View previous topic :: View next topic |
Author |
Message |
Joes924Racer
Joined: 03 Nov 2002 Posts: 11964 Location: Oregon, Denver Colorado native!
|
Posted: Sat Dec 14, 2002 12:46 pm Post subject: Lightweight Hatch |
|
|
So im full of envy for the porsche guy who has a lightweight hatch...
Has anyone made one here in the states from the ideas we thru
around last time.. _________________ 1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo. |
|
Back to top |
|
|
924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
|
Posted: Sat Dec 14, 2002 1:09 pm Post subject: |
|
|
GT Racing sells the lexan replacement for the glass, costs about $600USD, saves about 67lbs. _________________ Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
|
Back to top |
|
|
jpab924
Joined: 03 Nov 2002 Posts: 1538 Location: Crown pt. IN. 50 miles southeast of Chicago Ill.
|
Posted: Sat Dec 14, 2002 4:42 pm Post subject: |
|
|
So you got one on your car yet Vaughan? |
|
Back to top |
|
|
924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
|
Posted: Sat Dec 14, 2002 11:09 pm Post subject: |
|
|
No; I still have to pick up the donor hatch (maybe this weekend if I can get to it) and order the lexan. Have to wait for a fat paycheck opportunity to buy. It's a low priority, as I don't need it until I run 944Cup again, and that schedule's not out yet. _________________ Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
|
Back to top |
|
|
gwsg
Joined: 03 Nov 2002 Posts: 160 Location: Melbourne Australia
|
Posted: Mon Dec 16, 2002 5:40 pm Post subject: |
|
|
924RACR wrote: | GT Racing sells the lexan replacement for the glass, costs about $600USD, saves about 67lbs. |
I have never actually ordered bent Lexan but I deal with quite a bit of flat polycarbonate and acrylic and I have had glass custom bent. This price seems very high and I think it would be worth phoning a couple of plastics engineering firms and enquiring about the cost of custom bending using an existing glass hatch for the mould. Also, although not as strong, Perspex has better scratch resistance, better UV resistance and is cheaper than Lexan. Just a thought that may save dollars. Worth a try if you can find an enthusiastic plastics engineer and there are plenty in the Yellow Pages. _________________ My 80 924 loves me. |
|
Back to top |
|
|
924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
|
Posted: Tue Dec 17, 2002 1:42 am Post subject: |
|
|
Of course it's high - they've cornered the market.
We need to get Jeff @ 944Racing to get to work on some of these... _________________ Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
|
Back to top |
|
|
CBass
Joined: 03 Nov 2002 Posts: 2807 Location: Vancouver, Canada
|
Posted: Tue Dec 17, 2002 6:16 am Post subject: |
|
|
This would be a great way to reduce weight. Perhaps they could offer a combo of a lightweight hood, and hatch. On a side note, a friend of a friend works at the local plastics store here, and my friend can get whatever he wants at cost.
I've worked with acryllic tube before, and it's pretty easy if you have a heat gun. All the would really be needed is to remove the glass from the frame, bend the polycarbonate over it. I'm not quite sure what thickness to use however...
The greatest thing about these plastics is, they are very forgiving and easy to work with. The downside is you end up with burnt hands often as not |
|
Back to top |
|
|
Lizard
Joined: 03 Nov 2002 Posts: 9364 Location: Abbotsford BC. Canada
|
Posted: Tue Dec 17, 2002 6:19 am Post subject: |
|
|
hey it is worth a shot, hey cbass new job for you create us all light weight hatches _________________ 3 928s, |
|
Back to top |
|
|
Peter_in_AU
Joined: 29 Jul 2001 Posts: 2743 Location: Sydney, Australia
|
Posted: Tue Dec 17, 2002 7:33 am Post subject: |
|
|
as we discussed last time the problem with just laying a sheet of polycarbonate over the hatch glass and hitting it with the heat gun is that the polycarbonate won't fit the frame - think about it, it'll be too big.
What you need to do is make a mould from the glass (either inside or outside surface) then use the mould to shape the polycarbonate. Fibreglass would probably be OK for the mould as the service temp of fibreglass is greater than the mould temp of polycarbonate. You could just make a paper pattern from the glass to mark the polycarbonate for cutting.
It would be a great project and reasonably easy to do especially creating the mould from the glass. I'd do it if I had a spare hatch to play with (anyone in Sydney got one I can borrow for a week or two?). You could do the side glass the same way and that would be even easier. _________________ 1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)
Learn to love your multimeter and may the search be with you |
|
Back to top |
|
|
gwsg
Joined: 03 Nov 2002 Posts: 160 Location: Melbourne Australia
|
Posted: Tue Dec 17, 2002 7:53 am Post subject: |
|
|
Peter_in_AU wrote: | as we discussed last time the problem with just laying a sheet of polycarbonate over the hatch glass and hitting it with the heat gun is that the polycarbonate won't fit the frame - think about it, it'll be too big. |
You would not bend the plastic over the outside, you would slump it into the inside. The plastic screen would be made oversize and trimmed back to fit. Either Lexan or Perspex would be forgiving enough to accomodate minor shape difference. I also dont know the thickness of the rear hatch glass but using thinner plastic would also help fitting and the plastic would be strengthened by the curve. Many modern windscreens are now only 3mm thick because manufactureres have realised the increased strength of curved glass but I bet the Porsche glass would be 5-6mm thick. _________________ My 80 924 loves me. |
|
Back to top |
|
|
Peter_in_AU
Joined: 29 Jul 2001 Posts: 2743 Location: Sydney, Australia
|
Posted: Tue Dec 17, 2002 8:58 am Post subject: |
|
|
yeah, might be close enough. Only way to find out is build one and see. _________________ 1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)
Learn to love your multimeter and may the search be with you |
|
Back to top |
|
|
gwsg
Joined: 03 Nov 2002 Posts: 160 Location: Melbourne Australia
|
Posted: Tue Dec 17, 2002 4:28 pm Post subject: |
|
|
Been thinking about those 67lbs. If this is correct the glass would be closer to 8mm thick! Anybody got one that they can measure the thickness of.
I'm sure if you put your mind to it you could whip one up in your lunch hour Joe. _________________ My 80 924 loves me. |
|
Back to top |
|
|
Peter_in_AU
Joined: 29 Jul 2001 Posts: 2743 Location: Sydney, Australia
|
Posted: Tue Dec 17, 2002 5:59 pm Post subject: |
|
|
8mm? Which glass are you talking about?
Wrap your fingers around the rear hatch glass, it's 3mm tops. _________________ 1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)
Learn to love your multimeter and may the search be with you |
|
Back to top |
|
|
924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
|
Posted: Tue Dec 17, 2002 11:29 pm Post subject: |
|
|
I have a loose piece of glass but have no scale, so I won't be weighing it... unless my neighbor has a scale I can borrow. Will have to check. It's seperate of the frame. Yes, it is about 3mm thick. It also weighs somewhere from 60-80lbs. The frame weighs next-to-nothing. This should give us a really good idea of the potential weight savings. I'd think the completed unit couldn't weigh more than about 20lbs.
Bobby responded, he's been talking about it with Jeff, and they'd like to do it but it's much lower on the priority list. Maybe I should get off my butt and make my own. I agree, there should be some degree of tolerance using plastic and not putting struts on it - just prop it up when necessary. However he did express some concern about what to build a mold out of, due to the heat. _________________ Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
|
Back to top |
|
|
Zuffen
Joined: 31 Jul 2001 Posts: 1426 Location: Owasso, Oklahoma 74055
|
Posted: Wed Dec 18, 2002 1:12 am Post subject: |
|
|
I'm leaning more to 4mm thick.
If I can get my scale back to the house I'll weigh a hatch frame, glass and let everyone know the results. I'm going to have to find a fishing scale to do the hatch frame as it weighs like 5 lbs.
What we need is some research to find what is spec for most sanctioning bodies. If we go thinner we will have to NASCAR strap the piece in.
What do you guys think of this idea.
Use the outside of the old glass as a mold, but to allow for the extra width I'll diamond cut the glass in half and remove a small amount to make up for the exta mold width if it were whole. Then butt the two halves together and fix so it won't move. This should be a perfect mold and fit the width of the hatch frame (the curved section from one side to the other). Thenall that will need to be done is trim the outside edge to pattern and about 1/4 inch in for an exact fit.
I've got plans to build an oven to do the actual bend. Less stress on the piece if the entire unit is heated and fluid so the material forms too the mold versus heating and forcing in sections. _________________ Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S
I have Way too many cars, parts for the 931,944 and 951 |
|
Back to top |
|
|
|