Plated parts

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LanciaFin
Posts: 155
Joined: 04 Dec 2011, 16:40

Plated parts

Unread post by LanciaFin »

After over 40 years it's hard to say, if some parts have had yellow passivation or just bright zinc plating. How were the bolts and nuts in engine and engine room originally plated? How about the Dunlop brake cylinders (main, slave and wheel)? Now they have a rather good gray zinc plating externally, I just wish they were in such condition from inside too (pistons pushed almost completely in, sitting for 20-30 years => You know the results... :( )
Huib
Site Admin
Posts: 1778
Joined: 17 Dec 2008, 10:12

Re: Plated parts

Unread post by Huib »

I doubt that the bolts Lancia used in the sixties were just zinc plated.

The ones that were copper plated are obviously not zinc plated. However many look like they were zinc plated but they certainly lasted much longer than any zinc plated bolt you can buy today.
racing
Posts: 1366
Joined: 09 Jan 2009, 08:25
Location: cologne/Bonn

Re: Plated parts

Unread post by racing »

the copper plated are used only for screws and bolt with strength higher than 8.8.( expl.10.9 or 12.9 classes )
because there is the risk of hydrogen embrittlement if you use zinc plated ( yellow chromating)

If you use yellow chromating it is necessary to have a heat treating of the parts up to 180 C° for 2h
to avoid the risk of defect´s on high strength and to have the calcination of hydrogen.

The standard that i have mostly found was yellow chromating part´s. ( excl. the high strength screws and bolt )
So i do it for ex.for the caliper`s.

regards Andreas
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LanciaFin
Posts: 155
Joined: 04 Dec 2011, 16:40

Re: Plated parts

Unread post by LanciaFin »

Some of the nuts and bolts are in surprisingly good condition for their age, and still have the (originally or not) grey zinc plating on them, some seem to have traces of yellow passivation on them, but it's difficult to say anything surely. I didn't know about the hydrogen embrittlement when zinc plating, so you gave a valuable information here, thank you. I'm going to do the plating of these smaller parts by myself, and was planning to plate at least the crowns of the visible engine bolts. It may be a better idea to use paint on them.
Huib
Site Admin
Posts: 1778
Joined: 17 Dec 2008, 10:12

Re: Plated parts

Unread post by Huib »

I have a reasonable quantity of Lancia's from the sixties and seventies going through my workshop for either complete restoration, partial restoration or service / repair.
I notice on my own cars and customers cars which I did some years ago that bolts which were either zinc plated again (subcontracted by me) or replaced with new zinc plated bolts that these bolts have rusted already while on sixties cars the original bolts are usually in better condition.

I have not done any scientific research or statistics but it seems that:
1. bolts from the sixties "last forever". It hardly ever is a problem to take an S1 Fulvia apart. Bolts come off easily
2. on seventies cars like S2 and S3 Fulvia's it sometimes is a challenge.
3. later cars such as Delta's are a disaster. Everything rusted together.

It is more than a matter of cost. People doing the zinc plating charge by the bucket. I tell them to do the best possible job, money no object. On the total cost of restoration it is not really important if they charge 40€ or 80€ to zinc plate a bucket full of parts. Driving there for bringing it and picking it up already costs more. Nevertheless the zinc plating goes off much quicker than from the original S1 bolts.

Could it be that that the process was different? Environmental issues? Cadmium instead of zinc?

Years ago I also used electroless nickle plating for some parts such as the Dunlop wheel brake cilinders and callipers and some bolts. This lasts longer but does not look original. I am thinking more and more about going back to the electroless nickle plating.

For the 10.8 and 12.9 bolts I use new ones with Dacromet coating. This is a coating which is vapourized or sputtered onto the bolts and nuts. I think it lasts much longer. We will know for sure after 40 years.
racing
Posts: 1366
Joined: 09 Jan 2009, 08:25
Location: cologne/Bonn

Re: Plated parts

Unread post by racing »

Dacromet coating is one option for 10.9 etc.

In the past "they" reduced the thickness of the zinc depent on the cost. Today they have more or less 4-6µm
but it is possible to have it up to 12µm.
Moreover today it is not allowed inside the automotive industrie ( supplier etc. ) to use yellow chromating ( as i have done on the
kaliper ) This depent on the chrome 6 that is necessary for that.This is forbidden.

And the other ( silver colored but correct is blue chromating ) is not as resistant as the yellow chromating.

regards Andreas
2000HF
Posts: 30
Joined: 26 Sep 2009, 16:01

Re: Plated parts

Unread post by 2000HF »

That is an interesting topic. I wonder if you disassamble the brake calipers before plating? I heard a lot that it is quite difficult to open the callipers and even more to reassamble them and get them leak proof. Would you use a sealing compound?
I just refurbished the brakes on my `73 2000 Coupé. Being afraid of my security I did not open the callipers. I sandblasted the outside and derusted the cylinder surfaces with a rust removel jelly (acid). Than I painted them with silver "Rust Seal" paint. Not original, but looks good.

I also have the impression that the Lancia bolts are more resistant against corosion than the ones of other makes from the same period of time, thought most of the bolts on the suspension and frames of my car have "FIAT" stamped on them ;)
By the way most of these bolts of the Suspension and frame have a black finisch (browning- is that the right term?). These parts also look surprinsingly good, this kind of plating is usually not seen as rust resistant as other platings, Loosening nuts and bolt was in most cases not a big deal - apart from the parts that need high torque.

Also the suspension bolts had still the pumpkin yellow marking paint dots on them. I think that was done in the factory. Does someone know a colour code for this paint? I am thinking of using the same technique of marking the bolts after tightening.
Ed Levin
Posts: 500
Joined: 23 Dec 2008, 10:07

Re: Plated parts

Unread post by Ed Levin »

I don't think you'll find a color code for the quality control paint. It was originally bright yellow, but it ages to the darker shade you see now. If you want to replicate it, you can pick any color from bright to darkened, and it will be as correct as anything else.

2000HF Wrote:
-------------------------------------------------------
> Also the suspension bolts had still the pumpkin
> yellow marking paint dots on them. I think that
> was done in the factory. Does someone know a
> colour code for this paint? I am thinking of using
> the same technique of marking the bolts after
> tightening.
Huib
Site Admin
Posts: 1778
Joined: 17 Dec 2008, 10:12

Re: Plated parts

Unread post by Huib »

I always open the callipers. There is a so called rubber channel seal around each hole for the brake fluid. These channel seals are not included in the overhaul kits but they are available from brake shops. Just ask for half inch channel seals.

I make sure that the half callipers stay together. If you take a set of only one car to the zinc plating shop, you can't go wrong. If I have more than one set I mark the half callipers by stamping a number on them.

Do not zinc plate the bolts. They become brittle.

I always remove the zinc from the cilinders walls and Bottoms.
piggdekk
Posts: 47
Joined: 19 Sep 2020, 12:07

Re: Plated parts

Unread post by piggdekk »

I totally second Huib that S1 hardware is very durable. I still had to replace/restore it on my FZ s1, and while I do now know for sure which bolts were copper plated and which ones were zinc plated I went ahead and copper plated most of the ones that had copper to start with. Some others fell in the plating bath too...
I couldn't restore all the bolts, so I sourced new bolts of the correct sizes and then applied alkaline copper plating on them. It has to be Alkaline plating becuase it adds very little thickness compared with acid one, and so it preserves the threads. I bought my plating kit from Classic plating in the UK, and the results are really good.
The bolts I sourced were blued, so I had to remove blueing and oil before I could plate them. It's not a short process, but the results are worth it.
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