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#1 |
Registered Member
Join Date: May 2001
Location: Antioch, CA 94521
Posts: 181
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![]() I use to have 3.73s but have recently changed to 4.10s. I had the correct speedo gear installed for the 3.73s and it was just right. Now that I have the 4.10s in, it seems to be off about 10mph. Is there even a correct tooth gear for the 4.10s???
Could this problem also make my tach way off too??? Thanks, Tony
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N/A 94 GT vert w/aode...12.19 @110 w1.67 60' Some bolt ons |
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#2 | |
cranky old man
Join Date: Sep 2001
Location: Longview Texas
Posts: 683
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![]() Quote:
I don't see any way that could affect your tach.
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Under Construction: 64 Falcon 372 cu in. stroker 1:72 rod ratio 6.250" rods (long rod), Comp Cams XE274 230/236 520/526 @ .050, Scorpion Rollers, Roush 200 irons, 10:1 Keith Blacks, Hedman long tubes, 750 Holley DP, Edelbrock Victor Jr., C4 3500 stall, gears and tires to be anounced. |
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#3 |
Registered Member
Join Date: May 2001
Location: Antioch, CA 94521
Posts: 181
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![]() Yeah...maybe it's just because it's the stock tach which I guess could be off by a couple hundred rpms...
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N/A 94 GT vert w/aode...12.19 @110 w1.67 60' Some bolt ons |
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#4 |
Registered Member
Join Date: Oct 2003
Location: jacksonville fl.
Posts: 1
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![]() i have 4.10's and was read on another forum that i need a black 6 tooth drive gear for a t-5 and a black 22 tooth speedo gear for t-5.i think you have to pull the trans to replace the gear drive.that is suposed to make it dead on m.p.h. ihave not done this so i cant say if it works that my FYI.
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#5 |
Registered Member
Join Date: Jul 2000
Location: Norman, Oklahoma, USA
Posts: 597
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![]() Best way to do it is to go out on the highway and put your speedo on 60 and time how long it takes to go a mile (use the highway markers). Take the number of seconds it took to go a mile and divide 3600 by that number of seconds (so if it took 63 seconds, you'd have (3600/63) = 57.14. That's how fast you were actually going. so then, take 60 divided by your actual speed and multiply by the number of teeth you actually have on your speedo gear, and that will give you the number of teeth you need. then you can go to ford and ask for a gear with that many teeth. So say your actual speed when your speedo says 60 is 52, and your speedo gear has 21 teeth. you take (60/52) X 21 = 22.15 so the closest you can get to being correct is a 22 tooth speedo gear. Unless you change the drive gear in the tranny like someone said. But, actually, you should be able to take your new rear end gear ratio, divide by your old rear end ratio, and multiply by the number of teeth your speedo gear has, so like (4.10/3.73) X 21 = 23.08 so 23 teeth. See what I mean? Oh, and there's no way that your tach is off because of a rear end gear change. As a matter of fact, when you don't change your speedo gear, but you change your rear end gear, if you just look at the gauges, you won't be able to tell there was a change, because if you used to cruise at 70 in 5th gear at 2500 rpm, it will still say 70mph in 5th gear at that RPM. Untill you change your speedo gear. If you have any more questions, just ask me.
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Michael Black QuantumMotorsports Norman, OK 1984 LX Hatch 306 w/ TRW forged flat toppers, Comp Cams Magnum 292H, GT40P heads w/ 3 angle valve job, .550 lift springs, Angus Racing Roller Rockers, Weiand Stealth Intake, Holley 4150 650cfm carb, MAC 1 5/8 Long Tubes, Single Chamber Flowmasters, 91' T5 w/ Pro 5.0 shifter, Turbo Coupe 8.8 Rear w/ 3.55 gears, QA1 Motorsports tubular K member, no interior except steering wheel and seat. Coming soon: 6 or 8 point cage, Fuel Cell, Weld Draglites |
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#6 |
Domestic Rice really sucks!
Join Date: Apr 2002
Location: KY
Posts: 973
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![]() You can get a 23 tooth gear for the 4.10's from livernois motorsports. It is like $20.
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#7 |
Registered Member
Join Date: Sep 2002
Location: IL
Posts: 105
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![]() yea the
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89' GT with 5spd Hurst short throw, Keith Black 12:1 comp. pistons, Sealed Power drag racing rings, Fms F303 Cam, Ported and polished upper and lower intake with Ported E7TE heads that contain comp. cam double coiled springs with titainum locks and steel retainers, Fel-Pro Head Gaskets, 9mm ford racing wires, BBK chrome unequal shortys, Power Throttle bodies 70mm, Edlebrock 70mm EGR plate, 15inch K&N, Bassani X-pipe, Flowmaster 40 series, Eibach 1 1/2 lowering springs, Cobra R rims 17X9 with p235 on front and p275 on rear with Falken Zeix tires-RUNNING! |
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#8 |
Registered Member
Join Date: May 2001
Location: Antioch, CA 94521
Posts: 181
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![]() I already have the 23 tooth speedo gear and it's still off. I'm changing my output shaft drive gear today and hopefully that will resolve my speedo problem...
I'm also hoping that this will solve my rev limiter problem too. The chip I have was tuned for 3.73s. Since I put 4.10s in, the car constantly hits the rev limiter at about 5400 rpms. I'm hoping the speedo caused the VSS to not work right and thus made me hit the rev limiter. If not, then I guess I'll have to have the tuner re-check the rev limiter setting on my chip.
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N/A 94 GT vert w/aode...12.19 @110 w1.67 60' Some bolt ons |
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#9 |
Registered Member
Join Date: Aug 2001
Location: Palm Beach Gardens, Florida, USA
Posts: 191
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![]() but maybe it can help someone else...
The correct way to do this is go to Hanlon Motorsports and use their utility to figure out the correct drive AND driven gear, not just putting in a 23-tooth gear. I had mine done and it's within 1mph or so at 60. |
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