Fordmods Logo

Adjusting speed'o on FG 

 

Page 1 of 3 [ 33 posts ] Go to page 1, 2, 3  Next

 
 Post subject: Adjusting speed'o on FG
Posted: Sat Dec 01, 2012 12:27 pm 
Getting Side Ways
Offline

Age: 25

Posts: 1060

Joined: 5th Jan 2011

Gallery: 3 images

Ride: "08 XR6T Ute

Location: Northside - Brisbane
QLD, Australia

Im just about to go pick up a set of 20" rims for my FG, but was wondering if there was a cheap easy way to adjust the speedo to suit the different diameter tyre... or if i will just have to live with it...

cheers in advance for any help...

*CURRENT: Stock XT alloys
Front 215/60R16
-Cir. 2086.6mm
Rear 215/60R16
-Cir. 2086.6mm
*NEW: High Speed AS wheels (black spokes polished lip)
Front 225/35R20
-Cir. 2090.4mm (+0.201%)
Rear 275/35R20
-Cir. 2199.8mm (+5.434%)

Good site to compare tyres... plus gives a list of brands/models to suit that size. handy little online tool to use...
http://www.1010tires.com/tiresizecalcul ... ion=submit

 

_________________

"08 XR6T Ute

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sat Dec 01, 2012 12:48 pm 
Moderator
Offline

Posts: 14513

Joined: 7th Nov 2004

Ride: ford falcon au3 xr8

Location: a shit suburb in sydney
NSW, Australia

nope, only via flash tuner , speedo signal is read via abs sensors/ wheel speed..
and afaik changes made via flash tuner only give you the option to change by diff ratio only not %, i could be wrong though...
Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sat Dec 01, 2012 12:59 pm 
Getting Side Ways
Offline

Age: 25

Posts: 1060

Joined: 5th Jan 2011

Gallery: 3 images

Ride: "08 XR6T Ute

Location: Northside - Brisbane
QLD, Australia

And very dumb question, but read from sensor on the rear wheels right?

Hmm... So with a change of 5% in circumference, at speedo 100/hr I will actually be doing 105km/hr?

Just another excuse to buy a flash tuner :p haha

 

_________________

"08 XR6T Ute

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sat Dec 01, 2012 7:58 pm 
Getting Side Ways
Offline

Age: 37

Posts: 1273

Joined: 30th Sep 2007

Ride: g6e 2009

Location: hiding in the bushes
WA, Australia

i think you have your sums wrong. your proposed rim has on the fronts 225/35r20 and rears of 275/35r20.
yet you show a difference in front to rear circumference. both tyres have the same rolling diameter, all that changes is the width of the tyre. the 225 and 275 numbers are how wide the tyre is. the 35 is the profile, or how high the tyre sits on the rim. the 20 is the diameter rim the tyre goes on.
so you can change from a 17 to an 18 to a 19 without an effect on rolling circumference by opting for a smaller profile.

you will be going from a rim with a diameter of 16 inches and tyre height/profile of 60, to a rim with a diameter of 20 inches but a profile of 35.

using the calculator on their site a 275/35/20 tyre sits 17.272mm higher on the rim than a 225/35/20 tyre, id suggest asking another tyre company......
Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 12:25 am 
Getting Side Ways
Offline

Age: 25

Posts: 1060

Joined: 5th Jan 2011

Gallery: 3 images

Ride: "08 XR6T Ute

Location: Northside - Brisbane
QLD, Australia

Whoops typo, rears are 275/30R20...
But aside from that, isn't the second number (30, 35, etc) a percentage of the tyre width. Eg the profile is 30% of 275mm width? Or have I been dreaming things up lol

 

_________________

"08 XR6T Ute

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 5:41 am 
Fordmods Newbie
Offline

Age: 49

Posts: 18

Joined: 30th Dec 2011

Ride: Falcon BA 2004

Location: Airlie Beach
QLD, Australia

Have a look at this. Mighty car mods did a spot on a cheap way to adjust speedo reading. These guys do some cool s**t... http://www.youtube.com/watch?v=bMs7w72QTVM&feature=plcp
Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 10:43 am 
Getting Side Ways
Offline

Age: 25

Posts: 1060

Joined: 5th Jan 2011

Gallery: 3 images

Ride: "08 XR6T Ute

Location: Northside - Brisbane
QLD, Australia

Those guys have gotten a lot more professional since I last saw them lol

 

_________________

"08 XR6T Ute

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 1:30 pm 
Technical Contributor
Offline
User avatar

Age: 28

Posts: 3705

Joined: 27th Sep 2006

Gallery: 20 images

Ride: ED Falcon

Power: 133 rwkw

Location: Leeton
NSW, Australia

Pretty sure Ford's diagnostic gear has some provision to recalibrate speedos, but this may only be on police enabled vehicles...

That kit wont work because the ABS sensor looks at the tone wheels and then sends the via canbus to the pcm and computer and such... In the data wires it isn't just a square pulse you're modifying like on E series or equivalent...

You are right, first number is the width in mm second is percentage of the width in the side wall and next is the diameter of the rim...

Attachment:
Speedo Calc.xls [24 KiB]
Downloaded 88 times


I just jammed this together real quick... Don't take it as gospel... May have errors in it... But it shows the stages you do to work out tire sizing and then compares it... you sure your tire sizes are right? Massive difference in those tires...

Remember this is perfect world... Tires actually squash with weight on them and the rolling diameter is different from the theoretical diameter and will vary with tire pressure...

The spreadsheet assumes you're doing 100km/hr and then says if you had a GPS and the wheels were in perfect world this is how much real life (copper radar gun) speed change you should expect...

Cheers,
Tim

 

_________________

93 Red ED 5spd Manual Build Thread

Performance: Complete AUII VCT Wiring & Power Train, Pacey Headers, 2.5" Exhaust, Exedy Clutch, DBA Rotors
Visuals: FG XR Wheel, XR Front, 17's, BA 5 Spd Shifter, BA Ghia Window Switches, NL Cluster
Tunes: 8" Pioneer Sub, JBL Speakers, Clarion Double DIN Headunit

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 1:51 pm 
Getting Side Ways
Offline

Age: 25

Posts: 1060

Joined: 5th Jan 2011

Gallery: 3 images

Ride: "08 XR6T Ute

Location: Northside - Brisbane
QLD, Australia

Now I'm all confused... I'm standing in front of the tyres now, so this is what I'm reading off the tyres... No typos...

Fronts 225/35 ZR20 93W Achilles ATR Sport
Pretty much new. Tyre is narrower then rim.
Image

Rears 275/30R20 97Y Dunlop SP Sport Maxx
Pretty much illegal tread. Tyre as wide as the rim.
Image

 

_________________

"08 XR6T Ute

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 2:18 pm 
Getting Side Ways
Offline

Posts: 6166

Joined: 8th May 2007

phatba wrote:
i think you have your sums wrong. your proposed rim has on the fronts 225/35r20 and rears of 275/35r20.
yet you show a difference in front to rear circumference. both tyres have the same rolling diameter, all that changes is the width of the tyre.


wtf man, your completely wrong

to the op, 225mm tyre on a 9"-10" wide rim looks stupid and may even be dangerous. Im wondering do those front wheels even fit properly with the correct sized tyre on there like a 245?
Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 2:26 pm 
Getting Side Ways
Offline

Age: 25

Posts: 1060

Joined: 5th Jan 2011

Gallery: 3 images

Ride: "08 XR6T Ute

Location: Northside - Brisbane
QLD, Australia

Yeah I thought it looked dumb... That's how I bought them though. I didn't put those tyres on...
Thinking of selling the tyres when I take them off to do repairs on the rim. Then putting decent width tyres on. The fronts are narrower then my au xr wheels :/

 

_________________

"08 XR6T Ute

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 2:30 pm 
Getting Side Ways
Offline

Age: 25

Posts: 1060

Joined: 5th Jan 2011

Gallery: 3 images

Ride: "08 XR6T Ute

Location: Northside - Brisbane
QLD, Australia

And yeah need to seriously investigate some guard rolling...

 

_________________

"08 XR6T Ute

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 3:00 pm 
Technical Contributor
Offline
User avatar

Age: 28

Posts: 3705

Joined: 27th Sep 2006

Gallery: 20 images

Ride: ED Falcon

Power: 133 rwkw

Location: Leeton
NSW, Australia

I was more curious about if your sure your 16" tire size is right? I had 225's on my 15's. Seemed a bit skinny. And I second the stretched tire look being gay.

Cheers,
Tim

 

_________________

93 Red ED 5spd Manual Build Thread

Performance: Complete AUII VCT Wiring & Power Train, Pacey Headers, 2.5" Exhaust, Exedy Clutch, DBA Rotors
Visuals: FG XR Wheel, XR Front, 17's, BA 5 Spd Shifter, BA Ghia Window Switches, NL Cluster
Tunes: 8" Pioneer Sub, JBL Speakers, Clarion Double DIN Headunit

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 3:18 pm 
Getting Side Ways
Offline

Age: 25

Posts: 1060

Joined: 5th Jan 2011

Gallery: 3 images

Ride: "08 XR6T Ute

Location: Northside - Brisbane
QLD, Australia

215/60R16 99V Pirelli P7's all round. Yeah they are narrow :/

Well the guy I got them off had a v8 VL and a jdm s13 (I think), the Silvia looked like a full on drift pig. He took these rims off the BA and replaced them with stock 16 skyline rims lol

 

_________________

"08 XR6T Ute

Top
 Profile  
 
 
 Post subject: Re: Adjusting speed'o on FG
Posted: Sun Dec 02, 2012 3:23 pm 
Technical Contributor
Offline
User avatar

Age: 28

Posts: 3705

Joined: 27th Sep 2006

Gallery: 20 images

Ride: ED Falcon

Power: 133 rwkw

Location: Leeton
NSW, Australia

Ahh...

So have you gps'd these wheels at 100km/hr to see if they're over/under? Maybe they're 5km/hr under std?

What's the tire placard say it was fitted with?

Cheers,
Tim

 

_________________

93 Red ED 5spd Manual Build Thread

Performance: Complete AUII VCT Wiring & Power Train, Pacey Headers, 2.5" Exhaust, Exedy Clutch, DBA Rotors
Visuals: FG XR Wheel, XR Front, 17's, BA 5 Spd Shifter, BA Ghia Window Switches, NL Cluster
Tunes: 8" Pioneer Sub, JBL Speakers, Clarion Double DIN Headunit

Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 1 of 3  [ 33 posts ]  Go to page 1, 2, 3  Next

Who is online

Users browsing this forum: No registered users and 21 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

 

 

It is currently Sat Dec 16, 2017 4:55 pm All times are UTC + 11 hours

 

 

(c)2014 Total Web Solutions Australia - Australian Web Hosting and Domain Names