How much do I heat the paint before I roll the fenders?

It's time to roll the fenders on the Fubari (E36/V8).  I have the standard-issue Ebay fender roller, and my heat gun.  How much do I need to heat the paint? 

Anybody have data for a target temp? 

Didn't think so.  Any general guidance will be most appreciated.

At least as hot as if it were sitting in the sun on a hot summer day...

As hot as you can without blistering the paint.

And the paint will probably still crack.

KyAllroad (Jeremy) said:

As hot as you can without blistering the paint.

And the paint will probably still crack.

What he said. 

So, heat it until the paint blisters, then back it of a notch.  Done.  Kinda like tuning the turbo on an MR2:  Crank the boost, make it pig rich, start leaning it out until a chunk of the piston crown blows out the exhaust port.  Rich it up one notch, Done.

Even if it doesn't crack right away, it probably will in the future...

Actually I called Eastwood about this when a friend of mine was doing fenders on his SE-R. They told us that most OEM automotive paints will tolerate 130 deg F. So we used a heat gun and an infrared temp sensor and did exactly that, keeping it as close to 130 as we could while we worked things.

We did get some paint cracking on the underside of the fender lip after a while but nothing noticeable from the outside or above.

I had to roll the fenders on my G35 sedan to get the summer wheels to fit. Left side got plenty of heat and went great. Right side didn't get enough heat, so the paint under the arches cracked and the arches themselves are ever so slightly bacon-y. Thank goodness it's a black car with heavily swirl-marked paint.

Furious_E said:

KyAllroad (Jeremy) said:

As hot as you can without blistering the paint.

And the paint will probably still crack.

What he said. 

Same here.

boxedfox said:

Actually I called Eastwood about this when a friend of mine was doing fenders on his SE-R. They told us that most OEM automotive paints will tolerate 130 deg F. So we used a heat gun and an infrared temp sensor and did exactly that, keeping it as close to 130 as we could while we worked things.

We did get some paint cracking on the underside of the fender lip after a while but nothing noticeable from the outside or above.

You ROCK.  Thanks.

These days, I just skip the fender roller and go straight to a hammer. If the paint is going to crack either way (it always does), then there's no reason to waste extra time while you're cracking it. 

Rolled with a hammer:

And no, that's not actually a great idea on a nice car. But good luck, I've never rolled them without cracking paint.

Can I tag along on this thread?

I have a fender roller but I don't really know how to use it.  I need to fill the fenders on my chumpcar.  

Any advice or videos worth watching?

Thanks!

Rob R 

In reply to Tom Suddard :

Yeah, on my Miata I started with a borrowed roller, heat, and patience.  By the time the paint cracked and I gave up being nice it was a 2 lb plastic mallet and baseball bat.  For "racecar" it ended up looking good and fits 275 Hoosiers under factory NA bodywork.  I wouldn't do it to a nice car though.

I found that not enough heat on a cold day in not ideal.  Also watch out for pinch welds they will not roll but will cause ripples.

Cheap car with and expensive engine, carry on.

wvumtnbkr said:

Can I tag along on this thread?

 

I have a fender roller but I don't really know how to use it.  I need to fill the fenders on my chumpcar.  

 

Any advice or videos worth watching?

 

Thanks!

Rob R 

If you want some practice before getting to the race car, you can try it on my miata. I don't need the tire clearance, but the fenders are rusty enough to not be worth selling.

In reply to KyAllroad (Jeremy) :

I've gotten it clean before. Mostly new stuff though. I'm scared of single stage paint.