rear end ratio

apk · 09-18-2001, 05:34 PM

I recently changed the rear in my 99 Cobra from the stock 3.27 to a 3.73 ratio. How do I recalibrate the speedometer. The mechanic said the speedo uses a magnetic pickup and not a toothed gear at the transmission. Reprogram the computer???

Rev · 09-18-2001, 06:41 PM

Not being a late model Stang owner, I think you have to get an add-on or programable chip to fix that. Those in the modular forum probably will know.

Rev

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'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

[This message has been edited by Rev (edited 09-18-2001).]

topless tire fryer · 09-19-2001, 02:27 PM

I'm looking at the Saleen powerflash ECM, supposed to be programed to match your gear ratio and add extra HP across the board.

------------------
'95 Chrome Yellow GT ragtop, KN filter charger, Dynomax cat back, Accel plugs and wires, Chromed '95 Cobra R's (bought for $19.95, now 2 are warped!).
http://www.mustangworks.com/cgi-bin/moi-display.cgi?1883

Kevin Price · 09-19-2001, 06:15 PM

Moved to Windsor Power

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SVO siamesed 351 stroked to 417ci,Yates heads, solid roller,Trans King glide and a little blue bottle
of giggle gas. My Car

fiveohpatrol · 09-19-2001, 09:35 PM

find the friendly guy at your ford dealer's service department and ask him if he could do it on the side, i worked at one this summer and a guy there did the exact thing on a 99 cobra, even if you take it in for that it wouldnt be really expensive

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88 Notch, B&M Ripper, 3.73's, Ported E7's, Explorer int. w/ ported lower, pulleys, 1.7RR's, BBK headers, off-road H-pipe, flowmasters, subframes, 65mm TB, March ram air ,MSD coil, U/L control arms, 155lph f/p, Crane Adj.FPR, Nitto drag radials, best 1/4--> 13.76@101.4 on a 2.17 60ft

09-18-2001, 05:34 PM	#1
apk Registered Member Join Date: Sep 2001 Location: Baltimore MD USA Posts: 3	rear end ratio I recently changed the rear in my 99 Cobra from the stock 3.27 to a 3.73 ratio. How do I recalibrate the speedometer. The mechanic said the speedo uses a magnetic pickup and not a toothed gear at the transmission. Reprogram the computer???

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09-18-2001, 06:41 PM	#2
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Not being a late model Stang owner, I think you have to get an add-on or programable chip to fix that. Those in the modular forum probably will know. Rev ------------------ '66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph 1/4 mi. [This message has been edited by Rev (edited 09-18-2001).]

09-19-2001, 02:27 PM	#3
topless tire fryer All show, some go 4 now! Join Date: Jun 2001 Location: Franklin, NH Posts: 175	I'm looking at the Saleen powerflash ECM, supposed to be programed to match your gear ratio and add extra HP across the board. ------------------ '95 Chrome Yellow GT ragtop, KN filter charger, Dynomax cat back, Accel plugs and wires, Chromed '95 Cobra R's (bought for $19.95, now 2 are warped!). http://www.mustangworks.com/cgi-bin/moi-display.cgi?1883

09-19-2001, 06:15 PM	#4
Kevin Price Registered Member Join Date: Jan 1999 Location: Oxford, KS Posts: 935	Moved to Windsor Power ------------------ SVO siamesed 351 stroked to 417ci,Yates heads, solid roller,Trans King glide and a little blue bottle of giggle gas. My Car

09-19-2001, 09:35 PM	#5
fiveohpatrol I'd rather be basketweaving Join Date: Feb 2000 Location: Indianapolis Posts: 2,551	find the friendly guy at your ford dealer's service department and ask him if he could do it on the side, i worked at one this summer and a guy there did the exact thing on a 99 cobra, even if you take it in for that it wouldnt be really expensive ------------------ 88 Notch, B&M Ripper, 3.73's, Ported E7's, Explorer int. w/ ported lower, pulleys, 1.7RR's, BBK headers, off-road H-pipe, flowmasters, subframes, 65mm TB, March ram air ,MSD coil, U/L control arms, 155lph f/p, Crane Adj.FPR, Nitto drag radials, best 1/4--> 13.76@101.4 on a 2.17 60ft