1985 Supra speedometer 20MPH over what it should be

chrismc410 · 09-17-2005, 02:01 AM

Hi

I bought a 1985 Supra recently and discovered that the speedometer is 20MPH over what it should be. For example, if it says 40MPH, you're doing 20MPH and 85MPH, you're doing 65MPH. Its a manual transmission, as far as I know, the orginal, I've tried a new gauge cluster, same thing. I"m told I might need a gear to slow the cable down, but I have no idea what cable I need or how to find it. I'm told there are five possible gears. As far as I know, the car is stock, engine, wheels match exactly what the glove box says, so what can be done and who can do this kind of work?

Thanks

tonster · 09-17-2005, 02:20 AM

When you're just sitting does it read 20 mph? The instrument cluster analog or digital? It could just be that you need to reset the zero on the needle if it's analog and that is the case, otherwise I don't know. If it's digital maybe there's a short adding unwanted voltage somehow? It doesn't make sense that it would always be 20 mph off. I think the speedometer cable hooks directly into the transmission so thats where you would look I'd guess.

chrismc410 · 09-17-2005, 03:22 AM

When stopped, its at zero and its analog 130MPH speedometer

hangsupra · 09-24-2005, 10:13 PM

first of all take out your cluster n turn side way n see if the mph stays at 0 mph or it move back n forth. if it move back n forth then its your speeding metter.... replace with a new one. if it stays the same at 0 mph then its something else. let me know how u get to work.

86supraNa · 10-17-2005, 03:12 AM

i was driveing on the highway going bout80 and a toyota camery was right next seepeding up trying to pass me so i sped up to about 110 and it kept going to about 130 and bounceing i was goina prettyfast but im not sure if i was really going 130 cuz the last time i tryed to top it out it only hit 110 so maybe i got same problem felt more like 115 or 120 though im confussed

but when im going 20mph it says 20mph so i duno

hangsupra · 10-17-2005, 07:16 PM

but now does your speeding metter still working...

Quote:

Originally Posted by 86supraNa

i was driveing on the highway going bout80 and a toyota camery was right next seepeding up trying to pass me so i sped up to about 110 and it kept going to about 130 and bounceing i was goina prettyfast but im not sure if i was really going 130 cuz the last time i tryed to top it out it only hit 110 so maybe i got same problem felt more like 115 or 120 though im confussed

but when im going 20mph it says 20mph so i duno

09-17-2005, 02:01 AM	#1
chrismc410 Stock Join Date: Sep 2005 Posts: 2	1985 Supra speedometer 20MPH over what it should be Hi I bought a 1985 Supra recently and discovered that the speedometer is 20MPH over what it should be. For example, if it says 40MPH, you're doing 20MPH and 85MPH, you're doing 65MPH. Its a manual transmission, as far as I know, the orginal, I've tried a new gauge cluster, same thing. I"m told I might need a gear to slow the cable down, but I have no idea what cable I need or how to find it. I'm told there are five possible gears. As far as I know, the car is stock, engine, wheels match exactly what the glove box says, so what can be done and who can do this kind of work? Thanks

10-17-2005, 03:12 AM	#5
86supraNa Stock Join Date: Oct 2005 Posts: 4	happend to me today 2 i was driveing on the highway going bout80 and a toyota camery was right next seepeding up trying to pass me so i sped up to about 110 and it kept going to about 130 and bounceing i was goina prettyfast but im not sure if i was really going 130 cuz the last time i tryed to top it out it only hit 110 so maybe i got same problem felt more like 115 or 120 though im confussed but when im going 20mph it says 20mph so i duno Last edited by 86supraNa; 10-17-2005 at 03:25 AM.

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09-17-2005, 02:20 AM	#2
tonster Stock Join Date: Mar 2005 Posts: 14	When you're just sitting does it read 20 mph? The instrument cluster analog or digital? It could just be that you need to reset the zero on the needle if it's analog and that is the case, otherwise I don't know. If it's digital maybe there's a short adding unwanted voltage somehow? It doesn't make sense that it would always be 20 mph off. I think the speedometer cable hooks directly into the transmission so thats where you would look I'd guess.

09-17-2005, 03:22 AM	#3
chrismc410 Stock Join Date: Sep 2005 Posts: 2	When stopped, its at zero and its analog 130MPH speedometer

09-24-2005, 10:13 PM	#4
hangsupra 12psi boost Join Date: Jan 2005 Location: 209 area in cali. Posts: 397	first of all take out your cluster n turn side way n see if the mph stays at 0 mph or it move back n forth. if it move back n forth then its your speeding metter.... replace with a new one. if it stays the same at 0 mph then its something else. let me know how u get to work.