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The pot metal headlamp support is being held in place by a steel bolt... if you look at the corrosion chart you'll see they are way apart on the scale and subject to corrosion. It's very common to find this problem and if you place a steel plate in there to help hold the support you'd be best suited if you coated it in something like liquid rubber or a good heavy coating of paint. This will help prevent further corrosion.
To stop the galvanic action on the trailers when I worked at Fruehauf Trailers. The frames were painted in an enamel and baked. So the steel did have some layer of protection. When the guy in my department who hung the walls go the frame before they got to my station. He applied a layer of wide cellophane tape because the bottom rail of the wall was made out of aluminum.
So...ever since. I apply a layer of cellophane tape on the contact surfaces of the aluminum body biscuits..and I also apply a layer on the flat contact surfaces of the actuator supports where they come in contact with metal..and this is at the front two point points as long with the rear mounting area.
Whatever a person chooses to use...just do something that will provide a barrier.
To stop the galvanic action on the trailers when I worked at Fruehauf Trailers. The frames were painted in an enamel and baked. So the steel did have some layer of protection. When the guy in my department who hung the walls go the frame before they got to my station. He applied a layer of wide cellophane tape because the bottom rail of the wall was made out of aluminum.
So...ever since. I apply a layer of cellophane tape on the contact surfaces of the aluminum body biscuits..and I also apply a layer on the flat contact surfaces of the actuator supports where they come in contact with metal..and this is at the front two point points as long with the rear mounting area.
Whatever a person chooses to use...just do something that will provide a barrier.
DUB
Dub,
The plastic coat stuff works wonders for this after a good epoxy coating... you can get it in the dip it style can or the paint it on style... both work pretty darn good and for the cost it's a breeze.
The issue is that the header is steel, the bolts are steel and the support is pot metal... What ever nut job thunk up this combination wasn't thinking 20 to 30 years down the road.
The back side of the supports take the blunt of the corrosion where the bolts pass. In the past to save the original supports, I've milled flat washers to fit inside the old supports and while this is a nickle fix for a quarter repair it'll work for a while... but it's not a good fix at all.
The best results come from just replacing the support with a new one. However, the 1968-1974 new supports are a sparce replacement for the originals since they are just the 75-82 suppports that have been cut and welded.. But... it's all that is available and it works.
I do agree when this are is subjected to having salt coming in contact with the two metals...that is where the problem begins.
I have had some actuator supports on Corvettes that were really in bad shape.
I can see how on the surface if the actuator support where the washers of the bolts make contact...that the spray on rubber coating would work. I actually use the plastic protecting material off of my media blast cabinets and make plastic washers.
I will have to give your method a try. Not that making the washers is a big deal...but if I do not have to that is that much better if it still provides a good barrier. Which is seems it would.
Wow, great conversation here. I love this forum. I haven't had a chance to get back to my problem. I'm scared to death to try and take the nose off to fix this problem the right way. I know that's bad of me but I feel like I'd get way in over my head. I'm going to try the shim idea I put before and if it doesn't last long I'll go through the more heeded process you all spent time writing up. I'll let you know how it goes.
I do agree when this are is subjected to having salt coming in contact with the two metals...that is where the problem begins.
I have had some actuator supports on Corvettes that were really in bad shape.
I can see how on the surface if the actuator support where the washers of the bolts make contact...that the spray on rubber coating would work. I actually use the plastic protecting material off of my media blast cabinets and make plastic washers.
I will have to give your method a try. Not that making the washers is a big deal...but if I do not have to that is that much better if it still provides a good barrier. Which is seems it would.
DUB
Dub, I have a slight advantage, I've got milling machine here... so I can make a spacer/washer that will fit inside the rotted area at will right between the two webs of the support at will.. the question is if the time doing this worth the cost of a new support and just moving onward.
To me the cost of a temporary fix to me doesn't seem like the option but I've got to do what the customer wants. The cost effective way to do the repair is replacing the support. Even then coating the bolts and washers will make it last a lifetime.
The salt from harsh winters will act as an electrolyte and conduct electricity between the steel bolts/washers and the headlamp support. (same as the header bar rivets)... Once that salty water hits these items it's just a matter of time before they tank.
E
Last edited by Willcox Corvette; 05-04-2018 at 04:34 PM.
I can completely understand on weighing out what is the most cost effective way to repair something. Sometimes the repair can exceed the cost of new part.
On a related note, what's the easiest way to get at the 3 bolts to adjust that outer pivot bracket ? Pull the inner one, unpin the assembly, pull it out, and go in through the headlight hole ? Or is there a trick ?
If you are referring to these three bolts for the outside. I get to them from the backside. I can reach around the rear corner and get my socket and ratchet on them or use my small ratchet wrench.
I can do this with the hood up also.
For me doing it this way it allows me to get the height set and snug up one of the bolts an check it and then go back in and snug another bolts and so on and then tighten them when I get the headlight door where I want it.
well, I finally discovered the other half of the reason my passenger side headlight has been scrubbing on the way up... a chunk of that die cast aluminum mounting bracket is broken off from the bolt hole to the rest of that corner. That lets one side of that headlight assembly sit a good 3/8in low. One more thing that's gonna need to be addressed at some point.
Although it's not the recommended fix, this is how I braced the cross-member. It wasn't attached at all before so shimming this up has push it back into place and is solid again. I still need to do a bit of housing adjustment however, so I'm not done yet.
If the bond of the header support beam was lost and it is not bonded. Raising it back up and shimming may work or may not work due to the panel...if it is detached..can have a mind of its own and... do what it wants to do no matter how much you try to adjust the headlight door to work and not scrub.
My attempt at rebonding the header bar in place is actually holding so far, hopefully it'll continue to hold till winter rolls around. I managed a temporary fix for my sagging passenger side bracket, again hopefully the bracket holds for the season, until I have the downtime anyway, and replace the header bar and do a nice full cleanup on the whole headlight assemblies. Here's a pic of the cobble job I did on the busted bracket. It's obvious how bad a shape my header bar is in, too. The driver side bracket isn't in much better shape; both of those are going to be replaced when I have it all apart.
Is it possible to get the header bar out with the front portion of the body still on the car ? It seems like there would be enough room to get in there from the underside and clean off the fiberglass, then apply adhesive to the new header bar, bolt it in, then clamp everything in place to let the adhesive set... or is it really only feasible with the bodywork off ?
I can do ALL service work to this support beam and not have to remove any body panels...so YES...it can be done. Because the adhesive you will use has such a long work time and you will be doing so many test fits...you will figure it out.
Thanks ! That just because a whole lot less daunting. I had been under the impression the bodywork had to come off to reach a couple of the mounting bolts. I don't imagine it would take an unreasonable amount of persuasion to get the rebonded header bar to pop back off there either.
04-30-2018, 08:44 PM
