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Old 04-01-2012, 11:12 AM   #21 (permalink)
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I would check your speedometer first, to make sure you're going the speed you think you are. On my 2 Hondas, I guess maybe the spring in the speedometer got weaker with age or something but it caused the needle to read a constant amount high - 4mph in my Del Sol and 7mph in my my Civic DX.

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Old 04-10-2012, 11:50 PM   #22 (permalink)
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does anyone posses the attainment on how to measure your speed.
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Old 04-11-2012, 02:23 AM   #23 (permalink)
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Originally Posted by mycivic View Post
does anyone posses the attainment on how to measure your speed.
I used a GPS to measure mine.
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Old 04-11-2012, 07:09 PM   #24 (permalink)
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There's also finding a known distance, and traversing it over a given amount of time. Miles traveled / time taken == MPH (or km/h if you're using metric units). You can use that to calibrate your actual speed against the speedometer if you can manage to keep a steady speed for a known distance.

A longer distance (and time) will generally mean less error in your measurement this way, as well.

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Old 04-12-2012, 08:53 PM   #25 (permalink)
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Ok guys, I have some questions concerning transmission swaps in VXs... First off, other than RPM testing, is there any way to visually identify that I have a VX tranny?

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Originally Posted by Joe1234 View Post
I drive a VX and it is 2000RPM in 5th gear at 70MPH. Sounds like the shop you used is full of retards as usual. They either thought you'd be too stupid to notice or they were too stupid to pay attention to detail.
The reason I ask is above. I hear all different opinions on where the tach should be at Xmph... I just bought a VX that has HX rims with 185 tires. At 70mph I am above 2000RPM... And with bigger tires I should be slightly below, correct?

"check the engine rpm at 100 km h it should be 1900 rpm in fifth gear
if rpm is 2400 you got a tranny from civic 96-2000 hb
if rpm is 2700 you got a dx 92-95
if rpm is 2900 you got a si tranny"

Read that on another thread. I'll use my GPS unit to verify accurate speed and see what I get at 60 and 70 mph...

Question:" My 185 tires are 10.8% larger than the VX 165s. Does this mean my RPMs for a given speed should be about 11% lower than normal?
Thanks for the help.
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Old 04-12-2012, 09:15 PM   #26 (permalink)
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Click HERE for a list of ratios for Honda transmissions.

I have 185/65/15 tires on my Civic HX and I am around 2100-2200 at 60 MPH. Cant remember exactly I need to look tonight.
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Old 04-12-2012, 09:42 PM   #27 (permalink)
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Question:" My 185 tires are 10.8% larger than the VX 165s. Does this mean my RPMs for a given speed should be about 11% lower than normal?
Thanks for the help.
Yes, you are traveling 10.8% faster than what the speedometer says, so if your speedometer says you're doing 100km/h, divide your RPM by 1.108 to get the corrected value, or drive 10.8% faster.
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Old 04-13-2012, 01:14 PM   #28 (permalink)
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Quote:
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Question:" My 185 tires are 10.8% larger than the VX 165s. Does this mean my RPMs for a given speed should be about 11% lower than normal?
If you are asking if changing tire sizes will change what the speedometer reads for a given RPM in a given gear, then no.

If you are asking if it will change the actual speed for that RPM, then yes.

The speedometer only "sees" how fast the drive wheels are turning. Changing the tire size will change what that actual speed is, but the speedometer and tach will still read the same.

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Old 04-13-2012, 03:00 PM   #29 (permalink)
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Quote:
Originally Posted by some_other_dave View Post
If you are asking if changing tire sizes will change what the speedometer reads for a given RPM in a given gear, then no.

If you are asking if it will change the actual speed for that RPM, then yes.

The speedometer only "sees" how fast the drive wheels are turning. Changing the tire size will change what that actual speed is, but the speedometer and tach will still read the same.

-soD
Wow, that's a really good point. I did so much thinking and trying to convert tire size and come up with proper ratios, that I didn't even realize that the car doesnt know anything about that stuff... Duhhh. So I definately have the right tranny! Reading around 2000 RPM at abt 65mph. It's not the 70mph at 2krpm sum1 above mentioned. But hey, could just be electrical load and such.
Thanks Dave. I can calculate beam strength and force loads, just cant see the small picture lol.

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