Speedometer reading questions

gumpy · 03-04-2010, 05:04 PM

Hi

Just wanted to know two things about the speedo reading.

1. The speed is taken off the front tyres right?
2. How much does the Z speedo overestimate the actual speed?

thanks

vipor · 03-04-2010, 05:09 PM

It's taken from the transmission.

Mine seems accurate within 1-2 mpg when I pass some of those signs. 30-60mph range when I see them depending on where.

gumpy · 03-04-2010, 05:12 PM

Quote:

Originally Posted by vipor

It's taken from the transmission.

Mine seems accurate within 1-2 mpg when I pass some of those signs. 30-60mph range when I see them depending on where.

You sure it's from the transmission? Because wouldn't that mean that when you get rear wheel spin the speedo should fly up?

As I've never done a burnout i dont know if this happens or not. But thought the most accurate reading would be off the non-powered wheel.

Jeffblue · 03-04-2010, 05:17 PM

Quote:

Originally Posted by gumpy

You sure it's from the transmission? Because wouldn't that mean that when you get rear wheel spin the speedo should fly up?

Yea i am pretty sure when you get wheel spin the speedo should fly up

gumpy · 03-04-2010, 05:18 PM

hmm ok...

hmm... damn...

PapoZalsa · 03-04-2010, 10:14 PM

Quote:

Originally Posted by Jeffblue

Yea i am pretty sure when you get wheel spin the speedo should fly up

KillerBee370 · 03-04-2010, 10:36 PM

According to my GPS, my speedo is 1 mph fast.

gumpy · 03-05-2010, 12:40 AM

Quote:

Originally Posted by PapoZalsa

So where is the reading taken from?

I'm considering putting tyres with a larger RR on my rear to give it the effect of higher gearing but won't do so if it'll change teh speedo... doing to be doing some sydney to melbourne trips soon.

Vegitto-kun · 03-05-2010, 04:03 AM

Quote:

Originally Posted by PapoZalsa

um as far as I know this was true with my megane

when it was spinning its front wheels on the ice the speedo flew up in the air

rcm2525 · 03-05-2010, 06:18 AM

OK Guys...This is a legit question for those that might change tire sizes.
Also can the speedo be re-calibrated and if so how.

vipor · 03-05-2010, 08:22 AM

I've never heard of a car that uses an individual wheel for the speedo sending unit. Not saying it doesn't exist, but I've never heard of it.

rcm2525 · 03-05-2010, 08:26 AM

Ok so it's taken from the trans. Now can the speedo be re-calibrated and if so how.

vipor · 03-05-2010, 08:31 AM

I'm sure it's computer controlled. In older transmissions there was a gear/sprocket you would change to get as close as possible, but I bet it's a little more exact now.

vipor · 03-05-2010, 08:35 AM

Maybe this:

Universal Speedometer Signal Interface

rcm2525 · 03-05-2010, 10:26 AM

That's great thanks Vipor. There are even some on ebay for a little less money and free shipping.

03-04-2010, 05:04 PM	#1 (permalink)
gumpy Enthusiast Member Join Date: Oct 2009 Location: Sydney Posts: 449 Drives: 09 370z white manual Rep Power: 16	Speedometer reading questions Hi Just wanted to know two things about the speedo reading. 1. The speed is taken off the front tyres right? 2. How much does the Z speedo overestimate the actual speed? thanks

03-04-2010, 05:09 PM	#2 (permalink)
vipor A True Z Fanatic Join Date: Aug 2009 Location: Euless, TX [ DFW ] Age: 43 Posts: 13,531 Drives: Nismo 09-0183 QAB Rep Power: 49	It's taken from the transmission. Mine seems accurate within 1-2 mpg when I pass some of those signs. 30-60mph range when I see them depending on where. __________________ 2009 NISMO # 0193 \| QAB \| Albums! \| 05.04.10 (Dynojet) 291.94hp/248.28tq Oil Cooler (DIY) \| Custom Headlights \| GTSPEC Braces \| F.I. Long Tube Headers

03-05-2010, 06:18 AM	#10 (permalink)
rcm2525 Base Member Join Date: Oct 2009 Location: Mountains of VA Posts: 133 Drives: 370z NISMO PG #0260 Rep Power: 16	OK Guys...This is a legit question for those that might change tire sizes. Also can the speedo be re-calibrated and if so how. __________________ ____ "To live outside the law you must be honest" - B.D.

03-05-2010, 08:22 AM	#11 (permalink)
vipor A True Z Fanatic Join Date: Aug 2009 Location: Euless, TX [ DFW ] Age: 43 Posts: 13,531 Drives: Nismo 09-0183 QAB Rep Power: 49	I've never heard of a car that uses an individual wheel for the speedo sending unit. Not saying it doesn't exist, but I've never heard of it. __________________ 2009 NISMO # 0193 \| QAB \| Albums! \| 05.04.10 (Dynojet) 291.94hp/248.28tq Oil Cooler (DIY) \| Custom Headlights \| GTSPEC Braces \| F.I. Long Tube Headers

03-05-2010, 08:26 AM	#12 (permalink)
rcm2525 Base Member Join Date: Oct 2009 Location: Mountains of VA Posts: 133 Drives: 370z NISMO PG #0260 Rep Power: 16	Ok so it's taken from the trans. Now can the speedo be re-calibrated and if so how. __________________ ____ "To live outside the law you must be honest" - B.D.

03-04-2010, 05:18 PM	#5 (permalink)
gumpy Enthusiast Member Join Date: Oct 2009 Location: Sydney Posts: 449 Drives: 09 370z white manual Rep Power: 16	hmm ok... hmm... damn...

03-04-2010, 10:36 PM	#7 (permalink)
KillerBee370 A True Z Fanatic Join Date: Mar 2009 Location: So Cal baby! Age: 52 Posts: 5,964 Drives: with passion Rep Power: 322	According to my GPS, my speedo is 1 mph fast.

03-05-2010, 08:31 AM	#13 (permalink)
vipor A True Z Fanatic Join Date: Aug 2009 Location: Euless, TX [ DFW ] Age: 43 Posts: 13,531 Drives: Nismo 09-0183 QAB Rep Power: 49	I'm sure it's computer controlled. In older transmissions there was a gear/sprocket you would change to get as close as possible, but I bet it's a little more exact now. __________________ 2009 NISMO # 0193 \| QAB \| Albums! \| 05.04.10 (Dynojet) 291.94hp/248.28tq Oil Cooler (DIY) \| Custom Headlights \| GTSPEC Braces \| F.I. Long Tube Headers

03-05-2010, 08:35 AM	#14 (permalink)
vipor A True Z Fanatic Join Date: Aug 2009 Location: Euless, TX [ DFW ] Age: 43 Posts: 13,531 Drives: Nismo 09-0183 QAB Rep Power: 49	Maybe this: Universal Speedometer Signal Interface __________________ 2009 NISMO # 0193 \| QAB \| Albums! \| 05.04.10 (Dynojet) 291.94hp/248.28tq Oil Cooler (DIY) \| Custom Headlights \| GTSPEC Braces \| F.I. Long Tube Headers

03-05-2010, 10:26 AM	#15 (permalink)
rcm2525 Base Member Join Date: Oct 2009 Location: Mountains of VA Posts: 133 Drives: 370z NISMO PG #0260 Rep Power: 16	That's great thanks Vipor. There are even some on ebay for a little less money and free shipping. __________________ ____ "To live outside the law you must be honest" - B.D.

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