How To: Ford CMP "Blitz" miscellany

[Jacques Reed]

Good Day All,

Here's another snippet of miscellany which may be of interest:

Thought today, being a quiet day, I would look for some machine screws to fit the tapped holes in my doors for the check strap retainer screws. Luckily the tapped holes inside the passenger side door were unmolested as the screws must have gone missing years ago. Cannot say the same for the driver's side, however, where modern self tapping screws had been substituted damaging the original threads.

After looking at a number of Imperial size machine screws in my collection of which most were too large or to small in diameter or too coarse a thread I was stumped until I tried a tap from a cheap set of Japanese taps I picked up in the 80's. As it turned out it was a No.12-28 UNF threaded hole. See photos.

Ok, so now I knew what to look for so it should be easy to get the right screw- wrong!

Seems there are plenty of No.10 UNF machine screws (smaller) and 1/4 UNF screws (larger) around but No.12 screws are very hard to come by. Checked hardware store websites and bolt and nut supplier websites, no luck, then called Classic Vehicle Fasteners to no avail and finally by dumb luck searching for a while on the net, found that No.12-28 UNF Fillister head screws are available from gunsmith suppliers.

Have contacted my local gun dealer and indeed they can get them in so have ordered four. Perhaps others have found them here in Australia but if not try a local gunsmith for these obscure sized screws.

Always amazed at what various fasteners they used to put together these vehicles. Can add another one to the list.

Hope this is of some interest and help for other restorers.

Cheers,

[Jacques Reed]

Good Day All,

Has anyone had experience with using paintless dent removal techniques to remove a dent from a fuel tank?

Due to the internal baffles, it is impossible to get to the area of the dent from inside to push it out so reading about PDR thought that method might work. I don't think the little heat involved in the glue used to attach the pullers would be an issue on a tank that is empty and has been so for many months.

I have a 10 mm dent over a 250mm diameter area in the bottom of my F15-A tank, and although not a big issue, I would like to repair it. I had to pack it out with insertion rubber to make full contact on the front fuel tank bracket.

PDR slide hammer kits seem relatively inexpensive on-line. Professional repairers I contacted seem to get scared when you mention fuel tanks.

Any advice gratefully received.

And a Merry Christmas and a safe and Happy New Year to all fellow members.

Cheers,

[gjamo]

Hi Jacques.
Have you considered using a magnet. I use them for all sorts of things mainly in groups for lifting heavy plates. Be very careful though they are super powerful do not get any part of you between them and steel.

https://www.frenergy.com.au/neodymiu...dia-162kg.html

[Jacques Reed]

Originally Posted by gjamo

Hi Jacques.
Have you considered using a magnet. I use them for all sorts of things mainly in groups for lifting heavy plates. Be very careful though they are super powerful do not get any part of you between them and steel.

https://www.frenergy.com.au/neodymiu...dia-162kg.html

Hi Graeme,

Yes tried that. Used an old condemned magnetron magnet which I salvaged from a radar set on my ship. Darn powerful magnet but I was still able to pull it off the tank.

I use that magnet inside a plastic bucket on a bit of rope to pick up swarf from drilling steel. My kids used to laugh when I told them I was "taking the magnetic dog for a walk". Now it is just a lame Dad joke!
Very effective at getting every last bit of steel filings off the floor however.

Cheers,

[Jacques Reed]

Hi Graeme,

You got me thinking with your suggestion and a re-visit to my first attempt. The reason the magnet pulls off easily is because the relatively thin steel tank doesn't have enough material for the magnet to hold onto ie mass.

I use a bit of 50mm x 50mm x 2mm angle as a keeper for the magnet and it requires me to tip it away from the magnet just to break the grip on it and it still requires a great deal of effort to pull the keeper off the magnet. And yes, early in the piece I got a good pinch by not keeping fingers clear as I attached the keeper after using it.

If I can get a piece of say, 10mm thick flat bar into the area behind the dent perhaps the extra steel there will allow the magnet to hold with more force.

Stay tuned until after Christmas. I am getting an inspection camera/scope from Santa so I will be able to see if it can be done. Last thing I want is a big chunk of steel left stuck in the tank however.

And Phil, I think my tanks are lead coated inside and out. When I stripped the paint years ago there was virtually no rust under the paint except where the tank's coating had been scratched.

Cheers,

[Mike Cecil]

The fuel tanks were normally made from a lead (& a small amount of tin) -coated steel sheet called Terneplate.

Very common sheet for fuel tanks and for applications where deep pressing was required, as the lead/tin slid nicely against the die formers, allowing deeper pressing without tearing the steel sheet. Also a very easy sheet to run solder along joints to seal them.

Alas, has not been available for many years.

It may be part of the problem with adherence of the magnet, combined with the thin sheet steel, both of which diminish the magnet's 'grip'.

Mike

[Jacques Reed]

Hi Mike,

Thanks for that info regarding coatings on the fuel tanks.

It can only add to the problem of the magnet gripping the steel.
Will see how the thicker steel bar behind the dent works in the new year if I can get it in (but mainly out) of the tank.

Here's a photo of the magnetron magnet and the "magnetic dog" in use.

Phil, do you or anyone else, have photos of a cut open fuel tank?

Cheers

[Phil Waterman]

Hi Jacques

Some of the CMPs had gas tanks that been tinned or coated in lead both inside and out, which might make it hard to get the stud to stick. Out of 5 tanks only two had this coating, both from my late production HUP.

If you have a stud gun try welding a stud to a can of water, if that works and you are concerned about gas fumes then fill your tank with water.

Photos please of dent removal process.

Recently I cut the ends out of Pattern 12 gas tank, the only thing that caught fire was 40 year collection of mouse nests. Tank has some large rust holes and I cut the ends out to real see how to fabricate new tanks. But now that see the rust is really localized to the holes, may just cut out the holes and weld in new steel, then weld the end panels back in. The plasma cutter takes out just enough for a really smooth but weld.


Cheers Phil

[Hanno Spoelstra]

Jacgues,

Thanks for keeping us updated on your progress and thoughts to solve the problems you encounter!

Originally Posted by Jacques Reed

Due to the internal baffles, it is impossible to get to the area of the dent from inside to push it out so reading about PDR thought that method might work. I don't think the little heat involved in the glue used to attach the pullers would be an issue on a tank that is empty and has been so for many months.

I have a 10 mm dent over a 250mm diameter area in the bottom of my F15-A tank, and although not a big issue, I would like to repair it. I had to pack it out with insertion rubber to make full contact on the front fuel tank bracket.

PDR slide hammer kits seem relatively inexpensive on-line. Professional repairers I contacted seem to get scared when you mention fuel tanks.

I reckon they are scared of fuel tanks if they use tabs which are spot-welded in place.
If you can get your hands on a kit using hot melt glue to fix the tabs, I'd try that before moving on to the magnet method (which I am looking forward to see the results of).

Hanno

[Jacques Reed]

Hi Hanno,

Thought today would try some magnetism experiments as per attached photos.
It is a lot easier to find out if it works on a workbench than trying to retrieve balls and steel bars out of a fuel tank!

I used a sheet of 1.1mm galvanized steel as a test. A bit thinner steel than a CMP fuel tank.

Unfortunately the results were disappointing:

Using seven 25mm diameter CV joint balls resulted in very little extra holding power than just the magnet alone. That could be caused though by the alloy used to make the balls just as stainless steel is non-magnetic.

I then tried a piece of steel bar 40 mm wide, by 15 mm thick, by 160 mm long. The holding power was significantly increased but I doubt it would be enough to pull a dent out of a tank. I was able to break it free with what I estimate was about 15kg of force.

So it's "back to the drawing board"

One good thing is a PDR technician returned my call and is actually willing to at least have a look at it in the New Year. Many businesses shut down for a few weeks during the December January period here in Australia so I will see what can be done in January. I am thinking if the hot glue method has the holding power it will do the job. Just have to see what his opinion is and what the cost estimate is if he can do it.

Will update this when the technician attends.

Cheers,

[Bob Carriere]

Had a look at the dents you are trying to pull out.

Have you tried soldering a brass bolt or copper tab ??? then use the typical dent puller.

We have had good success at the barn soldering pin holes in tank bottoms... we dimple the pin hole with a small ball pein hammer and clean the area to bare metal
.... we use an electrical soldering iron ......once sanded down they do not even show and do not leak. So soldering should give a very good bond...... to attach a puller to.

You maybe able to pull enough to be able to finish the job by using solder to fill any indentation left... then sand down.

We used an acid solution to clean out the inside and once rinsed and sand blasted on the outside we discovered a lot of pin holes..... then we inserted a 12v bulb inside the tank and closed the barn doors....... there were a whole bunch of shinning little stars which were not seen in daylight.... all were dimpled and soldered. For good measure we used a gas tank sealer on the inside...... a real messy job but worthwhile.

Cheers

[gjamo]

Jacques you may even consider Phil's method and cut the end out before panel beating the bottom and rewelding a plate in.
http://www.mapleleafup.net/forums/sh...highlight=tank

[Phil Waterman]

Hi All

Please anyone considering repair of fuel tank, remember the risk of fire or explosion.

The tank I recently opened with plasma torch was known to have been open (no cap) to the elements for many years. Had there been any hint of fuel, probably would have filled the tank with water while cutting.

I know that people who have responded to this thread are well aware of the risks, I'm more concerned with people doing a web search on fuel tank repair not being aware of the hazards.

Cheers Phil

[Jacques Reed]

Originally Posted by Bob Carriere

Had a look at the dents you are trying to pull out.

Have you tried soldering a brass bolt or copper tab ??? then use the typical dent puller.

We have had good success at the barn soldering pin holes in tank bottoms... we dimple the pin hole with a small ball pein hammer and clean the area to bare metal
.... we use an electrical soldering iron ......once sanded down they do not even show and do not leak. So soldering should give a very good bond...... to attach a puller to.

You maybe able to pull enough to be able to finish the job by using solder to fill any indentation left... then sand down.

We used an acid solution to clean out the inside and once rinsed and sand blasted on the outside we discovered a lot of pin holes..... then we inserted a 12v bulb inside the tank and closed the barn doors....... there were a whole bunch of shinning little stars which were not seen in daylight.... all were dimpled and soldered. For good measure we used a gas tank sealer on the inside...... a real messy job but worthwhile.

Cheers

Hi Bob,

Haven't tried that method with a brass bolt or copper tab but it sounds like it is definitely worth a try. I am sure it will have a lot more holding power if the bolt or tab has a reasonable size area. I will give it a try on the bench first.

I like the idea too, that not a lot of heat or an open flame is used in soldering.

I repaired a pinhole in the other tank on the top where the retainer strap had rubbed a hole in the tank similar to your method. Dimpled it slightly and filled it with JB Weld. Great stuff.
At that time I didn't have a decent size electrical soldering iron and there was no way I wanted an open flame from a Bernz-O-Matic near a hole into a tank, even though the tank had been empty for years and washed our just prior to the repair. To do it again I would consider your method with the big electric soldering iron I now have.

Anyway guys, this thread has been very helpful and all suggestions have been gratefully received. I, and many others, have a better idea of the issues of repairing a dent in an enclosed tank. I even enjoyed my magnetic experiment that didn't work. Just more info to add to the wealth of information and ideas out there.

As Phil so rightly posted just be careful around fuel tanks with whatever repairs you do to it. Most of us know that but there is always someone perhaps new to auto repairs or restoration who doesn't realize the risks.

Have a safe and Merry Christmas and I will continue on after the Holidays with trying to get that darn dent out!

Cheers,

[Hanno Spoelstra]

Originally Posted by Jacques Reed

Anyway guys, this thread has been very helpful and all suggestions have been gratefully received. I, and many others, have a better idea of the issues of repairing a dent in an enclosed tank. I even enjoyed my magnetic experiment that didn't work. Just more info to add to the wealth of information and ideas out there.

Jacques, I like your inquisitive approach to solve problems and enjoy reading about it.

Thank you very much for your informative posts, I hope you continue to share your insights in the new year. Enjoy the Christmas break!

regards,
Hanno