedometer is calibrated for 195/55-15 tires. What size are your tires? What car where you comparing it with?

nighttrain33

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Targa250R &raquo;</TD></TR><TR><TD CLASS="quote">5mph difference at 55mph is normal. 10mph is not. The Si speedometer is calibrated for 195/55-15 tires. What size are your tires? What car where you comparing it with?</TD></TR></TABLE>

I don't even think that 5 mph would make a difference. I have 185 14's (stock sidewalls) on my car with an si speedo, and my speedo is right on. With my Sierra, it comes with 265/70/16, and I just got 285/70/16 and it is only about 3 mph off. There is almost no way that you should be more than 5 mph off.

-Shane

nighttrain33

Edit - my speedo on my Sierra is off by just over 3 mph at 65 mph.

-Shane

Targa250R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nighttrain33 &raquo;</TD></TR><TR><TD CLASS="quote">I don't even think that 5 mph would make a difference. I have 185 14's (stock sidewalls) on my car with an si speedo, and my speedo is right on.</TD></TR></TABLE>
A 185/65-14 tire (OEM size for '96-00 Civic with 14" wheels) is almost the exact same overall diameter as a 195/55-15 (23.4" vs. 23.5") and will not make a significant difference in indicated speed vs. ground speed. A 195/50-15 (popular size for 15" wheels on Civics) OTOH will throw off the speedometer reading by 7.5% - that's a difference of 4-5mph @ 60mph.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">With my Sierra, it comes with 265/70/16, and I just got 285/70/16 and it is only about 3 mph off.</TD></TR></TABLE>
A. That is irrelevent.

B. The difference in speed between a 265/70-16 and a 285/70-16 is only 3.6%, which is 2-3mph @ 60mph.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">There is almost no way that you should be more than 5 mph off.</TD></TR></TABLE>
My EM1 with heavily worn 205/50-15 tires would regularly indicate about 4-5mph faster than ground speed at as low as 40mph, verified by police radar signs. The speedo was slightly off to begin with, and the smaller diameter tires threw it off even more.

nighttrain33

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Targa250R &raquo;</TD></TR><TR><TD CLASS="quote">
A 185/65-14 tire (OEM size for '96-00 Civic with 14" wheels) is almost the exact same overall diameter as a 195/55-15 (23.4" vs. 23.5") and will not make a significant difference in indicated speed vs. ground speed. A 195/50-15 (popular size for 15" wheels on Civics) OTOH will throw off the speedometer reading by 7.5% - that's a difference of 4-5mph @ 60mph.


A. That is irrelevent.

B. The difference in speed between a 265/70-16 and a 285/70-16 is only 3.6%, which is 2-3mph @ 60mph.


My EM1 with heavily worn 205/50-15 tires would regularly indicate about 4-5mph faster than ground speed at as low as 40mph, verified by police radar signs. The speedo was slightly off to begin with, and the smaller diameter tires threw it off even more.</TD></TR></TABLE>

You said that the police radar signs usually read incorrectly from a previous conversation we had . But I guess you are right. I didn't really take into account the fact the the difference between 185's and 195's from 265's and 285's would make a difference.

-Shane

Targa250R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nighttrain33 &raquo;</TD></TR><TR><TD CLASS="quote">You said that the police radar signs usually read incorrectly from a previous conversation we had .</TD></TR></TABLE>
Most do seem to read slightly low. I'm guessing my actual ground speed in that instance is about 43. The indicated speed is 45, the radar sign shows 40. I figure about 2% difference from tire size + tread wear (less than 2/32" left at the time), plus another 2% difference for my speedometer being off calibration, then some more difference for the radar sign reading low - all of that can account for up to 5mph.

My point is that there are a lot of factors that can play into this. I'd say up to 5mph variations are normal. More than that is cause for concern.

strictly.business

i wasnt aware that tire width had anything to do with speedometer readings.

Targa250R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by strictly.business &raquo;</TD></TR><TR><TD CLASS="quote">i wasnt aware that tire width had anything to do with speedometer readings.</TD></TR></TABLE>
Read up on tire sizes some time.

http://www.tirerack.com/tires/...id=46

nighttrain33

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Targa250R &raquo;</TD></TR><TR><TD CLASS="quote">
Most do seem to read slightly low. I'm guessing my actual ground speed in that instance is about 43. The indicated speed is 45, the radar sign shows 40. I figure about 2% difference from tire size + tread wear (less than 2/32" left at the time), plus another 2% difference for my speedometer being off calibration, then some more difference for the radar sign reading low - all of that can account for up to 5mph.

My point is that there are a lot of factors that can play into this. I'd say up to 5mph variations are normal. More than that is cause for concern.</TD></TR></TABLE>

I know. I was actually thinking about this the other day when I got the 285's for the truck. According to this link, my speedo should be just over 3 mph off at 65. Then I got to thinking, my tires were almost bald when they were replaced, so that would mean that my speedo was off the to the negative in that case. I mean, I gained over an inch of ground clearance over stock tires with full tread, but I gained even more over tires that were bald!

-Shane

nighttrain33

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by strictly.business &raquo;</TD></TR><TR><TD CLASS="quote">i wasnt aware that tire width had anything to do with speedometer readings.</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Targa250R &raquo;</TD></TR><TR><TD CLASS="quote">
Read up on tire sizes some time.

http://www.tirerack.com/tires/...id=46</TD></TR></TABLE>

But it wouldn't matter depending on what sidewall was used.

-Shane

nighttrain33

Point proven with my 185's (I believe they are 185/65/14), they are taller than when I used to have 205/40/17's. Not by much, but they are taller, even though the width is greater.

-Shane

nighttrain33

Edit, the current wheels are 185/65/14's, and the old, shorter tires were 205/40/17's.

-Shane

strictly.business

i know a little bit about tires.

the 3 digit number is the width, the second number(55) is the percentage of the width and the other is obviously inner diameter.

i dont see how width could have anything to do with a speed reading, only the height change.

Eran

iTrader: (1)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by strictly.business &raquo;</TD></TR><TR><TD CLASS="quote">i wasnt aware that tire width had anything to do with speedometer readings.</TD></TR></TABLE>

Tire width and tire diameter are directly proportional.

195/55/15

195 = 195m wide

55 = 55% of 195mm

15 = 15" wheel diameter

55/15 = 15" + [(55% of 195mm) x 2] = total wheel diameter

Basically, the wider your tire, the taller your wheel, the more your speedo is thrown.

Targa250R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nighttrain33 &raquo;</TD></TR><TR><TD CLASS="quote">Point proven with my 185's (I believe they are 185/65/14), they are taller than when I used to have 205/40/17's. Not by much, but they are taller, even though the width is greater.</TD></TR></TABLE>
Just by theoretical calculations, they have almost the exact same radius (only 0.15mm difference). That's basically "the same."

In actuality, the difference includes a few more factors, including air pressure, sidewall flex, tread depth, and actual molded tire size (which can be significantly different than the rated size sometimes).

nighttrain33

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Targa250R &raquo;</TD></TR><TR><TD CLASS="quote">
Just by theoretical calculations, they have almost the exact same radius (only 0.15mm difference). That's basically "the same."

In actuality, the difference includes a few more factors, including air pressure, sidewall flex, tread depth, and actual molded tire size (which can be significantly different than the rated size sometimes).</TD></TR></TABLE>

I know what you are saying, but I guess I was just trying to say that supposing all factors being equal, wider tire width could be offset by greater sidewall proportions, thus making the overall height equal, or even less than on a tire of greater width.

-Shane

310HPS2k

i doubt this has anything with tires, has ANY of you actually changed our ur gauge cluster with another???

this is really bugging me. and i am not the only one either.

my friend who also owns a civic ek hatch, and many of you know that the ek hatch comes with a stock cluster that has no Tachometer, thats why we upgrade.

I upgraded to the Si cluster from the em1, the only difference between the hatch and the em1 is that one is that mine is a civic hatch and the other being the civic coupe.

ANYWAYS thats being said when me AND my friend upgraded out cluster, it was reading higher than the actual speed.

him being a stock motor and me a jdm h22a

my questions are mainly addressed towards those who ACTUALLY have upgraded their gauge cluster, more importantly, on their ek hatch.

This is a common modification, MANY upgrade their stock to si cluster, cmon now.

let me know thanks

and please no more about the tires, i am rolling on nothing special, just stocks.

strictly.business

the vss sensor in a d series and b series is different, might be an issue.

310HPS2k

Ah, now thats making some more sense to me. I have a H22 in mine..... what should i do about this? any one have any ideas?

Targa250R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 310HPS2k &raquo;</TD></TR><TR><TD CLASS="quote">i doubt this has anything with tires</TD></TR></TABLE>
Ground speed vs. speedometer reading ratio has everything to do with tires.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">and please no more about the tires, i am rolling on nothing special, just stocks.</TD></TR></TABLE>
WHAT SIZE ARE YOUR TIRES? Tell me so that we can eliminate that variable.

310HPS2k

I havent checked but they are borrowed, they are 15s i believe, i will check the exact specs on it tomorrow.

But listen, it was FINE on the same set of wheels, then i putin si cluster, and bam its off. i am telling you it cant be the tires.


ANYONE here upgraded their cluster to Si's??