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Hi,

I am in the process of scraping away surface rust and dirt from the under carriage of my 1967 GTO. I plan on painting and protecting it, I am just not sure with what. I am leaning towards POR 15 because it will create a permanent seal and prevent any future surface rust from appearing.

I am looking for feedback from others who have gone through the effort and painted their under carriage. What did you use? Why did you choose it and most importantly, are you happy with the results?

Thanks
 

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Have done/am doing my frame with the POR-15 rust encapsulator and then the POR-15 topcoat. The POR-15 is like water in consistency and suppose it needs to be to get into any rough rusty areas or crevices. It says to do 2 coats because it is so thin. I only did one coat as I sand blasted my frame so it was clean. I also planned on the POR-15 topcoat which seals over the POR-15 rust encapsulator. I read that some paints do not take well to the POR-15 encapsulator, but the POR-15 topcoat seals and can then be painted over with no problems. I plan on a final topcoat over the POR with a coating of Rustoleum black spray bomb just to ensure I got it all.

The POR is not cheap, but don't let that fool you - it goes a long way. I did my frame with 1 quart, but this is one coat only AND, I still have to do the bottom of the frame rails as I still have some welding to do in boxing the side rails. I will then "tip" my frame on its side and sandblast the bottom of the frame rails & the welded areas. So I would say another quart will complete it and give me some left over to do some of the front suspension parts when I get to them. On the POR-15 topcoat, I used a pint up. Again, will need another to complete. So I would recommend 1 quart of POR-15 rust encapsulator for 2 coats and 1 pint of the POR-15 topcoat. You will most likely have left over which can be used elsewhere.

Follow these directions. Stir the mix, don't shake as the pigments settle. Buy a few small tupperware bowls and only pour what you need into the bowl. If you contaminate the POR-15, it all goes bad. Better to lose a small amount than the whole can - especially if you drip sweat into it as you are holding the can and leaning over it. I used a cheapo $1 paint brush to apply because you will throw it away after use -along with the tupperware bowl. WIPE the excess POR-15 that fills the rim of the paint can when you pour it out. Mop it up with your brush to soak it up, then wipe it out as clean as possible before putting the lid back on. It will be a fight to get the lid off if you don't and go to use it next time. Some say use plastic wrap over the top then put the lid on. Just wipe it off dry with a rag or paper towel.

Lightly sand/scuff the base POR-15 as per instructions before putting on the POR topcoat. Follow the POR directions in putting 2 coats of the rust encapsulator on as I only put the one coat on. You want to get all the grease off your surfaces. I started using this product called "Totally Awesome" because the GUNK type engine degreaser doesn't work anymore. It is sold in a spray bottle and 1 gallon jugs. Bought 1 gallon today for $3.00 to do some degreasing. Spray it on, let it sit for a while or scrub off, and spray off with water. The EPA hasn't gotten hold of it to reformulate it, so it still works. It seems to be available at discount type stores here in my area.

I put my unused POR in the refrigerator after opening (was good for several months). The heat and the air introduced into the can will cause it to age/cure. Near the end of the POR-topcoat which I did not refrig, it developed a "skin" on the top of the paint and I thought I had lost it, but the paint underneath was good and had enough to be used for my needs. So you can extend the life of the POR in the frig.....if your wife is OK with it (I 'ain't got one so I can put anything I want in my fridge right next to the beer!).

The POR seems to be good stuff right now, in my opinion. The topcoat seems to be a pretty hard coating and I think worth it to put over your base POR rust encapsulator. Long term, it will be many years before I can give an opinion, but I can't see why it would not work. Putting a final coat of spray bomb over everything has got to be better than the dirt and light rust that has been on the frame for almost 50 years - so I think it will outlive me.
 

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Depends where you are and what rust you are dealing with. Out here in CA, I would never use POR15....simply not needed. I would use regular semi-flat Rustoleum paint. If you are in a rusty area, you need to follow Pontiac Jim's advice.
 

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POR 15....follow these steps......clean all loose rust / hitting with a pic hammer and get it all free....or if you sand blast clean....the Metal...clean or rusted MUST be treated with the POR Metal Prep . If this step is not done ,you will have poor adhesion. So spray all metal with the Metal Wash to be treated..it has to sit on rust/metal for 10-20 minutes and keep it wet for that period of time. Then you have to rinse the metal with water...let dry over night...blow dry next day to make sure it is dry..or put it outside or dry it with heat lamps. Once dry then you can apply 2 coats per instructions on can. I have been in the autobody field for the last 39 years...and have used plenty of POR 15 with the metal prep and without the metal prep.....so you can learn from my mistakes.
 

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I treated my under carriage with Ospho rust treatment, sprayed with an epoxy sealer/primer, then sprayed with 3M™ Rubberized Undercoating #08882, then I mixed 6 parts rustoleum gloss black with 4 parts rustoleum flat black and sprayed.

The 3m product is a great sound deadener and isn't your typical undercoat.
 

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my mechanic friend introduced me to por-15 when i started my build . He had build a few cars and swore by it so I bought a gallon and went to town. I sand blasted frame and rear end and coated that. It came out really nice for being brushed on. as we assembled the frame I saw that you could hit this stuff with a hammer and NO CHIPPING. I then went nuts on car- did whole underside of body,firewall, wheel wells, tranny hump( that was new steel) trunk, radiator support, bumper brackets,gas tank, spindles, inside of roof, anything that could ever rust was coated. Follow directions as stated above and it will not fail. DO NOT GET IT ON YOU I had black freckles on my face for 3-4 weeks.
 

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I did not do all the prep work because I sandblasted my frame and it looked like clean metal. I found this ad today in an autobody newspaper. This explains the POR-15 procedure and the assorted materials needed to do a complete job, from rusty metal to finish topcoat. :thumbsup:
 

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Discussion Starter #9
Here are the before pics, I took the rear out (gear swap to 3.42 from 3.73) and also the exhaust which is in good shape. I am on the fence with taking the exhaust to a shop that can shoot it with VHT paint and bake it on. One guy said he would sand blast the exhaust and bake it for $100 if I bought the VHT paint, another guy wanted $400 to blast it and use ceramic coating. I had the headers coated in ceramic already and paid jet hot $$$, but you can see those.

Decisions, decisions....
 

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Hey Tony goat and others. I'm about to follow your lead and am going the rout of POR15 since I'm on the east coast. I have a 64 with all original panels and no rust. I'm putting new body mounts in and decided to do the cleanup as well. My question is, is it advisable to leave the original undercoating on or scrape it off to bare? My original plan was to leave it on and just paint over it after I dust it off. There are only a few spots where it's flaked off but I'd say 90% of it is still there.
 

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Depends where you are and what rust you are dealing with. Out here in CA, I would never use POR15....simply not needed. I would use regular semi-flat Rustoleum paint. If you are in a rusty area, you need to follow Pontiac Jim's advice.
My frame is in great shape just dirty, I pressure washed the engine cradle while it is out and used Eastwood frame black spray bombs and hand held shields to paint.
The tranny support had old oil and dirt packed in it that had to be chiseled out, that got sand blasted, primed and painted.
My engine is on it's way back from CVMS and I am heading up to Mammoth tomorrow for a week to do some fly fishing so when I get back the fun begins!
 

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Hi Macs - In my case, whatever does not come off after briefly hitting with a wire wheel is staying. The flakey stuff comes right off but there are some spots that may as well be concrete and I have no interest/time/energy etc. in removing it. I just received my POR 15 + top coat + metal prep and will start applying this weekend.
 

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Hi Macs - In my case, whatever does not come off after briefly hitting with a wire wheel is staying. The flakey stuff comes right off but there are some spots that may as well be concrete and I have no interest/time/energy etc. in removing it. I just received my POR 15 + top coat + metal prep and will start applying this weekend.
Hey thanks for the insight. I think I'll be following your lead. Good luck and have fun with the painting, it'll be nice when finished.
 

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I do not think that the por-15 can go over the undercoating. POR wants to bond to a rough metal surface, either sand blasted or surface rusted. I may be mistaken but I think it would peel right off of the old undercoating. AND if you do not have the time to remove it dont start- it is a BRUTAL job, took me 40 hrs+ to strip it all off the underside of the body and wheel wells, plus about 80 grinder pads, 10 wire wheels, full face respirator, tyvek suits-- ahhhh the joys of car restoration
 

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Discussion Starter #16 (Edited)
Hi - Been a while since I posted on this, what started with a simple scuff and paint turned into a much larger ordeal that involved a heat gun, scrapper, acetone and plenty of elbow grease. I will post some more pics soon, but here are a few that show progress to date, I ended up using ceramic coating on the exhaust + POR 15 base coat and top coat on the rest of the underbody (except for the diff, that was Eastwood Chassis Black)

http://1drv.ms/1Ieg8aB
 

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Hi - Been a while since I posted on this, what started with a simple scuff and paint turned into a much larger ordeal that involved a heat gun, scrapper, acetone and plenty of elbow grease. I will post some more pics soon, but here are a few that show progress to date, I ended up using ceramic coating on the exhaust + POR 15 base coat and top coat on the rest of the underbody (except for the diff, that was Eastwood Chassis Black)

http://1drv.ms/1Ieg8aB

Looks great. Rear sway bar, adjustable upper control arms, and bolt-on no-hop bars to raise them up. What brand of no-hop bars did you use?
 

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Discussion Starter #18 (Edited)
Hi Pontiac Jim - Thanks for the compliment, the upper control arms are adjustable that I purchased from Sphon, the no hop bars are QA1. I had them sand blasted and painted them a metallic candy apple red along with the rear shocks , very happy with them, they stopped wheel hop for me where drag bags didn't quite get the job done.
 

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Hi Pontiac Jim - Thanks for the compliment, the upper control arms are adjustable that I purchased from Sphon, the no hop bars are QA1. I had them sand blasted and painted them a metallic candy apple red along with the rear shocks , very happy with them, they stopped wheel hop for me where drag bags didn't quite get the job done.
Thanks. I was just curious what you went with. I am running an aftermarket Ford 9" and am in the process of fabricating my own specific bolt-on no-hop bars as none are available and have the Spohn upper control arms which I have reversed and have had to fabricate my own mounting point to bolt to the crossmember frame.

The photo shows the two halves mocked up along with the UCA simply dropped in place for a visual. I have welded some plates to stiffen them up and a means to bolt the lower leg to the axle using a U-bolt. Yes, they look high, but I am cranking the rear end of my car up about 4" so this will change. I had them fabricated with the adjustment holes to fine tune the UCA. I am no chassis expert, so I am winging it with my design ideas and hope they work! :wink2:
 

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I joined looking for info and as I navigate the threads, I'm finding I came to the right place. I planned on pulling my relatively fresh engine and transmission just so I could renew all the undercarriage, lines, brakes, bushings etc. Also planned on the POR-15 route by simple green the bottom and pressure clean everything. Then the car went back into hiding. TG, you are doing a great job. I'm following your lead.
 
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