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Denial not keeping rust away.


Jedi Knight
Country flag
Whilst rejuvenating my rear suspension, I noticed that the trailing arm box section of the frame had some "surface" rust (I also noticed what looks like signs of previous welding repairs). With my paint scraper I was able to locate a pin size hole...which on further evaluation seems to be able to accomodate a 2 inch diameter pin! :cry: So it looks like I need to have that section repaired or replaced. The car is currently in a car port with no right rear suspension. Should I go ahead and proceed with my suspension repairs, then reassemble and drive carefully to a frame repair shop? Or do I need to rethink this entirely? (I'm afraid to think what lurks elsewhere). Is this a doable repair? What should I expect this to set me back (I figure I'll have it done to both sides since the left side looks worse, though it does have a repair done to it)?


Jedi Trainee
It's a do-able repair. As for what it costs, it depends whether you do the work or have a shop do it. The methods of repair are removing the body or cutting a big hole in the floors for access. In raw materials you are looking at around $300 for replacement trailing arm sections and new T-shirt plates.

To pay someone to do it I think you are looking at least $800-1500. For that amount of money I would seriously look at Ratco frames.

I recently repaired the exact same problem on my 6, but this was part of a frame off restoration. Needless to say there was more rust than that, once you went looking for it.

As for the safety of the car, I drove mine like that for a couple of years with no problems. But after cutting the trailing arm section of the frame off I was surprised how little metal remained.

Good luck.


I've seen a whole lot worse than your photo. And this is a very common rust prone area on the frame.

Use a hammer and knock around some more on both sides.

You can weld reinforcement plates over the rust hole(s) after treating inside the area with a rust convertor if the damage is not too extensive. By the look of the oil on the t-shirt, it's probably saved the frame from more rust. Unless you plan on a frame off repair, I'd use a 14ga piece across the entire bottom of the arm.

And keep looking for a frame if you want to swap out down the road.


Great Pumpkin
You may have a local welder who does emergency & routine repairs to construction equipment in your area. They have everything needed on their trucks and are experts in structural welding. Some of the guys moonlight and do small jobs after hours.

I'd look in the local phone book and see what you have available. They could be in and out of there in no time and you'd have a quality welding job done.


John, we're probably all in denial about rust. The vast majority of LBCs that have not had frame restoration have some frame rust. I'd be surprised if one did not.

The advice above is good. Get an experienced welding guy to inspect the frame. Unless the rust is pervasive, it can be repaired.

The degree of frame deterioration is, of course, the key concern. And, a frame with rust in a key, stressed area is a significant safety hazard. The hazard is adversely affected by your driving style. If you're an agressive driver and thrash the car regularly, then obviously you're at an increased risk with an unrestored frame.

It's something that's worth inspecting by experts, if we're not able to diagnose it ourselves.

Sadly, the frame is one of the most difficult parts of the car to inspect. I once bought a GT6 with a bent frame and didn't realize it for months. Not a happy day when I discovered it. It cost me $1600 (with the car in a shop for over 4 months) to have the frame pulled and straightened. :eeek:

Good luck, let us know . . .


Jedi Trainee
Hi John,
Here's how I did a out rigger repair on a tr 6 with a similar problem as you have a few years back.
First I went to a local machine shop and had them cut pieces out of 1/8inch flat steel.First piece was 6 1/8 wide by the full length of outrigger,which i did,nt record :wall: then had them bend a 90 at 3 1/16 as per "blue print" cut away for "T" so it fits flat on out rigger, measure for bracket mounting holes etc.On the inside I put a 1/8 flat plate drilled to fit the bolts. after all was installed with the shims etc. in place I welded the seams as per diagram and used POR 15 on the top seam to keep water out.

When you take it in for alignment and the guy is sharp,he'll tell you that your wheel base is to long by 1/4-1/2 inch especially if you only do one side. :crazyeyes:

Just another idea for ya to think about John.


This will not fix rust, but it will absolutely stop it.
Apply used engine oil (must be used) with a brush or sprayer, maybe a garden sprayer, to the rust area and under side of body panels, and inside the doors. It will soak into the seams and the rust will be stopped. In the 80's I repaired and painted a car with about 120,000 miles. I applied oil to one side and did not get around to the other side. After the 450,000 mile mark the oiled side had no new rust and the non-oiled side had rust appearing in many places. Best rust protection I have ever seen and the price is right.


Jedi Knight
That doesn't look too bad to me! The area that seems to rust out worst is the outer end of the outrigger.
You have managed to clean that area up well. If you clean up the entire length of the outrigger including the seam with the outer chassis rail you should be able to assess the whole outrigger. Hit it with a light hammer to help show up an rusty areas. You may be lucky and get away with localised repairs.
Then pour in plenty of rust-proofing wax.
It should then last you a few more years.


Darth Vader
Used engine oil is great for rust prevention, I also used it on wooden fences, that is I did until the neighbors threatened to call the EPA....


Jedi Trainee
Your picture reminded me a lot of my frame as well. I had a patch welded on to cover a similar hole. Eventually I decided it was not safe to drive any more (mind you this was after several years with the patch on). It is a little painful, look away if you must.







The last picture is what it looks like inside the main frame. The waist of this car is a natural low point, but it has no drain holes which is why I think rust is so prevalent in this area. There are countless ways for water to get into the frame but no way for it to get out other than rusting and finally evaporating out. After grafting in new metal, I drilled small drain holes at the low point of the frame, right next to and parallel to the lip on the frame rails. If you look closely the only place there is rust is right at the waist, and the factory paint still exists just outside that point.

I also taped up every hole on the frame and flooded it with POR15 and then rotated it on the rotisserie, then drained the excess. When I was done with the all of my metal work the frame measured true to within 1/8 of an inch, much to my surprise and pleasure. There is also countless frame strengthening that was done as well afterwards.



Jedi Knight
Country flag
Thanks everyone for your input. CRJ, those are great, albeit horrific photos! It makes me feel better about what I'm working with. I have not the time nor the means nor the space for a frame-off at this time so I'm sticking with localized repairs. I'll look into having the mobile welder come have a look. Opa, thanks for those diagrams. That looks very similar to what was done at some point on the driver's side outrigger, although in my case it looks like slots were cut out to go around the bracket holes. See below:

I bought my car in B.C. by the way.
Tom, I think what Triumph should have done was run a line from the oil pan to the front of the frame and put a pump and return line at the rear of the frame. Just convert the inside of the frame to an oil reservoir! Added weight, but a long lasting frame!
What would you all recommend for rust inhibitor prior to welding? I've been using "The Must for Rust" by KrudKutter with good results so far on other components.

Here's a picture of the outer portion of the right outrigger. There seems to be a canker next to the bottom left bracket hole, but I was not able to perforate it with a screwdriver.


Jedi Trainee
be careful John,that BC tin worm is of hardy stock :nonono: make sure you get the larvea when you go after it. I've broken up a few 6's where one could literally hear them chewing away. :jester:


That cross-section shot is a good one. Even though it appears that the outside metal is solid and clean, look what's going on within the support structure inside. I tossed out a frame that looked better because of safety.

I was lucky to find a near perfect replacement from a club member in Delaware. But today, I'd go straight to Ratco.

BTW, your repairs look great.
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