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View Full Version : How to modify Tamiya Speed Checker?


NoBrainer
2012.01.27, 08:10 AM
After what I have read on the net, the Tamiya Speed Checker shows the wrong speed for Mini-Z's.
I have ordered one just to compare different setup, without wondering about the actual speed.
But.....can it be modified to show correct speed as well?
If it can, do anybody of you know how?

ScoobyPete
2012.01.27, 08:32 AM
Never heard that tbh, what do you mean by the wrong Speed?

The Tamiya Speed checker gives reulsts in KPH rather than MPH, this isnt wrong, the Japanese use KPH like Norway do and England and the U.S. uses the "Proper English MPH" :)

You convert KPH into MPH by multiplying the KPH by 0.62137

so 18kph x 0.62137 = 11.2 mph

NoBrainer
2012.01.27, 08:42 AM
oh no, kph is "correct" speed. :D

But since there is no "wind" and there is no downforce on the car when you test it, you get this "unload" speed that is to high compared to what the car actually have on the tracks when you run the car.

So if my car can run at 25 kph on the track, it would show something like 45 kph on the speed checker at the same RPM and gear ratio. (these are just imaginary numbers and not taken from the real world).

ScoobyPete
2012.01.27, 08:50 AM
Now you mention it I can see where your coming from, tbh I think the difference is negliable though (not worth worrying about). In fact I don't belive that the speed checker itself prob is all that accurate in the 1st.

As long as you use the same speed checker for all your tests the results will be consistant.

Do you have a link to the page you got the info from, would be intrested to read it.

NoBrainer
2012.01.27, 08:58 AM
That's my "problem"...

This is "old news" and the ones who says it's wrong do have it from a friend of a friend who knows a friends friend who says it "might" be wrong.

So I don't have the "hard facts" to link to. I would love to read that too.


But as you say, it don't matter if it's wrong, since I'm just going to compare my own cars and how they handle.

But since I heard it was not showing the correct speed, I was wondering how it could show the correct speed. Anyway, I'm getting it next week, so then I can test some and see if it totaly wrong or not.

I belive they had a "lazer test" with one of the fastest at an PN event in germany?? that showed 37kph at max, so I think none of my cars should go faster than that.

I will compare pinion / spur, batteries, wires, tire size and such when I get it. Just for my own amusement.


If you find anything it would be really appreciated to read what you find.
Thanks for reply!

imxlr8ed
2012.01.27, 09:46 AM
Had a Tamiya Speed Checker years ago, me and my cousins messed with it once or twice, the younger guys in the club messed with it once or twice... it didn't really pop out of it's box much more than that. I think I ended up just giving it to someone.

Only speed checker that ever worked accurately for me was going to an event and watching the top drivers blow by me like I was standing still:

"yep... my cars not fast enough!"

So I'd pump up the charge rates, drown the comm in voodoo drops and try to keep up. Then it turns into:

"how are thay holding all that speed in the corners?!?!...

I don't think that speed checker gives any information on maximum cornering speed either. ;)

point being... don't waste your $$$.

NoBrainer
2012.01.27, 09:55 AM
hihi

Too late....

:rolleyes:

But I all ready know these things.
It's for "science" and fun, nothing else.

imxlr8ed
2012.01.27, 10:04 AM
They are cool, I've seen videos of xmodders topping them out with crazy motors and lithium ion cells (and glued tires). I don't recall ever seeing any kind of modification to make them more accurate... sorry!

Now if they ever put out a scale realistic dyno with actual resistance... I think you'd see alot of racers testing motors, gear ratios, tire diameters... etc...

ScoobyPete
2012.01.27, 10:05 AM
The only way I can think of to get a true track speed is to make a length of RCP straight say 20 tiles which would be 10 meters then time the car for the last 5 meters and work it out that way.

Speed= distance (5m) devided by Time, unless you have a freindly policeman with a lazer gun to speed trap you :)

Lot of hassle may aswell just stick with the speed checker as as we have said if it is wrong at least all the results will have the same error in them.

They are cool, I've seen videos of xmodders topping them out with crazy motors and lithium ion cells (and glued tires). I don't recall ever seeing any kind of modification to make them more accurate... sorry!

Now if they ever put out a scale realistic dyno with actual resistance... I think you'd see alot of racers testing motors, gear ratios, tire diameters... etc...

We built a Dyno theres a thread about it here http://mini-zracer.com/forums/showthread.php?t=35860, its not mega accurate but again if all the results carry the same error you can still use them to compare motors. It worked really well till i sat on it :( We have rebuilt but are looking at other methods of testing the motors as we want to start building our own motors.

NoBrainer
2012.01.27, 10:55 AM
My thought was a load on the spinning wheel. Some kind of resistance that is adjustable so you can find correct speed.
But the Tamiya Speed Checker will never be a Dyno without serious modification and I don't know that. But first I think I need to get my hands on it and check if there are any spare room inside it or what can be done with it.

But since you guys have never heard that it was "wrong" or never heard of how to fix it, then I guess this thread has doen it's purpose.
Before we rant on with all the things we should have had...

And I agree with the 10 meter straight and a timer, but that ain't so easy on top of my desk.

ScoobyPete
2012.01.27, 11:06 AM
we did look at combining the speed checker with a dyno but went down seperate roads in the end. http://mini-zracer.com/forums/showthread.php?t=35860

Heres a pic of the insides of the checker.

http://img138.imageshack.us/img138/7351/sc2be.jpg

NoBrainer
2012.01.27, 02:39 PM
ah cool

So the front rollers aren't really needed and there looks like it's room for some kind of pressure to the rollers.

I'm not thinking of making it into a Dyno, but that would be awesome.

NoBrainer
2012.02.01, 07:18 PM
got it today...

It should not be used with tires less than 24mm or more than 33mm

On my 360GTC I have 23.4mm tires
On my Vitz'n I have 24mm tires
On my 935 I have 26mm tires
On my 962C I have 26.5mm tires

All chassis are MR-03, but two of them are chase mode (tiki-tiki)
I do think I got 10T / 53T on all diff's
But I might have 11T / 53T on one or two...

Vitz with CTP70T and somewhat used Kyosho 20 slicks - 20km/h
935 with CTP70T and somewhat used Kyosho 20 slicks - 23km/h (might be 11T)
962C with CTP70T and somewhat used Kyosho 20 slicks - 23km/h (might be 11T)
F360 with Atomic Stock and new Atomic Radial 8 - 25km/h

Had to test with two brand new motors, not even runned for a second...

F360 with PN43T - 27km/h
F360 with PN33T - 34km/h


Fun....