Someone make me a light hatch

[JustenGT8]

Having had to lug my spare ST185 hatch around a bit recently i have concluded they are farking stupidly heavy....must be over 50kg!! Now alot of that would be glass so i could ditch that and go a sheet of acryllic but if it do that i may as well go the whole hog and do some type of composite...fibreglass, CF, whatever.

Can anyone suggest some places to try? Way beyond what i have the space to attempt myself.

[MR22ZZ]

you could probably work out the weight saving from changing the glass to Lexan pretty easilly.

the density of tempered glass is about 2.5 g/cm^3
the density of lexan is about 1.2 g/cm^3

So you cut the weight of 'glass' of a little more than half right there.

[CrUZida]

Yeah, the MA61 hatch is a bitch to lift when its complete (seriously struggled on my own, CANNOT install it by myself)
However remove the glass, and I can lift it wth 2 fingers no problems.

[JustCallMeOrlando]

I think once you replace the glass you'll be surprised how much lighter it is. The MA61 as Peewee described is much the same.

[Joshstix]

Maybe go to piccies and "remove" teh glass from a hatch and see if the steel portion is worth spending the money to have rebuilt.

On the topic of who to get to do it I'd be looking for boat building places and see if any of the guys do fibreglass work on the side. I have an uncle who was a foreman at Stebercraft and used to build all kinds of things from fibreglass on the side to make extra cash, he made heaps of SLR body kits etc

[Norbie]

You used to be able to get Ferrari GTO style hatches for the MA61, which have the advantage of replacing most of the glass with fibreglass. Even if you stayed with glass for the window it's much smaller than the original window so you'd save a lot of weight.



Yes it looks like arse but if you're only concerned about saving weight and you're getting stuff custom fabricated it might be something to consider?

[thechuckster]

I think the MAT folks - the dudes who rebuild uber-rally cars - had pics of them making plastic (acryllic) replacements for simple glass bits for one of their TA64s ... remove glass, locate suitable acryllic to cover glass, put both into largish oven to slump the acryllic over the glass, trim to fit car, fit, do skids.

Justen: have you looked thru Niel's workshop for a potential mould/donor?

[H1TMAN]

You used to be able to get Ferrari GTO style hatches for the MA61, which have the advantage of replacing most of the glass with fibreglass. Even if you stayed with glass for the window it's much smaller than the original window so you'd save a lot of weight.



Yes it looks like arse but if you're only concerned about saving weight and you're getting stuff custom fabricated it might be something to consider?

I would like to get my hands on one of those, just for the weight reduction.. and it looks different.

[MR22ZZ]

it's like an AW11 with growth hormones pumped directly into the C pillars.

[Draven]

I'm surprised by how much I actually like that.. it's not completely ugmo.

Sort-of on the same topic, how obvious is it that you've replaced (legal) glass with (illegal) lexan?

Supra is getting a bit of a new year's weight watchers job, and just working out the cost/benefit analysis of what I can lose/modify

[JustenGT8]

You used to be able to get Ferrari GTO style hatches for the MA61, which have the advantage of replacing most of the glass with fibreglass. Even if you stayed with glass for the window it's much smaller than the original window so you'd save a lot of weight.



Yes it looks like arse but if you're only concerned about saving weight and you're getting stuff custom fabricated it might be something to consider?

Yes it does look like arse No good for aero either i suspect?

Fark lexan, way too pricey. Acryllic is good enough and comes in a variety of thicknesses.

A lot of weight in the glass for sure so could just try this as a start.

I have a spare for moulds thanx chuckster

[oldcorollas]

acrylic can/will shatter. but being back screen, i suppose it is less of a concern for health.
either way, you want UV stabilised and scratch resistant sheet. if it is not scratch resistant, soon you won't be able to see out of it..

Draven, tap test will tell you straight away, or if it is seen wobbling over bumps..plus any extra "restraint" system required to keep it in.. oh.. and lexan is usually flat, not curved like usual screen...

[andrew_mx83]

i spoke to a bloke about getting all plastic windows for the race car as part of its diet.

perspex is cheap (about $100 would get enough to do all side windows & sunroof) and is apparently 10x stronger than glass
polycarb is about twice the price, and strength

i had a polycarb back window in my hilux after a 90kg gas bottle decided to come flying into the cabin and shattered the original glass one (was like $400 to replace!) and found it fine, it did flex a little and wasnt overly scratch resistant either. but the stuff is pretty cheap, once it scratches u just get out the ole jigsaw and cut another one.


i like the idea of heating it up over the original window to get the curve, i was wondering how i could replace the rear window too (im sure this weighs as much as all the side windows combined)

[JustenGT8]

I like the idea of heating it to get the original curve....might save on stress cracks that you often get from the pop rivet holes if the 'plastic' is a better fit?

[andrew_mx83]

i wouldnt bother pop riveting it, if u get the shape close enough u should be able to sit it in the rubber surround the same as the original glass.

[Mr Ed]

So whats your current weight distribution like Justen? Ive wanted to do a lightweight hatch on the A70 for a while but decided against it as Ive already got a substantial weight bias towards the front.

[JustenGT8]

Bias is around 55 Fr and 45 Rr. But i'll be adding an oil tank for the dry sump, hopefully losing some weight from the front if the turbo kit sells, CF bonnet and a few other bits so should b able to maintain current bias or even improve is i can.

[kaido]

lexan or polycarbonate absorbs water, so the problem with heating it to form a curve is if you heat it too much or too quick. bubbles form in it.
the proper way to do it is to dry it out buy heating it at a certain temp over a few days.

for scratch resistance, you can get tear off films, chuck one on and just replace it when it scratches up... dont know how cheap they are tho.

[oldcorollas]

I like the idea of heating it to get the original curve....might save on stress cracks that you often get from the pop rivet holes if the 'plastic' is a better fit?

proper polycarbonate shouldn't "crack" because it is soft and has high impact resistance/crack stopping properties..
perspex will crack, and will shatter if hit hard enough, because it is brittle. ie, not a huge amount better than glass (maybe 50% better?)

links
link2
http://allstarplastics.com.au/polycarbonate.htm

[JustenGT8]

What's all this talk of poly carb...i'm using ACRYLIC!!!!!!