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 Post subject: 1989 Daihatsu Charmant - Indonesia
PostPosted: Wed Jun 17, 2009 4:11 am 
Hi, Edgar here. I decided to share my project here also in JNC other than my blog. Anyone interested can head on to my blog on http://charmant4age.blogspot.com for more details. Pls leave comments if you visit :) Hopefully we can share more especially between those with common interest to Daihatsu Charmant.

I bought my Charmant mid March '09 and it went straight to the body workshop. I do wish i could work on my Charmant myself but work interfered. You see, my Charmant is in my hometown Jakarta while i have to work approx 8 hours of driving from it. i only get to go back to Jakarta every 3-4 weeks.

This was how it looked when i first bought it..
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Since March, many have happened to my Charmant and also i've bought some stuff while it is still being worked on in the workshop. This is how the Charmant looks like as of late May.
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Apparently, the rust underneath the old paint is horrible. That's why it still looks like that even after three months.. :( They had to replace most of the plates due to rust.

I'll post the progress both in my blog and JNC from now on.
Comments and critics are welcomed!


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 Post subject:
PostPosted: Thu Jun 18, 2009 12:57 am 
I managed to find a set of rims for my Charmant late April.

I couldn't find much info on the rims but this i know: they are made by Australian company called CSA and are from the series called Globeline. They measure 14" in diameter and 7" wide. I don't know the offset but that don't matter since it sits perfectly on my Charmant as can be seen from pictures below.

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Installed under rear fender:

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Anyone has more info on these rims? I know they are not the kind of rims you usually heard installed on classic Japs like Longchamps, RS Watanabe or SSR. I bought it because i liked how it looks and it supersedes the make of the rims. However, i do admit i am still hunting for those TRD rims like the one seen below.

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 Post subject:
PostPosted: Fri Jun 19, 2009 12:01 pm 
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Joined: Thu Nov 08, 2007 8:17 pm
Posts: 78
Location: Limerick Ireland
Snap! Almost the same rims as me!!


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 Post subject:
PostPosted: Sat Jun 20, 2009 12:36 pm 
mouwt wrote:
Snap! Almost the same rims as me!!


yeah, i also think they look like your SSR rims. still looking for something wider tho'.

latest update as of June 20th 09. nearly 30% of rear door plates replaced as can be seen from the pictures.

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 Post subject:
PostPosted: Mon Jun 22, 2009 1:36 am 
Since i failed to find a 2-inch fuel level gauge that looks similar to my other gauges (i am making a custom gauge cluster btw), i decided not to install it. However, since i still need to know if i have enough fuel, i need some kind of warning lamp to remind of of low fuel volume. Actually, i was surprised why didn't i think of this before. This is much useful than a fuel level gauge. I don't need to know how much fuel is left in my tank, i just need a reminder for me to fill up the tank so a warning lamp is the way to go. It takes less space and it should cost less to build.

Fuel level gauges are actually amp-meters. It measures the variation of current caused by varying resistance in the fuel level sender. It all goes down to the Ohm law:
Voltage = Current x Resistance
where voltage should be constant somewhere around 12 volts.

There could be slight variation but basically, the circuit is wired as such:
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If you've worked on fuel tanks before, you'll see an arm attached to a floater on the fuel sender unit. This floater will always float on the surface of your fuel. Thus, it would be high on full tank and it would be low on low tank. The arm is attached to a pointer which... uummm.. points to a certain position on a resistive material, which could be a wire wound or a simple carbon track. So, for those familiar with electronics, a fuel level sender unit is basically a potentiometer. Below is an example of a fuel level sender unit.
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In short, it works like this: fuel volume --> floater position --> pointer position --> resistance --> current --> amp-meter! Real simple, right?

The problem is, the resistance in the sender varies between makes and models of the car. I need to know what is the resistance for both full and empty position in Daihatsu Charmants. A dude in the local Daihatsu Charmant mailing list told me that there is a "KE70" writing on the fuel level sender when he opened up his Charmant tank recently. So i'll assume the sender unit is the same with Toyota KE70s*. Upon googling, i found that Toyota KE70 fuel sender unit spec is as follows:

empty = 3.0 +/- 2.1 ohm
1/2 = 32.5 +/- 4.8 ohm (float is 28.5 degrees off empty)
full = 110.0 +/- 7.7 ohm (float 57 degrees off empty)

putting those values into a graph, it would look like this:
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So, as can clearly be seen from the graph, the sender is a non-linear variable resistance. Now this is important: determine at what fuel volume would you like your warning light to turn on? I decided on 25%. At 25%, the resistance on the sender would be in between the ohm at empty and at 50% fuel volume. Although it's non linear, i'll just assume the value using the average ohm value since it's not really crucial so (3 ohm + 32.5 ohm)/2 ~ 18 ohm. So what i need to do is design a circuit which would turn on a light when the fuel level sender is below 18 ohm since that means the fuel volume is less that 25%.

To achieve aforementioned purpose, i'll use a cheap LM741 IC. LM741 is an operational amplifier (op-amp) which has 8-pins dual-in-line package. Discussing how op-amps work would really be boring (as if this post is not already boring!) so i'll skip it and go ahead to the circuit design:
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The LM741 inverting input is connected to a reference voltage (which is 6.8 volts as determined by the Zener diode). The Fuel Sender and Rx forms a voltage divider and connected to the non-inverting input. At above 25% fuel volume, the voltage on the non-inverting input should be higher than 6.8 volts so the output will remain high which keeps the lamp unlit.

Now, we will determine the value for Rx. At 25%, the fuel sender unit will measure 18 ohm. This resistance value combined with Rx should form a voltage divider which outputs 6.8 volts. We'll assume the supply voltage as 12 volts. Using voltage divider principle, we can determine Rx as follows:
6.8v / 12v = 18ohm / (18+Rx)ohm
Rx = 13.76 ohm.

I think the closest available resistor value is 15 ohm so we'll use it.

A note on the lamp: i don't know how much current can the LM741 sink on the output pin. So be safe and use the least wattage you can find for the 12 volt lamp. A 3-watt 12 volt lamp would flow 250mA on the pin and i think it's already too high for the LM741 to handle. You can use a PNP transistor driver before the lamp just to protect the LM741. Other way is to use a LED with resistor..

All of those components should cost very cheap and can be put inside a small housing. So, start heating that soldering iron and enjoy the smell of tin and resin..

I'll update this post when i have finished soldering.

(*) = While upon ACTUAL comparison, the fuel level sender units look different between KE70's and Charmant's, i am willing to assume that the resistance spec is the same. A clue is better than a wild guess, right?


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 Post subject:
PostPosted: Mon Jun 22, 2009 11:38 am 
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Joined: Mon Jun 15, 2009 11:33 am
Posts: 20
Location: Malaysia
hi bro.. Finally met you here also.

-Rosso @ Bumble Bee.
:D

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http://rossobloggy.blogspot.com/


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 Post subject:
PostPosted: Mon Jun 22, 2009 12:12 pm 

Joined: Mon Aug 13, 2007 6:42 am
Posts: 470
Location: Leeds in the UK
project looking good and i kinda like those wheels as well :tu:


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 Post subject:
PostPosted: Mon Jun 22, 2009 12:47 pm 
Administrator
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Joined: Thu Jan 18, 2007 5:41 pm
Posts: 5591
Location: LA
I love Charmants! If you can find 13" TRD wheels that would look awesome on your car. Welcome to JNC! :tu:

_________________
Tyler wrote:
How I long for a shit brown wagon.


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 Post subject:
PostPosted: Mon Jun 22, 2009 3:07 pm 
Amar 808 wrote:
hi bro.. Finally met you here also.

-Rosso @ Bumble Bee.
:D


LOL :lol: nice to see you here also Rosso.. Saw you got some new toys for your 808, got some successful fund raiser eh?

@ben & colink: thanks! my Charmant's not even out of the body workshop yet and i am already considering on buying another set of wheels!

Anyway, digging up old posts on my blog, here's a writeup on how to put a smallport 4A-GE into Charmants. Basically it's a guide on 4A-GE FWD to RWD conversion with some added touch to fit Charmants better..


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 Post subject: DIY Dashboard Panel - Mockup Finished
PostPosted: Thu Jul 09, 2009 4:10 am 
During my holiday in Jakarta, i managed to finish the design for my dashboard panel. I encountered a problem which reminded me of the most important thing in dashboard panel design: measurement. I found out that day my 3-3/4-inch tachometer is still too wide to be installed inside the panel! I bought the tach online and didn't make sure it will fit to the panel before buying it. I also found out that i need to reduce the switches and lamps for aesthetics reason. Below pic shows you the items removed from the design and how the tach is slightly too wide to be placed on the cardboard panel layout.

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Well i guess i have to put the tachometer somewhere else. After some measuring and pinpointing hole locations below is the end result of the mockup. Next step is to transfer this design to an aluminum sheet to have the sheet cut following the design.

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I can only fit five lamps and two toggle switches on the panel. So i decided to remove e-brake or check engine light, depending whether i can get a check engine light working for my ECU or not, and i also remove the fuel pump switch.

I managed to salvage some 1mm thick aluminum sheets from a glass display maker. Now that i got a hold of the aluminum sheet, i think it is slightly too thin to hold those gauges firmly but i decided to give it a go first. If it turns out being too wobbly for the panel, i'll have to find thicker aluminum sheets.

I brought the cardboard mockup and aluminum sheets to a lathe and milling workshop. Sadly, the price they offered was too expensive.. freakin US$75 just to put holes on an aluminum sheet! I had no more time to ask other workshop because i had other business to do while in Jakarta. So i guess the aluminum panel will have to wait..


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 Post subject:
PostPosted: Mon Jul 13, 2009 2:00 pm 
Administrator
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Joined: Thu Jan 18, 2007 5:41 pm
Posts: 5591
Location: LA
That is a big tach! :D

_________________
Tyler wrote:
How I long for a shit brown wagon.


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