Jump to content
  • Welcome to SAU Community

    Welcome to SAU Community, like most online communities you must register to view or post in our community, but don't worry this is a simple free process that requires minimal information for you to signup. Be apart of SAU Community by signing in or creating an account.

    • Start new topics and reply to others
    • Subscribe to topics and forums to get email updates
    • Get your own profile page, build reputation and make new friends
    • Send personal messages to other members.
    • See fewer ads!

    Consider joining our newsletter for the latest content updates

    Click here to register


Sign in to follow this  
Tumble

M35 Speedo re-calibration to compensate for wheel size

Recommended Posts

I would like to fit a wheel tire combo with a lager than stock diameter. Is it possible / is there a product out there... that would let you either make and adjustment somewhere in nissan data scan, or intercept and adjust the signal coming from the speed sensor - similar to a kph to mph converter, to compensate for the change of wheel size and not affet your speedo or overall trip km...

Share this post


Link to post
Share on other sites

Jaycar used to sell a speedo correction unit - a box inserted in the signal to speedo. But by how much are you going to increase the rolling circumference? Speedos read fast anyway. A small increase may just result in your speedo reading more accurately.

Share this post


Link to post
Share on other sites

Thanks, I'll have a look at Jaycar. Just to confirm, that's an electronics/gizmos shop?

I've not done the actual math, but gaining 2" od would help with ground clearance issues, and arch gap 😂

It would be more to keep the overall kph accurate, I tend to use gps for mph if I need to know the speed I'm traveling

Share this post


Link to post
Share on other sites

2" rolling diameter is a huge change.

You can't do it in the CU data, because the speed signal starts at the speed sensor as a +/-1 volt AC voltage and the speedo head converts it to the pulsed square wave 0-5v signal that everything else in the car uses. Thus you need to fix it in the signal coming from the sensor to the speedo.

Yes, Jaycar is an electronics chain in Australia. Their speedo correction kit should work, but there should also be somewhat freely available equivalents out on the net (in terms of circuit design) and I would imagine that there would have to be Arduino type projectes out there too.

Share this post


Link to post
Share on other sites

Thanks mate, surprised I've never heard of them, but looks like they are in the UK too :)

Will look into Arduino projects as well.. new wheels are quite a long way off but good to know there's a solution(s) out there..

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  



×
×
  • Create New...