The plastic ID usually stamped on the back of bumpers. I've never checked the Viggen bumper specifically.

 

Bob's right. Take off the bumper and the plastic type will be molded into the backside. Saab does that on just about every plastic part for recycling purposes.

 

Pp-epdm.

 

You should just be able to plastic weld it and then use urethane based flexible filler to tidy it up on the front side.

 

Are urethane fillers available at the local parts chains or body shops only?

 

It will depend on the store, but likely a national chain wont have it, but you should have a local independent store that carries an extensive body repair/paint selection that would.

 

Finally found it: PUR GF-20. When you say weld it, are you talking about plastic welding rods or a plastic stapler? I was wondering if I could use the hot air attachment from a soldering rework station with a soldering head- or do you need to use an airless welder for this type of repair?

 

You'll really want hot air (plain nitrogen is preferred since the lack of oxygen helps prevent the plastic from burning rather than melting). You'll then want to get the rods that match (or are right) for the plastic you are welding.

There seems to be a mismatch in info regarding the plastic that does make a difference to the process here.

The info that you have stated is that it is a polyurethane based resin, that is a plastic that wont melt really but rather just eventually burn.

Mimmi stated that its a polypropylene base, that plastic will melt and will aid in welding.

With the polyurethane base you will want to purely melt the stick that you are welding rather than the base material (basically you use it more like a glue/filler), with the polypropylene base you should be able to melt the base and rod together, this will create a much stronger repair.

Personally, I'd maybe skip trying to weld it and just use a bumper repair kit (it should consist of some adhesive and mesh), drill out the ends of each crack (to spread the stress and stop them extending) then drill some holes either side of the cracks, this will help the adhesive penetrate through the bumper and make a much stronger repair.

FWIW I think your info might be accurate, I've never had great success in melting to repair bumpers, while none have been Viggen specific I doubt the regular 9-3 bumpers where made out of something different than the Viggen despite it being a different shape.

 

I Have a Viggen front bumper that says pur-gf-20 and as described it burns rather than melt. So it is polyurethane glass fibre composite Right? The buper is in good condition but it has a larger about 5 inches vide tab on the inside that is for securing the bumper to the car that is completely missing on the left side. The same tab on the right side is still there so i made copy of it out of some more common plastic. But as regular plastic welding does not work and i can not afford something fancy, what glue bonds the best to polyurethane?

 

jmk: If you want to practice, I have a spare 9-3 (damaged) bumper that's made of the same material if you want it. You'd have to drive significantly in my direction, I could meet you part way... but if you want it, it's yours. It's just going to the recycler soon, so I am happy to pass it on.

I will also have a couple 9-3 bumpers that are in good shape if you need a temp. Available very, very cheap, some time soon.

PM me if you're interested.

 

Thanks for the offer. I'll probably just wing it though since some cracks are way underneath and will be good for practice.

 

FYI - stumbled across this while I was looking for a different bookmark: https://www.harborfreight.com/80-watt-iron-plastic-welding-kit-60662.html

 

I'm restoring a Viggen front bumper. It is in good condition but a there is one mounting point that are slightly broke and one is completely missing. I thought i could fix this relatively easy with plastic welding but that did not work as i planned since the bumper is made of PUR GF-20. The picture shows the part on the left side that is ok. On the right side this part is completely missing. I have made a copy of the left side part that is "L Shaped" so it has a base surface that is about a inch wide that i thought would give good support when plastic welded to the bumper. I realised that i should have a image for this also but i will update with it if necessary. But since PUR GF is very hard to weld i have no idea what to do now. Is there a glue that works good enough?

ave no clue what

 

 

Thx for the video. But this kind of welder and materials are way out of my budget and time to spend learning. At this point i'm just looking for a glue that would work well with this kinda plastic.

 

I used JB Weld Plastic Bonder on a Viggen bumper recently. It's been a few months now, and it seems to be pretty sturdy.

 

Interesting. I've never had much luck with that stuff even on much less demanding tasks. Tried it a few times and it never worked.

I have a small crack on the underside of my bumper. I might give it a shot for kicks.

What did you do for prep? Just sand a little and clean with alcohol?