Brake ducting vs. 968 scoops

[74goldtarga]

My 951 is used mainly for the track although I do occasionally drive it on the street. I have heard that people get good use from the 968 brake scoops on the track for brake cooling. I have thought about going this way, however, before I heard about the 968 scoops I bought high temp ducting and some plastic scoops that I modified to duct air from the 951 plastic brake ducts, I didn't buy the plate for the spindle end however. I am familiar with the plates sold by Pelican and also the Broadfoot racing plates that Lindsey sells.

I have the plumbing worked out so that the tires won't rub except at extreme steering angles I don't think I'll encounter except maybe in backing (I'll have to be careful, anyway...). Do you all think that the ducting with the plates Pelican sells would be superior in performance to the 968 brake scoops all other things being equal?

[Techno Duck]

There was recently a thread about this on Rennlist in the 951 forum.

Personally i think any direct ducting to the center of the disc / hubs is going to be more effective than the scoops. That is not to say the scoops are probably more efficient than the stock 951 setup with the deflectors.

[74goldtarga]

Thanks Duck. You always come through with a pithy answer, I saw the rennlist thread actually but it really focused more on the 968 deflectors, do you think the design available through Pelican looks good, I realize it is a bit pricey but I think they look great/well engineered. I think I will get enough airflow going from the factory front ducts - agreed?

[flash968]

ducting can be more effective for sure - however, the key to brake cooling is to get the air directly onto the rotor - stopping a few inches away is almost as bad as not doing it at all - the problem is the vortex created by the wheel spinning - it creates a high pressure zone that you have to overcome, and you can't do it by blowing on it from afar

there are basically two ways people normally do this:

like the 968, you can use scoops, which effectively create a wind block, allowing passing air to be directed toward the rotor, while staying out of the vortex - it works, and is less subject to placement issues, but doesn't get the same ram effect and volume of air as ducting, especially if you use a bell mouthed pickup to maximize the flow into the duct

or you can duct it, but the exit really needs to be no more than an inch away from the rotor to have any real effectiveness - most guys create a bracket or plate that holds the duct in place and lets it dump directly onto the rotor's edge

[Techno Duck]

I have seen the backing plates on Pelican but have not seen them mounted on the car so cant comment really. The Broadfoot / Lindsey plates that bolt onto the spindle are widely used but the same thing is always said about them, they do not place the air in the right spot really. You ideally want the air to be ducted right to the inside of the disc where its going to be picked up by the the vanes in the rotor. They throw air for the most part on the disc which is not really correct for cooling.

There are alot of pictures of custom designs that almost completley cover the center of the rotor hat. These are the best designs as you are forcing air through the center of the rotor and across the vanes (and also cooling the hub) as the rotor was designed to be cooled.

Personally i dont think you can go wrong with either method. The 968 ducts are cheap (about $60-70 for the set) and easy to retrofit. If you feel they arent enough, you can always go with the ducting.

[74goldtarga]

Flash and Duck, perfect. I am going to order the plates from Pelican. I will post photos to this thread when installed. Thanks much.

BTW, it looks like I will have to remove my hubs from the spindles to do this, is this a hard thing to do, will I need to replace bearing parts to do it (my bearings are almost new)? Thanks again.

[Techno Duck]

Not hard to do, just make sure you set the locking collar correctly. Take note of how tight the thrust washer is against the bearing / locking collar before taking it apart so you know how tight to make it when you put it back together.