Honda Car Forum

A few decades ago when I worked on cars life was so simple. You had
a speedometer cable attached to a gear in the tranny, and if the
speedometer was wrong, you just changed the number of teeth on the
gear until you were happy with the result. That was then ...

Today I know that some cars use a Digital Ratio Adapter Controller
(DRAC) module to take readings from a sensor, apply some multiplier
value and then send the result on to yet another electronic brain
assembly which uses that value and then displays your speed in your
speedometer / odometer display.

There are even web sites on how you modify them to correct your
speedometer if it's wrong for no reason in particular, or because you
changed your tires / wheels in some non-standard way.

How does it work for Honda? What are the parts that do this
calculation?

-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| cl+at+ncdm+dot+com | Pawtucket RI 02860 |
+-----------------------------------------+

To answer your question I have to ask you a question.

What is your end goal here? What are you trying to do?


"Charles Lasitter" <check.sig4@ddress.com> wrote in message
news:Xns963398746425Cclncdmcom@68.1.17.6...
>A few decades ago when I worked on cars life was so simple. You had
> a speedometer cable attached to a gear in the tranny, and if the
> speedometer was wrong, you just changed the number of teeth on the
> gear until you were happy with the result. That was then ...
>
> Today I know that some cars use a Digital Ratio Adapter Controller
> (DRAC) module to take readings from a sensor, apply some multiplier
> value and then send the result on to yet another electronic brain
> assembly which uses that value and then displays your speed in your
> speedometer / odometer display.
>
> There are even web sites on how you modify them to correct your
> speedometer if it's wrong for no reason in particular, or because you
> changed your tires / wheels in some non-standard way.
>
> How does it work for Honda? What are the parts that do this
> calculation?
>
> -- CL.
>
> +-----------------------------------------+
> | Charles Lasitter | Mailing / Shipping |
> | 401/728-1987 | 14 Cooke St |
> | cl+at+ncdm+dot+com | Pawtucket RI 02860 |
> +-----------------------------------------+

"halo2 guy" <somewhereovethe@rainbow.com> wrote in news:kO-
dnWBqgosB0sXfRVn-uQ@comcast.com:

> To answer your question I have to ask you a question.

> What is your end goal here? What are you trying to do?

Change the speedometer reading, if necessary.

-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| cl+at+ncdm+dot+com | Pawtucket RI 02860 |
+-----------------------------------------+

I have a 96 accord 4 cyl auto vtec and I have the factory service manual.
There is no mention of calibration of this unit that I can find.

Hopefully somebody can answer your question

"Charles Lasitter" <check.sig4@ddress.com> wrote in message
news:Xns9633B9F009034clncdmcom@68.1.17.6...
> "halo2 guy" <somewhereovethe@rainbow.com> wrote in news:kO-
> dnWBqgosB0sXfRVn-uQ@comcast.com:
>
>> To answer your question I have to ask you a question.
>
>> What is your end goal here? What are you trying to do?
>
> Change the speedometer reading, if necessary.
>
> -- CL.
>
> +-----------------------------------------+
> | Charles Lasitter | Mailing / Shipping |
> | 401/728-1987 | 14 Cooke St |
> | cl+at+ncdm+dot+com | Pawtucket RI 02860 |
> +-----------------------------------------+

Charles Lasitter wrote:
> "halo2 guy" <somewhereovethe@rainbow.com> wrote in news:kO-
> dnWBqgosB0sXfRVn-uQ@comcast.com:
>
>
>>To answer your question I have to ask you a question.
>
>
>>What is your end goal here? What are you trying to do?
>
>
> Change the speedometer reading, if necessary.

you shouldnt need to, unless youre going with a completely off the wall
wheel/tire combo.

as it stands now ,your speedo might read up to 10% higher than you
actually drive. bigger wheels/tires will lower that ratio to something
more acceptable.
>
> -- CL.
>
> +-----------------------------------------+
> | Charles Lasitter | Mailing / Shipping |
> | 401/728-1987 | 14 Cooke St |
> | cl+at+ncdm+dot+com | Pawtucket RI 02860 |
> +-----------------------------------------+

SoCalMike <mikein562athotmail@hotmail.com> wrote in
news:K6qdncGk6OiO5MXfRVn-rw@comcast.com:

> you shouldnt need to, unless youre going with a completely off the
> wall wheel/tire combo.

> as it stands now ,your speedo might read up to 10% higher than you
> actually drive. bigger wheels/tires will lower that ratio to
> something more acceptable.

With some auto makers (BMW), that's 10% PLUS 2.4 mph. It means that
you could be doing 50 with the speedometer reading 57.4 mph, and BMW
would decline to fix it because it was "within spec".

I don't know if Honda has the same spec or not, but if my speedometer
were off by more than two miles per hour at that speed, I'd want to
know that it could be adjusted so that the correct speed was shown.

Now I know that the odometer can be reprogrammed to display a
different number of miles (which I'm not so happy about), but I'm not
sure about what can be done for the speedometer.

Now it may turn out that nothing can be adjusted, but I still plan to
get the speedometer checked because I'd like to know my actual speed
even if I can't change it.

-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| cl+at+ncdm+dot+com | Pawtucket RI 02860 |
+-----------------------------------------+

Charles Lasitter wrote:
> SoCalMike <mikein562athotmail@hotmail.com> wrote in
> news:K6qdncGk6OiO5MXfRVn-rw@comcast.com:
>
>>you shouldnt need to, unless youre going with a completely off the
>>wall wheel/tire combo.
>
>>as it stands now ,your speedo might read up to 10% higher than you
>>actually drive. bigger wheels/tires will lower that ratio to
>>something more acceptable.
>
> With some auto makers (BMW), that's 10% PLUS 2.4 mph. It means that
> you could be doing 50 with the speedometer reading 57.4 mph, and BMW
> would decline to fix it because it was "within spec".
>

> Now it may turn out that nothing can be adjusted, but I still plan to
> get the speedometer checked because I'd like to know my actual speed
> even if I can't change it.
>
> -- CL.

That has always been a minor source of irritation for me. In my SOL
VTEC, if the speed limit is 45, I need to drive what appears to be 55 on
my speedo, which is about 5 over the limit plus 5 for the speedo error,
and I've driven right through numerous radar traps like this without
being stopped.

I gave some thought to buying something like one of the below items, but
the $ was always needed elsewhere, and I actually know nothing about how
well either of these works.

http://www.ricks2k.com/products/yellowbox.php

http://www.ntwonline.com/acb/showdet...=1973&CATID=15

When this speedo error is really a problem is when I get in my wife's
Mazda which has a speedo that is a lot closer to right. If I drive *it*
10 over the limit, I'll end up with a ticket. Just have to remember
which car I'm driving.

--

George

http://people.delphiforums.com/gmcc

gmccx <gmccx@notvalid.com> wrote in
newscudnUb7ioCdwMTfRVn-rA@comcast.com:

> I gave some thought to buying something like one of the below
> items, but the $ was always needed elsewhere, and I actually know
> nothing about how well either of these works.

> http://www.ricks2k.com/products/yellowbox.php

> http://www.ntwonline.com/acb/showdet...duct_ID=1973&C
> ATID=15

Dude! Killer info!

If it worked (research needed), it would be much less costly than a
speeding ticket!

-- CL.

+-----------------------------------------+
| Charles Lasitter | Mailing / Shipping |
| 401/728-1987 | 14 Cooke St |
| cl+at+ncdm+dot+com | Pawtucket RI 02860 |
+-----------------------------------------+

Charles Lasitter wrote:
> Now it may turn out that nothing can be adjusted, but I still plan to
> get the speedometer checked because I'd like to know my actual speed
> even if I can't change it.

a GPS would be the best thing to do that, and it makes a neat
map-viewing toy, too.

Charles Lasitter wrote:

<snip>

> Now it may turn out that nothing can be adjusted, but I still plan to
> get the speedometer checked because I'd like to know my actual speed
> even if I can't change it.

What do you mean you can't change it? Just let of the throttle, and the
actual speed will change.

Sorry, couldn't resist.

>
> -- CL.
>
> +-----------------------------------------+
> | Charles Lasitter | Mailing / Shipping |
> | 401/728-1987 | 14 Cooke St |
> | cl+at+ncdm+dot+com | Pawtucket RI 02860 |
> +-----------------------------------------+

--
================================================== =====
A very modest collection of Honda tech info can be found at:
http://www.geocities.com/ng_randolph