Undercoating removal with heat?

Tom '74 911 · 01-04-2014, 07:04 PM

Hi,

So we all know that removing undercoating is a bugger of a project. I ran across the photo below showing someone using a flame/torch to heat up and soften the undercoating. Subsequent photos show the undercoating being scraping off with a scraper and wire wheel.

I did an accidental small test using this method when I used a MAAP torch to heat up a rusted/stuck suspension bolt for removal and burned the nearby undercoating on the front inner fender. I ran to get a scraper and wow, the undercoating sure came off easily!

I was wondering if heat like this could damage things... possibly cause warping etc...

Any thoughts?

Thanks,
Tom

drcoastline · 01-04-2014, 09:07 PM

Yes it can. To much heat can cause warping. I'm not positive if a propane torch like in your photo will create enough heat but if it were me to be on the safe side I would use a heat gun to ensure it didn't cause any warping issues.

David McLaughlin · David McLaughlin's Garage

I remember someone telling me that 220 degrees is the magic number. Over that and metal gets deformed; under that and it won't work well.

962porsche · 01-05-2014, 06:13 AM

with the right tools chip guard comes off ez !
we can remove the chip guard on the hole chassis of a 911 /944 and alike in about two to three hours .
heat is the dumbest why to remove it not just for the cars chassis but your health also .
if your set on trying it with heat maybe you should think about wearing a respirator ?

Tom '74 911 · 01-05-2014, 06:22 AM

Quote:

Originally Posted by 962porsche

with the right tools chip guard comes off ez !
we can remove the chip guard on the hole chassis of a 911 /944 and alike in about two to three hours .
heat is the dumbest why to remove it not just for the cars chassis but your health also .
if your set on trying it with heat maybe you should think about wearing a respirator ?

Just to be clear, that is just a photo I found on the internets, not a selfie. I DO value my lungs & body enough to wear a respirator while undertaking such activities.

I'd love to learn more about your chip guard removal technique! To complete an entire chassis in 1/2 a day or less sounds too good to be true! Do you use one of these:

962porsche · 01-05-2014, 09:15 AM

that's one of the tools you would need to do the tight areas .
also a air scrapper and air scaler for the stick on sound matting material .
a good air scrapper will come with 4 to 5 blades 3" , 2", 1" and most with one or two angle blades .
as for tekneek that's ez to master and you should get the hang of it in no time .
keep the blades sharp and watch the edges so you don't scratch up the sheet metal .
once you get the hang of it you will be able to start at one end of the chassis and in one pass go right to the other end with out stopping .

Tom '74 911 · 01-05-2014, 10:45 AM

So just to complete the circle... An image of an air scraper and needle scaler below. Both of these are good for the rubberized (or at least seemingly rubberized) undercoating/chip guard in the fender wells and underside of the tub? I will definitely have to give these a go! A friend has a needle scaler that I'm sure I could borrow for a test run. I could see how the air scraper could work well. I'm assuming you'd probably have to go over everything with a wire wheel to get the remnants as the last step?

Thanks again for the help & suggestions! I've got some experimenting to do!

Tom

962porsche · 01-05-2014, 01:07 PM

rubberized undercoating sucks to be removed . it should in no case be used on a car at all !
it's just a product that does nothing in any way shape of form .

chip-guard is the product the car makers use for a reason .

but yes they are the tools that will remove the chip guard with as little work as there could be .
it takes the chip-guard off dam clean once you get used to the way you have to use the tool to do it do there is not much to much wire wheeling you should have to do .
we tend to scrap the chip-guard then sand blast what little is left behind . if we are not blasting the hole car we will wire wheel the rest off .

I just did a customers 944 last week that i'm building for a track car .
it took a total of 3.7 hours to do the car inside and out all the chip-guard and sound pads on the inside .
the needle scraper works great for the sound padding on the inside of the car . the cooler the sound padding is the cleaner it comes off with little clean up after .

cnielsen · 01-05-2014, 07:29 PM

Heat also tends to initiate a quick surface rust in the inner layers of the stripped panels. I know it's tempting but don't use heat if you can avoid it.

drcoastline · 01-07-2014, 04:19 AM

962porsche what tool do you use behind the door posts, the upper portion of the rear wheel wells and behind the tail lights? I can't find anything that will fit in those areas. I even tried manufacturing a tool to get up in those areas.

Just for the record for my car I found the easiest way to take the black tar sound deadening substance off the floor was to peel it off in sheets. I started to do what others suggested thinking it would be a B!tch to remove. Which it was. Then I found that if I used my heat gun and a 5 in 1 scrapper and a little patience it would peel right off in large sheets. I heated the sound deadening with my heat gun. evenly across the surface. I then got the 5 in 1 under a loose piece of deadener and shot the heat between the floor pan and the sound deadener. As the deadener and pan heated the bond loosened and the deadener peel right off. I would estimate I had the entire floor cleaner in about 30 minutes.

962porsche · 01-07-2014, 08:57 AM

I have a straight stripper wire wheel to get up in the tight areas not one like shown here that's a right angle one .
there are different wire wheels you can use on it from 1" wide to 3" wide .

because of the age type and so on with the sticky sound padding
it's more what ever works for you to remove it .
I have found in most cases having cool works best to also not have a sticky glue left behind .

Tom '74 911 · 01-07-2014, 03:18 PM

Since I have more than one tub to do, I decided to throw down and bought a few of the air tools discussed here to experiment with. Once they arrive and I have some spare time, I will try to do a little review of each.

Undercoating removal methods seems to be a recurring topic so having a review thread with photos and real life info, to go along with the great info from 962porsche, might be helpful to a lot of folks...

More later after UPS delivers my 2nd christmas...

962porsche · 01-08-2014, 05:04 AM

if you look you will fine so many topic's on removing chip-guard what it all comes down to is the quality of the tools you have and knowledge of using them .
so there is the learning curve to finding the little tricks that will work for you .
the more cars you do the faster you will become with the task at hand . it's the same thing with every part of body and paint work even when it comes to masking a car for paint .
so one that has never done it before will no doubt take much longer than some one that has done 1000 of cars .

drcoastline · 01-08-2014, 08:20 AM

Quote:

Originally Posted by 962porsche

I have a straight stripper wire wheel to get up in the tight areas not one like shown here that's a right angle one .
there are different wire wheels you can use on it from 1" wide to 3" wide .

because of the age type and so on with the sticky sound padding
it's more what ever works for you to remove it .
I have found in most cases having cool works best to also not have a sticky glue left behind .

I would like to see this tool. I have wire wheels, scalers, Long point pipe cleaner wire brushes to put in my drill or air grinder you name it. I still can't get in the crevice above the door striker or above the engine cable housing or back into the tail light. How about blasting with glass bead or walnut shells?

BTW 962 I'll post pics on my Upol thread of where I am later today.

village idiot · village idiot's Garage

I went from this:

To this in about a 1/2 hour:

Using a tool similar to the one posted by Tom '74 911 above(the spitznagel thing)

962porsche · 01-17-2014, 04:18 AM

village the car looks good !

with the right tools it's not a bad job to remove the chip guard at all .
but you need different tools to strip it off the car the scrapper all by it's self will not do it all .
you need wire wheels too and all different types to get into the corners and edges .
then you need the air supply and quality air tools that don't bog down when you dig the wire wheels onto the chip guard .
the 3" wire wheel tool I have uses a crap load of air and will rip the chip guard right off .
the down side is when some dumb ass sprayed the black rubber undercoating on the car . that gets gummy and clogs the wire wheels up bad . when that happens the wheels don't work well at all .
it's like any task the more you do it the more proficient you will become at it .
the more you will learn what type of wire wheels will work best and what blades and how sharp they have to be to work there best also .