Drilled and Vented Drum Brakes - Fronts

[Brad K]

hey guys - my 356 was up on the mechanic's rack today, so i took a few photos of my front drum brakes vent/drilled set-up

- Denny Akers set this up for me here in seattle, and this is the set up his son, Mark, runs in local vintage races here in the pacific nw

- i was thinking about fabricating some 911 vents, which do away with the hoses, and just have attachments on each backing plate, but this is what i have for now - fyi: the front "scoops" are actually Zenith carb "velocity stacks"!

- unfortunately, i can't tell you how well these work because even on the race track, my 356s stock engine just doesn't push it enough to get a bunch of fade - hopefully my new "built" engine (from leonard turnbeaugh) should get things going quicker out there!!!

cheers, brad in seattle

[Vic Skirmants]

Brad,
It does not appear you have re-inforced the swaybar attachment points. You WILL get bending and eventual breakage.

[Brad K]

thanks vic - i just read that thread - do you think this reinforcement can be done with everything still attached to the 356? same question for the control arm reinforcement? (you did the carrier reinforcement when you decambered carriers - thanks again!) brad

[Vic Skirmants]

Sorry; you'll have to pull everything off the car.

[Ashley Page]

Brad
Not trying to be over critical here; just trying to help. Your brake duct is not going to offer much additional cooling air. The air will take the path of least resistance which in this case is around your brake duct hose inlet - not into it. The length of the long hose going up high and turning down into the rear side of the backing plate is restricting flow. You are not getting much air through that hose.
If you are going to use the opening in the nose that is in front of your velocity stack as an air source for the brake duct then use the whole thing, sealing your velocity stack to it by fabricating a transition from the grill opening to the velocity stack. Then get rid of the grill and the other piece hanging down into the picture which both are obstructing the opening. That way whatever air is there is forced into the duct hose. Then run the hose straight back, maybe between the control arms if it fits and turn into the front side of the backing plate. Brake duct rule: keep the duct hose as short and straight as possible and keep the cross sectional area of the duct consistent from the opening to where it enters the back plate. Do not “oval” the round duct hose. The ideal location for the duct entry is the center of the car – or as close to there as you can get. There is more to it but that’s the basics.

[Brad K]

ashley - thanks for the comments - i know exactly what you mean - i tried a more direct route, but i had problem with the hose getting pulled around when steering

- check out this photo of the 911 style cooling duct - this looks like a much more efficient system, and one i may try to figure out how to soon install - i can also see the problems with this set-up having its own air flow issues - i know several early 911 track guys who state this set up works well (i know the drums vs disk thing)

advice, comments, always appreciated - brad

[Brad K]

i just checked my old notes - i was looking for brake cooling ducts to seal up the front intakes - summit racing looked promising and cheap - here's a representative cooling duct for the front (7.7 in. x 3.0 in., ABS Plastic, Black, $24 Each):

[leonard turnbeaugh]

Hi Brad,
Having raced at Seattle SOVERN July 4th races for many years with my drum brakes racing against disc brake Porsches, I know the thrill of complete brake fade in turn 3A. Petal to the medal takes on a whole different meaning.
No brake fade to report from this year's races, however
We need to talk but there isn't enough room or time on the chat line.

Leonard Turnbeaugh

[Brad K]

hey leonard - nice to hear from you, and to meet you at the seattle historics! - i really liked your entire set-up, especially your front "undercarriage wind diverter," and your lightened engine bits! again, thanks for building a great engine, which i am enjoying immensely - i'll give you a call soon to chat - brad in seattle

(also, based on some feedback from this thread, i am making the recommended changes, and i will post pix when complete!)