"AWD OFF" Light

[ZSHO]

Bruce how did you measure your 0-60 in your sig?

Side note: when i drag race pretty much everytime at the end i get "service advance trac " indicator. I restart the car and its fine...ive gone 150mph in the car before and its fine....i think its from brake boosting at the launch that it doesnt like....at the strip is the only time i brake boost

AJ Doing 150mph how long is the Track.?  BTW Please be safe.  Z

No track

I would advise caution but you already know that,please be safe my friend.  Z

 

[Brucelinc]

I have measured 0-60 2 ways.  Using my Aeroforce gauge, I consistently get 3.99 - 4.09.  The number in my sig is from using the Wallace racing calculator.  It bases 0-60 off 1/8 mile time and speed.  Since that number is in the range I see with the gauge, I feel pretty comfortable using it.

I have never had the advance track light come on at the track.  The only time I have ever seen it was when I was deliberately trying to powerslide around on a snowy parking lot.

I am probably a wimp when it comes to brake boosting.  I don't even start until the first yellow light comes on and then only to around 1800 so it is very short and mild.

 

[ajpturbo]

Could be mars for all you know...i could say exactly where and when i did it on a public street...wont hold water if authorities tried to use it as evidence....how would you know i wasnt lying about it?...even if i video recorded it....maybe i flashed the ecu with a really large number for the circumference of the tire scalar making the speedo way off?

I dont think many of the you tube charges stand up...internet gossip

Had a coworker tell me a cop looked at the max speed in his gps ...when u touch the speed box it shows max speed....mine was from the drag strip so if thats true it would be dumb for a cop to use that

 

[askoncemore]

If we are looking at % difference this is what I calculated:

Calculated 2 ways...

--Circumference--
Speedo Error:
Diameter 728mm 744mm
Circumference 2287.1mm 2337.3mm
Poke 82.7mm 82.7mm
Inset 158.7mm 158.7mm
Speedo error 0% -2.15%
Reading at 30mph 30mph 29.35mph
Reading at 60mph 60mph 58.71mph
Ride height gain 0mm 8mm
Arch gap loss 0mm 8mm

--Revs/Mile--

275/40-20: 706/mi
296/40-20: 690/mi
706/690 = 1.0232 = 2.32%


Both of these calculations are under the 3% recommended between front to back.


Any other suggestions for this calculation?



Tire Size 275/40R20
mm inches
Tire
Width 275 10.83
Aspect
Ratio 40 -
Rim
Diameter 508 20.00
Sidewall
Height 110 4.33
Tire
Diameter 728 28.66
Circum-
ference 2286 90.00
Revolutions 437/km 706/m

Tire Size 295/40R20
mm inches
Tire
Width 295 11.61
Aspect
Ratio 40 -
Rim
Diameter 508 20.00
Sidewall
Height 118 4.65
Tire
Diameter 744 29.29
Circum-
ference 2336 91.97
Revolutions 428/km 690/mi

 

[ZSHO]

We will always promote the safety related aspects of driving in this Fine Forum,please lets stick to the Topic posted by the OP,thanks.  Z 

 

[Blackhawk]

We've now seen 3 different numbers for calculations.  I still think it's pretty safe to say it's coming the tire height differences being that's the only recent change you have made..  I'd bring it to the dealer and let them weigh in but I am fairly certain they will say the tires are the issue the second they figure out the height differences.

If we are looking at % difference this is what I calculated:

Calculated 2 ways...

--Circumference--
Speedo Error:
Diameter 728mm 744mm
Circumference 2287.1mm 2337.3mm
Poke 82.7mm 82.7mm
Inset 158.7mm 158.7mm
Speedo error 0% -2.15%
Reading at 30mph 30mph 29.35mph
Reading at 60mph 60mph 58.71mph
Ride height gain 0mm 8mm
Arch gap loss 0mm 8mm

--Revs/Mile--

275/40-20: 706/mi
296/40-20: 690/mi
706/690 = 1.0232 = 2.32%


Both of these calculations are under the 3% recommended between front to back.


Any other suggestions for this calculation?



Tire Size 275/40R20
mm inches
Tire
Width 275 10.83
Aspect
Ratio 40 -
Rim
Diameter 508 20.00
Sidewall
Height 110 4.33
Tire
Diameter 728 28.66
Circum-
ference 2286 90.00
Revolutions 437/km 706/m

Tire Size 295/40R20
mm inches
Tire
Width 295 11.61
Aspect
Ratio 40 -
Rim
Diameter 508 20.00
Sidewall
Height 118 4.65
Tire
Diameter 744 29.29
Circum-
ference 2336 91.97
Revolutions 428/km 690/mi

 

[askoncemore]

Does anyone have the official statement on what is acceptable from Ford on the difference on size from the front/back tires?

Thank you.

 

[ajpturbo]

Does anyone have the official statement on what is acceptable from Ford on the difference on size from the front/back tires?

Thank you.

I would say the official statement is the size listed on the door tag....even though a staggered size has been done before and people have not had problems , i cant see ford saying that any amount of difference would be without consequence

 

[Brucelinc]

I have never heard the difference stated as a percentage.  It is common to warn that if all tires are the same brand and size, a difference in tread depth of more than 3/32 is unacceptable. 

 

[pmezo33]

I have never heard the difference stated as a percentage.  It is common to warn that if all tires are the same brand and size, a difference in tread depth of more than 3/32 is unacceptable.

That's always been my understanding too.  With AWD, I always go same size all around.

 

[askoncemore]

Problem solved..... shaved the rear tires 5/32"
The fronts and rears are within 1% now.
If needed I can run a little less tire pressure in the rear to make up for this.

 

[SHOdded]

:thumb:

 

[askoncemore]

295-40/20 rear 91.5" circumference
275-40/20 front 90" circumference

1.66% difference between front and back.

This is  about half of the recommended difference recommended by Ford of 3%

No worries about putting stress on the drive train now.

 

[cror1]

How did you shave the tires?

 

[askoncemore]

A few racing companies offer it as a service.
I Googled "tire shaving"
None of the large tire companies offer it.

$20/tire

I had them take off 5/32"

 

[cror1]

Interesting, I didn't know that.