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Mon Nov 21, 2011 3:15 pm

So I just recently mediablasted my entire frame and pans and sprayed it all with epoxy primer and then seam sealed everwhere. What i am wondering is will the epoxy primer be fine by itself or does it need to have a rubberized undercoating be put on or something similar to that ect?

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Mon Nov 21, 2011 3:38 pm

nice job.....

depends on what the car will be used for and where you live.

I drive mine on weekends only, have three coats of gloss black over epoxy primer and don't have any issues after over a year of driving... no undercoat on the floor pans at all.

it just looks so nice that way.

if you are willing to roll under the car every 6 months and do touch-up, keep it pretty.... if you are going to drive it every day and let dirt build up under the car, then undercoat it.

undercoating the fenders is important because thats where all the dirt and rock get thrown up, but the pan is a matter of you choice and use....

Mon Nov 21, 2011 5:00 pm

how does epoxy prime stand up against chipping and cracking? that my main concern. Also I sprayed that like two weeks ago so if I were to put an undercoating on does it need to be scuffed up to give it a mechanical hook like paint does or can you just spray to it after its been cleaned? I live in British Columbia and wont be driving it in the winter.

Mon Nov 21, 2011 5:05 pm

as posted it really depends on the way the car is being used,, I well say under coat the fenders!! it well save the paint job, driving on the freeway little rocks git thrown up into the fenders and dent them and you'll git spider cracks in the paint

Mon Nov 21, 2011 5:31 pm

tar it !

Mon Nov 21, 2011 5:56 pm

ok what is a good product to use for undercoating

Mon Nov 21, 2011 6:01 pm

I took the underside fenders down to the metal, sprayed flat black rustolium, then sprayed rubberized undercoat. Frequent dry weather driver, has held up perfect for a few years now. Left pan with factory coating, brushed on rustolium flat black, sprayed same rubberized undercoating. Holds up well under my driving conditions.

Mon Nov 21, 2011 6:06 pm

I took the underside fenders down to the metal, sprayed flat black rustolium, then sprayed rubberized undercoat. Frequent dry weather driver, has held up perfect for a few years now. Left pan with factory coating, brushed on rustolium flat black, sprayed same rubberized undercoating. Holds up well under my driving conditions.

Mon Nov 21, 2011 6:18 pm

Just painted mine with por15 then seam sealed .. then Dupli color rubberized under coat ....
https://www.thesamba.com/vw/gallery/pix/868458.jpg

Mon Nov 21, 2011 6:23 pm

same stuff that they are using on bedliners-
But if your around lost of rocks -- then tar it like I said !

Jerry

Mon Nov 21, 2011 6:39 pm

These discussions come up frequently and can get rather opinionated. I know, I've participated in them.

It is known that I vote NO, do not undercoat. My experience, having been in auto repair and service on a dealership level since the early 70's, is that when it works, it works very well. When it doesn't work, it actually promotes rust and masks your ability to view any paint damage to bare metal and make repairs.

It's totally a personal choice. I choose not to and feel quite adamantly about my decision. Other's feel that you should and feel just as strongly about their decision.

IF you do it, DO IT RIGHT!!!! make sure it sticks and is applied evenly and not deeply pitted or sprayed on in clumps.
I feel one of the biggest problems with undercoating is that most of it is applied by 18 year olds without any training or supervision thus the job is not prepped properly, the product isn't applied properly and follow up inspections are ignored.

IF I were to do anything similar today, I'd use a high quality truck bed lining product that had the surface properly prepared and the product properly applied. I'd forgo the goo in a spray can crap that sits on every auto parts distributors shelves.

Search these forums for undercoating, you'll find pages of questions and responses.

Dave

Mon Nov 21, 2011 7:04 pm

PresidentWiggum wrote: how does epoxy prime stand up against chipping and cracking? that my main concern. Also I sprayed that like two weeks ago so if I were to put an undercoating on does it need to be scuffed up to give it a mechanical hook like paint does or can you just spray to it after its been cleaned? I live in British Columbia and wont be driving it in the winter.

Primer needs a top coat ... it is not a protectant. So, you need to put something over primer, like paint. Whether you use undercoating over that is a personal choice, but you can't leave primer out in the open, it won't last.

Mon Nov 21, 2011 7:39 pm

all these fair weather drivers. my my. what's the advice for those who drive in snow and after they've salted the roads?

Mon Nov 21, 2011 7:53 pm

gooser wrote: all these fair weather drivers. my my. what's the advice for those who drive in snow and after they've salted the roads?

There's a lot of good stuff in here, some newer tips toward the end.

http://www.thesamba.com/vw/forum/viewtopic.php?t=436064&highlight=salt+roads

Tue Nov 22, 2011 1:57 am

so since it is just the epoxy primer it does need a top coat then... do you need to scuff it to give it a mechanical tooth of will a rubberized coating stick to the primer as is? (again keeping in mind it is just over 2 weeks old)

thanks for all the info!

Tue Nov 22, 2011 3:16 am

gooser wrote: all these fair weather drivers. my my. what's the advice for those who drive in snow and after they've salted the roads? Primer, seem sealer, and A good paint like rustoleum. Then under coat the fenders only.. The only reason I say to do the fenders is that the tires kick up rocks and gravel that well dent the shit out of the fenders and kill your paint job

Tue Nov 22, 2011 3:20 am

PresidentWiggum wrote: so since it is just the epoxy primer it does need a top coat then... do you need to scuff it to give it a mechanical tooth of will a rubberized coating stick to the primer as is? (again keeping in mind it is just over 2 weeks old)

thanks for all the info! primer is pores, that's why you need to put A top coat on it. you don't need to scuff it, the paint grabs the pores :wink:

Tue Nov 22, 2011 4:25 am

if you look up your local auto paint distribution store and go see them you will find that they have very good undercoating products. Autozone type spray can's work, but the stuff you can get at the real auto paint store is a more professional product.

When I did my fenders, I used professional undercoating. It dries hard like bedliner and is paintable. So in the end, my fenders are painted and clearcoated over the undercoating giving a professional look.

Also, there is professional undercoating with small spray straws you can purchase too. it allows you to spray undercoating in all the void areas like the "A" pillars.....

Tue Nov 22, 2011 5:27 am

Put some paint over the primer. That's what the primer is for. You can use undercoating over the paint if you want to, but I wouldn't put undercoating over bare primer.

Primer helps paint stick to the metal. It has no long-term protective properties. Moisture can pass through the pores in the primer and rust the metal under it. If you put undercoating over primer and moisture gets under the undercoating it will rust your car as fast as if you had just left it bare.

Tue Nov 22, 2011 7:40 am

I credit the undercoating job "Elsie" was given 40 years ago with having saved it from rusty destruction. By the time I got it, there were areas that were flaking off and needed attention, but no serious rust issues to speak of. Just my 2 cents...