Brake Proportioning Valve Qusetion

[Carson]

Re: Brake Proportioning Valve Qusetion

What I had done was to remove the power brake booster and convert the brakes to full manual. This resulted in a huge increase in pedal effort...which was exactly what you wanted to easily modulate the brakes. The factory Power Brake booster supplied far too much assist, and made it very hard to modulate the brakes. way too " touchy ".

Funny joe mentioned the same thing to me yesterday about engineering the best brake system by calculating all the components to result in optimal PSI without brake booster for maximum brake feel. Just checked on the scca rule book, for SM "Brakes, including calipers, caliper mounts, disks, drums, lines, backing plates, pedals, boosters, master cylinders, handles, ABS systems, proportioning valves, etc. are unrestricted".

Maybe removing the booster and going with a smaller MC is the way to go? how do you go about calculating something like that?

[lowside67]

Re: Brake Proportioning Valve Qusetion

I can tell you I've been chasing crummy pedal feel in my BMW for years... now that I have dual masters and a dead simple system with no proportioning valves, ABS pump, booster, etc. it is rock hard and feels AWESOME.

Mark

[Jaker]

Re: Brake Proportioning Valve Qusetion

Maybe removing the booster and going with a smaller MC is the way to go? how do you go about calculating something like that?

Be careful with this Cars. The Wagon is set up with no booster, Wilwood 6 pistons front calipers, Polymatrix A pads (very aggressive cold pads), ITR rear calipers with OEM pads, and a Tilton brake proportioning valve. The MC is 13/16" (0.812"). I find the pedal WAY too hard for autocross. Sure it's drivable, but it's really difficult to brake well/effectively for autocross.

The next try is going to be with a 17mm (0.67") Porsche 914 MC. If that doesn't quite get me there, the attachment point of the MC pushrod to the pedal arm will be moved to increase the fulcrum effect (more leverage). I'd love to go with some aftermarket MC (Wilwood, Tilton, etc...), but none of them come in a dual circuit configuration (required for autocross) in appropriate dimensions (5/8" diameter and not 3 feet long). I don't have room in the engine bay for a dual master setup. I had one with an adjustable balance bar, and had to sell it because I couldn't get it to fit.

[Sead]

Re: Brake Proportioning Valve Qusetion

I ended up removing my booster as well and love the brake feel for racing. People that have never driven manual brakes get freaked out, but I like that I can modulate the brakes by my leg muscles
20mm MC, Wilwood 4piston calipers/Polymatrix A pads on front.

[lowside67]

Re: Brake Proportioning Valve Qusetion

Tilton's 75 series shorty masters wont fit still??

[Jaker]

Re: Brake Proportioning Valve Qusetion

Tilton's 75 series shorty masters wont fit still??

They're single circuit. Autocross rules demand dual circuit unless the car was OEM single circuit. I did actually drive the car at 1st with a single 75 series 5/8". At the time the front brake pads were a much harder compound. It was better than it is right now but still not good enough. I then re-read the rules, and changed out to the OEM 15/16s. That was impossible, so I moved to the 13/16s. That was still pretty hard, but the pad change to the "A"s helped tons. I'm still trying for better.

The dual setup I tried to use had a pair of 5/8s Tilton 75s, but with the mounting bracket and the balance bar arrangement, it wouldn't clear the drive snout on the supercharger.

[Derek128]

Re: Brake Proportioning Valve Qusetion

Are you saying that the M/C has been changed to something other than what it came equipped with? If so that could be the issue.

Carson: As others have said, you may want to investigate why the braking is so sensitive. Sounds like the previous owner may have messed things up. You may want to check the M/Cyl part numbers and specs very carefully.

the brake system he has now is kinda of a mix and match

The RSX type -S's MC is 15/16 (for ABS car) but on a non ABS car
not sure about booster(booster seems like the same one that I have on my car stock)
we are both running the same brake calipers ITR(front and rear)

[Chickenman]

Re: Brake Proportioning Valve Qusetion

the brake system he has now is kinda of a mix and match

The RSX type -S's MC is 15/16 (for ABS car) but on a non ABS car
not sure about booster(booster seems like the same one that I have on my car stock)
we are both running the same brake calipers ITR(front and rear)

Is there a part number on that M/Cyl to 100% identify it? At thais point I think I would be pulling the M/Cyla and measuring it's bore diameter with some Digital calipers.

What are the maximum M/Cyl that you can get from Honda?

BTW..what year is Carson's car? I have some Raybestos Hydraulic Parts Manuals that I can check size and applications if I know a starting year.

[Derek128]

Re: Brake Proportioning Valve Qusetion

i think the biggest one is 1" from ITR
his Civic is a 1997 Civic CX

[Carson]

Re: Brake Proportioning Valve Qusetion

Some interesting info on this page, confirmed a lot of the things said on this thread.

http://www.ek9.org/forum/brakes/22316-brake-master-cylinder-questions.html

Thanks for those who contributed and gave advices, at this point I am going to go with the biggest MC from honda I can find (1" ITR/GSR). Some mentioned that AP2 S2k one is even a little bigger, but can't confirm. If that doesn't work, next step I would think is to try a ITR booster and proportioning valve too, by then the whole system will be ITR brakes and should work well together.

Some info on this page was also interesting:

http://www.inlinefour.com/oem98intybrm.html

The OEM 98-01 Integra Type-R Brake Master Cylinder is the perfect upgrade when you need to improve the performance and feel of your braking system. We use this specific brake master clyinder on the 96-00 Civic. All 96-00 Civic's have the same brake "hard line" configuration and will match up to the Integra Type-R brake master cylinder. The Integra Type-R brake master cylinder is larger and holds more volume of fluid in the reservoir and the cylinder body is also larger in overall diameter. What this equates to is better brake modulation and less pedal travel. This is an ideal brake upgrade for your 96-00 Civic, but a total necessity when upgrading your 96-00 Civic from a 4-lug brake/suspension to a 5-lug brake/suspension.

EDIT:
According to this thread I will need the ITR Booster too.

http://htarchive.org/showthread.php?p=6022809

I have an itr mc and was going to swap it in when I foudn that it doesn't bolt up. stock ek cx is a female while itr mc is a male.

[Carson]

Re: Brake Proportioning Valve Qusetion

They're single circuit. Autocross rules demand dual circuit unless the car was OEM single circuit. I did actually drive the car at 1st with a single 75 series 5/8". At the time the front brake pads were a much harder compound. It was better than it is right now but still not good enough. I then re-read the rules, and changed out to the OEM 15/16s. That was impossible, so I moved to the 13/16s. That was still pretty hard, but the pad change to the "A"s helped tons. I'm still trying for better.

The dual setup I tried to use had a pair of 5/8s Tilton 75s, but with the mounting bracket and the balance bar arrangement, it wouldn't clear the drive snout on the supercharger.

Which part of the rule are you referring to? The SM rules seems to suggest that Brakes are unrestricted, am I missing something?

Brakes, including calipers, caliper mounts, disks, drums, lines, backing plates, pedals, boosters, master cylinders, handles, ABS systems, proportioning valves, etc. are unrestricted.