Door sealing issues at high speed? Design flaw?

[Bob Winn]

see this video

Around min 3, as the car is hitting its speed max, the doors look like they are separating from the body. I can't tell if it is downforce on the body, or pressure venting from the cabin. But that behavior can't be right? Someone has to know the owner. Is this a behavior all SLC have, or is something unique here. It is the first time I have seen video of a slc from this angle.

Bob

 

[Larry L.]

Wow.
That cannot be something one just has to 'live with'...

 

[JP Verweij]

Thats common on GT40's, and in worst case scenario's it opens the door aswell

Thats why we fit those door tongue kits

 

[Neil]

I remember reading a road test of Bill Thomas' "Cheetah" in an old magazine where they said that it was the only car they ever tested that blew its own doors off.

 

[Ken Roberts]

That car was built by Dean Lampe. He has a build log on here (I bumped it back up to the top). It was built as a race car only so sealing the cab was not a big consideration.

 

[Bob Winn]

Yeah, so is pressure differential in side to out, or air acting on the doors? Seems sealing might not help too much, there really isn't anything holding that back corner of the door closed

 

[Ken Roberts]

The car has full side windows so I would guess the interior is pressurizing at high speed. Top front and sides of the foot box should be carefully sealed where the foot box meets the body.

 

[Howard Jones]

"full side windows so I would guess the interior is pressurizing at high speed." Mind did it too until I added big wave-by holes in the side windows, then it went completely away.

 

[Paul W]

This is the same problem 40s have, air rushing over the screen creates a low pressure area above the door tops which causes lift.
On a normal car with standard roof you'd never notice it. Simply lower pressure above the door than below it.

 

[Fran Hall RCR]

physics can’t be beaten
nothing has changed during the last 50 years from a gt40 to an SLC
in reality i’m happy to have my SLC share the same issues a multi million dollar design team had .. in fact the most expensive race program in history
it’s an easy fix though in reality
feel free to call the factory for a solution in your SLC

 

[Shaun]

Sorry could not resist

 

[Fran Hall RCR]

Shaun
that’s awesome lol

 

[John Symonds]

Fran,
Could you share the easy fix on the forum so the factory doesn’t have to take 20 phone calls requesting the information?

 

[Paul Hendrickx]

coming back on an old(....) treat where does the air go's which come in the cabin through the ventilations on the dash bord? ever thought about it?
on passengers cars you have mostly in the booth some one -way opening to let cabine pressure out coming from forced or dynamic cabin ventilation... in my build I provide one- way cabine pressure outlets ...
Paul

 

[Paul Hendrickx]

forgot to put the link.... when age arrives early

Here's What Those Secret Rubber Flaps Behind Your Rear Bumper Are For

I recently strolled through a junkyard with my friend Taylor when he asked: “What are these flaps on the rear corners of all these cars?” Realizing that he may not be the only one wondering, I decided to write this post about these devices, which act as vital pressure relief valves.

jalopnik.com

 

[DaveC]

You guys aren't dealing with high pressure in the car, you are dealing with Bernoulli's principle. The high speed air over the car is causing a negative pressure on that wide upper part of the door, sucking it upwards. If it's not cracking the paintwork, I wouldn't worry about it...does it even happen at less than 120mph? To fix this, you need to make the door part of the roof, like the tab modification posted above, or suck the interior of the car down to vacuum... which may kill the occupants.

 

[Jeff W]

Those bolt-on tabs look rigged, even if they are effective. If it's a race car NBD, but if someone's going for a finished street car look those tabs are ugly. Anyone tried something else like a hidden fixed pin/hole or a tab/slot on the edge of the door/body that meet at that corner when the door is closed to keep it from lifting? I don't have the car yet to answer my own question, but is there any way to stiffen that part of the upper rear portion of the door so it doesn't flex so much?

 

[Neil]

Years ago a national magazine wrote a performance test of a Bill Thomas "Cheetah". They tested it on a high-speed oval track and, as they wrote "It is the only car we've ever tested that blew it's own doors off!".

 

[Rich Kruger]

Neil you are a national treasure of useful AND useless information.

 

[DaveC]

Years ago a national magazine wrote a performance test of a Bill Thomas "Cheetah". They tested it on a high-speed oval track and, as they wrote "It is the only car we've ever tested that blew it's own doors off!".

Year ago a nationally known forum member...