well as started in another post here in the forum i have a restoration of our fuel level senders going on .

luckily on previous restorations the fuel level resistor - wiper has been in relatively good condition enabling me to just clean the rust off and resurface the resistance winding for a good operational result.

but i did acquire another unit via "frank the rat " from thom Hellbreakers ..(sp?) in holland , who offers  a lot of recycled parts .

this one was well and truly cactus . with just the mechanical parts seeming to be ...erm ...existing?



so on disassembly found the resistive windings actually corroded through in quite a few places .....bugga !!!!




ill step ahead here with the pic , having found a what seems to me a suitable resistance wire to replicate the winding , after a couple of attempts to buy the correct thing .
 it seems that 50 ohms per meter will suffice for the job , with just some simple calculations , available from a local (aussie) supplier ....



here it is , with now a sample of the nichrome wire i found that should be suitable across the windings . notice the frayed windings of the base backing  ...


just using my favorite nylon brush on the drill i was able to clean up the assembly , reasonably well .... with a rotary tool used to polish it up a bit more , but still leaving some traces of corrosion in there .






just arrived today i purchased a litre of "kbs Rust Blast ", which is supposed to cut the rust , etch the base material and leave a coating of zinc phosphate ...ready for electroplating some zinc back onto the surfaces . Well thats the plan going forward , possibly with a little nickle as well . unsure if i need to apply chromate after the zinc plating ...?



here's the result of the rust blaster ...looks as though it has done what it says ...win !!





so now considering the way to wind the coil across the base , keeping in mind the length needed to cover the wiper sweep ... i think ill have to find a .75 or .50 mm pitch bolt to lay down the windings with more or less equal turns


hopefully i have some bees wax on the way , as the windings are retained with something waxy ....and also to cover the electrical connections whilst in the electrolysis bath whilst plating happens ..
the journey continues

what do you think ...so far ?

Bloody Marvellous, :1B:cant wait for next bit.

Nice one Charlie.

Nice work.  Quite the task you've taken on.  As for winding the wire resistor unit, maybe a lathe with an adapter on the carriage that can guide the wire and maintain tension, and power the carriage with the lead screw for the given pitch.  Experiment with disposable wire first (like 30GA wire wrap wire).

Thanks guys

Yes Rob thats the intertion to try with something relativly cheap as the nichrome wire is about $2 per metre  (34ga) i have in mind a small hand winder worth about $50  which looks to have a suitable gearset , ill gave to make a few arms for auto tensioning as the nichrome wants to run away from the bobin pretty quickly

Anyhow not impossible to do  

But i have a trip to plan end of the month so everything will be on hiatus till after then  tyres to buy etc 

Cheers

I have a question for Charlie and Rob. For Bricks not running a fuel gauge would it not be possible to do away with the windings and just have on and off for the low level light. I think that Bruce's K75s has stuffed windings but his low level light still functions due to dual wiper arms.
Regards Martin.

Yes @Martin, that should be possible.  The wire-wound resistor plate is a separate circuit card from the one that detects low fuel level.  There are also two wiper arms - one for the resistor and one for the low fuel.  So, just remove the resistor circuit card and leave the low fuel circuit card in place and you have achieved your goal.  Make sure the upper wiper arm does not interfere with the operation of the sender.

Thanks Rob you have confirmed my thinking. Most of the Bricks in the K Kronie Kluster don't have fuel gauges so repairs would be simplified. Maybe you could set up a organ donor scheme with non gauge owners donating their circuit cards.
Regards Martin.

as Rob says , no real issue 
but i have found many are unreliable 

but that could be because i have only ever been inside tanks that have extraordinarily high kilometers

anyhow this is what came off this sender 

it appears to be just single sided phenolic circuit board , etched for the desired operation , then tinned .

this one seems to have bent with the corrosion forming behind the "board " on the metal , evidence is seen with remains of rusty crap impregnated into the surface.

in any case it must have been fiddled with during its service life , with deep scores of the wiper into the surface , where a light sweep should have been calibrated (or is that just a hamfisted fix for someone that relies on the 4 litre lamp ?)

 



its pretty much just held in place by a plasic rivet of sorts to the body of the mechanism

i guess ill have to cutout, etch and Tin a replacement to suit

Charlie I've never seen one like that. Do you know it's origins as in model and year?
Regards Martin.

martin all the ones i have seen look the same but that  gouge is deep

perhaps never seen it off the backing plate ?

Arrr the light illuminates the dim dark recesses of my mind.
Regards Martin.

Hi guys and girls...it's been a while, but never-the-less, I still sneak a peek to see what's going on.

Charlie, I hope all is well with you. I was looking at a video of a bloke here in Oz bringing back to life a VB Commodore (V8 engine).

He was pulling apart the fuel tank and had a good shot of the original fuel gauge sender.

It looks remarkably like your busted K100 sender unit (the guts of it...not the tank mounting bit).

I could be wrong, I could be right (I should make that into a song!).

Google VB Commodore fuel sender and have a squiz.

good to see you call in occasionally ol mate 

yes have played and sorted a few fuel senders , (with the local sports car club , getting things working again )

ill take a look ,, and thanks for the comments

I would fix the windings with a bit of epoxy adhesive at the sides, anything else may well dissolve in the fuel.

hope it all goes well.

Love this thread... I've just pulled the fuel sender from a k100 I bought on a whim this summer.

well ive abandoned the rewiring of the resistor windings ....having found what seems to be an already manufactured part ...(likely out of china for this particular sample ) 

with the help of  Burkhard Förster...in another place , who had an injured wiper resistor assembly .
he pointed me towards a vw replacement sender .

which looks remarkably similar ... although i predict the differences in metal parts are a concoction of a copy of the original part , the original vw sender likely made in the same factory as the original bmw unit ....  seems likely .

anyhow the costs involved in getting a winder that would hold the board whilst i rewind it  the tensioning device for the really thin but resiliently straight wire and all that stuff , makes it a reasonable trade off to buy the part for under $25.00 (aussie) and mod it to fit .

some pics may help tell the story better ?









 the mod being to file back about 1/2 a millimeter across the board height , so that it fits into the locating jaws of the original assembly .

the resistance of the swept area is about the same as the bmw unit , although being speced at 10 to 90 ohms ...i measure about 107 ohms for this one .
so careful placement should give a good fuel gauge meter sweep of full to empty ..

one thing that is evident is that the sample here is not coated with a waxy compound like the bmw unit , im sure the waxy stuff would likely protect the windings from corrosion .. and hold them in place during operation ...
more research to be done ... 

you might notice that the oxidization of the base metal after  several weeks without carrying forward with electroplating ....yet 
...the rust blast stuff seems to work well .

 the journey continues

charlie99 wrote:he pointed me towards a vw replacement sender .

Assuming the replacement works out, could you point to a source, part number, or similar?

Yes no problem   i have the part identifier

On the computer ....when i can get to it

charlie99 wrote:Yes no problem   i have the part identifier

On the computer ....when i can get to it

 No rush, and much appreciated.