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Tue Nov 09, 2004 7:03 pm

I just finished installing the rear disk kit brakes on my car...it is a porsche spyder kit :) . I did the front disk (from drums) some time ago and all worked fine... last night i got the rear disk and the pedal is low...same level as the gas pedal... no fun! :?

No air is present in all the lines. anyone with experience similar to mine? The pedal is a hydraulic set made by Neal co.

The master has independent lines -one for the front and one for the rear...single bore/piston.

Anyway i am searching for ideas....the breakes are made by empi..single bleed port calipers (front and rear).

It appears that I do not have sufficient brake fluid... the pedal is near bottoming the floor. said that...any ideas? :idea: bigger master?

Wed Nov 10, 2004 7:43 am

Quote: It appears that I do not have sufficient brake fluid... the pedal is near bottoming the floor. said that...any ideas? bigger master?

Yes.
Although I don't know the specific requirements of the calipers you used, nor the bore size of the Neal master (though I' guess it's the industry std. @ 3/4") ~ drums "like" a small master beause the wheel cylinders are very small compared to any disc caliper & they also respond well to the high line pressures you can create with a small MC. Disc's by contrast love & need volume. The only way you're going to find the "right" bore size is through trial & error to match the volume requirements of you system with the pedal ratio & pedal "feel". Go too large and the pedal will feel like a rock with no whoa action, & it seems you already have an idea of what too small feels like. The bad thing is, since you can't change the pedal ratio, the brakes are going to "get harder" as you increase bore size - bad if you like the "power brake" feel/ease you probably have right now, but good if you'd like them to be more responsive. Now that I think about that, you might be able to re-drill the cyl/pedal clevis mount without creating too much of a plunger rod angle to increase the pedal ratio (that'd probably be neat - more responsive & powerful brakes w/a easy pedal feel)

Check out Wilwood's site. They have a good tech section that'll get you pointed in the right direction & and doing some calc's, will help you ballpark where to start with bore size, but ultimately figure on buying 2 or more diff. MC bore sizes to really dial it in & get the feel & action you really want. There are way too many variables + everyone "likes" a differant pedal feel to state "Oh, you need a 1" bore". 1" may work, but you might like a 1-1/8", or maybe a 7/8" better with your pedal ratio, leg strength, car weight, volume requirements, driving style, seating position, blah, blah, blah, etc.

Sat Nov 13, 2004 6:51 pm

They dicuss the subject here as well.

http://www.1800vw.bizhosting.com/brakehowto.htm

Sun Nov 14, 2004 9:23 am

Well, thanks for the information...
I have a 3/4 inc mc and found (with the help of my wife...who is a great trooper that tolerate my crazy ordeals) some additional air in the passenger side rear caliper...
The air was airlock (I think) because the supply line loop is at a higher elevation than the caliper ... :shock: after some additional bleeds front and rear (8), the air was expelled and the pedal gained some more body, but it was a little low. 8)

The Neal pedal set was designed with an adjustable pedal and I followed that path. Now the pedal feels more like a normal setting...I did not pursue the idea to increase the mc bore size due to the effort and feel changes.

I drove the car for a few minutes and it feels good. This improvement will meet my expectations as a weekend mechanic. The E brake works great too.... :D

Thanks for your input.