How to repair a front bar or other fibreglass cracks

This guide shows you how to repair minor cracks in a fibreglass (or probably plastic) frontbar, sideskirts, or the like. Wrote it a while ago actually, just for some reason forgot to put it up....Here 'tis..

1. Here you can see the crack. Doesn't look major but left unfilled eventually will just keep spreading upwards, causing further damage. In this case it also extends under the bar right to the end - the result of what cracked it in the first place.

You can see its been repaired previously by me. Maybe looks a bit “rough” even when it wasn't cracked, but from 1-2 metres away you probably would spot it.

And before you go “the last job musta been crap, therefore it cracked again” .... That's not really why,.. going at 100km/hr and bottoming out not much is going to save it :wassup:

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2. Here is what you'll need to fix it. I've used Selly's Plastibond here. I got mine from Kmart for about $15, or probably any hardware store. Seems to be pretty heavy duty, and that is what its specifically designed for so I decided to go with that. You'll also need a scraper. Plastic ones are cheap and you can throw em away - otherwise just buy a thin metal one for $5 or so.

The other method would be to use Fibreglass resin and hardener. You can follow a similar method using that. I've used that previously, but couldn't be bothered stuffing with that in this case. That sort of stuff is probably better in combination with fibreglass mats (if you've ever worked with fibreglass you'll know what i mean) anyway, to give its full strength.

To be honest I'm not sure which would be stronger. I just was banking on Plastibond being a specific filler, whereas fibreglass+resin is for other uses.

3. Ok, now to start. Grab a container of water, and some fairly course wet & dry sandpaper (any hardware store, the black paper).. around 200gritt or so to start.

Just start sanding the crack area, wetting the sandpaper now and then. Be careful that you don't "overshoot" too much and sand back a perfectly good paintjob.. even if you don't sand it right back you'll take the shine off it. If you're just using touchup paint (see later) you'll have to go over it with that, and its nowhere near as good as proper paint.

Keep going until you basically get it all smooth to the touch, and back to the fibreglass itself. You can use some lighter grades (say 800) of sandpaper if you like to get the smoother finish, but not so important here.

You should be left with something that looks like the last pic. Nice and smoothed back. You can see the old filler in there too (the yellowish stuff).

Once you sand it all back you should have a better idea of the full extent of the damage and often smaller micro-cracks will become visible. Like in this shot, you can see how when I actually pull like shown, you can see how it comes apart there (and this also goes underneath).

4. Here comes the fun part. Start digging away near the crack, flaking off any chips that look they're about to come off. Basically you want to remove any bits of surrounding fibregalss or chips of paint around the crack that look like they're weak or going to fall off. Can just use your fingers or a flathead screw driver.

Now you're probably looking at the photo - going what the f.uck has he done? Its looking 5 times worse than before! Well yeah, true But getting rid of all the surrounding debris also gives a much better area to fill and more surface area for the filler to bond to.

And once its filled, it will be totally new, and small miniature cracks left from the last incident can easily cause it to crack up later. Best to remove anything that isn't nice and solid and replace it with filler.

5. Start mixing the plastibond. Instructions are on the tub and its pretty easy. Just apply the right amount of hardener and Plastibond and start mixing using your spatula.

Be careful that you only put a smidgen of hardener in. Depending on outside temperature, amount of hardener used, and other things will depend how quickly it starts to set. If it sets too quickly, it'll be impossible to apply properly and set on your mixing area before you've had a chance to blob it on. If it hardens as you're applying it , it also may not bond properly with the surrounding surfaces. This can be from less than 1 minute to 10 minutes or more depending on how much hardener you use. You probably want something around the 5-10 minute mark - this way it remains fairly gooey for about 5-10 minutes that should be plenty of time to apply it.

Apply it liberally, trying to squeeze a fair bit into the hole (if you have one), this will set behind it, and add extra strength later. Try not to get it on any good paint, as it will basically stuff it even if you wipe it off quickly. Try not to get too much on areas that are outside the basic crack area, as its going to be a bitch to sand it all back the more you use.

You're basically aiming for something like the last pic:

6. Let things dry for about 2 hours in the sun until its nice and hard. Probably best off leaving it overnight if you can.

7. Time to get out the wet & dry sandpaper again, and the bucket of water. Start with 120 or 240 grade paper to start with and that should really get the roughness out of it. Again be careful not to sand back too much more than the filler area itself, as you've have to touch that area up as well.

You should gradually start feeling it getting smoother and smoother, and the main goal is to sand it back to the original level/curve of the bar. For the end parts you will probably want to use finer grade paper such as 800 or so to get that really smooth finish, although 1200 would probably be overkill. Run your finger over it, you shouldn't notice too much abnormal roughness or extra "lumpiness" from the rest of the bar now.

You should be left with something resembling the following:

8. Once you're happy with it, wash everything down with a sponge, remove any excess powder and otherwise get it nice and clean. Wait until its dry as the next step is the painting.

9. Its up to you how you wish to do the final finish. If you've done an excellent job with no obvious lumps or indentations, a good spray painter may be able to respray just that section for maybe $50-100 and it might come up as good as new.

Generally I've just used the "touchup paint" method. As knowing me it won't be long before i had to do it again. Go to an autopaint wholesaler closer to you (use yellowpages!). They are the guys that supply panel shops and the like with all the raw paint, etc.

Ask them to mix up a 50ml or so bottle of "touchup paint" for your paint code. To find your Nissan paint code and, just do a search on here, or how to find it on your chassis plate. Just explain what its for and they should be nice and mix it up for you for around $10.


10. Generally the bottle will come with a paintbrush in the lid, or you can choose to buy some decent fine brushes for $5 or something to do the job a little nicer. '

Shake it up to mix it well, and start painting over the repaired area! I've found long smooth strokes is best so that you don't get too much rough bits. With my job its kinda a "2nd used" bottle, so had become a little gluggy which didn't help me get a perfectly smooth finish - so when i get another fresh bottle may try again.

If you end up with a poxy job you're not happy with, the best part is you can get out the sandpaper, sand all the paint off in a minute or so, and try again.

This should be it. Let it dry and all is done. Attached are the results of my fix-it.

The bad news: from 1 metre away or so so (as shown), its going to be noticeable and you're always going to know where to look. On casual inspection or anything other than total brightness probably others aren't going to notice. You'll never get it "perfect" but at least it won't stick out like a sore thumb, and its not going to crack further.

The good news: From 2-3 metres away though, you're never going to be able to tell. See my the final shots and you can see what I mean.

11. Pat yourself on the back for a job well done and back to driving like a maniac

haha love it

Great guide Gordon, i was going to do a guide to install IC and AVCR cos i did them both in one day, but didnt have digicam.. owell

That'll be really handy for me when i get round to my front bar. Good work

Haha! A very good guide on how to do a dodgy fibreglass repair.

It doesn't take much more effort and substitute a small fibreglass repair kit for the Plastibond and you would have an invisible repair that is as strong as the origional. In either case the final appearance depends on the quality of the paint repair

erm... are the pics invisible or is it just me?

dudde the links are broken - this thread is over 2 years old!

yes, they're invisible pictures - look veeery closely

*/me stares...*



*...still staring...*



*/me thinks to myself: hope i see them soon cos i really need to fix my front bar...*