Gears & speedo

da89cup · 01-30-2002, 03:56 AM

I went from 2.73s-4.10s & my speedo went nuts. I installed a white face dash cluster & put all the needles back in the wrong position. But the speedo needle is easy to put back because it has a stopper so I put it in at the stopper. I went to a Ford dealer & they had a book that said exactly which driven gear I needed for my tranny, so I bought the 20 tooth gear & installed it, & it's stilll screwed. I don't know what else to do. My tires are P235/50R15, which are pretty close to the stock P225/60R15. Please help.

vlahos19 · 01-30-2002, 07:15 PM

Dude when you find out the answer to that questoin let me know cause i have been dealing with that s**t for two years now. Good luck.

avbcon12 · 01-30-2002, 07:20 PM

this link will fix your problems....
http://www.hanlonmotorsports.com/t5speedo.asp

take care,
adam

RED92LX50 · 01-30-2002, 10:33 PM

I just ordered 4.10's and I am in a similar situation - I have an 8 tooth drive gear and 19 tooth driven gear in my T5 with 3.08 gears. The 23 tooth driven gear will still put me about 15% off. I sent an e-mail to a Speedometer shop that builds mechanical correction boxes. They quoted me $60 for a new speedometer cable, and $65 for the correction box. I guess you can't just splice your current cable?

The other option is to replace the Drive gear with a 6 tooth gear, and keep the 19 tooth drive gear. That would put me very close with the 4.10's, but apparently changing this Drive gear (at the end of the tailshaft) is a PITA.

So, no easy (or cheap) answers... if anyone can say definitvely the best way to go...please let us know.

todd95GT · 01-31-2002, 05:20 AM

When it was gear time for my '95, it cost more for the disc rear to begin with . It then went from 400 to 600 by the time all was said and done, parts and labor including the gear in the T-5 tailshaft. Supposed to be within 2-3% at that point and right now, I guarantee any factory speedometer at any speed is 2% off anyway.
Not to start a flame war either, but every car, don't care how much or how little, is not 100% accurate from the factory. Too many variances right down to air pressure in the tire that offsets sidewall height that will change a speedometer. Law prohibits the writing of speeding violations for anything under 5mph over the speed limit because of the vehicle manufacturer's admittance that they can not get a speedometer to be perfect and there need be a way to account for that variance in actual speed versus read speed. I have seen cars within one mph or dead on within a certain range, but take the same car at 10mph that read perfectly dead on at 50, and it might be 3% off. No one will ever have a perfect speedometer, it's just impossible.

5ohCOUPE · 01-31-2002, 11:40 AM

20 TOOTH SPEEDO GEAR AND A 7 TOOTH OUTPUT SHAFT GEAR. That will make it perfect. I have 3.73's and i have a 21 tooth speedo gear and a 7 tooth output shaft gear and it is within 1 MPH.

01-30-2002, 03:56 AM	#1
da89cup Registered Member Join Date: Feb 2001 Location: edmonton, alberta, canada Posts: 55	Gears & speedo I went from 2.73s-4.10s & my speedo went nuts. I installed a white face dash cluster & put all the needles back in the wrong position. But the speedo needle is easy to put back because it has a stopper so I put it in at the stopper. I went to a Ford dealer & they had a book that said exactly which driven gear I needed for my tranny, so I bought the 20 tooth gear & installed it, & it's stilll screwed. I don't know what else to do. My tires are P235/50R15, which are pretty close to the stock P225/60R15. Please help. __________________ 89 coupe, 351W, 351W heads, 30lb injectors, 190lph pump, 80 maf, 70 tb, ? cam, cobra upper, gt 40 lower, 4.10s, (14.1@98)

01-30-2002, 07:20 PM	#3
avbcon12 Registered Member Join Date: Jul 2001 Location: West Bloomfield, MI Posts: 391	this link will fix your problems.... http://www.hanlonmotorsports.com/t5speedo.asp take care, adam __________________ 90 GT black/ grey leather ported GT-40 heads w/ 1.7RR, Cobra intake w/ ported lower, 24# injectors, 190LPH pump, 75mm Pro-M MAF, 65mm TB, K&N panel, BBK long tubes, Off road H-pipe, 2 ch. Flowmaster, Black magic fan, Kirban FPR, 180 deg. T-stat, 3.73's, Steeda Tri-Ax, 130 amp alt. Accell 8.8 race wires/cap/rotor, motorcraft plugs, Factory Five suspension, etc etc etc.... http://avbcon12.stangnet.com

01-30-2002, 10:33 PM	#4
RED92LX50 Registered Member Join Date: Aug 1999 Location: Fairfax, VA Posts: 220	I just ordered 4.10's and I am in a similar situation - I have an 8 tooth drive gear and 19 tooth driven gear in my T5 with 3.08 gears. The 23 tooth driven gear will still put me about 15% off. I sent an e-mail to a Speedometer shop that builds mechanical correction boxes. They quoted me $60 for a new speedometer cable, and $65 for the correction box. I guess you can't just splice your current cable? The other option is to replace the Drive gear with a 6 tooth gear, and keep the 19 tooth drive gear. That would put me very close with the 4.10's, but apparently changing this Drive gear (at the end of the tailshaft) is a PITA. So, no easy (or cheap) answers... if anyone can say definitvely the best way to go...please let us know. __________________ 1992 LX 5.0 Convertible Red/Blk Gears, Exhaust, bolt-ons... R.H.C. #51

01-31-2002, 05:20 AM	#5
todd95GT Registered Member Join Date: Aug 2001 Location: Palm Beach Gardens, Florida, USA Posts: 191	PAY THE MONEY When it was gear time for my '95, it cost more for the disc rear to begin with . It then went from 400 to 600 by the time all was said and done, parts and labor including the gear in the T-5 tailshaft. Supposed to be within 2-3% at that point and right now, I guarantee any factory speedometer at any speed is 2% off anyway. Not to start a flame war either, but every car, don't care how much or how little, is not 100% accurate from the factory. Too many variances right down to air pressure in the tire that offsets sidewall height that will change a speedometer. Law prohibits the writing of speeding violations for anything under 5mph over the speed limit because of the vehicle manufacturer's admittance that they can not get a speedometer to be perfect and there need be a way to account for that variance in actual speed versus read speed. I have seen cars within one mph or dead on within a certain range, but take the same car at 10mph that read perfectly dead on at 50, and it might be 3% off. No one will ever have a perfect speedometer, it's just impossible. __________________ Todd Last edited by todd95GT; 01-31-2002 at 11:49 AM..

01-31-2002, 11:40 AM	#6
5ohCOUPE Registered Member Join Date: Sep 2001 Location: ORANGE PARK FL. USA Posts: 208	20 TOOTH SPEEDO GEAR AND A 7 TOOTH OUTPUT SHAFT GEAR. That will make it perfect. I have 3.73's and i have a 21 tooth speedo gear and a 7 tooth output shaft gear and it is within 1 MPH. __________________ 91 LX COUPE, 3.73 gears, 2 1/2 inch H-Pipe, 1 5/8 MAC long tube headers, 73 MM C&L MAF, 70 MM MAC TB, LUNATI cam,1.7 TFS Rockers, TFS Track Heat heads, TFS Track Heat intake, T5 with PRO 5.0 shifter, Griffin aluminum radiator, Fluid Damper, SSM traction bars, 190 GPH in tank fuel pump. And more to come.

01-30-2002, 07:15 PM	#2
vlahos19 Registered Member Join Date: Nov 2001 Location: Laramie, Wy Posts: 8	Dude when you find out the answer to that questoin let me know cause i have been dealing with that s**t for two years now. Good luck.

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