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Texas Mile => Texas Mile General Chat => Topic started by: Slide on November 03, 2015, 10:43:40 AM

Title: Brake question
Post by: Slide on November 03, 2015, 10:43:40 AM
We are still building this Subaru for the mile... Before it was engine problems that delayed is going to the event...then it was a scare with the wife...then this last one I went down for surgery...

However...this has been giving me time to consider more safety concerns and save up

The car is making around 750 whp and 720 wtq... Which is asinine...

I have a set of the stoptech trophy brakes up front, but just the stockers out back. It seems to me there is a lot of front bias in this set up...

We are in the process of building a flat bottom and a real rear diffuser, relocating some more weight to the rear and less at the front etc...and of course the design weight from the upcoming cage has mathematically transferred more theoretical weight towards the rear; all in the hopes of clearing 206 mph...

We will be running either continental slicks (GtO compound and build) or Achilles slicks depending...

Stoptech makes a brake kit for the rear using the st22 caliper. The pad area is quite small, if not near the same as stock, however it will add a little more mass in the rotor (I think it brings the diameter up)

Should I see if they can build a kit using the st41r caliper which is a rear caliper, using a larger pad surface area and see if they can run a large Disc for mechanical tq and extra heat ability...hoping to get a little more rear bias to slow this guy?

I really don't want to go to a chute if I don't have too.

I'd like to have some knowledge in my pocket for when I call stoptech...
Thanks for any help

Title: Re: Brake question
Post by: rouse on November 03, 2015, 11:26:28 AM
You may need to take a good long look at you CG vs CP before making up your mind on how much brake bias you need to have.

Also the parachute question may have already been answered for you if you read the Texas Mile rule book.


Title: Re: Brake question
Post by: Captthundarr on November 03, 2015, 05:03:47 PM

Title: Re: Brake question
Post by: bbarn on November 04, 2015, 01:54:27 PM
Chutes are cool!!!

They also have the added benefit of helping you out of an aerodynamically unstable platform. Pay close attention to the advice given above about the relationship of Center of Pressure to Center of Gravity - it is the most critical part of an aerodynamically balanced car.

Chutes actually move the center of pressure WAY to the rear of the car. If you are having handling issues related to this ratio, throwing the chutes will correct the condition pronto AND stop the car. When in doubt throw the laundry out!

Foot braking in a car starts weight transfer/weight jacking, compressing shocks, loading springs... all the things that make an unstable car worse. It is good to have foot brakes but if you are going to be running 200+ get a chute regardless of what the books says you "have" to do.

Title: Re: Brake question
Post by: rouse on November 05, 2015, 09:56:30 AM
Another thing to keep in mind and it's a very important thing at that.

Petal brakes and chutes don't really go that well together with out some prior thinking.

Always drive into the chute and then get onto the petal. If you do the opposite, the chute will cause you to lockup the brakes when it hits,
which is a sure recipe for a wreck. There are plenty of examples of that on YouTube.


Title: Re: Brake question
Post by: Slide on November 14, 2015, 01:19:55 AM
copy that...

Chute it will be...Also now looking at the Mojave 1.5 mile...So that will be a chance to go even a little faster (or to actually attain our speed goal)
So now I am off looking for a cage builder familiar with LSR cages...and chute mounts...

Title: Re: Brake question
Post by: gkabbt on November 14, 2015, 07:06:56 AM
I think I remember hearing that Texas has a really short shutdown. If true, I would want all the brakes I could get as well as a chute!
Chute mounting, size and tow is VERY important. Talk to Stroud.