5 replies to this topic

[jchomme]

Hi, Has anyone done  a subframe repair where the rubber cone meets the subframe.  The reason for not just replacing whole is because this is a 1960 sub frame and I want to keep the originality and subtle differences.

 

Besides some dings and surface rust, the subframe is solid everywhere but the place I described.  The other side is solid, but for some reason this one has some corrosion around the edge.  The part in question is probably fully functional, and would never be seen, but I am thinking of how to repair this.  

 

What I have come up with is getting my mig gun in there , lay a bead around inside the circle to build up and strengthen the  the whole ring.

 

The round panel seems to just be spot welded in and I was thinking I could possibly find or fab a new mount point and plug weld it in.  Any and all insight greatly appreciated.

 

 

[sonikk4]

I would get it properly sand blasted first before doing anything else. That really does not look clean enough. If it's only surface corrosion the either get the whole subbie blasted, then galvanised. Job done. You could if you wanted to add some extra seam welds on the whole subbie to give a bit more strength.

[tiger99]

The ring provides location and should not be all that important structurally, and the spot welds are ok. But the metal behind it is heavily loaded and rather vital as you will be aware.

 

I would do exactly as Neil suggests, because I like things to be as strong as possible and would be concerned that corrosion in the seams may have weakened some of the spot welds. The panel behind the ring can be seam welded to its surroundings fairly easily.

 

When it is galvanised it will be acid dipped first to remove residual rust, and this will penetrate into the seams. The zinc bath will boil off any residual acid so you need not fear that it will continue to eat away metal.

 

Once galvanised it is good for about 60 years, more if painted with a suitable process, starting with a special primer to bond to the zinc, which used to be zinc chromate based. I think that is now banned. Anyway, it is a primer FOR zinc rather than a ZINC primer, which we commonly use to protect bare steel. Confusing?

 

Over the primer, I would suggest a fairly standard epoxy primer and top coat of your choice, which will be black if you want to be original.

 

I wish that it was possible to galvanise complete shells. It isn't, due to the absolute necessity of providing both vent and drain holes in every place where air or zinc may be trapped.

[jchomme]

Galvanizing sounds great, but it might be overkill and cost prohibitive.  I plan to epoxy prime and satin black single stage urethane.  

 

So, the weird part is that this is the only real corrosion.  The other side is solid and as a whole the subframe just seems rock solid.   the brown is from an electrolysis bath I didn't really set up right.  

 

 I think I will go with the blasting and Report back with more pics of the whole thing.  I think I may do another electrolysis bath too.  Was considering citric acid, but I don't now much about it.   

 

Thanks for the input!

[sonikk4]

I don't know about Georgia, but in the UK I can get both subframes galvanised for £100 give or take a few pounds. Now with that in mind plus powder coating then they will last for a very long time.

[jchomme]

yeah, I've looked for that kind of service and I can't find anyone who would do this. Mostly industrial applications here.  Plus, Georgia's climate is very mild. 

 

It is difficult  to find a shop that does piece work for individuals. I feel like I have to pretty much do everything on my own because even if it is available, the cost is high.  Plus I like the challenge and I like learning new skills.  

 

so, As long as I get all of the rust out, epoxy and 2 pack paint I think it will be more than sufficient.  I am also led to believe the quality of this old steel and manufacuring practices were better.

 

I don't want anyone to think I am cutting corners.  If the subby was questionable, I wouldn't use it.  

Edited by jchomme, 19 September 2016 - 09:07 PM.