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MG MGA - Glue or weld
|Hey Folks, I am in the process of removing the front fenders on my "rust free" 1960 MGA purchase. This is in order to assess the extent of the ferris oxside damage to the bottom of the "A" posts.|
In my research I have discoverd that a lot of body repair work done today is with adhesives instead of welding. Has anyone used this methode on thier MGA?
I do not have a welder or the skills but I am sure I can glue and pop rivet. Thanks, Tom
|"Has anyone used this methode on thier MGA?"|
No, definitely not me! I am sure it is "possible" but I imagine the metal fabrication and surface preparation would be far more difficult.
I am sure it would be easier, quicker and better overall for you to learn to weld!
Of course you could always go the aluminium mesh and filler (bondo) route. That doesn't even require removing any rust. LOL.
|While body repair can be done with adhesives, I would not use that method on a classic or collector car. The value will not be there at the end of the day. Also, whether the adhesive holds up for an extended period or not, the next buyer will certainly see the "DPO" repairs and lowball even if the repair is good.|
The problem with any mesh and filler route, at least as I have heard and experienced, is that the filler doesn't fully bond to the metal, but rather through the holes and to itself. After a couple of years expansion and contraction, the filler will "delaminate" from the substrate and you will have a larger mess than you started with.
|Thomas, first let me say that I'm not an engineer! That disclaimer out of the way here's my reasoning for using only the type of fastening systems used originally by the manufacturer, especially were structural items are involved. While modern adhsesives are literally "wonders" their use is also engineered into the design of the structure and panel overlaps and such are designed to give enough surface area for thay type of bonding to be safe. That's not the case in a MGA or any other early MG. Those panels were designed for electric spot welding and arc or MIG welding in the case of the chassis and the panel and part overlaps and joints were engineered to be safe with that type of joint. I try to stick with the joining method that is closest to the original design when repairing any car. If it was spot welded then a spot weld or a plug weld with a MIG machine will be a reasonable substitute in terms of strength. In the case of the MGA the main structural strength is in the chassis, but the body needs it's own strength to be able to maintain panel alignment so proper repair of the sills and A and B posts is a must there as well. Once the body is bolted to the chassis they do form sort of a support one for the other as well, so the body does add some strength to the chassis. |
These days you can buy relatively inexpensive MIG welders using 110v that won't require you to rewire your work area and are relatively easy to learn how to use. Those will enable you to do 99% of all the repair work on an MGA chassis and body you'll ever be likely to need. You should be able to get a pretty good welder ready to use for around $500 or perhaps a bit more. Check out the various brands and get some idea of the better units and the features that are recommended then check places like craigslist for some deals. I've picked up a couple of nice units for less that $250 within the past couple of years, add the price of a bottle of CO2/Argon mix and an auto darkening helment and you're ready to go.
With minimum practice you'll be making good plug welds in a matter of minutes, certainly less than a couple of hours of practice time and you'll then be set to work on your car.
|Hey Folks, thanks for all of the advice and enlightenment. I am not looking to become a "DPO", but new technology and methods are often a "better" way.|
I will stick with the welding on this car as I did on the TC, TD and MGB.
Is it possible to use galvinized panels to prevent future problems in the rust prone areas? At this writing I am planning on Waxoil and Por-15 but rust resistant panels could be an option? regards, Tom
|I wouldn't use galvanised sheet because of potential paint priming problems plus welding it gives off copious toxic zinc fumes. However, you could try zintec sheet which is ordinary mild steel plated with a very thin layer of zinc ( 1 micron compared to around 40 microns for gavanising). It has a matt grey finish unlike the shiny galvanised zinc surface. I used it this summer for some repairs to my lawn tractor and it welded well and the paint is holding up so far. The much thinner zinc layer is less of a health concern but I welded outside just in case. It is a bit more expensive than ordinary mild steel but not prohibitively so. Mike|
|It is my intention to try the adhesive the next time. In the past I have used pop rivits and it is still hilding up fine with the same paint job for 16 years. The last time I welded a front fender pannel I warped the fender something terible. For the inner rockers and underneath work the welder is best but all the body shops are now using addhesive. At my local supply house I bought a kit to work in a caulking gun and tried it and it seems to hold good.|
|Dear Thomas. I have used glue in 2 cases on classic cars so far and in both cases with no problem.|
First case was MGB rear wing where it is impossible to make a welded replacement without stripping off many more panels. Here the top edge of the wing was glued with a PU automotive adhesive and front and rear edges plug welded. The wing is still on and the paint is not cracking around the glue so I am happy.
The second usage is an "as original" replacement of the strengthening frame inside my e-type bonnet. This was again made using a PU glue, this time with bridging properties and more flexible as per the original. The frame was glued in and left to set overnight and by morning I could not unstick them, so again happy with the result.
The key to glueing is the area to be glued versus the force excerted on the panels. With welding the actual jointed area is much stronger than glue but the area is often quite small (spot weld or a bead of weld from a mig welder). If the area to join is wide enough then there should be no big problem in using a glue. I would however leave this for non-structural members and leave glued structures to the experts like Lotus?
This thread was discussed between 03/12/2009 and 04/12/2009
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