TheSamba.com :: View topic - Brown Bosch Distributor Cap & Bosch Black Cap- Differences.

Sat Sep 09, 2017 6:10 pm

Hello, been looking threw the threads and did not find any info on this topic but is there a material difference and metal difference between the Black Bosch Distributor Cap and Brown Bosch Distributor Caps?

Yea, just been wondering about Quality?

Thanks for y'alls time and if anyone knows some data.. RB

Sat Sep 09, 2017 6:16 pm

Brown is Bakelite and black is plastic. Both have copper terminals and are functionally identical.

Sat Sep 09, 2017 6:20 pm

Quick question there Glenn on something, when it comes to weather, is there a preference to have, since winter is coming? Mean, not to be a wussy, but don't want to be stranded or have a miss do to a crack do to extreme temp changes. RB

Sat Sep 09, 2017 6:37 pm

I never had a problem with either.

Old Bakelite are getting pretty rare and expensive. Bosch discontinued the black 010/019 cap.

If you have a cast iron mechanical, just use the Bremi. They work, are readily available and reasonably priced.

Sat Sep 09, 2017 6:42 pm

Glenn, did read in the threads that people can get 100,000 miles on a cap and rotor, little Emory Cloth I guess is the key, is this true? Running a Cast Iron.. RB

Sat Sep 09, 2017 6:54 pm

I never tried.

I have a box full of old caps. I guess you could use a Dremel with a wire brush attachment to clean the terminals. But the center carbon button does wear.

Now if you have a KDF or a Split with a 383 distributor that uses the flat top cap, i can see cleaning them since genuine Bosch caps are "stupid" expensive.

Sat Sep 09, 2017 6:59 pm

Glenn wrote: Brown is Bakelite and black is plastic. Both have copper terminals and are functionally identical.

For the record......actually they are ALL Bakelite......meaning they are made of phenolic resin.....but the newer orange and black ones are a different blend of fillers. The base resin is still "Bakelite".

The early dark brown resin was old school classic bakelite and was reknowned for its casting accuracy.

The newer stuff...still pretty accurate...but not quite as brittle. A little more flex.

Also.....Grinding on ANY of them at high speed ....enough to produce smoke from burning.....is HIGHLY toxic. The old school ones even more so.

And though I know what you were getting at.....actually....bakelite IS a plastic. Ray

Sat Sep 09, 2017 7:08 pm

You wanna try it... pay for postage an i'll send it. You just have to use it for 20,000 miles.

Sat Sep 09, 2017 7:17 pm

Guess the Black Holds Up Well with the Cold & Rain in Winter for I did not see any reports on that in the threads... RB

Sat Sep 09, 2017 8:54 pm

I'm guessing the black & brown Bosch caps are made in different countries. My brown 009 cap is marked "Made In Spain" on the box and my black 009 cap is "Made In Brazil"

Sat Sep 09, 2017 9:19 pm

Why not run em till they malfunction??
ain't broke don't fix it, but carry a spare!
Stealing them to be a pretty common prank you know :shock:

Sat Sep 09, 2017 10:27 pm

I have had them in every color made in virtually every country Bosch operates in....Germany, Mexico, Brazil, Spain.... whatever.

I have no idea why they changed colors between orange-ish and black......but they are the same material (the electrodes not withstanding....some aluminum....some copper).

It may have to do with both the cost and the toxicity in the material. Bakelite was never really the cheapest material to make......and milling, drilling and machining it is highely toxic id it creates smoke......no kidding!
The new ones are too.

But its interesting. You break an old bakelite part and the grain is totally different from the new ones.

Bakelight....or phemolic resins can be made in ANY color. The ability to be easily tinted is one or the hallmarks that made bakelite popular. Its high temp range and huge dielectric capability made it perfect for electrical parts.
Ray

Sat Sep 09, 2017 10:31 pm

Glenn wrote: I never tried.

I have a box full of old caps. I guess you could use a Dremel with a wire brush attachment to clean the terminals. But the center carbon button does wear.

I have done this - it worked fine.
I did not clean the center button underneath.

I have had an original brown one crack up the side.
I didn't notice any issue driving the vehicle but I did replace it.

Sat Sep 09, 2017 11:25 pm

carbon tracks are the main concern.or a burnt up carbon buttin. Also and effing around in there may cause the carbon tracks.....play with the button& wipe you finger around in there spreading a nice little layer of carbon for the voltage to fallow....it might, it might not. aluminum caps are poop, the copper/brass units should last almost for ever.... a wonkey rotor can eff up the carbon button too and put a nice layer of crabon in there... or the effed/wonkey rotor can wack the terminal... unless there is a issue I see no reason to eff with the cap :shock: my see through green cap is awesome! it's atleast 15 years old now. I dont know where it is.... but it's oh so pretty.

Sat Sep 09, 2017 11:31 pm

I'm going with vanity, I like the look of the black ones, but replacements are always rust brown...so I paint them...right now it's yellow...at least it's not one of the clear ones from the '80's or are those still available?

Sun Sep 10, 2017 2:52 am

Original bakolite here from the gallery:

High quality dark brown from Mexico:

color choices:

same part/quality, different part numbers.

The dark brown caps are older and likely have the older Bosch part number systems on them. The black seems to have followed as I see both old and newer part numbering systems on them. The orange caps I've only seen with the newer part numbers.

FWIW the truely older post flat top caps did not have the Bosch logo or part number on the outside. The logo and number were on the inside much like the Bremi or Wolfsburg West caps sold today.

Sun Sep 10, 2017 3:29 am

I've never seen anything but copper contacts on Bosch caps. There are a lot of other manufacturers out there and some use brass or aluminum. The aluminum is a less expensive metal. but is still a good conductor, viewed as inferior which may/may not, be a fair assessment.

Sun Sep 10, 2017 6:54 am

Glenn wrote: I guess you could use a Dremel with a wire brush attachment to clean the terminals. But the center carbon button does wear.

with the high prices of nos original Bosch dark brown caps, i have cleaned the copper terminals on used ones with good success, as long as there is not a seriously burned groove in them. heck, i'll even buy used dark brown caps for $5-10 if the terminals look good. they go well on not-full-blown-restoration / clean up/patina distributor rebuilds.

yes, the carbon post does wear, chip, break, etc. fortunately i have a small stash of nos posts that i use for saving special caps.

Sun Sep 10, 2017 9:14 am

Actually...this idea that caps never wear out....is not true.

When you get carbon build up on the electrodes....that carbon does not materialize out of thin air. That carbon is a combined production of elements in the metals of the electrodes, moisture, oil vapor....all of it.

If you can clean off just the carbon without scraping away actual metal...you will see over time that the carbon removal actually leaves a groove where the metal the carbon was made from is largely gone.

Over time as the gap both from rotor wear and cap electrode wear becomes excessive....the amount of current consumed to jump the gap will produce a weaker spark.

Does this mean that it will not work any longer? No...on a basic carburetted beetle engine where the ignition is not stressed that much....you may never have enough spark degradation to make a big difference. Thats why they seem to "funtion" for eons.

However as compression rises and leaner fuel mixtures are used on the later engines like type 4 ....its a definite problem. Even if you keep the carbon totally cleaned off...you can reach a point where you have a noticeable weak spark especially at idle. Just snapping on a new cap and sometimes just a new rotor or both...instantly fixes it.

Back in the day...like mid to late 80's....it was not hard to find actual "copper" brushes for the Dremel tool...which are soft and worked well to only remove the carbon and virtually no metal.

All I can find these days...and its been this way for a while...is brass brushes. they work pretty well but you have to be careful. They are a bit harder than the copper electrodes.
Well....I can get them on Ali-Ba ba....but thats an adventure my credit card does not want to experience. :lol:

Quote: Mark Tucker wrote:
carbon tracks are the main concern.or a burnt up carbon buttin. Also and effing around in there may cause the carbon tracks.....play with the button& wipe you finger around in there spreading a nice little layer of carbon for the voltage to fallow....it might, it might not. aluminum caps are poop, the copper/brass units should last almost for ever.... a wonkey rotor can eff up the carbon button too and put a nice layer of crabon in there... or the effed/wonkey rotor can wack the terminal... unless there is a issue I see no reason to eff with the cap Shocked my see through green cap is awesome! it's atleast 15 years old now. I dont know where it is.... but it's oh so pretty.

What you are speaking of here ....is "carbon contamination". Its different from an actual carbon "track". Both will cause the same effect....but one is fixable and the other is not.

People get them confused.

When you get enough carbon "residue" or dust....and it sticks to surfaces in a high voltage environment.....if the carbon particles (which are highly conductive)....are close enough together....the voltage can arc across these little conductive "rocks". It will literally arc from rock to rock like lightning until it reaches an area where the "rocks" are too far apart.

You can clean this off...if you catch it early enough.....but the success of cleaning depends on what you use and what the polarity of these rocks are and the cleaning solvent. Typically the most assured cleaner is something like a water based cleaner with a wetting agent to break surface tension and carry away the dust.
Dish washing liquid like Dawn works good. Or any detergent and some Jet-dry from the dishwasher.

We have the same problems with phenolic plastic and other insulators in electronics enclosures and most go into a DI water bath wit ha caustic to break surface tension.

An actual "carbon track".....is one that follows a MICROSCOPIC fissure in the actual plastic. It will NOT go away....and cannot be washed away. Its actually material from inside of the plastic escaping through the fissure (which may be a molding defect or a stress crack)...and being carbonized by initial arcing.

The more that material carbonizes....the more there is to conduct electricity and the worse it gets.

And...a carbon tracking situation caused by just conductive dust like Mark described...if left alone too long...will overheat the surface where its arcing and eventually cause a fissure that will be a permanent carbon track.

Yes....the aluminum cap electrodes have less conductivity. Aluminum is only about 55-60% as conductive as copper.

I have only seen a handful of actual Bosch brand...black caps...with aluminum electrodes.
From memory...it was also in a very short amount of time in and around maybe 1989 to 1991?
Back then both aluminum and copper prices were at a high....but there was not enough difference for the cost in metal to explain why aluminum was used or tried.

It may have been an experiment. Aluminum while less electrically conductive is much more thermally conductive. Also...one problem with copper....is that when left to sit for long periods in humid places.....the "green patina" that grows on copper....is NOT electrically conductive. Aluminum has a little less of this issue and less high temperature heat erosion from carbon tracking. Ray

Mon Sep 11, 2017 9:42 pm

I sacrificed a black Bosch cap, actually had to hit it pretty hard with a hammer.

Looks to be the same material as the brown.