speedo calibration ???? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bark · 06-23-2012, 11:27 PM

Hello, I recently swapped in a 700 r4 into my 77 stepper. When I hook up the speedo at gps speed of 60mph it is bouncing off the peg....

what kinda gears do I need to put into it, do I need one of those ratio reducer boxes?

I am runnng 3:73 ratio with a 26.6 tall tire 2wd?

king-918 · 06-23-2012, 11:40 PM

Gps?

king-918 · 06-23-2012, 11:46 PM

http://pw2.netcom.com/~gnenad/speedo.html

What I found O_o

**hatzie** · 06-24-2012, 09:14 AM

Look at the table here.
http://www.transmissioncenter.net/sp...__va.htm#700r4

The best options still have @ 1% error.
3.73:1 26.6" DIA tires 15T drive with 42T driven = 0.9% error
3.73:1 26.6" DIA tires 15T drive with 43T driven = 1.5% error
3.73:1 26.6" DIA tires 17T drive with 35T driven & 37.5% slow down ratio box= 0.6% error
3.73:1 26.6" DIA tires 19T drive with 36T driven & 50% slow down ratio box= 0.6% error

85gmcguy · 06-24-2012, 12:13 PM

Quote:

Originally Posted by hatzie

Look at the table here.
http://www.transmissioncenter.net/sp...__va.htm#700r4

The best options still have @ 1% error.
3.73:1 26.6" DIA tires 15T drive with 42T driven = 0.9% error
3.73:1 26.6" DIA tires 15T drive with 43T driven = 1.5% error
3.73:1 26.6" DIA tires 17T drive with 35T driven & 37.5% slow down ratio box= 0.6% error
3.73:1 26.6" DIA tires 19T drive with 36T driven & 50% slow down ratio box= 0.6% error

These guys are really good to deal with. Just got new gears from them, nobody else had them, they are getting harder to find.

06-23-2012, 11:27 PM	#1
bark Registered User Join Date: Jun 2010 Location: Manitoba Posts: 223	speedo calibration ???? Hello, I recently swapped in a 700 r4 into my 77 stepper. When I hook up the speedo at gps speed of 60mph it is bouncing off the peg.... what kinda gears do I need to put into it, do I need one of those ratio reducer boxes? I am runnng 3:73 ratio with a 26.6 tall tire 2wd?

06-23-2012, 11:40 PM	#2
king-918 Registered User Join Date: Nov 2011 Location: Oklahoma City Oklahoma Posts: 1,056	Re: speedo calibration ???? Gps? Attached Images

06-23-2012, 11:46 PM	#3
king-918 Registered User Join Date: Nov 2011 Location: Oklahoma City Oklahoma Posts: 1,056	Re: speedo calibration ???? http://pw2.netcom.com/~gnenad/speedo.html What I found O_o

06-24-2012, 09:14 AM	#4
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,950	Re: speedo calibration ???? Look at the table here. http://www.transmissioncenter.net/sp...__va.htm#700r4 The best options still have @ 1% error. 3.73:1 26.6" DIA tires 15T drive with 42T driven = 0.9% error 3.73:1 26.6" DIA tires 15T drive with 43T driven = 1.5% error 3.73:1 26.6" DIA tires 17T drive with 35T driven & 37.5% slow down ratio box= 0.6% error 3.73:1 26.6" DIA tires 19T drive with 36T driven & 50% slow down ratio box= 0.6% error __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful. Last edited by hatzie; 06-24-2012 at 09:30 AM.



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