Speedo accuracy
10-06-2007, 10:00 PM
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Speedo accuracy
Went from 4.30 to 4.10 gears today, and now I'm wondering if I need to do something about my speedo. I'm curious if anyone's tried checking their speedo with GPS. I'd think that it reads 5-10% high (like pretty much every car on the road) so with my taller gear, it's probably pretty close to being right. 
I'm going to try to check it against GPS tomorrow.
I'm going to try to check it against GPS tomorrow.
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10-06-2007, 10:03 PM
#2
I'm curious as well. When checking my car against my buddies Jetta my car read 5 mph slow. Not sure if that was the 17" wheels or what causing that.
How does the 4.10s feel compared to the 4.30s. I'll be doing the same swap soon with my torsen. Hoping 1st gear is a bit more useful and 2nd gear gets me to 60mph.(Think it gets me to like 57mph now, could be mistaken and full of **** on that one.)
How does the 4.10s feel compared to the 4.30s. I'll be doing the same swap soon with my torsen. Hoping 1st gear is a bit more useful and 2nd gear gets me to 60mph.(Think it gets me to like 57mph now, could be mistaken and full of **** on that one.)
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10-06-2007, 10:26 PM
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so far its baller. I noticed the taller gear right away, the first time I put the car in 1st and started from a stop. The car took more throttle to get moving. The 3rd time I started from a stop, I was used to it.
the car seems more relaxed, more so than the slight change in gear would indicate. at very light throttle openings, the car isn't as quick. at moderate openings, I can't tell a difference. I'd suspect that the additional load just results in additional boost, essentially canceling out acceleration lost due to the gear change by forcing the motor to produce additional torque.
the mazda comp diff mounts made all the difference in the world as far as shift quality. gears are actually where they're supposed to be. shifting no longer feels forced. the 2-3 shift especially. i also must have had some front to back slop in the driveshaft/diff before, which is gone now. Or perhaps the old diff mounts were toast.
this rx7 diff has a lot of lock up. the pedal feels much more connected to the back of the car when cornering, meaning mild changes in throttle position result in more change in yaw than I was expecting. I'll have to seriously adjust my driving habits.
I haven't seen more than partial throttle, partial boost yet. I've got my original ignition on the car, which won't fire the plugs. It's like hitting a rev limiter at 8 psi. (took the COPs off the car as the model to mock up another). I'm going to put the COPs back on the car tomorrow and see what's up.
oh, I'm running 205-45-16 tires
the car seems more relaxed, more so than the slight change in gear would indicate. at very light throttle openings, the car isn't as quick. at moderate openings, I can't tell a difference. I'd suspect that the additional load just results in additional boost, essentially canceling out acceleration lost due to the gear change by forcing the motor to produce additional torque.
the mazda comp diff mounts made all the difference in the world as far as shift quality. gears are actually where they're supposed to be. shifting no longer feels forced. the 2-3 shift especially. i also must have had some front to back slop in the driveshaft/diff before, which is gone now. Or perhaps the old diff mounts were toast.
this rx7 diff has a lot of lock up. the pedal feels much more connected to the back of the car when cornering, meaning mild changes in throttle position result in more change in yaw than I was expecting. I'll have to seriously adjust my driving habits.
I haven't seen more than partial throttle, partial boost yet. I've got my original ignition on the car, which won't fire the plugs. It's like hitting a rev limiter at 8 psi. (took the COPs off the car as the model to mock up another). I'm going to put the COPs back on the car tomorrow and see what's up.
oh, I'm running 205-45-16 tires
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10-07-2007, 08:09 PM
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Well, it took 3 hours to change the mounts out, if that tells you anything. However, we got the second side done much more quickly than the first.
Best method:
Use a hole saw to knock the mount centers out. Use a deep 1 3/4" (44mm) saw. Then use a press to push the outer casing of the bushing out. Grease up the carrier good and press the new bushing in. I bet that if I had to do it again, it would only take an hour or so.
Best method:
Use a hole saw to knock the mount centers out. Use a deep 1 3/4" (44mm) saw. Then use a press to push the outer casing of the bushing out. Grease up the carrier good and press the new bushing in. I bet that if I had to do it again, it would only take an hour or so.
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10-07-2007, 10:58 PM
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FYI You can get the speedo verified (had to do this to get out of a ticket) mine showed abuot 4.5mph faster than what I was doing on the rollers. Cost ~50$ if you really wanna find out or if ya need to get out of a ticket ;-)
Last edited by mtncrvr; 10-08-2007 at 10:11 AM.
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