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#1 |
Registered User
Join Date: Jan 2002
Location: Rhome, TX
Posts: 209
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speedometer gear size for 3:43 rear end
My speedometer is off about 10 mph, I have an original 3 speed manual transmission. Several years ago i switched out the 4:11 rear end gears for 3:43's so I think that is why my speedometer is off. I found where I can purchase a different transmission speedometer gear but I dont know which one to use for the 3:43 gears. Any ideas on how to figure this out?
The link below is an example of what I am looking for. http://www.classicparts.com/1963-78-...ctinfo/91-930/
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1968 C10 LWB 327 bored 40 over, RHS heads, KB pistons, Eagle rods, Edlebrock carb & intake 1968 C10 flatbed 307 w/ 4 spd manual (dads old ride) 1936 1/2 tn pickup, 400sb 350 turbo (partially restored) 1949 1/2 tn, needs complete restore (future project) 1969 Chevy impala 4 dr no post (wifes future car) 2010 GMC Serria 4x4 crew, leveling kit |
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#2 |
member #16
![]() Join Date: Dec 1999
Location: Yuba City Ca.
Posts: 3,618
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Re: speedometer gear size for 3:43 rear end
Heres a site to calculate gear ratio, tire size, etc for speedo gear size.
http://www.transmissioncenter.net/sp...FQE0xgodER69XQ .
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john http://67-72chevytrucks.com/vboard/showgroups.php board vendors ![]() http://www.flickr.com/photos/1745471...7602865984234/ |
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#3 |
Registered User
Join Date: Jan 2002
Location: Rhome, TX
Posts: 209
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Re: speedometer gear size for 3:43 rear end
Thanks John, this should help me figure it out.
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1968 C10 LWB 327 bored 40 over, RHS heads, KB pistons, Eagle rods, Edlebrock carb & intake 1968 C10 flatbed 307 w/ 4 spd manual (dads old ride) 1936 1/2 tn pickup, 400sb 350 turbo (partially restored) 1949 1/2 tn, needs complete restore (future project) 1969 Chevy impala 4 dr no post (wifes future car) 2010 GMC Serria 4x4 crew, leveling kit |
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#4 |
454 MAKES IT ROAR
Join Date: Jan 2008
Location: Essex, U.K
Posts: 2,701
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Re: speedometer gear size for 3:43 rear end
I'm running a 4.11 rear end, i'm registering about 5-10 mph over depending on overall speed, the gear I have in there has a 39 tooth count and using the calculator I need 44 tooth....but something I didn't realise is....if you need a speedo gear in the 40-45 tooth range as I do then I have to also buy a new housing which is $56 well they can poke it, i'll stick with my 39 tooth and put up with the incorrect reading.
If your reading was correct before the swap Red, that means you may need to change your housing to be able to run the lower tooth count gear.
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Nigel. An American living in a British body. 1971 Chevy Cheyenne 10 454 "In a time of universal deceit, telling the truth becomes a revolutionary act." - George Orwell "When injustice becomes law, resistance becomes duty" - Thomas Jefferson No more pain. 03.12.60 -- 12.28.10 http://www.youtube.com/Eightbanger Last edited by eightbanger; 05-28-2011 at 07:37 PM. |
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#5 |
Registered User
Join Date: Jan 2002
Location: Rhome, TX
Posts: 209
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Re: speedometer gear size for 3:43 rear end
I am running 10 mph under, I suppose it does not matter if it is over or under. I have not taken out the gear in my transmission, is it right where the speedometer connects? How do you change the housing?
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1968 C10 LWB 327 bored 40 over, RHS heads, KB pistons, Eagle rods, Edlebrock carb & intake 1968 C10 flatbed 307 w/ 4 spd manual (dads old ride) 1936 1/2 tn pickup, 400sb 350 turbo (partially restored) 1949 1/2 tn, needs complete restore (future project) 1969 Chevy impala 4 dr no post (wifes future car) 2010 GMC Serria 4x4 crew, leveling kit |
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#6 |
454 MAKES IT ROAR
Join Date: Jan 2008
Location: Essex, U.K
Posts: 2,701
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Re: speedometer gear size for 3:43 rear end
It's a very easy job Red, the housing is the aluminum doohickey that the plastic gear sits in...(see pic) and yes it is where the speedo connects.
Plenty on Ebay..http://shop.ebay.com/i.html?_kw=Spee...ts_Accessories
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Nigel. An American living in a British body. 1971 Chevy Cheyenne 10 454 "In a time of universal deceit, telling the truth becomes a revolutionary act." - George Orwell "When injustice becomes law, resistance becomes duty" - Thomas Jefferson No more pain. 03.12.60 -- 12.28.10 http://www.youtube.com/Eightbanger Last edited by eightbanger; 05-29-2011 at 08:23 AM. |
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