Effects of Galvanizing Car Parts

[Jerry]

My 67 Austin Healey was received about 12 years ago as a project car. All torn apart. But the PO galvanized almost everything once he had it apart. Nuts and bolts, brake parts, fenders. You name it, it was galvanized. We did not use the nuts and bolts on the car. I preferred at the time to use new bolts. I had planned on keeping the car forever and wanted to know they would not stretch or break. Now I am working on a 1964 BJ8 and may decide to use all those bolts and nuts. My wife asked about the galvanizing process and what that would do to the parts? Anyone know?

 

[HealeyRick]

Use the Harbor Freight rule, "If your life depends on it, don't use it" This chart will show you what can be galvanized safely. https://www.portlandbolt.com/technical/faqs/galvanizing-high-strength-bolts/ I wouldn't use any of them in any critical function

 

[Bob_Spidell]

Interesting question. Are the parts galvanized by electrolysis, or hot-plated? Galvanizing would help stave off rusting for longer than non-treated steel, but rust will occur eventually anyway (the plating is sacrificial). According to Wikipedia, 'true' galvanizing involves dipping things in molten zinc, but 'cold galvanizing' products are available as well. I believe cadmium plating is superior to zinc galvanizing--it's used on aircraft fasteners--but is a more expensive process.

If the question is "Should I re-use the galvanized parts?" the answer from me is "It depends." If the part is in good shape, and esp. if it's expensive, it should be OK to re-use; if there's any sign of wear or corrosion I'd chuck it. In my limited experience, stainless steel fasteners seem to be a more brittle than plain steel, and I've not seen larger fasteners made of it (it may not 'stretch' as well as plain steel). Paint adhesion might be affected.

As usual, Wikipedia is a good starting point: https://en.wikipedia.org/wiki/Galvanization

 

[Madflyer]

Galvanizing is hot dipped I do not think it is to hot to temper but paint will not stay and threads need to be cleaned. I had my TR 6 powdered coated all removable parts under hood and steering brake parts and all 25 years later still like new. cleans easy and shows well all these years later. As for bolts of any size should be not greater than Grade 5 and new aircraft locking nuts best. Just like tires your life is on the line and don't want the wheels to fall off at the first pot hole. But as a trained aircraft mec. we just can not pull over. Madflyer

 

[Bob_Spidell]

... As for bolts of any size should be not greater than Grade 5 and new aircraft locking nuts best....

Please elaborate.

 

[mwagon]

Its possible that your parts have been Zinc Plated by electrolysis & not Galvanized. Galvanizing applies Zinc by hot dipping, as mentioned already, but leaves a thicker layer then by electrolysis application. Probably preferred in this cae since its at room Temp. during process vs ~850F during Hot Melt Galvanizing.

 

[Jerry]

They look galvanized to me. Zinc plating is a different color. I also bet that none of the bolts are grade 8 which the chart says don't galvanize. I agree with above at replacing lock nuts. I can't imagine them still working as original after 60 years. The other interesting thing about all these parts is the body guy's comment. He said that he had never seen fenders galvanized and had to look up how to prep them prior to painting. I think what he did was lightly media blast them to smooth out the surface.

The spindles on the car had to be sanded to get them back to stock size for the bearings to fit. Certainly an interesting individual who did this. We also noted that he kept extra parts around from the donor parts car. Many of the parts were labeled left or right. We finally decided that he did not know his left and right and ignored those labels. And why do you decide to keep an extra left side part, but not the right side? Oh well, I got an extra engine out of the buy.
Jerry

 

[Madflyer]

I do not know what years GM tried to use Galvanizing on body parts and as seen to day much of their paint fell off.
As you look at your bolts by size and fine thread at grade 5 can be reused as most only torque to 15 to 45 # Most MEC. say do not reuse head bolt unless you know your motor history then only ounce. I would make sure driveline bolts and nuts are next to new. Brakes the same. An I used anticize on threads years latter still come right off. CAUTION if it is a shoulder bolt use a shoulder bolt not all threads. If you spend more you can get zing plate and or stainless steel. I used SS where I found a great deal of rust. Madflyer

 

[Jack T]

I used SS where I found a great deal of rust. Madflyer

NEVER use SS bolts in a structural application that calls for Grade 5. They cannot be heat treated to provide the shear or tensile strength as a carbon steel bolt can.

 

[Jerry]

Paint has been on the galvanized fenders for 11 years now and no problems. whatever they did to prep them has worked. Did the Austin Healey factory paint or treat the nuts and bolts as components were attached?