Filling track bodywork

[Petorius]

Paint prepping my bodywork... should I fill the divots and roughness on the outside of spots that were previously patched? For the upper especially, it flexes a lot during normal use/crashing. I feel like filler will separate from the glass when it is flexed. Is there a flexible filler or something similar I can use for this? Dont want it crumbling underneath paint.

[Paul_E_D]

Filler sucks. glassing and sanding is the correct way. If that is too much work, use filler with glass fiber in it.

[jasnmar]

Paul is correct. Repairing all but the smallest surface imperfections in fiberglass should be done in fiberglass.

I've never tried this specifically, but things like Amazon.com: Bondo 272 Bondo-Glass Fiberglass Reinforced Filler Quart Can, - 2 lbs 9 oz., 1 oz. Hardener: Automotive seem to be intended as a bit of an in-between for body filler and real fiberglass repairs.

[Petorius]

I usually tape over the outside of the area being patched, then glass over it from the inside. Depending on how well the tape conforms, this comes out near perfect or (more often) leaves the outside surface of the patch slightly recessed from the rest of the fairing. I can't just sand it down since it is recessed.

Is there a better way to do this? Final layer of glass on the outside before sanding?

[Paul_E_D]

yes, layer in glass and sand

[nhbubba]

Could you fill the void with plain resin, maybe with a filler mixed in? (ie sawdust)
I've had good luck using regular automotive filler (bondo) on my bodywork.

[jasnmar]

The tape over bit is just so you have some backing, correct?

Correct. Once you've laid the glass on the inside, repeat (after it dries and the tape is removed) on the outside, then sand the outside down to "original height". If you do a good job with your resin / fabric sanding will produce a very nice finish surface.

[Petorius]

The tape over bit is just so you have some backing, correct?

Primarily for backing, but it has the added benefit of leaving a near perfect finish on the outside of the patch when done on flat surfaces. Around curves the tape tends to deform and press into the void slightly, hence the current round of questions.

Come to think of it, I did use regular bondo filler with seemingly good results on my previous tail fairing, but I destroyed that fairing before it ever got real paint.

[Tas]

Funny you mention this Pete, I'll be doing the exact same thing this weekend to the left side of my upper fairing. I plan to re-vinyl though.

[sdog30]

Your going to crash again, so just use racers tape and be done with it.

[Tas]

Your going to crash again, so just use racers tape and be done with it.

True Sam however, I don't want it to be a habit and I'm going to try to avoid it at most costs.

[Paul_E_D]

True Sam however, I don't want it to be a habit and I'm going to try to avoid it at most costs.

THat's magical thinking. LOL