[Verdoro 68]

Started stripping my endura bumper down today. It has a fair number of cracks in the surface, some made it through to the old paint but many of the fine hairline cracks didn't. How deep does a crack in the endura have to be before I need to v them out and fill them?

The ones around the corner of the grills seem like likely candidates to be ground out and filled since they cracked through the old paint job, but what about all the fine hairlines? Would a coat of 3M 2 part flexible repair filler over the entire bumper followed by a sanding be sufficient?

By the way, as I'm sanding this thing down it appears the shop that did the work back in '91 just sprayed either a high build primer or put a thin coat of bondo over the whole thing before painting it. That's the cream colored stuff you see in the pics. No wonder it cracked.

[Cammer-6]

first you want to sandblast the whole thing
sand with 80 grit to see what cracks remain
see the pics of the 70 I did that looked just as bad

[Verdoro 68]

Are these the pics you are talking about?

http://forums.maxperformanceinc.com/...d.php?t=661034

I stripped it by hand with 80 grit. The first pic is down to the raw Endura, second pic is down to whatever primer was under the top coat and the last pic is stripped endura with a few remnants of primer. It's darker in some spots because I wiped the dust away with a wet rag.

What did you do for all the spider cracks? A majority of those didn't show in the top coat and none of them can be felt with my fingernail. I'm thinking a skim coat of 3M should take care of them.

[PaulatFast]

Sandblast the bumper as suggested above. If those little cracks are just on top of the surface, they will be gone when the bumper comes back. If they are still there, they need v'd out and filled with a 2 part flexible EPOXY, doesn't matter who makes it. spreading any filler over the top of a crack is asking for problems, I'd rather see you spray the over the cracks with epoxy primer than skim over them. Good luck.

[Verdoro 68]

Gotcha. Appreciate the info.

[salem1912]

I used a da on the whole bumper 180grit then used 2part epoxy from 3M. happy with the outcome and hope it holds up. BTW had to twist,bend,pull and push this thing but finally got it to line up.

[Verdoro 68]

Looks great!

I did a little more sanding with 80 grit and got a majority of the tiny cracks out. I v'd out the remaining ones and am in the process of applying the 3M epoxy and hand sanding with 180. It's tedious but I'm liking the way the bumper is looking.

[68ragtop]

Hi Guys, going through the exact same process right now, & am glad to see its a common issue & have read through all the posts.

Thanks Paul, for offering the experience & success with these bumpers. However, I am hoping for just a little more clarification.

My bumper, which seemed to just have cracked paint, is exactly like the above pictures. Many, many, hairline cracks through 30+ year old paint. I had thought up until yesterday, that they where just in the paint. Upon sand blasting the bumper, I learned quickly that the cracks originate from the bumper itself. Bit of a surprise to me, because its a very nice bumper otherwise. Almost no damage at all. The hairline cracks are literally everywhere & are so small they almost can't be seen.

If I am understanding Pauls Process correctly, I am just to fill nicks & large areas with the flexible two part epoxy filler repair material, then cover the whole bumper with SPI epoxy primer & use it as my surfacer. Obviously these hairline cracks will still be under there, & the thought would be the flexible SPI primer will hold together as the substrate & not transfer these cracks to the top coats?

Seems like a scary proposition covering cracks, & obviously explains as to why there are so many paint failures on these bumpers.

Also, I would assume its ok to still use a wax & grease remover/cleaner to go over the prepped bumper before the epoxy coats?

[F ROCK]

i'm no paint/body guy but i have noticed on my 71 that if you jack one side of the car up, at the frame jacking locations, it twists the bumper a little and the paint cracks on the endura.
now i try to use a lift or ramps or in the rear i jack the whole back up by the center of the rear axle.
i never jack one side. my endura was fine till i did my brakes.
slightly off topic but just sayin.

[PaulatFast]

F ROCK, I am glad you posted that, in all of my endura question answering I had never considered that anyone would actually try and use the bumper jack!

To clarify the crack issue, if the "crack" is just a hairline and can't be spread apart or even felt with your finger nail, we will not "V" it out and fill it. We will prime it with epoxy, the epoxy doesn't just go over the crack, it fills and seals it. If the crack is big enough that you are thinking it will be coreved over, it needs fixed before primer. I don't use ANY cleaner or prep on the endura other than soap and hot water.

[F ROCK]

Originally Posted by PaulatFast

F ROCK, I am glad you posted that, in all of my endura question answering I had never considered that anyone would actually try and use the bumper jack!

.

respectfully, Paul, I said jacking at the FRAME locations, not the bumper. I'd never try the bumper locations.

edit: ok i did try to use the bumper locations once on an old car, i cant remember what kind of car, it was 30 years ago, rusty steel bumper, and the bumper ripped like cardboard!!!

[68ragtop]

Paul, I was just amazed how many "cracks there are in the bumper. Never hit that I am aware of & still had what I believe could have been factory paint. There are some cracks that I can push my nail into & catch, & many that I can see, but don't seem to open up. But overall, there are a just lot of them. was very disappointing to see.

When I sand blasted it, the blue top color coat & red oxide primer came off very easily. What was left was a primer that was a tan, to slight pinkish color. Sand blasting really wasn't taking that layer off, So I sanded that off by hand with 80 grit. Took quite a few hours. Could that have been a factory primer? There were no repairs revealed,

[F ROCK]

it is kinda funny how the jack, supplied with the car, would damage the bumper tho.
and i bet it would.

[Cammer-6]

most are missing the round rubber pad that helped prevent damage.
But other than display for a show car I wouldnt use one.

[68ragtop]

I am having a hard time deciding how many cracks to v out & fill. There are just so many of them. Some are obvious, I can see them & catch my fingernail on them. There are probably about 20+ like this. However, there are smaller ones I can see, but don't really catch my fingernail, however I can catch them if I press my fingernail into them. These are everywhere in mass amounts. Some that are only visible if I wipe it with W&G remover. Then they vanish to the naked eye when it evaporates. These would be impossible to grind out. There wold be nothing left afterwords & would take an eternity to do.

I am guessing these are the ones that you guys are filling with epoxy. After having this bumper for so many years, I never guessed the troubles that were waiting for me...

[68ragtop]

Originally Posted by PaulatFast

Sandblast the bumper as suggested above. If those little cracks are just on top of the surface, they will be gone when the bumper comes back. If they are still there, they need v'd out and filled with a 2 part flexible EPOXY, doesn't matter who makes it. spreading any filler over the top of a crack is asking for problems, I'd rather see you spray the over the cracks with epoxy primer than skim over them. Good luck.

Paul, for clarification, when you say: "they will be gone when the bumper comes back" Are you talking about coming back from sand blasting, or back from the first coat of epoxy? Seeing the sanding blasting didn't phase the rubber at all, are we just discriminating between paint cracks & rubber cracks? All of the cracks I mention in the post above, are in the the raw endura surface.

Whats incredible to me, is this bumper is one that was undamaged & appeared to still hold the oem paint. The paint was cracked, but this bumper had/has no other damage, & not one gouge in it. Its had a pretty easy life. I was surprised & disappointed to find all these cracks & micro cracks in surface.

[PaulatFast]

Been there several times myself! For reference we focus on the top, center and sides of the bumper. For instance if a hairline crack is on the inside of the nose, or underneath, we will be more likely to leave it. A lite but thorough coating of the flex epoxy repair product will do wonders for some of those little cracks. hen I mentioned earlier that some of those little cracks would be gone when the bumper comes back, I was referring to the sand blaster. It sounds as if your nose is pliable enough that wasn't the case. We wrap up some serious time on these noses! Don't forget to fit it at this time as well, there is always an edge that needs shaved or filled to get the alignment just right!

[68ragtop]

So with these smaller cracks, are you just pushing epoxy filler into them, or are you v'ing out all of them you can find on the top & sides no matter what their size? Are you leaving a mil or two of sanded flexible epoxy covering the cracks before epoxy primer to help them bond?

Sorry for beating the life out of this topic, but seeing you've already experienced all the heartache, I just want to follow your advise. Hard Lessons learned in auto paint are time consuming & expensive..

I do have the bumper fitting like a glove. That took some time, but worth every minute. (although it took many hours)

[PaulatFast]

I don't cover anything I think will haunt me, I guess it might be a judgement thing and experience is the only way to make the final decision. I would not take any chances. Yes, I like to leave a bit of the epoxy repair stuff over the repaired areas (v-ed). a hard line of filler is sure to come back and cause an issue. When we open up a crack, I sort of feather the edges a bit so the filler makes a transition into the v-ed area. I hope I didn't just muddy the water...

[68ragtop]

Not at all, makes perfect sense. There are just soooooo many cracks..... this is going to be a lengthy project. I am guessing when you put your first coats of epoxy primer on, your hoping to see no missed cracks, just possible sanding marks from the repairs.