Smoothing mk5/6 bumpers - Updated at last!!

Post Instructions on DIY modifications here - use all information with caution!
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vdubit
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Smoothing mk5/6 bumpers - Updated at last!!

Post by vdubit »

Ok due to several requests and PM's, thought i'd let you know the easy way of doing it.

There's 5 ways it can be done.

(1) The best method without a doubt is plastic welding. Not only is this very hard for diy purposes but the smell is unbearable! This includes welding (via heating the plastic) a bridge over the recess where the rubbing strip was followed by a light skimming of plastic filler. Give this method a go if you dare! I know a chap on clublupo did it and it was very successful. Unfortunatly I didnt have the money to buy a plastic welder so didnt use this method.

(2) Second method is very easy, but i would never recommend it as the results probably wouldn't last long. Basically remove the rubbing strips from the bumpers and wodge lots of plastic filler in the recess. Flat black and admire. Filler tends to have problems when its applied thick, usually resulting in it sinking. It'll look lovely the day you do it, a week or two later there will be a dip in the paint where the filler was. According to the tin of the plastic filler I used, it will not sink. I don't know how true that is, and i know wouldnt do this method!

(3) Fibreglass. Cut narrow strips of fibreglass off your roll. Around and inch wide, about a foot long. Key up the recess using so real evil sandpaper, like 40 or 60grit. Doing a small area at a time, soak the recess in resin (obviously with hardner) and apply your strips. Gradually build up the layers until its just below the level of the bumper. Apply your filler in light skimmings and flat off smooth. Prime, spray etc. Problem with this method is fibreglass doesnt flex much. Therefore a slight ding to your bumper will result in lots of damage. I was originally intending to use this method but then had the brainwave i did...

(4) Expanding foam. One of the messiest methods there are, and gets some funny looks whilst your 'in progress'. The bumper can still 'twist' and retains flexiblity. I've had someone do a handbrake turn (b*stard) in to the back of my car. There was a little crack to repair but it was very minor considering the impact. I found after several months of this being done, the foam appeared to continue expanding, raising the filler up, looking pants.

(5) Plastic bonded strips. This appears to be working fine, but only time will tell.

So firstly, remove the rubbing strips and key up the recess. On the rear bumper there are a few 'lumps', which will require flatting down level with a dremel or similar.

Right, so only a few pics so look carefully. So using a high quality bond n seal ( i found bodyline pu sealer the best) Fill the upper and lower indents (the bits where the rubbing strip used to 'clip') so there more or less flush. Wait at least 24hours, preferably 48 hours, until the sealer is rock hard. The sealer needs 3-4 days to set completely rigid.

Find some thin (1-1.5mm thick) plastic that is flexible. You know the plastic trunking you get around your office that holds all the wires neatly to the walls? Well I used that. Cut this stuff into strips, measuring just under the height of the recess (aound 1.25") and about a foot long each.

Using the most evil self tapping wood screw you can find, Screw the strips to the recess so they meet up nicely. Now remove these, and gunk as much sealant in the recess as you can. Now, screw them back on. With them on, fill every nook and cranny you see with sealant, till it looks something like the pics.

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Once dry (at least 3 days later) remove the self tapping screws you put in the plastic. Now, using a valetor's scraper blade, scrape off al the excess sealant so it cant peel in any places.

Now get some plastic filler. I found Upol Plastx 6 to be the best stuff. You'll probably need 2 tins to do both bumpers. Mix up to right ratio and apply in light skimmings. Once set (about half hour) Flat with 60grit sandpaper on a block. The block is crutial. Hold the block so it runs on both the edge of the bumper. This is what makes sure the 'bridge' of filler is level. Repeat the process (skim then sand) many a time until all is perfect.

For the final coat i mixed the plastic filler 50/50 with top stop gold, which s basically a very very fine filler, with a lot of flexibility.

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Change your paper on the block for 180 grit to rub this stuff down. Follow this by 240grit wet or dry paper to remove any scratches (used wet), then 400grit (again used wet).

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When your happy with how smooth it is, apply the primer. I originally used aerosol primer. Buy the best high build primer you can if your aerosoling it.

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Ideally, prime using 2k build primer. This will fill any nooks and cranny's you missed with the filler. Flat the primer back with 600grit paper (wet) followed by 1200 wet.

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If your being a whimp and getting a bodyshop to spray them, this is where you finish, take to the bodyshop and give them your paint code. Expect to pay somewhere around £200 to get them both sprayed up.

Congratulations, you now have smooth bumpers.

If you are spraying yourself: Wipe down using panel wipe, then go over with a tack rag. Mix up your basecoat and spray in light even coats, building up gradually. Take your time and dont rush. Allow to dry. Then apply your lacquer in the same way.

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Allow to dry properly, give it a few days. Rub the whole bumper down using 1500grit (wet) until all is like glass and perfectly smooth. Buff up using g3 or finesse-it, followed by a good polishing. I use Autoglym High Resin polish as its relatively cheap and extremely effective.

Bolts your bumpers back on (if your removed them) and Wahay! smooth bumpers!

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If you get bored with it, heck, why not change the colour again

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Last edited by vdubit on Thu Oct 04, 2007 7:33 pm, edited 2 times in total.
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h4r1s
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Location: Leicester/Sheffield Drives: Polo MKV-6N2 1.4SE 16v 75BHP

Post by h4r1s »

Thanks, Greatly appreciated :!: Will give it a go in the summer
99
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Post by 99 »

An excellent guide, thanks a lot for doing it!

One question though - do you wet and dry with 1200/1500 between the basecoat and the lacquer?

Thanks

90
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Post by 99 »

An excellent guide, thanks a lot for doing it!

One question though - do you wet and dry with 1200/1500 between the basecoat and the lacquer?

Thanks

90
VwPo1o
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Post by VwPo1o »

Definately an excellent post. 8) I was thinking of debadging my polo and getting rid of the boot lock altogether and fill it all. I suppose I could use the same procedure as you did. I was a bit dubious about the whole do it yourself thing, and was gona take it to a garage. But I think I might give it go and get my hands dirty.

One question: I've heard you have to sand down any original paint off before you paint over it ... is that true??

Without sounding too stupid... what's a tack rag?

Thanx
vdubit
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Post by vdubit »

Finally updated!!!
leeriley
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Post by leeriley »

i noticed taht youve also removed your side strips, what did you do to fill in the rivet holes? thanks
vdubit
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Post by vdubit »

Welded the holes up, then skimmed with filler. To be honest its not worth doing unless your intending to respray your car!
leeriley
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Post by leeriley »

vdubit wrote:Welded the holes up, then skimmed with filler. To be honest its not worth doing unless your intending to respray your car!
aaaahh i see, yes i wanted to do this, but my cars red so would definetly need a full respray otherwise would look crap, and i was told that it takes lots of work because when you weld it, it distorts the metal because of the heat ? car looks mint though!
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Re: Smoothing mk5/6 bumpers - Updated at last!!

Post by adummy »

jus spotted the car on ebay :(

http://cgi.ebay.co.uk/2000-VOLKSWAGEN-P ... otohosting

shame about the engine

such a stunnig car
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