FE-FC Holden Discussion Forum

Technical Board => Restoration Help => Topic started by: freddyc on July 31, 2019, 02:50:33 PM



Title: Sub frame rust repairs
Post by: freddyc on July 31, 2019, 02:50:33 PM
I have started working on the wagon and are wondering can the subframe rust repairs (under radiator) be done with engine and everything still in car. Or is it best to remove everything?
fred


Title: Re: Sub frame rust repairs
Post by: JB on August 03, 2019, 07:57:43 PM
I think it all depends on how far the rust has progressed mate.
If you start and find more then it comes out anyway. Everything in also makes it harder to paint.


Title: Re: Sub frame rust repairs
Post by: ekute on August 04, 2019, 05:45:37 PM
I have replaced the tie panel between the rails after removing sway bar and tacking a piece of scrap steel to each side before removing the tie


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Title: Re: Sub frame rust repairs
Post by: hsv-001 on August 05, 2019, 07:01:22 PM
I replaced one a while back from rail to rail . Just folded up a new one and spotted it back where it was . Keep it clean and keep it neat and it is not that hard .



Title: Re: Sub frame rust repairs
Post by: Errol62 on August 05, 2019, 11:04:29 PM
As others have said it isn’t that hard to do it with the engine in, but you’ll probably want to pull it out anyway. Easier to do a tidy job with the driveline out.

You should use a zinc rich (some use copper rich I’ve seen lately) primer wherever you have two sheet surfaces sandwiched together. Paint each surface prior to assembly. Drill through top hat brim on the underside into the top section and weld, thus replicating a spot weld. You can also stitch weld along the side of the mating surfaces. When it’s all finished and painted I used a Schutz gun with flexible 9mm tube and 360 nozzle to coat the insides liberally with multiple coats of fish oil.

I just use Dymark zinc galv etch prime rattle can. The theory is that the zinc in the paint dissolved in the weld pool, giving ongoing rust inhibition to the welds. Also, you are getting protection on where it is hard to get after welding.


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Title: Re: Sub frame rust repairs
Post by: waynos on August 09, 2019, 09:58:26 PM
errol can you show me where you learnt this?
the  zinc paint would burn  off,not into the weld pool i think
i welded through paint today....it doesnt like getting in the pool
well i burn it off step back as i go in the pool
prove me wrong,i like learning


Title: Re: Sub frame rust repairs
Post by: Errol62 on August 09, 2019, 11:51:20 PM
Some reading for you wayno
https://rts.i-car.com/collision-repair-news/weld-through-primer-guidelines.html


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Title: Re: Sub frame rust repairs
Post by: Errol62 on August 10, 2019, 12:51:42 AM
Further reading reveals this to be a controversial topic. Using WTP was advocated to me on the FB EK forum, and I have been using it when plug welding lapped seams. I lightly coat the mating surfaces with zinc rich primer prior to clamping. I then use 5/16 bit to drill through top sheet and well in to bottom sheet so that no paint is present in the hole. This us for 20# sheet. 18# use 7/16 or 3/8” bit. Then hot mig weld perpendicular to surface, aiming at centre of hole. The panels need to be tightly clamped so no air gap or the result is blow out and contaminated weld.

Just what I’ve been told and developed a technique to make it work. It makes sense to me at least that the mating surfaces have some protection sandwiched between them as it is not practical to get fish oil or cavity wax in every seam. Likewise seam sealer.
Cheers
Clay


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Title: Re: Sub frame rust repairs
Post by: waynos on August 11, 2019, 12:18:20 AM
try a smaller hole and hotter weld on the plug welds ....over the years my holes are smaller and welds way hotter.better result for me and less grinding......win win