Landracing Forum

Tech Information => Technical Discussion => Topic started by: Cajun Kid on December 03, 2009, 08:52:00 PM

Title: Roof Rails ?
Post by: Cajun Kid on December 03, 2009, 08:52:00 PM

For my 53 Studebaker (under Build Diaries) From what I read I am required to have roof rails and those rails need to be a max of 3/4" tall.   If that is the case I guess I should make them the maximum height of 3/4" ??
 Then where do I put them ?  I know,,, silly on the roof would be a good place,,, but seriously,,,should they run from the the windshield back to the back glass ?  then how far apart.. side to side,, as far out towards the doors  or what ?

I was thinking of using .060 aluminum  1.5" wide and bending it to make 90 degree angle,,, 3/4" vertical rail and the other 3/4" flat attached  Rivet ? or Bolted?  to the Roof ...


Thanks

Charles

Title: Re: Roof Rails ?
Post by: stratman59 on December 03, 2009, 09:03:53 PM

Charles,

From what I found out 1/2" to 3/4" with the 1/2" having less drag.
They to be as close to outside as possible and parallel.
From the windsheild to the backglass and I have seen some go to the rear cowl panel'
We pop rivet ours on and haven't had any problems.
I'm sure someone way smarter than me will tell you more.

Robbie

Title: Re: Roof Rails ?
Post by: Glen on December 03, 2009, 09:10:28 PM

Charles' mount from the wind shield to the front edge of the rear window and along the roof where the radius starts to the side. DO NOT mount with sheet metal screws, they come loose. You can use riv-nuts or 10-32 flat head screws counter sunk and elastic stop nuts about every foot. I am sure others will have some input as well.

Title: Re: Roof Rails ?
Post by: Cajun Kid on December 03, 2009, 09:35:52 PM

Robbie & Glen,

Thanks for the info... Ok which way is best way to mount the rails with the flat part where it is riveted or screwed to the roof on the inside towards the middle of the car facing each other or to the outside ?


  This way  is facing in       L      J     or the opposite.... facing out ?

Title: Re: Roof Rails ?
Post by: Glen on December 03, 2009, 09:42:06 PM

flat side out     L

Title: Re: Roof Rails ?
Post by: Cajun Kid on December 03, 2009, 09:44:08 PM

Verticle  Side out ?


      L   roof   J     like that ?

Title: Re: Roof Rails ?
Post by: stratman59 on December 03, 2009, 09:47:08 PM

the screw flange  to the inside facing each other.

L on the diver side.
J on the pass.

Robbie

Title: Re: Roof Rails ?
Post by: Bville701 on December 03, 2009, 09:48:00 PM

Yep you got it CK.    :cheers:

Title: Re: Roof Rails ?
Post by: Cajun Kid on December 03, 2009, 09:58:31 PM

Thanks guys... may build them tomorrow too.....if time permits

Title: Re: Roof Rails ?
Post by: Glen on December 03, 2009, 10:01:39 PM

You can buy 1/8 x 3/4 x 3/4 x 6 ft alum at Ace, Home Depot and Lowes hardware stores, soft and easy to form for roof curve.

Title: Re: Roof Rails ?
Post by: Cajun Kid on December 03, 2009, 10:29:46 PM

Glen,

I will look for the Aluminum angle as you describe...

we have plenty of flat aluminum,, was just going to bend a 1.5 inch strip in a 90 angle to make a 3/4 x 3/4

but the store bought angle will work too..

Charles

Title: Re: Roof Rails ?
Post by: Glen on December 03, 2009, 10:31:43 PM

There is also thinner wall like 1/16"

Title: Re: Roof Rails ?
Post by: Jonny Hotnuts on December 07, 2009, 04:17:19 PM

Quote

From what I found out 1/2" to 3/4" with the 1/2" having less drag

I would not understand how, providing the rails are dead parallel to the direction of travel, there would be any noticeable (or measurable) difference between .5 and .75 rail height.


I am just curious how you came to this conclusion.


I have always suggested that a person should use as tall of a rail as possible. While I have not seen any data on rail height vs. decrease in lift generated by traveling laterally  I made the assumption that bigger is better…..especially if its not causing any significant increase in Cd.


~JH

Title: Re: Roof Rails ?
Post by: Cajun Kid on December 07, 2009, 06:42:49 PM

JH,

I am going  with the max height or  3/4" on my roof rails.

Now do I use  3/4 x 3/4  by .125 thick material  or .100 or .090. or .080  ?

Charles

Title: Re: Roof Rails ?
Post by: McRat on December 07, 2009, 06:50:54 PM

I used .060"
It's pretty rigid. 
.125 is way too thick IMO.

Title: Re: Roof Rails ?
Post by: stratman59 on December 07, 2009, 07:24:39 PM

Jonny,

I did a google search on roof rails and don't remember the exact site.
I think it was Robert Yates Racing doing wind tunnel on 1/2" and the 3/4" rails.
The 1/2" had less drag but the 3/4" was bettr at keeping the  car on the ground.
I thought the same thing as you.

Robbie

Title: Re: Roof Rails ?
Post by: Cajun Kid on December 07, 2009, 09:45:20 PM

I will call Yates or A2  tomorrow and find out.. (if I can get an answer)

Charles

Title: Re: Roof Rails ?
Post by: stratman59 on December 07, 2009, 10:17:17 PM

Charles,

I think I'm right about the Yates story on roof rails. I read so much on it that day.
You know i have CRS.
Just what i remember and i save it on my old computer but will have to get it back out to see.

Robbie

Title: Re: Roof Rails ?
Post by: Rex Schimmer on December 08, 2009, 09:37:54 AM

I have not read the Yates information regarding the drag imposed by roof rails but remember their function is to "trip" the air when your car is side ways to reduce the lift on the roof panel caused when the air it traveling across it side ways, helps keep you on the ground so I would certainly go with the 3/4 inch regardless of the probably small additional drag they may impose.

Rex

Title: Re: Roof Rails ?
Post by: Stan Back on December 08, 2009, 11:28:35 AM

I've seen a couple cars where they come from beneath the roof surface.  No flange (?) sitting on the inside or outside.  Sure looks cool and gives a bigger surface on both sides, but is a lot harder to install.

Stan

Title: Re: Roof Rails ?
Post by: Cajun Kid on December 08, 2009, 07:02:15 PM

Stan,  to difficult to do...

Charles