Speedo is WAY off
08-07-2009, 04:00 AM
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Speedo is WAY off I bought a 2000 camaro z28 last year. i bought the car used and i can see little mods done to it, lid, tires/rims, coolant line bypasses throttle body. well the speedo is way off and i dont know if it is becouse of somthing the last owner did to the car or what. i had a friend drive next to me and this is how bad the speedo is:
at 35 it reads 25
at 45 it reads 30
at 55 it reads 35
at 65 it reads about 43 or 44
its like the faster i go the worse it is! when fourth gear is almost redlined i think it says 80!
how can a speedo be so far off? and how fast was i going when i topped out fourth gear!? i really want to get this thing fixed!
at 35 it reads 25
at 45 it reads 30
at 55 it reads 35
at 65 it reads about 43 or 44
its like the faster i go the worse it is! when fourth gear is almost redlined i think it says 80!
how can a speedo be so far off? and how fast was i going when i topped out fourth gear!? i really want to get this thing fixed!
08-07-2009, 04:38 AM
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Sounds like it may be a cluster issue. Cause if it was a gear issue, the speedo should read faster than your actual speed. Top of fourth should be around 125-130 if I remember correctly.
08-07-2009, 07:11 AM
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Is it a T56 Swap car?
I swapped a T56 into mine and changed the Rear Gears.. I don't have it tuned yet, it's exactly 2.5 times off. I have to take what the speedo says and multiply it by 2.5.
20x2.5=50mph
It's not too bad to do..but easy for me since I have a refrence to work with.
Friends of mine notice it and are like WTF..lol
I swapped a T56 into mine and changed the Rear Gears.. I don't have it tuned yet, it's exactly 2.5 times off. I have to take what the speedo says and multiply it by 2.5.
20x2.5=50mph
It's not too bad to do..but easy for me since I have a refrence to work with.
Friends of mine notice it and are like WTF..lol
08-07-2009, 01:18 PM
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See what your RPM is on the highway with someone next to you, then compare it to a calculator like www.f-body.org/gears/
08-07-2009, 01:35 PM
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I dont think the wheels could put it that far off, but it could compound the issue if they are not stock sized and were never calibrated for the change. What size are they
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08-08-2009, 02:08 AM
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i cant go to that site 2001NBMZ28 but i will try on another computer later, im sure thats the prob.
i looked up the stock size and this is what i found
stock- 235/55/r16
this is what i have now
275/45/r17
after research i found out that would only change the speedo by 1 mph. if im wrong please let me know.
how would i know if it has a diffrent gear in it?
i looked up the stock size and this is what i found
stock- 235/55/r16
this is what i have now
275/45/r17
after research i found out that would only change the speedo by 1 mph. if im wrong please let me know.
how would i know if it has a diffrent gear in it?
08-08-2009, 02:27 AM
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Mine was almost exactly like yours. I dropped the differential cover and calculated the gear ratio. Turns out someone put 2.73 gears in my car when it originally had 3.23's but they didn't tune for it. I borrowed a friend's HP Tuner, put in the right values, and walla...speedometer is dead on (checked it with a GPS).
08-08-2009, 08:30 PM
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Mine was almost exactly like yours. I dropped the differential cover and calculated the gear ratio. Turns out someone put 2.73 gears in my car when it originally had 3.23's but they didn't tune for it. I borrowed a friend's HP Tuner, put in the right values, and walla...speedometer is dead on (checked it with a GPS).
08-09-2009, 02:05 AM
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It does make it slower off the line, but it is nice to have in a daily driver for highway driving. Anyways, I personally calculated it by dropping the cover. Once you have done this, on the main gear, there will be two stamped numbers on the gear. You divide the larger number by the smaller to get your gear size. Here is another method that someone else used also, you kind of need two people though to do the counting. http://www.youtube.com/watch?v=i_Enyf67KTs
08-09-2009, 10:27 AM
#13
As far as the tires: A 275/45/17 versus a stock tire will make the speedo read about 4% slow, meaning when it says 60, you're doing about 62.5.
Is the car an A4 or an M6?
the_merv may be on to something. According to the spreadsheet I've got for this kind of stuff, what you're saying sounds like it's got a manual transmission and 3.42 gear and the speedo is still programmed for an auto with 2.73's.
Is the car an A4 or an M6?
the_merv may be on to something. According to the spreadsheet I've got for this kind of stuff, what you're saying sounds like it's got a manual transmission and 3.42 gear and the speedo is still programmed for an auto with 2.73's.
08-10-2009, 02:37 PM
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thanks everyone for the help! this site is great. does anyone know if i can get it calibrated or do i have to get diff gears? i kinda want more power off the line anyway.
