Rear Bumper Repair - plastic welding - pictures

[mikeonb4c]

The BF Search is driving me mad. I cant find the thread I started on the repair NeilT and I did to my rear bumper. Briefly, we discovered that by melting plastic from the spare pieces I had from the foglight cutouts (which I sensibly kept) onto a putty knife using a hot air gun, we were able to weld up splits and fill in using the melted plastic. And - unlike a lot of plastics - the material bonded really well with the bumper plastic. We also managed to soften the bumper plastic and gently push large areas around to restore the shape (I used a cloth wrapped round my hand as a pad for pushing/pressing with and a broad wooden baton to act as a surface to restrain the bumper wile I pressed from the other side. We even managed to straighten up buckled webbing and to weld up a lot of splits where it joined the bumper. And it wasn't difficult. It was much easier with two people and we worked rather like a surgeon does with an assistant. Great fun and very satisfying. I then finished off with some P38 type filler designed for plastic bumper repairs and - belt and braces - I backed the repair across the main split with nylon and Sikaflex 221 though I suspect we needn't have done that.

Anyway, NeilT has just sent me some pics he took as we worked and they are at:

http://s185.photobucket.com/albums/x259 ... onablo.jpg

http://s185.photobucket.com/albums/x259 ... aping1.jpg

http://s185.photobucket.com/albums/x259 ... aping2.jpg

http://s185.photobucket.com/albums/x259 ... tykn-1.jpg

http://s185.photobucket.com/albums/x259 ... tykn-2.jpg

The observant among you will have noticed that there is a bracket rivetted across te bumper base - from a previous repair prior to my ownership. Mango had signs of another dent on the offside part of the bumper and on removal the webbing and mounting points were found to be crushed and split. All of this damage responded very well to heating, reshaping and crude hot plastic welding and the bumper is now fully secure.

The finished result, after respraying the whole bumper with Silent Silver using a compressor and gun I got off ebay for £50 (yep it is possible to get a real bargain off ebay) can be seen here (along with the rear step I got for £8.49 off ebay and sprayed with the same Silent Silver):

http://s185.photobucket.com/albums/x259 ... 010628.jpg

I'm a happy bunny. Hope this may help others wondering if it can be done

Mike

PS - sorry I didnt tinyurl this lot but its late and I'm tired!!

[helen&tony]

Hi Mike
Excellent! I've seen a super plastic welding set for use with a particular firm's hot air gun, and lots of accessories....I expect they could be adapted to other makes....didn't have time to look, but next time I'll grab some details, as the plastic welding rods etc. looked quite good.
Cheers
Helen

[mikeonb4c]

Tee hee. It was surprisingly easy. As usual, what helped was having a 'what have I got to lose' attitude (the SAS call it who dares wins but I'm not quite that bold).

Helen - what impressed me was that the price of plastic welding kits (and skills to with them) looked very daunting. And yet with a standard hot air gun and a bit of scrap bumper material, we seemed to be able to get an adequate result. I wouldn't like to subject it it extreme load testing, but it was fine for what we needed to do. Even if all you do is 'tack' using it, it allows you to jig everything up before using a backing material like nylon/sikaflex to strengthen everything up (mind you I suspect the backing material is what will screw up teh job if you have to make a fresh repair in that area, but still......)

[bigdaddycain]

Looks good mike,it appears you suffered less damage to your rear bumper than i had. I had to drill holes into my bumper,(after heating didn't work) then use mole grips on the inserted screws to pull the corner of the bumper roughly back into shape

I don't recall having any cracks,i think that the damage i received was from a direct blow,as opposed to a glancing one,so maybe that's why the dent was so severe...

I used sikaflex on the repair i did, to fill the holes,and to secure a scrap piece of plastic on the inside of the bumper,to offer extra rigidity, and an inner shield to keep out the elements... (it's directly in the line of spray in wet weather)

Good work that mike and neilT,its great to see a couple of forum members offer each other support ( i know who to phone the next time i stuff mine! )

[mikeonb4c]

Yep I'll be there. I'm running out of money and jobs to do on Mango (or at least ones I can trust myself to do with a back that is getting more troublesome).

Her Indoors was straight on the case regarding my bad back. She has always been antipathetic to the Bongo (lovely word that). So the slightest slip and she's on my case. She fixed me with a steely look and said:

"This all seems to have started happening since you got THAT Bongo."

[vic swan]

Nice job Mike. You have inspired me to have a go at mine. On second thoughts it can wait until its a bit warmer Incidentaly, I had a nasty dent on the front bumper and while I was having a puncture repaired; the fitter pushed it out with a hammer handle. No charge.

[Pete & Sue]

Well done Mike, The finished job looks damn good.

[Pete & Sue]

Helen&Tony, Interested in any details regarding plastic welding tool. I used to do that at a firm called 'Osma Plastics', many moons ago, and could have done with a welding tool for my motorbike fairings. Now that I've moved on I can see how useful it would be with the 'Bong' should I suffer trolley damage in our local Tesco car park.

[mikeonb4c]

Yep - its strange (and wonderful) stuff, the bumper plastic. The scary bit is worrying you might ruin it if you get it wrong. But as long as you are reasonablly good with your hands and don't overheat the plastic (i.e. feel your way into the job) then its not difficult (NeilT will attest to that as he was there). Obviously make sure that anything you use to push things out with has a suitably large radius t it (that hammer would have left an impression of the hammerhead had the plastic been hot and soft!). Also, for smaller dents' have a flat (or suitably radiused) backing piece to press the dent out against or you may 'overshoot' and 'blow' the bumper out. Mind you, I found applying pressure with a serious of 'dabs' using the cloth seemed to work quite well 'freehand'.

[helen&tony]

Ahhh, Pete & Sue
I remember Osma Plastics from Aeons ago.
Regarding the plastic welding kits, they were in a DIY store over here, and we saw them in passing...looked interesting, and the consumables didn't look dear. It was for use with a particular firm's hot air gun, and I suspect that the only difference is the nozzle size. When we next go that way (beginning of December), I'll take a look. If youv'e got an infinitely variable hot air gun, there would be no probs....the one with the kit looked a bit basic, and I suspect it is governed to a particular setting. I'll ask Tony's opinion, as he's a plastics engineer.
Cheers
Helen

[mikeonb4c]

I'll ask Tony's opinion, as he's a plastics engineer.
Cheers
Helen

Wow, thats handy. What a range of talent we have here on BF

[NeilT]

Good to see the pics up.. FYI Mike was doctor, I was nurse in uniform!

Have to back up what Mike say, the actual job went really well, and in fact I bet parts of the bumper are strong now than before we started the job.