HOW TO RECALIBRATE THE SPEEDOMETER ON 92-96 FORD F-SERIES AN

birdco85 · Post by **birdco85** » Mon Jan 04, 2016 8:31 am

Shoot 10.19! It's too early

birdco85 · Post by **birdco85** » Mon Jan 04, 2016 9:18 am

Well I did it at 10.19 and when the speedo says 60 the leadnav app says 55-56. But the speedo at 40 the app says 39. It's close but I want it closer. I have 5 more changes but don't want to waste them all on these tires. I may go to 37 in the future

snowman429 · Post by **snowman429** » Thu Feb 04, 2016 11:43 pm

So here's a question, if you have newer (95) knuckles and hubs with the abs ring could you use that for your signal for the speedometer?

birdco85 · Post by **birdco85** » Sun Feb 07, 2016 3:13 pm

That is a great question. I don't think the ratio is there. There probably isn't enough range in the speedo.

snowman429 · Post by **snowman429** » Sun Feb 07, 2016 4:00 pm

After I posted that and got home from work I counted the teeth on the tone ring and with my General grabbers I can up with a conversion constance in the 4's which is to low.

birdco85 · Post by **birdco85** » Mon Feb 08, 2016 3:32 pm

Bummer ,that would have been pretty sweet.

PaulW · Post by **PaulW** » Mon Feb 08, 2016 4:19 pm

subscribed

birdco85 · Post by **birdco85** » Sat Feb 11, 2017 9:23 am

Ok this is driving me crazy. I recounted the vss magnets and there are 29, not 28, my fault. So I did the recalculation and came up with 10.57 for my conversion constant. Now it is even further off, in the neighborhood of 15mph and I'm down to just 2 more adjustments. Previously I was running 10.19 and it was about 10mph off.

If I didn't have the vss kit, my CC should be about 8.1. I have general red letters (594 rotation per mile) currently but will be going to BFG a/t (602 rotations per mile) next so I am doing the calculation off of those. In reality it's only 8 more rotations per mile. I rounded down the BFG to 600 rotations per mile to account for I'm still running the generals, so 600x.0135 = 8.1.

So could someone who is running 4.86 with a vss kit from Hollander or solo and running 35's PLEASE tell me how you calculated it or what your CC is? Please!!!

I'm thinking, since my VSS pings approximately 31% more per rotation, that I need to take about 31% of the difference away from 8.1 and 10.57. So my next guess would be 9.8. Every tire rotation, my vss pings 140.94 (4.86 x 29) times, as opposed to the stock vss at 108 times. So 140.94/108 is 1.305, so if I round up its 31% more per rotation. 10.57 - 8.1 = 2.47. 31% of 2.47 is .765, so .77. Then 10.57 - .77 = 9.8. Wheewwwww!!! How does that math look? My brain hurts...

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birdco85 · Post by **birdco85** » Sat Feb 11, 2017 9:26 am

Or do I add that to the 8.1? Should it be 8.87?

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birdco85 · Post by **birdco85** » Mon Feb 13, 2017 2:26 pm

Someone has to know this. Or is someone able to make me a new tone ring with 22.2222222222222222 notches/magnets? Haha.

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cwrisley · Post by **cwrisley** » Mon Feb 13, 2017 5:24 pm

Carb and C6. Done and done.

VintageIronFab · Post by **VintageIronFab** » Sat Feb 18, 2017 1:13 am

This stupid ass speedo is exactly why people do that very thing! If I have the space in a few more years I'd love a 80 Bronco with all the newer engine goodie, stand alone EFI and a C6! The electronic Speedo is lane!

hollandermotorsports · Wed Mar 01, 2017 10:11 am

birdco85 wrote:Or do I add that to the 8.1? Should it be 8.87?

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Darren did you get this figured out? Or do you you need assistance still? Shoot me a text if you need a hand.

birdco85 · Post by **birdco85** » Sat Mar 04, 2017 8:19 am

Sure didn't. I also haven't driven it since this post

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birdco85 · Post by **birdco85** » Fri Mar 31, 2017 9:39 am

I figured this nonsense out finally. I'm down to one more change on this speedo but it's within 2-3 mph now. If anyone needs help figuring this out, feel free to contact me.

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OldBroncoRacer · Post by **OldBroncoRacer** » Tue Sep 12, 2017 10:25 am

So what did you come up with for the final formula, and answer?