Hi All

I need to repair the rear bumper on my MX5 race car (up for sale) - I've seen a few cold repair kits BUMPER PLASTIC REPAIR KIT Weld adhesive car trim lugs | eBay but was wondering if these are any good?

I can get the cracks lined up pretty much as they should be and I'm not looking for a show car finish!

I think I have a spare bumper so not a show stopper if I can't repair the existing one.

Ta in advance

Wyn

I had good results some years ago repairing a plastic panel... I made a number of "figure of eight" shapes from thin steel wire.... Heated the wire in a blow lamp and then pressed them into the back of the panel whilst holding it in shape.... This worked well enough to pull the parts together so I could then use some composite to reinforce the area from behind.

Sounds good! I was going to use some strips of ali riveted in place, and maybe remove them after.

I"ve just repaired a small crack in a plastic bumper with some of that plastic pipe weld glue used on waste pipes. It melts the plastic slightly, so I coated the mating faces, pushed it together then smeared the back of it with. Its seems pretty good, was planning to add a small patch of grp to rear side but might not bother

I used a hot melt glue gun to repair cracks from the back then disguised them at the front by melting with the hot air gun and a spatula on the soft grey plastic Nissan bumper material on my old van.

If its ABS plastic
Acetone will soften (and then melt)

Lego bricks are also conveniently made from ABS

Had some fairings on a motorbike that needed attention (snapped bits and cracks and a couple of missing bits)

I put some lego bricks (cut them up into small bits first) into a jam jar and added some acetone
Left it for a while giving it a stirr now and again
(lid on when not stirring it up)

It formed a goop that could be scooped/poured and moulded
adhered great as well - took ages to dry and set though so make sure the items are well supported whilst the acetone evapourates
(I put masking tape behind the missing bits and poured it in and let it set)
It did shrink during the curing so I had to add more material to the face (that was under the masking tape)

excess sanded down nice and easy

I also used a soldering iron to stitch the broken pieces back together and added lego as the filler (much quicker method as soon as it cools its ready to sand /shape)

The repairs have all held up for the last couple of years (and its a pretty lumpy vibey bike!)
Almost invisible after a respray

If the stuff you are playing with is not ABS YMMV

Regards
Rob

[Edited on 7/2/12 by robocog]

Thanks guys - loads of good ideas to think about!!

The bumper looks easy (ish) to repair but the rear panel (number plate bit) is in bits - and I don't have a spare and they are pretty expensive - MX5 MK1 REAR PANEL FREE P+P EXP DEL SLAM NUMBER PLATE BACK PANEL EUNOS MAZDA | eBay

BUMPER PLASTIC REPAIR KIT Weld adhesive car trim lugs | eBay

We use this type of stuff all the time at work for repairing plastic panels on buses we V the crack on the inside before gluing it [ welding ]
Jacko