brake line setup

[rmicroys]

... but the search didn't provide the answers I was looking for.

I've seen some threads discuss the differences between keeping the OEM diagonal braking line steup, vs having the fronts on one m/c cct, and the rears on the other. So, it really doesn't sound like a good idea to run both front calipers off one side, and the two smaller calipers off the other - mainly because the volume differences. They are sized to be diagonal - so I figure then if the setup is changed, one will need more pedal travel to get the volume to the fronts, and thus too much pressure goes to the rear.

I'd like to know if anybody has actually experienced both, and which one produced the most reliable, consisent brake feel. I just got a tilton adjustable brake bias lever, so I'm going to have to change my setup. I'm just wondering if I should leave it in the diagonal mode - that is the way that I'm leaning. I understand how to tee the lines together up by the m/c, then go through the bias adjuster, locate it near the shifter area, and then take a line back to the rear axle and tee it there again.

Other comments?

[VW16VRacer]

I have both rear lines tee-d into the tilton then back to the rear calipers. I guess you might say it is still the diagonal because the fronts are still off the oppsite chambers. The pedal feel is good. I used as much hard line as possible to miniumize line swell.

Jon

[racer14itc]

Originally posted by rmicroys@Jan 23 2006, 02:46 PM
... but the search didn't provide the answers I was looking for.

I've seen some threads discuss the differences between keeping the OEM diagonal braking line steup, vs having the fronts on one m/c cct, and the rears on the other. So, it really doesn't sound like a good idea to run both front calipers off one side, and the two smaller calipers off the other - mainly because the volume differences. They are sized to be diagonal - so I figure then if the setup is changed, one will need more pedal travel to get the volume to the fronts, and thus too much pressure goes to the rear.

I'd like to know if anybody has actually experienced both, and which one produced the most reliable, consisent brake feel. I just got a tilton adjustable brake bias lever, so I'm going to have to change my setup. I'm just wondering if I should leave it in the diagonal mode - that is the way that I'm leaning. I understand how to tee the lines together up by the m/c, then go through the bias adjuster, locate it near the shifter area, and then take a line back to the rear axle and tee it there again.

Other comments?

71679


Just be aware that when you 'tee' the lines in this manner, you no longer have diagonal braking. If you lose a brake (caliper seal or piston seal for example) you will have NO braking at all (since both chambers in the master cylinder now are open due to the "tee"). :119:

The better way to do it is to use two tilton proportioning valves, one for each rear brake line.

MC

[shwah]

I run both fronts off the front half of the MC, and from the rear half run a single line through a pressure reducing valve then a tee to the rears. The 4th hole has a plug in it. Pedal feels fine for me.

[racer14itc]

Originally posted by shwah@Jan 24 2006, 01:50 PM
I run both fronts off the front half of the MC, and from the rear half run a single line through a pressure reducing valve then a tee to the rears. The 4th hole has a plug in it. Pedal feels fine for me.

71852


Been there, done that. Just remember that the pistons in the OEM master cylinder were sized for one front caliper/one rear cylinder combo. The calipers use WAY more fluid than a wheel cylinder. So when the pads get a little taper in them, or things heat up and expand, it's possible for you to run out of pedal travel because the fluid displacement in the master cylinder isn't enough to generate full pressure on the pads/shoes.

If you keep fresh pads in the calipers you'll be fine. If you don't...well let's just say there are a few Hondas out there with a little rear bumper damage from a certain ITC Scirocco... :ph34r:

MC

[rmicroys]

Thanks for the replies. Yes, I think I will agree. Teeing the rear lines, particularly if they are still dual diagonal will eventually result in complete brake failure with a leak anywhere in the system. With at least the split master front to rear one will at least have 'some' brakes. Because I don't want to spring for dual levers (yet - but that would seem to be the best way to do it with the OEM brake pedal and M/C setup) or tilton dual m/c pedals etc... I'm going to try it with the front brakes on the front of the m/c and the rears off the back for next year and see how it goes. Next year will be a rather limited season for me - I'm building a new house, so funds will be limited for me. I'll likely only be able to make a few events. :(

[shwah]

Originally posted by racer14itc@Jan 24 2006, 02:02 PM


If you keep fresh pads in the calipers you'll be fine. If you don't...well let's just say there are a few Hondas out there with a little rear bumper damage from a certain ITC Scirocco... :ph34r:

MC

71854


Great point. Probably a good idea to consider a spacer behind the pad as wear increases. Maybe just some old backing plates. Just brainstorming.

[psykokid]

Been there, done that. Just remember that the pistons in the OEM master cylinder were sized for one front caliper/one rear cylinder combo. The calipers use WAY more fluid than a wheel cylinder. So when the pads get a little taper in them, or things heat up and expand, it's possible for you to run out of pedal travel because the fluid displacement in the master cylinder isn't enough to generate full pressure on the pads/shoes.

If you keep fresh pads in the calipers you'll be fine. If you don't...well let's just say there are a few Hondas out there with a little rear bumper damage from a certain ITC Scirocco... :ph34r:

MC
[/b]

I was thinking about this the other day, as we're getting ready to re-plumb the braking system in our 84 rabbit and use rear discs. While the m/c for the earlier cars was sized for 1 caliper / 1 drum brake cylinder, the 16v sciroccos/mk2/mk3 cars with front and rear discs should have a better balance as far as the M/C goes. expecially the earlier cars with 9.4 fronts and 8.9 rears. I'll need to measure the piston diameters in the front vs rears but it shouldnt be a terribly large difference between the two.

So thinking along these lines: How about using the later 22mm master cylinder and keeping the front brakes on the front half of the M/C. Then plugging one port on the rear half of the M/C and running a single line to the manual prop valve and then a T fitting after that to split the lines to the rear discs. Since that later m/c is designed to move a larger volume of fluid vs the earlier style you think the running out of pedal bit would still apply in this situation?

[JamesB]

well I would have to double check my manual for mk1 but I believe that scirocco used the 22mm for all disk but I believe the lines where setup the same way. What I would do is just remove the rear two lines and reroute them into a T that runs through the cabin to adjust brake bias and then out the e brake holes and T back out.