Any of you ever make your own Fiberglass parts? Looking at doing some Bumpers for my 70 Road Runner. Plan is to make molds from my steel bumpers. What I'm not sure yet is if the mold needs to be two piece. I'm thinking so, to get it off the steel bumper and then to help get the fiberglass part out of the mold. And, haven't quite figured out how to reinforce the mold yet. Any tips, tricks any of you can share?

I can give more details this evening. Short version is it should be pretty simple. As long as the bumpers are in good shape they will make a fine mold. Look carefully to determine that you need a two piece mould. I suspect not. Remember the bumper was stamped with a big ass die so unlikely there is no relief in the shape.
Composite bumpers are on the list for our 70 RR but there are multiple projects on the car (like completely rebuilding the body) ahead of new bumpers.

The shape will determine If it needs to be multiple pieces. I'm guessing it will because the ends wrap around. You reinforce the mold while its on the original piece so it retains the correct shape. You reinforce it with just about anything - 2 x 4 lumber works great. Where pieces of the mold have to attach to make a full mold you make your reinforcements so they bolt together and keep the mold aligned. A multiple part mold is made in sections. You can use plasticine to form a "dam" to make the flanges. Make the first large section and pop it off. Clean up the flange and put it back on the bumper and glass on the reinforcements. Make sure the flanges have mold release applied then make the next part of the mold. Before popping it off, drill bolt/reference holes in the flange. Hopefully this short explanation gives you a good idea of the process. Note: you cannot use too much mold release. When you think you've applied enough, give it another coat.

and then get lightweight brackets here

https://www.facebook.com/LingenfeltersBrackets/

Understand, approx 70% of your projects effort will be in getting the mold right. If this is a one item project, you can cut a few corners, problem is, best if one has some experience first before deciding which corners to cut. Not sure if a gel coat is needed here, gel coat adds another complication/cost/step, and it mainly only adds to looks in finished project, and gel has a potential for "alligatoring", which defeats its whole purpose.

Some molds can be fudged as a single mold, by making the mold flexible and/or sacrificial/sectional, or in your case when the plug is the bumper or making the finished part in multi lay ups, a thin layup to be easy to remove from the mold, and then another after pulled from the mold to gain needed ,strength. Risky because you need to somehow maintain shape outside the mold for second layup.

It can be done, but its a learning process.

I used cardboard wrapping paper tube's cut in 1/2 to make stiffners for the mold

I see Unlimited lists them, and they do a lot of bumpers in carbon you might check with them.

Shipping from Unlimited is almost as much as the darn Bumpers. I figured if I'm going to spend that kind of dough, I'd rather learn something. I've done fiberglass work, just not made a mold.

Being that Unlimited is the only ones to offer them, maybe I'll make the molds for multiple use.

Thanx for the input!

STEF, here is a write up from Jay Brown, a friend of mine, and HEMI Joel's, on how he made a mold for his Shelby bumpers. I did the finish sanding and paint on these, and they turned up very nice.

http://fepower.net/simplemachinesforum/index.php?topic=3783.0

I'm not sure, but I suspect you are looking to build some higher appearance quality bumpers, so this article may not be what you are looking for. www.midwestattachment.com/hood shows how do fiberglass reproductions by doing a splash over on existing parts. Great for race only,lesser detailed vehicles.Much less expensive, and time consuming as it doesn't require that detailed primary mold. My son and I built a hood (pin on) for our Lancer drag car,with a snorkel scoop. Very pleased with the way it came out.For those of you , like us, with nothing readily available or economicaly feasible, this is a viable option.We have to use the coins where they are best spent or our project wont make it.Hope this helps some of you

Extremely Helpful!! Thanx Jeff!!

On a side note, I read some posts on Speedtalk your Buddy posted when he made Rockers for his motor. Very Cool Car!!

He is making his own Cylinder heads, rockers, intakes, valve covers, and a few other things. Very smart guy, and not sure where he gets his ambition.

I've done the splash process with some bumper brackets years ago and they worked well, but yes for the Bumpers I want a nicer finish. With shipping, the Bumpers from Unlimited, would be $480. Not a deal breaker, but $200 just for shipping blows. So, even if it costs me $480 to make my own, I don't care. I get to learn something, I've not done yet.

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Verrry interesting !

I know you are the master at this. Care to divulge any tips?

That was a SOHC motor, correct?

200$ for shipping is uNsane ! Someone at unlimited didn’t figure that out correctly. Each bumper should ship as though they were 25 pounds each.!PLUS I’ll bet you could send them by TRUCK FREIGHT (terminal to terminal)!for about that kind of money

Just talked to Unlimited, apparently UPS and FED Ex, really jacked up their rates for long packages regardless of weight. They said they don't pad their shipping. Is what it is...

My thoughts exactly.

Another fiberglass thread, and Doc thinks it's still 1982... He can build it better, cheaper, and ship it for next to nothing, but never does.