Post by Mark Huber on Aug 26, 2014 10:19:31 GMT -5
I cut out the sections for two reasons 1) they were open on the prototype and 2) I've found that especially on the very small cars (and the Lotus 25 is especially small) the more room the better in areas around the motor, gears, rear axle, etc.
Post by Chris Wright on Feb 4, 2016 13:37:29 GMT -5
"Try to keep it as thick as you can over the front suspension cut out as that's the week point on all half tonner shells."
Absolutely Martin, and I recommend several layers of glass cloth applied with spray glue, and the soaked on viscous super glue. I've had a BRM and a Lotus break across there, and seen an original Vintage personal Dave Jones BRM (proxy race car) arrive in two pieces, broken across the suspension cut out.
Of course the wise builder would detect these areas of weakness and strengthen them accordingly....I am not that wise myself and have had a car break in two. It was a Brabham I entered for a Tasman series. It hit the floor (concrete) and the rear section snapped cleanly at the exhaust exit line.
That's all OK unless you want the chassis to hold all the suspension, in which case it has to go in from underneath. The Honda is a problem in that there is a section of body at the bottom, but then you must design suspension to effectively plug in to something from the sides, but how would you hold it in? The axle, if a one piece, would have to be removed each time the chassis was removed. If not, the wheels would be on stub axles built into the suspension set-up.....back to being able to plug the suspension in, firmly and with great accuracy to a plate fixed to the chassis. Possible, but very fiddly. On most of the cars of that era, there is NO bodywork under the suspension, so we're back to strengthening that area of bodywork that breaks. And that is best done as Chris has outlined, with a fabric section for resilience.
OR......we're back to nice accurate vac-forms<G> Martin
I have found that Dave Jones material is very brittle, as is the similar white stuff that Classic shells are made from. And I have not found any fabric or fibres at all in either! If indeed they are supposed to be GRP...Glass Reinforced Plastic, they seem to be merely plastic, no glass and so, very little reinforcement.
Yes, what to do about those weak sections that span the front suspension? This problem arises with every build.
A Honda RA300 resin body showing the bodywork that is intertwined with the front suspension arms. The front nose section would have possessed adequate strength if the material had been left in place. But the resin material was removed to allow the body to fit over the chassis-mounted suspension arms. The result was a significantly weakened structure.
Because the nose was not merely weakened, but actually severed from the shell, I didn't think a fiber based reinforcement would be rigid enough to support the piece when it was reattached. Steel splice plates were attached to the underside of the sections. As shown, it still flexes enough to crack the paint.
The Honda began life as a MelShell and was a great platform to start with, but after I was finished, very little of the original resin remained. The back end was replaced, as were lots of other bits and pieces.
I can't remember the exact details, but I think that Mel said the shell I purchased, at a discount, was a defect due to a problem with the mold. It may have also had a problem with the resin compound, hence the yellowish color. It worked out well, as I didn't need a perfect shell, because I suspected I was going to modify it anyway.