Hud vs dic speed difference

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Jan 25, 2017 | 10:51 AM

#21

Corvette_Ed

Race Director

Joined: May 2012

Posts: 15,733

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From: Phoenix area, AZ

Quote:

Originally Posted by MGMDET

If the guy who couldn't drive his C6 because of the ebrake button has a HUD, I think this will send him straight to the for sale section.

Jan 25, 2017 | 10:53 AM

#22

MH663

Burning Brakes

Joined: Jul 2014

Posts: 781

Likes: 84

From: Dayton OH

Quote:

Originally Posted by RicK T

The reason is that the HUD always rounds speeds down by truncating, while the DIC rounds correctly, ie: down if xx.5 or less and up if more than xx.5.

There's your answer fellas.

I believe there are two different types of algorithms used. One by the DIC and one by HUD which causes this issue. Basically the same thing Rick implied. I, being no engineer, can only speculate if that is 100% accurate but I do believe I remember reading it somewhere years ago.

Last edited by MH663; Jan 25, 2017 at 11:01 AM.

Jan 25, 2017 | 11:04 AM

#23

BROCKYJACK

Thread Starter

Burning Brakes

Joined: Dec 2013

Posts: 901

Likes: 45

From: Winter Haven FL

Quote:

Originally Posted by MGMDET

But sleep easy sir, your OCD is completely understandable.

I hope so

Jan 25, 2017 | 11:10 AM

#24

BROCKYJACK

Thread Starter

Burning Brakes

Joined: Dec 2013

Posts: 901

Likes: 45

From: Winter Haven FL

Quote:

Originally Posted by MH663

There's your answer fellas.

Thanks guys. At least there seems to be a plausible explanation and I am not the only one.

Jan 25, 2017 | 11:36 AM

#25

Bob Paris

Safety Car

Joined: Jul 2013

Posts: 4,405

Likes: 3,480

From: Granada Hills CA

Quote:

Originally Posted by extrapilot

At least they are consistently 1 mph off..I can live with that...

Jan 25, 2017 | 02:11 PM

#26

EVRose

Race Director

Joined: Oct 2010

Posts: 14,475

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From: Las Vegas NV

This must be another one of those "improvements" they made after 05. All 3 of my readings match.

Jan 25, 2017 | 02:46 PM

#27

CadVette

Burning Brakes

Joined: Oct 2015

Posts: 1,139

Likes: 108

From: Arlington Texas

Don't worry, be happy. 1 MPH is nothing.

Jan 25, 2017 | 07:48 PM

#28

cclive

Team Owner

Joined: Mar 2008

Posts: 21,502

Likes: 461

From: Southern Utah

Quote:

Originally Posted by MGMDET

If the guy who couldn't drive his C6 because of the ebrake button has a HUD, I think this will send him straight to the for sale section.

My mind immediately went to that intolerable e-brake button too...off to Carmax to turn it in!

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Jan 25, 2017 | 10:19 PM

#29

Kahunah911

Instructor

Joined: Mar 2007

Posts: 194

Likes: 10

From: King George Virginia

Every time I set the cruise I have to take a deep breath and tell myself over and over the 1mph difference is nothing to sweat. It's okay...it's okay.....

Jan 26, 2017 | 09:57 PM

#30

BROCKYJACK

Thread Starter

Burning Brakes

Joined: Dec 2013

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From: Winter Haven FL

Quote:

Originally Posted by Kahunah911

Every time I set the cruise I have to take a deep breath and tell myself over and over the 1mph difference is nothing to sweat. It's okay...it's okay.....

LOL......I feel it

Jan 26, 2017 | 10:19 PM

#31

Vette_DD

Team Owner

Joined: May 2004

Posts: 82,175

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From: McKinney TX

St. Jude Donor '21-'22-'23-'24

One of them rounds up the fraction of a MPH to the next whole number, the other one doesn't. Don't remember which one is which.

Jan 27, 2017 | 02:05 PM

#32

TxLefty

Race Director

Joined: Apr 2014

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From: North Texas

Glad that is settled. Same reason my speedometer reads 1 mph faster than the HUD?

Jan 27, 2017 | 10:04 PM

#33

Bellebuddy1

Instructor

Joined: Aug 2012

Posts: 163

Likes: 6

From: Nashville Arkansas

Same thing with mine. I, too, thought I was the only one.

Jan 27, 2017 | 10:08 PM

#34

rkj427

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From: Washington Township Michigan

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aren't you guys worried that the 1 mph difference will make your odometer readings inaccurate.................

if it is based off the higher reading the miles will accumulate faster....

Jan 28, 2017 | 10:18 AM

#35

BROCKYJACK

Thread Starter

Burning Brakes

Joined: Dec 2013

Posts: 901

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From: Winter Haven FL

Quote:

Originally Posted by rkj427

aren't you guys worried that the 1 mph difference will make your odometer readings inaccurate.................

if it is based off the higher reading the miles will accumulate faster....

Damn you Sir. Had not thought of that now there is one more thing to worry about. Lol

Jan 28, 2017 | 07:06 PM

#36

rsparks64

Melting Slicks

Joined: Oct 2013

Posts: 2,136

Likes: 295

From: Hill Country, Texas

Quote:

Originally Posted by BROCKYJACK

When I set my cruise control, the speed message that shows on the dic is always 1mph faster than the speed displayed on the HUD. Obviously they should be the same. Anybody else notice that? How would you sync them?

Same here on my 08.

Jan 28, 2017 | 07:37 PM

#37

RandallC6

Intermediate

Joined: Jan 2017

Posts: 29

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From: Long Island, NY

Quote:

Originally Posted by rkj427

aren't you guys worried that the 1 mph difference will make your odometer readings inaccurate.................

if it is based off the higher reading the miles will accumulate faster....

The speedo on my '14 Harley Ultra Limited is off 3 MPH at 70 MPH, verified with a GPS and a common complaint on the Harley Forums. IIRC it reads 70 when you're actually doing 67 so it adds mileage on the odometer plus if you follow the odo for service intervals the 5K services are about 4,787 mile services.