Recalibration Confusion
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Junior User
Joined: Mar 2003
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Recalibration Confusion
Ive searched through the old threads on recalibrating the speedo on my 95 and seemed to understand what I read and how to do it untill I checked out the BFG web-site to get the Revs for my 285/70/15 BFG TA's (not AT's). The number I found there was 675 revs per mile at 45mph. Now these are eqivalent to a 31x11.5x15 and the other posts were saying a number of 816 for the CAL number.
When I checked mine it came up 967CAL and I know that it came stock with 235/75/15 on it. Also the initial "screen" said E 08 6, so it hasnt been messed with before. This then didnt agree with another post that said the stock 235's should have had a 972CAL. Did Ford mess up?
Im confused by this and am unsure how to use the REV's to recalibrate. Please help.
When I checked mine it came up 967CAL and I know that it came stock with 235/75/15 on it. Also the initial "screen" said E 08 6, so it hasnt been messed with before. This then didnt agree with another post that said the stock 235's should have had a 972CAL. Did Ford mess up?
Im confused by this and am unsure how to use the REV's to recalibrate. Please help.
Fleet Mechanic
Joined: Aug 2001
Posts: 1,526
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From: Round Rock, TX
Scroll down in this thread for how to calculate everything:
https://www.ford-trucks.com/forums/s...hreadid=104045
https://www.ford-trucks.com/forums/s...hreadid=104045
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Junior User
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Thanks for the link, thats one I must have missed. This leaves me with 2 questions though
1) How do I find out the number of teeth on my tone ring for my 95 i think it has an 8.8' rearend never been changed so if that was stock (the one given was for an 87 with an 8.8') and
2) Why are my calculation of revs per mile (657) different from those listed on Tire Rack and the BF Goodrich site (675) even if I use their given tire height?
Which should I trust my own or theirs?
1) How do I find out the number of teeth on my tone ring for my 95 i think it has an 8.8' rearend never been changed so if that was stock (the one given was for an 87 with an 8.8') and
2) Why are my calculation of revs per mile (657) different from those listed on Tire Rack and the BF Goodrich site (675) even if I use their given tire height?
Which should I trust my own or theirs?
Fleet Mechanic
Joined: Aug 2001
Posts: 1,526
Likes: 0
From: Round Rock, TX
You have 108 teeth on your tone ring. He meant 87-current year models had 108 teeth.
I'm not sure why your calculations are different. You've still got six changes to lockout; you could always try them both...
I'm not sure why your calculations are different. You've still got six changes to lockout; you could always try them both...
