McLaren replica build base on a Manta

[Leon]

Hi Terry. good to see some more work being done. Can't say the same for me, though I did go to a race meeting this weekend so I'm a bit fired up again. Keep the up dates coming and I promiss to have some more on mine soon, as always great workmanship and a pleasure to read about.
Cheers Leon.

 

[Brandon]

Maybe you should take a mould off that when you are done? :idea:

 

[Terry Oxandale]

To be honest, I don't know that there would be any reason other than for me to have a means of replacing a damaged piece, and even then, I'm not sure it wouldn't be quicker and more efficient to simply repair the broken fiberglass. If I was 20 years younger, and knew I was going to be driving the car a lot, and have room to store the molds properly, then perhaps yes, the mold fabrication would be more practical.

 

[Terry Oxandale]

Hi Terry. good to see some more work being done. Can't say the same for me, though I did go to a race meeting this weekend so I'm a bit fired up again. Keep the up dates coming and I promiss to have some more on mine soon, as always great workmanship and a pleasure to read about.
Cheers Leon.

I mixed up a batch of yellow and red gelcoat (about 75/25) and experimented with the resulting orange gelcoat that will be the final finishing material prior to any bondo/filler-primer. It was nice to see a bit of color on part of the car, even if short-lived. I was surprised at how well it would build up without sags or running, but also surprised at the final hardness as compared to the fiberglass in regards to sanding. The lesson is, keep the gelcoat to a minimum (to avoid cracking as well), and make the fiberglass as close to the final shape as is possible.

 

[Fred W Ballinger]

Hi Terry

I would stongly reccomend you look into sourcing Duratech/Durabuild surfacing primer to spray on to give you a material to final finish, rather than gell coat.

I used this material to put the surface on my plug, applied over filler over bare fibreglass. It sands very easily, and gives excellent results.

It's designed as a finishing material for pattern building, but can be used to give good results on parts as well. Apparently some people even use it as a first coat in a mould, rather than gell, as then when the part comes out it is then already primed for painting.

The picture below is of the grey primer (with some blue pigment added), sanded through the grits up to 1200 and polished. You would only have to go to 600 grit or so before applying paint.


Cheers

Fred W B

Duratec Gray Surfacing Primer

Perfect for Plug Finishing and Hiding Repairs
Duratec Surfacing Primer is the best choice for coating your plug or reconditioning your mold.It can be thinned using Fast Lacquer Thinner to be sprayed through a siphon or HVLP gun minimizing costly sanding steps to remove orange-peel.This surface primer can be applied as heavily as 45 mils to fill fabric pores on plugs or over repairs. With a higher heat distortion temperature, shrinkage is reduced. This further hides the repair.The gray primer sands easily and is then buffed to a Class 'A' mirror finish before building the mold. Catalyze with 2% MEKP.

 

[Terry Oxandale]

Thanks for the tip Fred. The only concern I have is when I've used other filler materials, when they age or shrink slightly, the mat/cloth print-through seems to become more prominent with age. If Duratech/Durabuild prevents this from happening as effectively as gelcoat does, then by all means, I would rather use it. I just don't want to see the shape of the individual strands 10 years from now after repeated sun beat-downs on the paint.

I'll look into your recommendation. BTW. fantastic job on your Lola!!

 

[Mike S.]

I've been doing fiberglass for many years & my "guru" for fg always said to never use cloth as a top layer & he'd done many show cars. The weave will always bleed through. With high quallity hand layed glass bodies. They gell coat on layer of matt then the cloth (depending on the use of the body how many layers depends race? 2 road 3 or 4). But cloth will "bleed" through whether gell coat or paint.

 

[Terry Oxandale]

Thanks Mike. The only other time I built a complete scratch-built body, I used mat as the top layer, and it did "bleed through", but you had to look hard for it, under a blazing sun, on hot dark blue paint. Other than that, it was nearly invisible. But I'll keep your advice in mind and avoid the cloth top layer, and avoid the more obvious bleed-through.

 

[Jack]

Terry, what Mike says is true. Always use a layer of mat (even .75 Oz.) before a bulk layup. Let it cure to around a 40 barcol hardness (until you can scratch it with a quarter and leave a white mark) before adding additional layers of cloth. This will eliminate print through of the cloth weave, or at least minimize it over time. The Duratec primer is a good surfacer for the finished parts, and high build too. Sands quite nicely and is a good primer for automotive paints. IMO, of course. I prefer to use gelcoat in open molding rather than Duratec simply because it's harder. For male molding, the Duratec works better (sanding).

 

[Bill B]

Sorry for the thread drift, but I am curious what exactly is gel coat made of? Is it just pigmented resin, or something else? The reason I ask is that I have a 1961 Lotus Elite (in parts) that I will eventually get around to restoring. This car is unique in that it is a full fiberglass monocoque construction. The body / monocoque is badly weathered and the gel coat has flaked off of much of the surface. I had assumed that I would just strip it all of the way to bare glass and then use some combination of modern primers / fillers / sealers and paint system. But perhaps I should think about trying to re cover in gel coat first? Any advice from the seasoned fiber glass experts here? Thanks.

 

[Jack]

strip it all of the way to bare glass and then use some combination of modern primers / fillers / sealers and paint system. But perhaps I should think about trying to re cover in gel coat first? Any advice from the seasoned fiber glass experts here? Thanks.

This would probably be your best solution as a good bit of filler will be needed. Media blasting of the body will remove the gelcoat. Better than
sanding/grinding off. Finish as above. Much too labor intensive to re-gel the bodywork given the uneven surface you will wind up with. Anyone else comments...

 

[Terry Oxandale]

Gelcoat is NOT a fancy resin, as resin alone provides little protection and weathering capability.

I finally took the advice, and ordered the Duratec, and much to my displeasure, I must sign for it during delivery, and FedEx will not hold it at the local depot for my pickup due to it being a hazardous chemical. So basically, I must wait for the FexEx delivery (or take vacation to drive 40 minutes one way to pick it up), or it goes back to the vendor. The vendors should place some kind of notification that a business address is prefered, and at least let the purchaser know of the onerous delivery process.

I'm going to experiment a bit and mix a small amount of the Duratec and gelcoat together to see how it sets up, as well as its finishing characteristics.

Thanks for the tips guys. One last mechanical note; I discovered Holley makes a self-learning ecm for the LS1 that appears to work well with ITB set-ups, thus minimizing the computer related mapping and reduces the tuning time. From what I've read thus far, nobody has found any issues, and that it seems to work well, especially if you'll settle for 95% perfect tuning.

Oh, and the very little visual progress to date. All the work is being done on the underside, hinges, flanges, reinforcement, etc.

 

[zollis]

Terry I always enjoy your up dates. How do you manage to keep the floor so clean?










Z.C.

 

[Mike S.]

One other thing to remember about gelcoat. It is not a self curing surface in the air. It will (like laminating resine) stay tacky to the touch unless a coating is sprayed on over it to exclude air. Most usually PVA sprayed on over the gelcoat (then it can just be washed off). But because of it's high viscossity it's very hard to spray & get a nice smooth top surface. Usually requiring sanding & polishing. A "finishing" resin has parfin oil in it that forms an airexclusion surface. But because of that parafin, paint won't stick to it without first sanding. There are quite a number of resin based primers &/or paints you can use especially from the boat & aircraft people.

 

[Randy V]

Why not just use a product like Featherfill or some other epoxy type coating?

 

[Doug]

I have had good results with a 50-50 mixture of gelcoat and Duratec. The surface will dry nontacky and sand easily also. Just be aware that different compositions of materials have different hardnesses. If you sand through from one layer to another the difference makes it harder to sand "flat" for a class A finish, since the softer material sands away easier.

 

[Mike S.]

Terry you've come a long way from the Manta to a McLaren. Looks great, there were always things that just weren't right in the Manta. But you've got it looking very cool (maybe not 100% to the purist) but looking much better/closer. to the real thing. Sometimes it would be easier to start from scratch than remodel something. You really should think about building molds for it. I'd bet you could sell copies of your work there. Then you might get a new fresh body free. Without a bunch of grafts & fill-ins etc. The Manta is still a popular car when they show up at car shows. A windshield might still be a sticking point though. There are those who would love a Can-Am type body to build up. My wife wife would probably kill me, but I'd possably be interested.
Mike S

 

[Terry Oxandale]

Thanks for the comments Mike. I've got a standing offer to have the body "scanned" for an aftermarket tube frame, so this may happen. You are spot on in the purest statement. I could get it a good bit closer, but I struggle between making the flat parts slightly rounded just to soften the shape up a bit, and to give it more street appeal to those who've never experienced the wonder of CanAm. I'm working on the interior and dash cover at this point, so hopefully it will be "moldable" this time next year. There are a lot of things I would do differently, but I'm ready to have some road fun, and less garage fun.

 

[Mike S.]

I think you have the rounded edges about right for a 8c. M8F was a different look much more square & with those (well what ever you call those "fences" along the fenders LOL). I never really cared for that look. Then the M20 came along now that's one squared off body! Style wise I never cared for the squared off wedge shape of the late Can-Ams. I'm too old school I guess. I like my cars & women to have nice curves & roundness LOL
Mike S

 

[Terry Oxandale]

Style wise I never cared for the squared off wedge shape of the late Can-Ams. I'm too old school I guess. I like my cars & women to have nice curves & roundness LOL
Mike S

Amen!