Will ANYTHING correct this speedo/gear combo?

91LXConv · 04-16-2001, 03:43 PM

Well, here's all the pertinent info:
Just swapped stock 2.73's for FMS 3.73's. Ordered and installed purple 21 tooth driven gear for AOD output shaft that appears to be 7 tooth. I say appears because the damn thing is hard to see (may be 8 tooth). This is the correct combo IF the output shaft is 7 tooth. Now I believe it is 8 tooth because speedo is off (reads 75 when it should read 60). I can live with the speedo error but NOT the consequent odometer reading. Using the equation from FMS assuming now that I have an 8 tooth output shaft: I now need a 24 tooth driven gear (no such thing). Is there ANYTHING I can do (I'm not touching the gears, I'm too happy with them!)
Sorry for length, thanks for info!
PS- this is posted on a couple of websites, don't want you to have to reply twice!

------------------
1991 LX 5.0 Convertible:
AOD w/ shift kit, Steeda 3-pc. chassis stiffening kit, 4-pt. AutoPower roll-bar, the K&N, MAC shorties and cat-backs, 3.73's.

go4it · 04-16-2001, 06:48 PM

http://www.charliesmustangs.com/streets7.htm

Check this site out it tells about the gears and transmissions.

------------------
93GT, S-trim (2.95 pulley), SFMU, Stage 2 TFS TW heads, Stage 2 Cobra intake, AFM powerpipe, PRO-M 75mm massair, 75mm throttle body, 42lb.inj. 1 5/8 headers, 2 1/2 h-pipe and exhaust, 2 chamber Flowmasters, 3.55 gears, Ultradyne cam, Elder.timing gears, Black Magic fan, 3 row alum.rad. MSD6al/BTM, MSD coil, MSD shift light, subframe connectors, A-pillar gauges, Pro-5.0 shifter.

Oldschoolpony · 04-16-2001, 08:18 PM

Mustangs unlimited has all kinds of parts for speedo correction. I beleive you'd need the 23 tooth gear. They have it. and the adaptor to change the tooth ratio in the tranny too.
I think 23 tooth works for auto w 3.73's and t-5's w 4.10's

[This message has been edited by Oldschoolpony (edited 04-16-2001).]

[This message has been edited by Oldschoolpony (edited 04-17-2001).]

04-16-2001, 03:43 PM	#1
91LXConv Registered Member Join Date: Feb 2001 Location: Pensacola, FL, USA Posts: 36	Will ANYTHING correct this speedo/gear combo? Well, here's all the pertinent info: Just swapped stock 2.73's for FMS 3.73's. Ordered and installed purple 21 tooth driven gear for AOD output shaft that appears to be 7 tooth. I say appears because the damn thing is hard to see (may be 8 tooth). This is the correct combo IF the output shaft is 7 tooth. Now I believe it is 8 tooth because speedo is off (reads 75 when it should read 60). I can live with the speedo error but NOT the consequent odometer reading. Using the equation from FMS assuming now that I have an 8 tooth output shaft: I now need a 24 tooth driven gear (no such thing). Is there ANYTHING I can do (I'm not touching the gears, I'm too happy with them!) Sorry for length, thanks for info! PS- this is posted on a couple of websites, don't want you to have to reply twice! ------------------ 1991 LX 5.0 Convertible: AOD w/ shift kit, Steeda 3-pc. chassis stiffening kit, 4-pt. AutoPower roll-bar, the K&N, MAC shorties and cat-backs, 3.73's.

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04-16-2001, 06:48 PM	#2
go4it Registered Member Join Date: Sep 1998 Location: Wise,Va. Posts: 248	http://www.charliesmustangs.com/streets7.htm Check this site out it tells about the gears and transmissions. ------------------ 93GT, S-trim (2.95 pulley), SFMU, Stage 2 TFS TW heads, Stage 2 Cobra intake, AFM powerpipe, PRO-M 75mm massair, 75mm throttle body, 42lb.inj. 1 5/8 headers, 2 1/2 h-pipe and exhaust, 2 chamber Flowmasters, 3.55 gears, Ultradyne cam, Elder.timing gears, Black Magic fan, 3 row alum.rad. MSD6al/BTM, MSD coil, MSD shift light, subframe connectors, A-pillar gauges, Pro-5.0 shifter.

04-16-2001, 08:18 PM	#3
Oldschoolpony Registered Member Join Date: Mar 2001 Location: Gainsville,Fl Posts: 229	Mustangs unlimited has all kinds of parts for speedo correction. I beleive you'd need the 23 tooth gear. They have it. and the adaptor to change the tooth ratio in the tranny too. I think 23 tooth works for auto w 3.73's and t-5's w 4.10's [This message has been edited by Oldschoolpony (edited 04-16-2001).] [This message has been edited by Oldschoolpony (edited 04-17-2001).]