In-tube brake line trick

Just finished some new a-arms made from store-bought streamline tube. And then I saw those vile external brake-lines in place and I'm thinking... man, that probably creates as much drag and wake disturbance as regular round tubing would (if it didn't have a brake-line)!

So what is the trick to safely creating a portal so the lines can be thread through the aerotube? I know I've seen it, but can't remember what kind of stress-relief was done around the hole the brake-line would be fed into (and out of). A great big form-fit washer?

Also this, I'm using AN -3 lines and fittings, and their already attached to the braided ss/teflon lines. Is the trick to put the fittings on the lines post their being strung through the tubing? (That way, the holes would be quite small).

Has anyone been through this exercise?

Thanks,

Chris

PS: Funny how small your world becomes when you're thinking about things like parasitic drag. You start thinking in micro-vision. A radio antenna begins to look like a telephone pole, etc. !

Chris, I know VD did this on my last car, but I think it's becoming a thing of the past due to a few things such as overly complex, expense, extra time to repair in case of shunting, etc...

What seems to have replaced it is a thin aluminum shield, bent to match the radius of the A Arm, capturing the brake line in a pocket along the leading edge and held in place w/ a few zip ties. Quick, elegant, light, and cheap.

Yes, I know - I'm a bit amazed that I just commented on a technical issue.
There is now officially hope for peace in the Middle East...

GC

chris

A arms i have seen this on, the opening is already in the tubes, i put the fittings on after the-3 hose goes through the A arm.

I've never taken one apart to see if the tubing inside the a-arm is one piece to the other end or just a section at each opening. The welding process itself, attaching the inner tube to the a-arm, removes any sharp edges normally associated with drilling a hole..

and potential problems.

Isn't it easier to make an aero-shaped clamshell of carbon or glass?

Chris:

The usual way of running the line through the arm is to bend a length of tube that the braided line can go through, and run it through the arm, welded to the arm at each end, and with a doubler plate at each opening. Looks nice and clean, but is a lot of work. The brake line is then run through the tube, and the fittings attached afterwards.

The easier route, but not as "elegant", is to bend 3 AN washers (so that they form a "U") and weld them to the trailing edge. The brake line is then tie-wrapped to each washer. Optional is to cover it with a Vee-shaped piece of alu sheet, again tye-wrapped to the arm to clean up the air flow.

Quote:

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Originally Posted by R. Pare

Chris:

The easier route, but not as "elegant", is to bend 3 AN washers (so that they form a "U") and weld them to the trailing edge. The brake line is then tie-wrapped to each washer. Optional is to cover it with a Vee-shaped piece of alu sheet, again tye-wrapped to the arm to clean up the air flow.

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That's what came on Ralts from RT-4 all the way through the RT-41.

I've seen the sheet metal overlay done on alot of FM cars. I almost couldn't see the overlay from 6 ft away.

Through the tube....

and i use them ......

http://www.apexspeed.com/forums/show...t=BERNIE+CLIPS

http://www.apexspeed.com/forums/show...t=BERNIE+CLIPS

Another idea using just tywraps (or with protective sleeving to protect the finish on new a-arms). (The sleeving is the woven split type sold by Pegasus). I copied the idea from Nick Myer's car. I believe that Nick credits Mark Lamm (former member of Bruce May's crew) with the idea. The only "tricky part" is to get the tywrap orientation correct so it can do the two loops correctly (think figure 8 with one large and one small circle) with the tywrap lock on the outside.

The Universal Racing Services front replacements have simple loops for tywraps. The original VD arms had "C" shaped "clips".

Dick
CM 85
85 VD