MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - rotten roadster frame

Gentlemen,

I noticed some of the powder coating on the bottom of my frame under the passenger door was bubbling a little so I took a closer look. I found that the frame was rusted through (with a little help from a screwdriver) for about 18" long and the width of the frame - the rib on the bottom of the frame is hanging out in space - the rest of the frame sounds solid. I restored the car top to bottom about three years ago and am astonished that this occured. How should I approach this? I sure don't want to remove the body if I can help it. The inside of the frame looks pretty good (surface rust)and the damage surrounds a drain hole in the frame. I'm open to suggestion.

Randy Myers

Randy Myers

Here's a closer look.

Randy

Randy Myers

Randy,
Do you have access to an old frame that you could cut out a repair section? It would not be to difficult to weld it in place with a mig machine if it is only on the bottom of the frame. You would need a repair section from exactly the same frame location as your rotten section due to the bend of the frame. Good luck and have a good day.

John
John Progess

I am not an expert, so hopefully someone will chime in if this is a bad idea. It is hard to tell from pictures, but if it is just the bottom section and the vertical sections are solid, perhaps you could cut a piece from flat steel that would span the entire bottom of the frame section. That would allow it be cut and bent to conform to the curve. Then you could cut a rib and weld it down the middle of the repair piece.

My frame was rusted thru and I repaired it without removing the body, but mine was on the inside rails along the floorboards. I cut and welded in pieces from flat steel and it worked out well even in the very curved sections around the footwell. I measured an unrusted area to get the steel thickness, but don't remember what it was. I think the consensus in the archives is that it is 16 ga. I know that overhead welding is a lot more difficult than vertical, but as long as the sections of frame hidden by the inner sill are solid it could probably be done.

Jeff Schultz

I had been told that one potential problem with powder coating the frame is that if the powder coating gets chipped, moisture can enter and rust away the metal underneath the coating. Do you think that's what happened here?
Mark J Michalak

Mark,

While I can understand how that would happen, I can't help but be suspicious of the drain hole and its relationship to the damage. The appearance of the rust that came out was akin to shale. It was layered and very hard as if it had been working for a while, not something that had developed in the last 3 or 4 years since the powder coating was done. What mystifies me is that the car was a CA car that was absolutely rust free - on the surface anyway. This is the last thing I woud have suspected.

Randy
Randy

Randy, your experience just reinforces my belief that one needs to somehow flood the insides of the chassis rails with some form of preservitive/rust killer to stop internal rust (rust forms if air/water and bare steel is present and the MGA frame is perfect for this to occur). In my case the local paint supplier suggests I do what he did to his Hilux 4X4 that he takes into the surf beaches fishing. I intend to block all holes (temp only) then after raising chassis on its nose, drill 2 1/2 inch holes in the end plates of each rail and fill the rails with a 50/50 mix of diesel oil and an Aussie lanolin based corrosion guard, leaving it for 24 hours before draining it out to hopefully eliminate any rust and prevent it in the future. By the way try the repair yourself, MIG is fairly easy and your repair will be too. Just cut up an old cereal box to make the template of your repair panel and then shape the steel sheet accordingls, running a fake bead down the centre. Good luck,
regards
mark
Mark Mathiesen

With the body in place it will be a little harder to patch this area, but it should be possible. Carl Heideman and the guys at Eclectic Motor Works did a similar repair and documented it well on their web site. http://www.eclecticmotorworks.com/jwtc02.html
There are several pages that cover the frame repairs on this chassis.
You can form the repair pieces from sheet metal of the correct thickness and weld them in place. They managed to replicate the factory seam weld along the bottom of the rail as well, but it wouldn't be absolutely necessary.
Bill Young

Randy, I agree with Bill about this repair. However, to really address this problem, it looks to me like the frame rusted from the inside. No amount of paint or powder coating on the outside of the frame can stop this. When I finish repairing and painting a frame, I drill about six 1/2" holes per side and spray a Waxoyl type of product in side the frame and goal post section then plug the holes with plactic plugs. I've NEVER had a frame rust through since. I don't know if Carl Heideman does a similar thing or not but, I do know they do good work.
John
j. p. mangles

Gentlemen,

Waxol is the first thing that came to mind when I unearthed this disaster. This is the one precaution I didn't take and wished that I had.

Bill- thanks for the Eclectic reference. I was interested to see that the bottom of the frame in their pictures rusted out right where mine has, just behind where the square cross bar enters the frame rail.

Yes, I will repair it myself as soon as I've transended the need to think it to death first. Thanks for your help.

Randy
Randy

Hi Randy,

If you are thinking about going the frame cut and replace method I have an old frame that could act as a donor due some other damage. If you are interested just drop me a line.

Ken
Ken Bowen

Randy,
If that occurred in 3 years, in California, I'd be real concerned about the integrity of the frame. The pictures appear to show major corrosion inside the frame. Do you know the history of the car? I live in the NE and drove my MG all year long (snow, ice, salt) for years and then stored it for 20 years and had no where near that level of corrosion. Still, if probing the rest of the frame (bang it hard with a screw driver or Awl) does not reveal problems, you could just "fish plate" the area (weld plates over the bad spots) and probably be OK.
Good luck with this,
Gerry
G T Foster

GT,

Judging from the stratification of the rust chunks that came out I would say that it was developing for quite some time but hadn't gotten bad enough to show at the time of powder coating. I'm inclined to do as you have suggested and clean it up and patch/reinforce it. I have checked the rest of the frame and didn't discover anything that scared me. By the way, I found a block (felt absorbsion block)inside of the frame just behind the end of the damaged area that was completely rotted (powdered when prodded) but in one piece.

Ken, Thanks for your kind offer. I have a metal shop here who can form a repair piece for me.

Randy
Randy

This thread was discussed between 24/02/2008 and 28/02/2008

MG MGA index

This thread is from the archives. Join the live MG MGA BBS now