Speedo Gear with 4.10's

rwhite65 · 01-21-2003, 06:53 PM

DO any of you know what gear (how many teeth) I need to make my speedo as accurate as possible with my 4.10 gears. Seems like a while ago, someone told me there was not a gear they could find to correct the difference made witht he 4.10 gears.
Ryan

hobgoblin351 · 01-24-2003, 01:39 PM

Ok so here is the formula: Driven gear teeth= Drive gear teeth x Axle Ratio x tire rev. per mile /1000 The drive gear is the one inside the tranny, (there are 2 kinds pink has 6 teeth and the brown has 8) and there are 5,280 feet in a mile measure the circumferance of the tire and divide.

rwhite65 · 01-24-2003, 01:57 PM

I appreciate the help!!!
Ryan

hobgoblin351 · 01-25-2003, 11:29 AM

Ryan I just realized you're running an AOD. I got the formula out of the Mustangs Unlimited Catalog. Thats what I used to get my new spedo gear. The formula is still good. But, when the specified the drive gear teeth(pink or brown) they were probably only talking about the older trannies. c4/c6/fmx You should check to see if they are the same in the new AOD. Somewhere somebody has to have the specs on that. a local tranny shop or ford's part counter. Good luck

rwhite65 · 01-25-2003, 01:29 PM

WEll, I am trying to get an idea of how to get it close to correct. Seems like if you bump the speedo gear 1 tooth up or down, that will get u roughly 3 miles per hour. Maybe to get in the ball park I need to do it the old way, and pull the squad car out of my drive and hit it with the radar. Can't do that til nice weather

thanks for all the help though,
Ryan

01-21-2003, 06:53 PM	#1
rwhite65 Ride Hard Join Date: Oct 2000 Location: Wyoming IL Posts: 1,094	Speedo Gear with 4.10's DO any of you know what gear (how many teeth) I need to make my speedo as accurate as possible with my 4.10 gears. Seems like a while ago, someone told me there was not a gear they could find to correct the difference made witht he 4.10 gears. Ryan __________________ 65 Fastback 91 roller 306, H/C/I AOD-Bauman, PI Stallion, 4.10's and traction loc 04 Grand Cherokee Freedom Edition 79 Ford F-250 4x4 - Restored

01-24-2003, 01:39 PM	#2
hobgoblin351 Registered Member Join Date: Sep 2002 Location: NYC Posts: 245	Ok so here is the formula: Driven gear teeth= Drive gear teeth x Axle Ratio x tire rev. per mile /1000 The drive gear is the one inside the tranny, (there are 2 kinds pink has 6 teeth and the brown has 8) and there are 5,280 feet in a mile measure the circumferance of the tire and divide. __________________ 1970 Stang Conv: en:Boss351 (balanced/blueprinted) mech cam(240*@.050/.540 lift) Scrw in studs/comp cams rllr rkr Mldn valves 2.19in 1.71ex ported polished cc'd hrdnd ex Keith Black FT pistons(10.25/1) Weiand Excellorator manifold Holley700 DP mech 2nds MSD 6 box and Dis Headers/2 1/2 inch duels tr: modified FMX re:9-inch/3.89 limited slip

01-24-2003, 01:57 PM	#3
rwhite65 Ride Hard Join Date: Oct 2000 Location: Wyoming IL Posts: 1,094	thanks I appreciate the help!!! Ryan __________________ 65 Fastback 91 roller 306, H/C/I AOD-Bauman, PI Stallion, 4.10's and traction loc 04 Grand Cherokee Freedom Edition 79 Ford F-250 4x4 - Restored

01-25-2003, 11:29 AM	#4
hobgoblin351 Registered Member Join Date: Sep 2002 Location: NYC Posts: 245	Ryan I just realized you're running an AOD. I got the formula out of the Mustangs Unlimited Catalog. Thats what I used to get my new spedo gear. The formula is still good. But, when the specified the drive gear teeth(pink or brown) they were probably only talking about the older trannies. c4/c6/fmx You should check to see if they are the same in the new AOD. Somewhere somebody has to have the specs on that. a local tranny shop or ford's part counter. Good luck __________________ 1970 Stang Conv: en:Boss351 (balanced/blueprinted) mech cam(240*@.050/.540 lift) Scrw in studs/comp cams rllr rkr Mldn valves 2.19in 1.71ex ported polished cc'd hrdnd ex Keith Black FT pistons(10.25/1) Weiand Excellorator manifold Holley700 DP mech 2nds MSD 6 box and Dis Headers/2 1/2 inch duels tr: modified FMX re:9-inch/3.89 limited slip

01-25-2003, 01:29 PM	#5
rwhite65 Ride Hard Join Date: Oct 2000 Location: Wyoming IL Posts: 1,094	trying to get in the ball park WEll, I am trying to get an idea of how to get it close to correct. Seems like if you bump the speedo gear 1 tooth up or down, that will get u roughly 3 miles per hour. Maybe to get in the ball park I need to do it the old way, and pull the squad car out of my drive and hit it with the radar. Can't do that til nice weather thanks for all the help though, Ryan __________________ 65 Fastback 91 roller 306, H/C/I AOD-Bauman, PI Stallion, 4.10's and traction loc 04 Grand Cherokee Freedom Edition 79 Ford F-250 4x4 - Restored

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