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#1 |
Registered User
Join Date: Feb 2005
Location: Carl Junction, Missouri
Posts: 2,061
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speedometer issue
i have bought a new speedo cable and housing, new speedo (the odometer messed up my last one) and i have messed around with the driven gear a few times.
the tires are smaller than original, they're 60 series on 15 inch rims. the transmission is a th350. the speedo drive gear in the transmission was yellow-ish so that means it's a 19 tooth. the driven gear i had was brown-ish and it should be a 18 tooth, i proved it was an 18 tooth because i counted. i bought a natural colored driven gear that is a 19 tooth. with the 18 tooth driven gear my speedo read 10-12 mph too slow with the 19 tooth driven gear my speedo reads 10-12 mph too fast can anyone help me? Last edited by matthufham; 09-18-2006 at 08:11 PM. |
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#2 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: speedometer issue
there's calculators on line .. I'll see if I can find a link, you'll need to know the diameter of your tire. 60 series tells you nothing without the cross section width too.
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#3 |
Registered User
Join Date: Feb 2005
Location: Carl Junction, Missouri
Posts: 2,061
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Re: speedometer issue
275s on the rear, i found one at tci but i couldn't get it to work.. it told me my tire height however is 27.99999 or 28 inches tall
http://www.tciauto.com/tech_info/speedo_gears.htm Last edited by matthufham; 09-18-2006 at 08:21 PM. |
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#4 |
Registered User
Join Date: Sep 2005
Location: 9000' Mountain Man
Posts: 326
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Re: speedometer issue
Use a speedometer adapter. They are available from many sources including eBay.
Last edited by jacobs; 09-18-2006 at 09:55 PM. |
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#5 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: speedometer issue
here's some reading and guidence for gears;
http://www.novaresource.org/speedo.htm |
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#6 | |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: speedometer issue
Since you haven't mentioned your rear gear ratio, I'll assume your truck was originally a small block with automatic...
Quote:
Looking at the chart, there's a few ways to get the 2.21. |
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#7 |
Registered User
Join Date: Feb 2005
Location: Carl Junction, Missouri
Posts: 2,061
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Re: speedometer issue
with my 3.73's i get an answer of 2.69, and the closest match is a 2.71. that calls for a 7 tooth drive gear and a 19 tooth driven gear (which i have). i looked for a 7 tooth drive gear and couldn't find one on tci's website, it went as low as 8 for a gm transmission. what's the deal
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#8 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: speedometer issue
take a look again, they list it there.
You can go to the dealer for these parts still, most places will have them on hand or get them pretty quick. |
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#9 |
Registered User
Join Date: Feb 2005
Location: Carl Junction, Missouri
Posts: 2,061
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Re: speedometer issue
it's on their table that lists the colors designated to their teeth count, but wasn't on the table where you could buy them. i found a 7 tooth drive gear on ebay for a th350 for $8 bucks. i think i'm gonna "buy it now" since it's not too expensive. thanks for the help, i'll keep you updated.
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