new brake design ABS delete

[puma]

Hey guys, just thought i'd share what we came up with for our race car.

For some reason after our wiring clean up in the race car we realised the ABS didn't work anymore, no biggie didn't think of using it anyway but what we realised is that when there is no ABS there is no bias either so we ended up with basically no brakes in the back. So we diecided to bypass the ABS by using this setup just to see if it would work well.







And it did work better but still not enough brake in the rear so we had to use more aggressive pads back there which made things pretty nice. But in our previous race car we used to have an adjustment for the bias so we wanted it too for this car. Plus, we found the brake booster to be way too much assisted and we had almost no feeling on the pedal, it was like on-off. Our car was pretty light too at less than 2300lbs back then.

My driver really wanted a balance bar with a set of pedals but it is pretty expensive and a lot of fab work is needed so i found an other solution. Found this on ebay and decided i would give it a shot, unfortunatly they didn't make a kit for the FRS.



So i had to build an adaptor plate to be able to fix the box to the existing holes in the firewall.



looks like this once installed



And here it is finally installed, the fitment is extremly close to the strut tower and the Ground Control strut bar/camber plate. Also, the factory diagonal bar would touch the reservoir so we had to slot the holes a little bit in order to fit it back in place.

Luckily, Subaru made a junction in the rear brake line so building the custom brake lines was pretty easy since we didn't need to route them all the way to the back. the front passenger line was cut and flared because i thought it looked cleaner with the OEM line well routed at the top of the firewall, the other 3 are custom braided hoses but they are really short. Here is the picture of everything installed. Sorry for the crappy pics but it is thight in there.





When we first tried it, we had like 1 inch of travel on the pedal, really not enough and really stiff. We didn't have a chance to try it on the road yet as we still have several feet of snow around here but we knew just by trying it in the garage that it would not work as planned. The solution we came up with was to do other holes in the pedal itself for adjustment, which would give us more leverage so more force applied to the cylinders for the same force on the pedal and more travel also to be able to modulate the brakes better. Unfortunatly i forgot to take pictures of that step but i had to remove the whole pedal assembly from the car. Pretty easy, but not when you have a roll cage i can tell you that.

Very satisfied with the result, let's hope it works as good as it looks. We can't see it really good in the other pics but there is a line at the end of the balance bar shaft which goes inside where the driver will be able to adjust the bias when the car is on the track as the conditions evolve. You can see it in that picture, it is the big round clown nose in the switch panel, seem to be working really well.



After everything is done, it was almost as much work as installing a set of pedals but at least i don't have to figure out a way to make the electronic throttle work with that and doing a custom line for the clutch. we try to keep things as OEM as possible as we have a deadline and having a part number handy at the dealership is nice if you need to repair something which doesn't happen when it gets too customised.

Let me know what you guys think.

[Captain Snooze]

Originally Posted by puma

Let me know what you guys think.

This picture doesn't show a very wide angle but from what I can see the cabin looks super neat and tidy in there. I mean really neat and tidy. Which I like a lot.

Could you please explain what the clown nose knob/cable actually adjusts? I can't work it out from the pics.

[puma]

you have to first understand what a balance bar is, here is what a quick google search provides

https://obpltd.wordpress.com/2010/07...-tech-session/

so basically you push on a pivot with your pedal and depending if the pivot is more on one side or the other this will put more or less pressure on each cylinder, shifting predal pressure from one to the other. In order to adjust the pivot point, you simply turn the threaded rod which makes the bearing move in the case either towards the front or the rear cylinder. Problem is you have to stop to pop the hood and turn the rod to move the pivot.

With this thing, you can see it in one of the picture, there is a cable attached at the end of the threaded rod and when ou turn the knob, the cable turns the rod which will change the bias by moving the pivot. The pedal must not be pushed for it to work but you can adjust when you are in the straights for example.

I hope that makes senses?

[burdickjp]

That's the most frightening brake line mess I've ever seen. That includes FSAE cars. Please say something about you fixing that before putting it on the track with other cars.

[puma]

i am confused, what are you talking about? you mean the abs delete kit in the first pictures? That was something to test the car without ABS, it is not in the car anymore.


But anyway, i don't see why that would be scary, it certainly didn't look good, but all the line were done by an hydraulic shop and tested to 3000PSI. The goal was to do a bypass of the abs without removing the OEM lines for testings.Tthank god we did it that way before making a whole new system because it ended up not being what we wanted.


it wasn't pretty but it was 100% safe, i wouldn't let the car out if i didn't think it was safe enough.

[burdickjp]

Hard lines into soft lines back into hard lines without any hard mounting, then zip tying them together would definitely work for testing, but would fail eventually if left on the car for any extended period of time.

[gramicci101]

Originally Posted by bur****jp

Hard lines into soft lines back into hard lines without any hard mounting, then zip tying them together would definitely work for testing, but would fail eventually if left on the car for any extended period of time.

Which is why it was only used for testing the concept and then scrapped in favor of the dual reservoir setup when they decided that it didn't meet their needs.

[puma]

there you go, if just deleting the abs would have been enough, i would have obviously built new lines, just the fact that it looked like that was enough to start from scratch.

[Nigelr32]

I'm also interested in doing an ABS delete. Can you tell me, did you get any electronics problems with the rest of the car.


I heard a rumour that the engine won't start if the ABS is removed??

[puma]

well mine is removed and we won a couple of races so i guess the engine does start?

[Nigelr32]

Originally Posted by puma

well mine is removed and we won a couple of races so i guess the engine does start?

Are you sure lol??


I have discovered that the engine will only rev to 4K if the ABS is completely disconnected. Any idea why??


BTW, I think your test set up with the flexi hoses was a brilliant idea. How else would you have found out how it all felt without the module??

[puma]

i suppose it has to do with the fact that it can't see speed from any wheel, i don't see what else it could be used for.

the flexi hose kit can be for sale if you want to try it.