How to restor bolts and the like????

[Brandon Metzger]

I am in the middle of a frame off restor. on a '72 LS5 M40.

What is the best way to restor or return to "like new" condition all the nuts and bults?

I know you can buy them new and if this is the best option then.... If you sand blast the bolts then they turn out gray and I don't believe the bolts were painted. If they were then then when you install them wouldn't the paint chip.

Perhaps a simple and silly question but I have been mulling this over for a while and haven't come upt with a satisfactory answer.

Lastly, are there any paint charts out ther to tell me what color and gloss all of these parts are, espessialy on the chassis?

Thank you much,
Brandon

[Michael F.]

Re: How to restor bolts and the like????

in the 60s bolts were usually cadium plated and i think they changed over to zinc plating in the 70s, correct me if i am wrong clem, john, duke or anybody, anyway you can usually get a bucket of plating done for around 345-50 so you can just gather up all your plating needs and take it down and still have the original stuff. some bolts had a black phosphate but i believe most were zinc plated

[Jack H.]

It also take a calibrated eyeball....

to assess the safety issue of re-using factory original fastners. If they're BADLY chewed up, rusted, or stretched you do NOT want to media blast, chase the threads and send those out for replating! Restoration is one thing, but SAFETY is a much more important issue than factory originality....

You'll find many of the serious restorers go on scrap yard hikes to gather original fasteners from donor cars assembled in the same era as their cars to have a sufficient quantity of 'known good' ones to either run through their home plating systems or send to a plating shop in a 'bucket run'. The trick lies in knowing what the correct/original fastner's size and head marks were as well as being able to visually assess the condition of a given used fastener.

Most all of the critically examined fasteners are available from reproduction sources, but there generally ARE minor differences in the specifics of headmarks because the original supplier's tooling wore out and was replaced over time. Also, rule of thumb says you'll pay $1/bolt for fresh repro fasteners (on average) and this, along with pride of restoration (get the real McCoy, from the era fastener) is why scrap yard treks and bucket runs through plating shops is done in the hobby....

[Chuck S.]

Re: How to restor bolts and the like????

Brandon, fasteners are one area where you can't really buy enough accurate repro parts to do a full restoration. There are some repro bolts, and I have found some (bumper bolts, M headstamp) that were identical to the originals. If you have fasteners that are so heavily rusted that they are cosmetically unacceptable, your best hope is to find original, correct headstamp fasteners from the junk dealers at Carlisle or from same or close MY donor cars.

Fasteners are typically plated and not painted (raises heck by gumming-up the threads). Fasteners may be black phosphate, zinc, black oxide, chrome (primarily interior), and even natural. It seems to me that the type of plating depends on the application: chassis fasteners tend to be primarily black phospate with some zinc, underhood has zinc and black phosphate, and the engine has a lot of black oxide and some zinc.

There is information on DIY black phosphate in the archives and The Corvette Restorer CD. Zinc plating kits are available (see link below)...I never felt comfortable turning my original fasteners over to a stranger. Black oxide is durable, but restoring is another matter; you may have to resort to one of the spray finishes.

It's very important to examine the fasteners closely to determine and record the original finish BEFORE bead-blasting or wire-brushing. Once the fasteners are cleaned using these methods, it will be impossible to determine the original finish. If your car is fairly original, it will be your best reference source, and this is particularly true on fasteners. You have to be aware that after 30 years, technicians may have exchanged or replaced fasteners. You will get to know and recognize the correct headstamps, and this will help you sort out the Home Depot or aftermarket fasteners that will need to be replaced.

BTW, if your fasteners are "gray" after bead-blasting, maybe they are not clean yet...thoroughly bead-blasted fasteners will be silver, a condition also known as "white metal".




Caswell Plating

[Dick W.]

Re: How to restor bolts and the like????

In addition to what Chuck said, I have had good luck with soaking fastners in a metal etching bath, such as Twin Etch, Metal Prep. They are a phosphoric acid solution. This does a pretty good job of removing rust. Then you can blast them

[Chuck S.]

Re: How to restor bolts and the like????

Good point, Dick. I forgot to mention that I had also used muriatic acid to clean severely rusted fasteners, and then bead blasted for a final finish. Muriatic acid creates some other problems, and I would rather not mess with it unless it's necessary.

Be advised that any fasteners that are to be zinc or chrome plated will have a matte finish after bead blasting...If your objective is a slick, reflective finish, then you should only acid clean and skip the bead blasting altogether. Of course, if the fasteners are already heavily rusted, they aren't going to be slick and reflective regardless of cleaning method.

[Jeffrey S.]

Re: How to restor bolts and the like????

Brandon:
I have had great success in restoring USABLE fasteners by doing the following:
To clesn the fastener I either soak the piece in naval jelly overnight or sand blast. After either I buff the part with a "scotch bright" type wheel on an arbor in my drill press. This gives the part a nice shine. Then I use the Caswell plating system-"Copy-Cad" with or without the zink brightener to replicate either a cad plate or zink plate. I also use their blackening system and gold cad wash depending on what was original. To find out what the part was originally, there are some good reference books. One good one for chassis fateners is Joseph Tripoli's book "Corvette Chassis Restoration Guide". It's available through the NCRS. Hope this helps.
Jeff