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Is powder coating a frame such a bad idea?

29K views 42 replies 21 participants last post by  Pharisee 
#1 ·
Hi,
Happy New Year to one and all - I hope 2016 brings you plenty of biking enjoyment.

I had a disastrous result getting a frame painted in 2k paint so now I've manged to get my money back I'm thinking of getting it redone in powder coat.

However, I've heard lots of people say, "Don't do it because when it gets corrosion under it, it comes off in sheets", or "Don't do it because if it gets chipped you can't touch it up", but I've never met anyone who has actually experienced any of those problems themselves - they all seem to have 'heard it from someone else'.

So, is powder coating a frame such a big 'no-no'? I'm confused by the statement that 'it comes off in sheets'. That seems to imply that the powder coating doesn't adhere to the steel but instead just forms a kind of 'unattached' covering - but surely it must stick to the metal when heated during the curing process?

Also, the statement about not being able to touch it up if it gets chipped. I can understand that you might not be able to get a perfect invisible finish like you could with conventional paints, but surely if you got a stone chip in the plastic coating, you could just put a blob of Hammerite/Rustoleum on the frame to cover the 'hole' in the coating? It might not be pretty but surely it would stop any corrosion at that point?

Are these problems I've been told about real or are they just part of the restoration folklore that seems to get circulated?

Regards
Tony
 
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#34 ·
I often wonder why the screw/bolt threads don't supply enough ground. Even if the washer or electrical tab is screwed to the powder or painted surface the screw head grounds the terminal and is in fresh metal where the threads are in the frame. If I know that spot is a grounding spot I will use a masking dot there so it is bare when the coating job is done.
 
#36 ·
Hi Marc,

I often wonder why the screw/bolt threads don't supply enough ground.
It might do initially. But it's exposed; sooner or later, the corrosion stops it working. :(

I have a feeling that by 1970 Lucas were providing return wires in the harnesses?
Afaict, Lucas knew all along how to construct robust, long-lasting electrics, just BSA (or any other bike maker) wouldn't pay for 'em. :rolleyes: The number of Red wires connected between components and battery +ve seem to increase gradually through the 1960's ... then BSA added indicators in '71 and Lucas forgot the Red wires ... :D

It is daft to me to "save wire" and rely on a poor electrical connection
+1. I work on old Jap bike electrics as well and they always use the cycle parts as one circuit conductor ... amazing how many 'faults' disappear as if by magic when you connect all the "grounds" with a piece of wire ... :whistle

Hth.

Regards,
 
#39 ·
Hi Rocky,


Originals had "wired earth returns" ... the only ones missing tend to be for the indicators.

BUT (and ime it's a J-Lo):-

. Any '71-on original harness was made entirely of 14-strand wires.

. Even if an off-the-shelf harness uses the modern metric equivalent, those wires are rated for 8.75A, so the capacity of, say, the Brown/Blue, is exceeded by even the standard RM21 alternator above about 3,000~3,500 rpm. :eek:

. I've never known a '71-on off-the-shelf harness use the pre-'71 much-thicker wire dimensions for wires like the Brown/Blue and main Red.

. I've never known a '71-on off-the-shelf harness not copy the original when including wires for rectifier, Zener, points, condensers, etc., etc., all of which have to be traced and taped up when fitting now-common upgrades like 3-phase alternator, electronic rec./reg., electronic ignition, etc.

Fwiw, the first rewire I did, I wanted to change so much, I decided it wasn't worth trying to adapt an off-the-shelf harness; that what I made proved a pleasant surprise when it was so easy and robust. Subsequently, all my experience of off-the-shelf harnesses has been terrible ... really not worth the aggravation and cost. I appreciate that the first rewire looks daunting from the beginning but, as long as you possess the ability to work logically, a Britbike rewire using easily-available off-the-shelf wire and terminals really is very, very easy.

Hth.

Regards,
 
#43 ·
I tried using 'thinwall' wires. While they undoubtedly take up less space and make up into a 'thinner' loom, I found that when using crimp connectors that have two crimping areas (1 for the conductor and 1 for the insulation), the crimp onto the insulation didn't seem to be as secure as it was with 'regular' insulation. In the end, I used the thicker insulation for all the wiring on my T120R with one exception... I used thinwall wire for the indicators as it was easier to get two of them up the stem to give me a proper ground return.

I built a kit car based on a Triumph Herald chassis many years ago. Money was a bit tight so I went to the local car breakers and bought a couple of old car harnesses for a few shillings. I stripped them down and used the wire to make up a new harness for the kit car. Never had any problems with that.
 
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