TR2/3/3A TR3 Fender dum-dum use?

[CraigLandrum]

We are getting close to bolting the fenders, etc back on the body tub. The TR3 restoration book recommends the use of dum-dum (some kind of putty?) in the joints to keep out moisture and prevent rust. Looks like it has the potential to be really messy.

Should we use dum-dum or a similar product? Where to get it? Use nothing at all? What have others done and what does the forum recommend?

 

[NickMorgan]

I used a silicone based sealer on the car I completely rebuilt. However, I am sure that if anyone ever tries to remove the wings they will not be pleased with me! Ideally you want something that will remain flexible and allow the wings to come off again if necessary. One option is to paint something like waxoyl thickly onto both surfaces before bolting them up.

 

[Don Elliott]

Don't use anything ! My 1958 TR3A was at the same state as yours is - back in 1990 when I was finishing my full body-off restoration. All the tub had been painted and all the panels were sprayed separately. I took it apart to have it re-sprayed in 2007. There were 94,000 miles of stone chips and I wanted to get it looking new again. There was no rust anywhere on the car and none at all in any of the joints. During that time, with all that driving during 16 years, I had driven only about 4,000 miles in the rain. I was glad I hadn't put any dum-dum in the joints. The rain water just drained right down and out. The car (and all these joints) were dry minutes after the rain stopped. Just like when I would wash the TR.

If you use dum-dum, it will be really hard to remove the fenders, etc. at a later date and the rain, etc. will sit in the joints and rust away because the dum-dum will seal the bottom of the joints and the water won't be able to drain out.

If you're planning lots of driving in the rain, or if you live where it's always humid, you may have a case for it, but even them, I wouldn't use it.

BTW, at VTR in 2007, I was awarded 2nd in the early TR3A class with 384 points out of 400.

 

[NickMorgan]

BTW, at VTR in 2007, I was awarded 2nd in the early TR3A class with 384 points out of 400.

Ahh, was that six point deducted for no sealer in the wings?!!! lol :laugh:

 

[Moseso]

I used 3M rope caulk. 1 box is plenty to do the car, including the transmission tunnel.

 

[CraigLandrum]

Don;

Your suggestion of using nothing in the joints sort of mirrors my own thinking. Not only because I'm a lazy slob, but because of the drainage issue. For insurance purposes our TR3 must be garage-kept, so will be out of the weather most of the time. WIll wait and see what others have to say before we start bolting things on...

 

[Moseso]

Well, if you let it, the water will drain down into the cavity between the body tub and the front wing -- the ONLY place on my car that needed any serious metal restoration. I had good floors, good rockers -- and rusty wings where they bolt to the body tub at the bottom. There's no particularly good way for the water to drain out of there. My advice is to not let it drain into there.

 

[angelfj1]

My impressions from the major restorations I have seen are that much more care is taken in preparing the sheet metal surfaces than they did at Canley. I'm not sure if the inner wings ever had anything but primer. We are not using any sealer between the wings, beading and body. We are concerned that despite proper application, all sealers eventually fail. We painted everything with finish color coat AND we have applied undercoat to the backside of the wings and doors and the inner wings since these will not be seen. So, in theory, any water that enters these areas will eventually drain away or evaporate. The undercoat will prevent contact with the metal. Actually we are using an undercoat designed for rockers (sills) that is almost transparent.

I do have a question for Don E. - when you restorred TRusty the first time, when you removed the wings, was there evidence that the factory used sealer?

 

[tomshobby]

Is is possible that it could deaden sound in the panels or maybe even prevent "squeaky" joints?

 

[Don Elliott]

There was so much dum-dum sticking it all together, I had a really hard time to get the wings un-stuck. In fact, most f the flanges on the rear fenders as well as where the captive boxes are hidden inside had rusted away. I had to re-built all that.

In the photo, the front clip is totally separate from the rear clip.

 

[Number_6]

Is is possible that it could deaden sound in the panels or maybe even prevent "squeaky" joints?

That's probably the best reason to put something in the joint is to stop the inevitable squeaks from metal against metal. If you were going to be driving it in all weather then you would want some seam sealant to keep moisture from getting trapped in the seam. But since you probably wont be driving it in the rain very often that really wont be an issue.

Maybe use a thin strip of rubber? I did a quick google and came across this place.

Rubber sheets

 

[TR6oldtimer]

I know on my TR6, the factory used two types of caulk. Around the rear side lights, they used Dum-Dum as they did on the floor to frame bolts. It was still off white and soft. No rust where it was applied. Along the wing to body seams they used a hard caulk. The areas where this was applied dried out and broke a long time ago. Once that happened, water was allowed to come into contact with the primed surface. A lot of rust all along the wing seam.

Restorers do tend to prepare the metal much better then the factory, and the restored cars tend not to see, or sit out in the weather, as they did when first bought. These cars do not see the miles they did when first sold. Over time, dirt accumulation and body flexing will cause scratches and cracks that will eventually rust. The question is, will the rust that forms on these pamper cars rear it's ugly head in two years, five years, or the 10-15 years it took to show on the original? I doubt it.

That said, I will be using the 3M strip product previously mentioned to seal out the water and provide a tighter bond for the joint.

Oh, on undercoating, if the bottom of the wing's lip is sealed with undercoating and the joint is not sealed, water and dirt will collect and eventually rust.

 

[Don Elliott]

With all the wings etc. painted off the car, the insides of all my fenders are just a smooth and shiny as the exterior. I don't have any undercoating. The paint held up for 16 summers of modtly sunny driving and, with no undercoating, the water in the seams drains straight through.

 

[MGTF1250Dave]

I will agree with Don and say go with out dum-dum. Most of any water getting past the beading will generally end up between the inner and outer fender. As Moseso points out a common place for rust to form is at the rear of front fenders between them and the sills. I think is caused by the water that ends up there coming as run off from the Windscreen and bonnet. The gutter under the bonnet at the top of the front bulkhead directs the moisture to each side of the car and down inside the front fenders. By design the front fenders have two holes about 1/2" diameter to allow this water to escape. The same is true for the outer sills. These holes can be blocked with road debris or filled with bondo by a well meaning PO. IMHO may sure the inner fender areas, inside of the fenders and lower front bulkheads are painted with a durable weather repellent coating since these area will get wet if the car is driven in the rain.

The exception is you may want to use some type of sealer where the guttering around the boot attach to the rear fenders to prevent any leakage into the boot.

 

[alfa33047]

Hi Craig, 3M DUM-DUM works great on front fenders, I have never used it on rear fenders. The front fenders move and will squeak. There is nothing between the inner and outer fenders on my TR-3 Smallmouth that was restored in Old Mexico, and it squeaks when I hit bumps. My other TR-3s have the DUM-DUM and do not squeak. Put it on when you install the fenders and then peal off the excess. Good Luck, Bill C. Mesa, Az.

 

[martx-5]

I'm in the "no dum-dum" corner. It was just someting I didn't want to wrestle with while I was trying to get the wings on, especially the fronts. There's enough stuff going on with getting the front wings mated up to all they attach to.

 

[Marvin Gruber]

Have built several TR3's and 4's, plus a couple of Healeys. I have never used anything between the fenders. I got the first TR3 back that I did in 1976, it had a couple of dents and scratches on the outside but no issues of rust on fender joints. I use an industrial two part epoxy when putting floors and tub panels in. Car will rust into before that stuff breaks down. I do put extra coat of paint on tub and fender bolted areas.

Marv