Manifold vacuum for brakes question

[ncbrock]

Ever since I started my weber swap Ive been struggling with brakes. Before the swap with my stock 8v the brake pedal was very firm and grabbed high up. Ever since I swapped my pedal feel is terrible and grabs down low and is way too squishy, but when the car is off it is perfect. Ive bled my brakes probably 10 times with a power bleeder theres no air coming out anywhere, the car stops very well and with my new girling 60's up front and hawk pads it will pull your eye sockets out it stops so well, but the pedal is absolutely terrible you think its going to the floor and doesnt feel comfortable. I have ss lines all around also. Ive also got a brand new 25mm master cylinder, the only not new brake part is my brake booster.

I was wondering if it has something to do with my vacuum from my manifold. Im using 5\16ths hose from a 5\16ths barb drilled in one of the runners. I was wondering if I drilled all 4 and t'd them together if I would yield better pedal firmness or run a restrictor in my current line or run a bigger line or something because it feels unsafe to drive the way it is right now.

[psychobandito]

Run a restrictor. I had the same problem, i used a pair of vice grips to slowly clamp is shut until it felt ok. i then stuck a small hose inside the larger hose, and it made a bit of a difference.

I haven't really pushed the issue as i'm going to be swapping in a tilton floor mount set-up.

[ncbrock]

I haven't really pushed the issue as i'm going to be swapping in a tilton floor mount set-up.

I dream of upgrading to a wilwood setup one day... and a motorsports shifter, but only dreams so far.
thanks for the info ill try the restrictor out

[bonesaw]

I have my Itbs set up with -4 lines from each runner to a vacuum manifold. It then goes to a 1/2 line with check valve to brake booster

[antichristonwheels]

I drilled a small pilot hole into the intake runner and then a bigger hole only deep enough to hold the brass fitting so my actual opening into the runner is only 3-4 mm. New 21mm master cylinder with 1982 booster, 2000 gti 11.3 fronts and mk4 rears. works good.

[candm]

you only need to tap 1 runner. the problem with your pedal is something else. most people use the scirocco 16v brake booster and master cylinder setup and if you can get the pedal cluster out of the same car that is a bonus

[candm]

i forgot that yours is MK2. i was thinkin MK1. there are alot of braking combinations that work but again, 1 runner is all you need

[ncbrock]

I found some some plastic nozzle with an opening about 3mm and shoved it up the hose and helped a lot I guess I can play around with different sizes and see what's best.

[candm]

do you have a check valve at the brake booster?

[ncbrock]

do you have a check valve at the brake booster?

yes I do, and I tried another one from my other mk2 didnt help the problem. I like the feel with this restrictor but havnt heard of the idea before. The only thing left to replace in my brake system is my booster, but a bad booster would yield a hard pedal. So Im assuming the issue has to be with the way I drilled the hole or the location or somewhere along those lines, because again before I swapped, my brakes were how they should be.

[psychobandito]

I only suggested it because i had the EXACT same problem with my ITBs.

I have great pedal feel and power. Before i had INSANE brakes but no feel at all, it was on or off with a pedal that felt like a marshmallow.

[ncbrock]

I only suggested it because i had the EXACT same problem with my ITBs.

I have great pedal feel and power. Before i had INSANE brakes but no feel at all, it was on or off with a pedal that felt like a marshmallow.

thats the problem I had, with the g60s up front they grab insanely hard once heated up with my hawk pads, its all good now thanks for the tip!

[candm]

im glad their working better but i have never heard of restricting the vacuum line to make your brakes work better. on my rabbit, i have a 16v master cylinder, brake booster and the pedal assembly. i have the #1 runner tapped for vacuum. its probably the same as yours. drilled and tapped for 1/4NPT with 5/16s hose going to a universal check valve i found at a parts store. that valve is a 90 degree fitting that is approximately 7/16s on the side that plugs into the booster and of course, 5/16s on the other barb. my brake setup is G60 up front and scirocco 16v in back. my brake pedal goes down about 1-11/2" and thats it. i cold only guess that your lack of brake pedal has to be with your booster or master cylinder since you say that you have it bled properly. if you had a huge cam it might be a little weaker but it really shouldnt. i run 288s in my setup. as long as the restrictor tip works thats great, but i think it is only masking something not working properly

[psychobandito]

The issue here is not bad brakes, its an extremely over zealous booster. The brakes work TO well. Barely tapping the brakes is enough to almost lock them up.

[ncbrock]

I can always try a different booster but that will be another weekend project. I don't have big cams either. 268 intake and 288 exhaust

[candm]

The issue here is not bad brakes, its an extremely over zealous booster. The brakes work TO well. Barely tapping the brakes is enough to almost lock them up.

his post is about the brake pedal not feeling solid and grabbing way down low. if you have no leaks, have bled the system, have bled the master cylinder and its working fine, have changed the check valve, and the booster is working properly, about the only other thing i can think of is that maybe try adjusting the pushrod on the booster so that it engages a little more. good luck

[ncbrock]

his post is about the brake pedal not feeling solid and grabbing way down low. if you have no leaks, have bled the system, have bled the master cylinder and its working fine, have changed the check valve, and the booster is working properly, about the only other thing i can think of is that maybe try adjusting the pushrod on the booster so that it engages a little more. good luck

hmmmm i had no idea they were adjustable this will be something I have to research!