Can anyone tell me the size of tire my speedo is cal'd for? When I got into the codes (following procedure elsewhere on this board) I came up with "E 08 06" Which tells me that the cal has never been done after factory setting (still have 06 cals remaining). Then when I call up the current cal I get "972CAL".
According to my calculations, that is for approximately a 31" tire. Can anyone confirm that? This doesn't make much sense, since the stock tire is NOT a 31" tire.

 

The 9.72 setting is for P235/75R/15XL/A/S at 720 revs per mile. The setting for 31X10.50's is 9.18 for 680 revs per mile. I have a 95 Bronco and just put on 31's and changed the speedo calibration and it made a huge difference in shifting and performance. Also I had the 9.72 setting in my truck initialy too. Good luck. Ben

 

Thanks for your reply. That's 2 people now that have told me 9.18. I don't understand the number of revs though. isn't the formula:

63360/DiameterX3.14159
(inches in a mile devided by diameterXpi)
that comes out to 650 revs by my calcs....anyway, I'll set it to 9.18 like you said. Thanks again

 

I'm not sure about the formula, I'm just referring to the Ford manual. I have a factory manual for the 95 trucks and Bronco. The tire rev's were just included beside the tire size in the manual, that's why I put it in there, but it's just for info. Good luck, Ben

 

Thanks for your response.

 

what is the method for calculation? I used one that I found in the Ford diesel website,and I came up with a calibration code of 976 for 31x10.50.15 tires.I am wondering if that is correct, because ever since i have done that, the transmission shifts HARD between 1st and 2nd sometimes, not all the time, and I am wondering if this may have something to do with it.
Thanks,
Rich

 

You should change it to 918 if you have 31's. That is the correct ratio from Ford. I guarantee you will see an improvement. Not sure about your formula but I know all diesels came with 16" rims and that could have thrown off your numbers. Remember you are only allowed 6 changes of the speedo calibration. Good luck, Ben

 

976 is definately wrong for 31's. Use 918 like previous responder says...it's on the money.

 

I changed it over to 918, and the hard shifting seems to have gone away now. Never even thought that the CAL# number could've been wrong!!
Thanks to the group AGAIN!
Rich

 

[font size="1" color="#FF0000"]LAST EDITED ON 10-Oct-01 AT 12:54 PM (EST)[/font][p]Perhaps this has been asked before (and forgive me if it has), but how did you guys recalibrate the speedometer? I changed to 265/75s (30.65", pretty close to 31)last year and need to do the same. Would 918 work for these as well? And if so, what do I do to change it?

Thanks,
Cragar

Nevermind!!!!! Found it......

 

Is the terminal 567 just a single wire??

 

It you're talking about the PSOM terminal, yes, it's just one wire

 

Ok where can I find out the info on calibrating my speedo? I have a '96 F-250 could that be part of my hard shift problem???? it has 35's on it and i know that the speedo is off by about 10%.

 

Yes that's probably your problem. 35's are a pretty big jump from stock tire size and will throw off the shift points on the E4OD. Just go to tech articles and there's an article on how to recalibrate your speedo.

 

you can get the revs @ 45 from your tire dealer. it is easy to do i have just done this to my 93... i have not had alot of time to drive it with out the plow on to see how the shifts are but it seems a little better. but here are my numbers for my tires YOKOHAMA GEOLANDER AT+ 31X10.50X15 671 REVS/MILE @ 45 671X.0135 = 9.O6 CALIBRATION # 906