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Bonnet hinging :: ideas please?
sgraber - 11/9/06 at 05:18 PM

Can people post up images of hinges for clamshell front ends?

I need ideas.


John Bonnett - 11/9/06 at 05:35 PM

Hi Steve

I was wondering whether the set up I have on the Phoenix might work for your car. There is a tubular cross piece onto which are fitted two sleeves each having a braket welded on. These brackets are made of 2mm thick x 30mm wide strip. the brackets bolt up to the radiator ducting on the bonnet as shown in the picture. I'm sorry that I do not have a picture of the hinge assembly before the bonnet was fitted but I hope you get the idea.

alb

John


John Bonnett - 11/9/06 at 05:42 PM

Sorry Steve the picture did not come over. Will try again


John Bonnett - 11/9/06 at 05:51 PM

Don't you just hate it when things fight back!

Here are the pics, I hope!!

John
http://i93.photobucket.com/albums/l57/bonnett_2006/phoenix38001Small.jpg
http://i93.photobucket.com/albums/l57/bonnett_2006/phoenix39003MediumSmall-1.jpg

John


sgraber - 11/9/06 at 05:59 PM

ahh, I see. So it hinges from the very bottom-front most part of the bonnet?

That was where I had though was the best place for mine. But I am concerned that the slightest impact to the bottom lip of the car would make it impossible to open the bonnet if the hinge were to get mis-aligned. Am I overthinking this?


StevieB - 11/9/06 at 06:06 PM

If it hinges at the very bottom edge, it'll need to be very far forward, or there's a chance of scraping the nose on the ground when it opens


sgraber - 11/9/06 at 06:15 PM

quote:
Originally posted by StevieB
If it hinges at the very bottom edge, it'll need to be very far forward, or there's a chance of scraping the nose on the ground when it opens


Understood. Are there any issues with placing the hinge so low and forward on the car? I am guessing that frontal impacts of any magnitude, no matter how small, will transmit forces into the frame directly rather than allowing the fiberglass to crush and crack and buffer?


StevieB - 11/9/06 at 06:19 PM

How about having the front edge being fixed and hinging from a foot or so back, that way you get around the impact potential to knacker the chassis, you have a scarificial zone for any crash damage and maybe better aerodynamics as well.


JonBowden - 11/9/06 at 06:59 PM

quote:

I am guessing that frontal impacts of any magnitude, no matter how small, will transmit forces into the frame directly rather than allowing the fiberglass to crush and crack and buffer?



My worry about such designs of bonnet where there is no windscreen is that in the event of a bad crash, the whole thing might come off and chop the driver's head off


Mark Allanson - 11/9/06 at 07:34 PM

Just about to post the very same thing!

I was going to recommend glassing in hooks that would engage onto the chassis in the event of an accident and restrain the rear of the bonnet, another upside of this is that the bonnet then absorbes masses of kinetic before the chassis takes over the decelleration. Tahe a look at any volvo front opening bonnet for parts/ideas.

Pantograph hinges are also a good idea because they will lift the front of the bonnet as it is opened (ideal for a low chinned sportscar).


sgraber - 11/9/06 at 11:23 PM

I'm considering pantographic hinges as they are not that difficult to fabricate. However. straight up hinges at the bottom/front are really so much simpler ...

I've been looking at a lot of tilt-clamshell 'kits' (google) and none that I have seen use anything but straight hinges...

My car has a windshield, so I feel that the decapitation issue is moot in my case.


John Bonnett - 12/9/06 at 07:11 AM

Hi Steve

I should have pointed out that the hinge assembly on the Phoenix is like a small subframe that is designed to be crushable. If you are really interested in the design, I can take the bonnet off and take some detailed photos.

Please let me know.

alb

John


chriscook - 12/9/06 at 09:31 AM

The same idea is used on the Fisher Fury - there are probably more photos of Furys around than Phoeni(?)
In fact after a quick look on the Sylva sportscar register I found this picture and you can see the frame at the front of the car with the hinges hanging down.

Chris


sgraber - 12/9/06 at 03:11 PM

Thanks Jon and Chris,

I now have a pretty good idea of how to attach a lightweight, sturdy and deformable hinge structure after looking at the Sylva.

Appreciated!

Graber


RazMan - 13/9/06 at 10:42 PM

Steve - This might give you an idea of how my Aeon's front end is hinged - basic but effective. I would consider a couple of largish rod ends to give adjustability though. Rescued attachment Front mounting frame.jpg
Rescued attachment Front mounting frame.jpg