[95968cab]

I took a front bumper cover to a body shop for crack repair.  Body shop says there is no suitable material that can be used to "weld" the cracks in the bumper cover.  Has anyone had success getting repairs done to the front bumper cover? What material was used for "welding" with the plastic?

 

Thanks.

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[jsheiry]

I think some of this depends on where your cracks are and if they are in some of the more structural areas and if you can easily get to the back side to reinforce the repair with something.

 

Good news is yours seems to be GP white and you are probably able to find a solid GP white front bumper as a bolt up replacement.  White, black, red seem to be available from the normal parts houses.  Now if you were Tahoe blue or Speed yellow I would say that you were out of luck!

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[Waylander]

You can buy the sticks off ebay and the welding gun,

 

on the inside bumper there will be a marking as to what its made off, I cant go and dig out my spare speed yellow front PU from behind the garden shed, its too burried right now

 

it will say something like PU/ABS this is what its made off just buy the correct sticks and a gun and have some fun.

 

I have fixed my cracked door box one side with this, and the other side with lego blocks melted in acetone....

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[94SilverCab]

Haven't you seen Wayanders car???

 

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[Ryan]

Now thats funny.

 

There are those double syringe things available for the repair of PUR bumper covers.

 

Ryan

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[MCL968]

Hey, don't knock it! The Lego blocks in acetone trick is brilliant, and works great for creating new parts from a mold made from the old broken part.

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[Waylander]

Lego is made of ABS, melting Lego in acetone is fine it does not alter its molecular structure, so it returns back to its original state once the acetone evaporates


It’s like a cold weld process works brilliantly

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[flash]

generally speaking, the polyurethane that the front bumper cover is made of is easily repaired.  any decent body shop knows how to do it.  1 out of 100 cars coming over from europe require bumper cover repair before going to the dealership.  i would seek out a shop that does insurance work for the dealerships.  they will likely be best versed in such a thing.

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[95968cab]

Thanks for sharing your ideas.  I'll follow-up with our local Porsche dealership for the shop they use and discuss the Lego/acetone with the body shop that has the cover now. 

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[Waylander]

That works for ABS, but wont work for PU that needs something different


But if you get wheeler dealers over there on discovery, last week they took a bumper to a bumper specialist repair shop where they hot welded a bumper


He said he could fix anything in that shop


The dealership will want to sell you a new one $1500

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[MCL968]

Believe it or not, another place that welds polyurethane is RV repair shops. RV Water tanks are made of PU and they tend to crack. These shops often have a lot of experience welding PU because tanks are expensive and often almost impossible to change.

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[robadams56]

Based on Flash's comment, I'm guessing a good body shop can fill scratches and scuffs then repaint.  I don't have any cracks in mine but had a piece of wood fall out of a truck on the freeway and put scratches in mine.

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[dlearl476]

I took a front bumper cover to a body shop for crack repair.  Body shop says there is no suitable material that can be used to "weld" the cracks in the bumper cover.  Has anyone had success getting repairs done to the front bumper cover? What material was used for "welding" with the plastic?

 

Thanks.

This is kind of timely for me, as I just finished a plastic/Paintless dent repair class at my local community college.


There are 40+ kinds of plastic, 10-11 of which are used in cars. Bumper covers are, as Flash mentioned, generally polyurethane, although polyethylene and polypropylene are also common. Recently, polypropylene hybrids are also common. If Porsche uses the common labeling (iffy as of '92-'95) you will find a code on the top line of the part info molding into the back side of the cover between two backwards greater than/less than symbols. >PP<, >PE<, >PP+PEA<, etc.


There are good adhesives, as well as airless and nitrogen welding processes. Imo, welding is better because, like metal welding, it makes two pieces one, rather than bonding them together with a second material. The one caveat is that you have to know what your bumper cover is made of. PP won't stick to anything but PP. PE, etc all require their own sticks.


Polyvance is a major supplier of plastic repair tools and materials. They have a bunch of videos on their site that you can see the process. FWIW, "So easy a caveman can do it" pretty much applies, but it depends on what you end your life do after the repair that matters. If you're going to require refinishing, you're better off letting a pro do it. If it's a simple tab repair or non-visible crack, you can buy an airless welder and sticks to DIY for less than what a pro will charge you.


Back to your OP and your interaction with the body shop, it's a matter of economics. It doesn't make sense for a body shop to pay someone to fix plastic, then do all the prep/paint work when a) 99% of customers are covered by insurance and b) it's faster for the body shop to simply buy a new cover and do the minor prep work prior to painting.


Remember the first rule of auto repair: Speed, Quality, Price. Pick any two.


PS: When I had my front/rear clips replaced, I never looked to see what the material was. Judging by how if feels, I'd guess Flash is correct with Polyurethane. 90% certain It's either that or Polypropylene. Polyethylene and ABS are harder plastics like those used in Motorcycle bodywork and gas tanks.

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[dlearl476]

Lego is made of ABS, melting Lego in acetone is fine it does not alter its molecular structure, so it returns back to its original state once the acetone evaporates

Its like a cold weld process works brilliantly

Polyvance makes a pretty good system for "molding" abs parts, too. It was just on sale (may still be, I don't know.)


https://youtu.be/gnCl6ogtfZI


Based on your description, I'd suspect that "Plasti-Fix" is powdered ABS and acetone.

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