Under Coating Reccomedations

No doubt this subject has been covered before. The body of my 1953 Special (41D) is on a rotisserie right now and is scheduled to be under coated next week. The products made today are probably better than those used 60 years ago and the method of applying them is probably better too.

This car was my grandfather's. He lost his eyesight in an industrial accident in 1955 after retiring from a 25 year career as a police officer. My youngest grandson just turned 1 on Sept. 11. My plan is for Gramp's car to be driven by the 5th generation of his family and beyond so I want to get this right in order to preserve it.

What do your folks recommend? With any luck there will be a consensus. Looking forward to your replies so that I can get it on order. Oh yeah.....how much will I need to buy....quart???

Thanks in advance!

Pat

Assuming the car will not be driven in inclement weather and is rotisserie restored, why not leave off the undercoating? Or are you talking about painting the chassis?

Pat, a very commendable plan. Good luck.

Today's spray on bed liner is some tough stuff. I used a rattle can version on the floor pans in my '50. Can hardly scratch it. Welding only burned it about 1/4 inch from the weld.

Ben

I'd vote on leaving it painted if you are in an area where it can be kept relatively dry. If you do undercoat, be careful not to close any weep holes.

Only put the undercoating where the factory (not the dealer) did it. In 55 for instance, only the rear wheel wells, seams near the rockers, and some of the transmission tunnel had it. After you spend hours and hours removing that nasty stuff during a restoration, you would not want to slather it on like the dealers and other aftermarket installer did.

Paul,

Thank you for your quick reply.

It will never be driven in an ice or snow storm. The worse that could happen is getting stuck in a rain storm. I may be going a bit overboard on my restoration but I had to replace/repair well over 50% of my floors and rear trunk area.

In order to help prevent it from happening again (over the next 60 years) I'm going to paint the interior floor pans and under coat the bottom. The metal in areas where I had to chip off the original under coating looked as it did when the car was assembled......the steel looked like new. My chassis is going to be powder coated.

Do you know of any BCA members that have under coated a car recently?

Pat

Ben,

I work part time at a truck up-fitter. We get in cab/chassis from Ford, GM & Dodge and then add the bodies to them (Dump, Utility, Flat Bed, Stake, etc.). We also install snow plows and sanders on pickup trucks. Our facility also does spray bed liners. The place is much too large and production oriented for them to do a one off body on a rotisserie, but I'm going to ask tomorrow if I can buy the material from them. Thanks for the suggestion.

Pat

John,

The weather In Rhode Island is about the same as in your area. Maybe I'm going a bit overboard but the metal on my floors that still had the undercoating intact was like new when I scraped it off. While I've got great access to it I just want to get it done.

Speaking of weep holes. The rockers have some slots in them. I take it they are for letting moisture/water out. A replacement rocker panel I used didn't have the slots. A heavy etching primer was sprayed inside the rocker before the floor pans were welded in. Should slots be added to the new rocker panel? Just where does the water come from that would get inside the rocker?

Thanks for replying to my inquiry.

Pat

Old Tank,

How would I find out what the GM factories did in 1953? My grandfather's car and a parts car I bought were both assembled at the Framingham, Massachusetts plant. Both of them have/had generous amounts of undercoating on them. How would one tell what was applied at the factory and what was applied by the dealer/aftermarket?

Thanks for your advice.

Pat

John,

The weather In Rhode Island is about the same as in your area. Maybe I'm going a bit overboard but the metal on my floors that still had the undercoating intact was like new when I scraped it off. While I've got great access to it I just want to get it done.

Speaking of weep holes. The rockers have some slots in them. I take it they are for letting moisture/water out. A replacement rocker panel I used didn't have the slots. A heavy etching primer was sprayed inside the rocker before the floor pans were welded in. Should slots be added to the new rocker panel? Just where does the water come from that would get inside the rocker?

Thanks for replying to my inquiry.

Pat

I can't say for certain where the weep holes are on your car. I have no actual experience with that year. I can tell you that on a 1969 Electra, the water that ran down the windshield and into the cowl was routed to weep holes in the rocker panels. But I don't know if the 53 has an open cowl?

Pat: Let's take a moment and try to reason this out. O.K. so if I understand everything correctly, you want to undercoat the pan area of the car that is now stripped and prepared to clean metal and ready to be painted.

First, in todays world we have a product available to us that the manufactures did not have in the fifties. That product is called Epoxy Science. The result of this technology renders an Epoxy to be available in many different variations. For example some are straight chain epoxies and some are blend epoxies like epoxy / urethane hybrids.

Second, Back then what one was attempting to do when they undercoated something and using the only technology they had at the time, was to apply a tar bitumen based material that served to Protect the prime painted metal underbelly of the car. Prime based paint was the only thing most car manufactures applied to the underbody as a metal surfacer protectant as it went through the assembly process. This bitumen undercoating helped to deflect objects that would otherwise cause chipping and exposure of the metal below the this primer coat. This primer coat was usually a lacquer or an early type alkyd enamel.

Today, one would choose to protect virgin metal first with a state of the art epoxy sealer primer paint system properly applied following manufactures directions and amount of coats and tack times. This epoxy or epoxy/urethane base primer sealer coat would be very tough and offer extreme long term protection. Next a couple coats of a high build primer could be used if so desired, followed by a proper single stage urethane based top coat system which would be tinted and flattened to look just like the factory original primer coat. With this system you would have no " Technical Reason " of why to choose to use an undercoating. The bed liner products discussed above are epoxy based and some urethane based. However with that said, their compositional makeup is designed for quite another type of duty and would be IMO overkill. Also they are very hard to repair or remove when and if needed. The proper application of the above coating system would really negate any positives that a bed liner application could offer.

Good luck.

Good reply buick man. In my recollection of the 50's in my dad's shop, Most undercoating was done at dealerships. Some did a good job, others just sprayed the goop over everything. Drive shafts coated on one side, missed spots and gobs hanging down where oversprayed. Car manufacturers were not interested in preservation of the cars! They just wanted to sell everyone a new car every 3 years. More undercoating was sold as a sound deadening than rust prevention. Today we have new products to absorb sound that gets applied in the interior of cars. In my opinion, the epoxy primers used over all bare metal is the best solution. I have seen epoxy primed body panels that have been out in the weather for years without any signs of rust. Make sure the inside of parts are coated. this includes doors, rocker panels and boxed frames.

Bob Engle

Old Tank,

How would I find out what the GM factories did in 1953? My grandfather's car and a parts car I bought were both assembled at the Framingham, Massachusetts plant. Both of them have/had generous amounts of undercoating on them. How would one tell what was applied at the factory and what was applied by the dealer/aftermarket?

Thanks for your advice.

Pat

I don't know where the factory put it in 53, most was put on by dealers and others. Applying undercoating takes time even for a sloppy job and there is not that much time on an assembly line. You need to see an original without. For judging you probably will not lose any points if you left it off.

In my opinion, in 1953 all undercoating was done as a dealer option. It was a way for dealers to get me $$ direct to them. I can't find any factory info that mentions undercoating.

Bob Engle

Pat, a very commendable plan. Good luck.

Today's spray on bed liner is some tough stuff. I used a rattle can version on the floor pans in my '50. Can hardly scratch it. Welding only burned it about 1/4 inch from the weld.

Ben

Rattle can version for me too... 3 years ago. Underside, fender wells, frame rails. It was a pain, but all worth it. Paint looks nice, but will constantly have to clean.

David,

Thank you for your detailed and well reasoned advice. I'm going to share your recommendation with the shop working on my car.....I'm pretty certain that's the route I'll take. The high build primer even looks like an undercoating. I appreciate the time you took to provide me with great information. Thanks again.

Pat

Bob,

Thanks for your concurrence with Buick Man. Pretty sure that's what I'm going to do.

Pat

Sometimes the stuff is called sound deadener. The first time I did the underside of my Riviera I removed all of it with a dull putty knife and a heat gun. Then I painted the underside with urethane satin black. Once it was back together I realized the value of the sound deadener. But I hated the thought of spraying my nice bottom with it. Cars without it are noticeably noisier.

The '60 Buick had a heavy, but dirty coat of factory sound deadener/undercoat on it when we did the rear end job. Experience taught me not to remove what had held on tight for 50 years. In that instance we thoroughly cleaned the existing stuff and scrapped off what little loose edges we could find. The we sprayed over with some new product my nephew buys near Buffalo. I will get the manufacturer info and update. I think it comes from a well on the old Love Canal site.

It does quiet the car.

I wouldn't leave it off another car.

Bernie

Pat: 3M has about 3 different grit/aggregate undercoating products that I have used and know of. It is applied with a Buck Rogers Ray Gun looking application gun that you buy at your paint jobbers for around $ 30 bucks. This attaches to the top of the large 1 and or 2 quart 3M bottles. It is atomized by a 3/8 shop air line you supply from your compressor. It looks very similar to what is on the car and application technique can be quickly adopted to achieve a matching texture and look. However with that said, in today's world and if you have the interior gutted to the pans, then use sound deading and heat shield materials on the inside pans, doors, tranny hump, inside firewall, roof areas etc. This achieves a very satisfactory rumble, thumble and resonance free environment.

Like! best solution yet.

I find it hard to reapply undercoating to areas that took hours to remove with heat gun, mineral spirits and sand blasting!

Unless the car is on a rotisserie then you will be wearing the undercoating.

Regarding undercoating, it does not homogeneously adhere to the entire metal surface areas below it. Yes when first applied but over time it shrinks and shears away from the metal surfaces in many places overall and recesses from the metal surfaces just enough to allow air/water to be forced into shrinking cracks, gouges and chips thus allowing rust to form. Often times when one removes the undercoating, you will find these sheared areas and pink powder rust underneath. IF one simply and vigorously cleans the overall treated surfaces well and applies a new coat of for example 3M undercoating, this will halt the pink powder rust blush from continuing its plaque of duties upon the metal surfaces by suffocating and depleting the areas of oxygen and hydrogen that rust needs working much in the same way that an encapsulator such as POR-15 does.

If you have a car that was a southwestern car or one that had been not exposed in it's history to road salts, then this method would work best and taking the entire mess off would be unnecessary if the car is undergoing a frame-on restoration or a preservation. Before applying a new undercoat overlay one would be well advised to administer a spay coating of a Phosphoric Acid solution such as A Must For Rust or similar product over the entire surface bottom areas to convert any exposed metal areas, cracks, gouges and chips and for increased adhesion overall once let to dry for the following undercoating applications that would follow.

Here is a link to the product. I am not associated with them in any way: http://www.amazon.com/Automotive-Spray-On-Rubberized-Undercoating-RUS-1020F6/dp/B00B3I2LKA.

This is another instance where "professional" application should be avoided. Do it yourself and get a high quality job for less money and no whining and excuses at the end.

Bernie