4.77 installed... what rpms @ 70mph
07-23-2005, 04:51 PM
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4.77 installed... what rpms @ 70mph
Ok, i'm a lil paranoid n i just want to make sure, n the search function is not working right now... the 4.77 gears were recently installed in my car, but haven't purchased the "speedometer corrector" lol - to correct the readings off the dash.. but right now, @ 70mph, its 3900 rpms... does that sound about right if i haven't installed the "yellow box" ( or i think thats what they call it...) I just want to make sure i didnt get "jipped" by the shop. Thanks for any input.
07-23-2005, 05:16 PM
#3
This is too late for you but it may be of help to others in future. You should have counted the teeth on each of the ring and pinion gear. Then divide it out and you'd know the answer without any doubt.
Without the Yellow Box, your speedometer and tach will read EXACTLY what it read before, except for the fact that when it says 70 mph, you are NOT going 70 mph. The tach will still read the same at 70 mph now as it did before since nothing has been corrected. You need to get paced by another S2000 or police car at 70 mph to see what your tach says. Then you have a point of comparison.
Without the Yellow Box, your speedometer and tach will read EXACTLY what it read before, except for the fact that when it says 70 mph, you are NOT going 70 mph. The tach will still read the same at 70 mph now as it did before since nothing has been corrected. You need to get paced by another S2000 or police car at 70 mph to see what your tach says. Then you have a point of comparison.
07-23-2005, 08:26 PM
#6
Originally Posted by steven975,Jul 23 2005, 07:43 PM
your true speed is 16.34% higher than indicated.
you do the math.
you do the math.
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07-24-2005, 07:16 AM
#8
Originally Posted by billman250,Jul 23 2005, 11:32 PM
On my stock s2k when it was stock:
At 4000 rpm's, I was doing 72.5 mph.
At 4000 rpm's, I was doing 72.5 mph.
@ 70mph, its 3900 rpms... does that sound about right if i haven't installed the "yellow box"
07-24-2005, 01:59 PM
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Originally Posted by xviper
Without the Yellow Box, your speedometer and tach will read EXACTLY what it read before...
These gears will, of course, affect the final drive ratio and therefore the speed; this is why you need the Yellow Box to correct the speedometer (just as you do if you change the tire size).
But the tach is the engine RPM, right? It really doesn't have anything to do with the gears or the Yellow Box correction. (And maybe this is what you're saying, but I want to un-confuse myself.) TIA. HPH
07-24-2005, 02:02 PM
#10
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what he's saying is that the rpms are reading correctly. as they should. but while the rpms and mph are both giving readings (the same reading as before) the mph is actually incorrect. so to come on here and say "my rpms are 3900 at 70mph" doesn't tell us anything.
Scenario A: if he was stock his car would show 3900rpm at 70mph.
Scenario B: if he had 4.77 gears and NO yellow box, it would still show 3900rpm at 70mph.
the ONLY difference from the first scenario to the second is that he would not actually be going 70mph in Scenario B.
Scenario A: if he was stock his car would show 3900rpm at 70mph.
Scenario B: if he had 4.77 gears and NO yellow box, it would still show 3900rpm at 70mph.
the ONLY difference from the first scenario to the second is that he would not actually be going 70mph in Scenario B.