my speedo is off 10 mph can it be adjusted??
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Joined: Aug 2001
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From: Cali
my speedo is off 10 mph can it be adjusted??
is there anyway of dialing in a speedo???
i have 16" eagles and now it reads 70 at 60
can i do something to dial it in?? thanks
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SPEED
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Joined: Jul 1999
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From: Tulsa, OK
If it's off pretty linearly, eg. 10mph off at 10mph, and 10mph off at 60mph, then you can just pull the needle off and place it correctly.
If it's off by a percentage (cumulative?), eg. 10% off due to a gear or tire size change, then only a speedometer gear change can accurately fix it. Or perhaps a specialty shop can specifically calibrate your speedometer (by changing magnets maybe? i dunno).
TCIs website has a calculator that outputs the actual gears' colors that you'd need to calibrate your speedometer.
If it's off by a percentage (cumulative?), eg. 10% off due to a gear or tire size change, then only a speedometer gear change can accurately fix it. Or perhaps a specialty shop can specifically calibrate your speedometer (by changing magnets maybe? i dunno).
TCIs website has a calculator that outputs the actual gears' colors that you'd need to calibrate your speedometer.
Joined: Jul 1999
Posts: 10,950
Likes: 26
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Dont pull the needle off. Its too easy to break it.
If you change tire sizes that much to effect the speedometer, you need to change the speedo gears in the transmission. Whats your tire size and rear end gears now? Automatic or manual?
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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-
If you change tire sizes that much to effect the speedometer, you need to change the speedo gears in the transmission. Whats your tire size and rear end gears now? Automatic or manual?
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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-
Junior Member
Joined: Sep 2001
Posts: 45
Likes: 0
From: South Bend, Indiana
Car: 1985 Trans Am
Engine: 305 TPI
Transmission: 4spd auto
I put 16" eagles on my car and much to my surprise didn't change the speedo at all. How did you determine that you were 10mph off? The most accurate way I know of is hit an interstate or toll road with mile markers. Set the cruise @ 60 and time yourself between mile markers. Should take 1 min.
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1985 Trans Am - 305TPI AT
SLP Cat-Back - Welded subframe conns
misc engine mods
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1985 Trans Am - 305TPI AT
SLP Cat-Back - Welded subframe conns
misc engine mods
Thread Starter
Junior Member
Joined: Aug 2001
Posts: 60
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From: Cali
<font face="Verdana, Arial" size="2">Originally posted by Kevin91Z:
Dont pull the needle off. Its too easy to break it.
If you change tire sizes that much to effect the speedometer, you need to change the speedo gears in the transmission. Whats your tire size and rear end gears now? Automatic or manual?
</font>
Dont pull the needle off. Its too easy to break it.
If you change tire sizes that much to effect the speedometer, you need to change the speedo gears in the transmission. Whats your tire size and rear end gears now? Automatic or manual?
</font>
drove along my buddies mustang
he was reading 60 but i was reading
70 mph..... i have a 5 speed w/ 3.08s
out back.... i gotta figure this prob. out
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SPEED
Joined: Jul 1999
Posts: 10,950
Likes: 26
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
16" eagles does not tell me what tire size you have. 245/50-16? 255/50-16? 235/55-16?
Junior Member
Joined: Sep 2001
Posts: 45
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From: South Bend, Indiana
Car: 1985 Trans Am
Engine: 305 TPI
Transmission: 4spd auto
My point is, how do you know your buddy's speedo is correct? I've got an old state trooper Caprice with a "certified" speedo, however the mile marker method is what I prefer.
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Thread Starter
Junior Member
Joined: Aug 2001
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From: Cali
<font face="Verdana, Arial" size="2">Originally posted by Kevin91Z:
16" eagles does not tell me what tire size you have. 245/50-16? 255/50-16? 235/55-16?</font>
16" eagles does not tell me what tire size you have. 245/50-16? 255/50-16? 235/55-16?</font>
15" eagles 225/50-16 ill try the mile
marker thing though... if i can figure
out how to use the damn cruise C.....
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SPEED
Junior Member
Joined: Apr 2001
Posts: 78
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From: Cleveland, OH
There are plenty of places (I think this site is one of them) that has a program for calculating what speedo gears you need. Do the gear swap and calibrate your speedo as described in previous posts.
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