E36 inline hydro problem

I

Ippeex

New Member
Hi!
I installed hydro to a -98 e36 328 and im having trouble to get the rear wheels to lock.
Cylinder is 0.625 and its installed between master cylinder and abs pump.
Brakes feel solid but handbrake does not lock the wheels and pulling the handbrake pushes brake pedal up and vice versa.
Ive ran close to 5 litres through the system trying to bleed it, tried with vacuum, pumping pedal, pumping pedal and hydro etc.
I have no more ideas other than the abs pump is faulty or a valve is stuck
 
I made new lines from master to handbrake cylinder to rear brakes and its still the same. Tried bleeding with pressure, vacuum and pumping
 
This is probably a master cylinder vs brake cylinder size issue.
There are two ways around it.
1: fit a smaller 0.5" master cylinder or bigger rear calipers.
2: change the pivot point at the handbrake to master cylinder, make the points closer together.
 
oscar said:
This is probably a master cylinder vs brake cylinder size issue.
There are two ways around it.
1: fit a smaller 0.5" master cylinder or bigger rear calipers.
2: change the pivot point at the handbrake to master cylinder, make the points closer together.
Click to expand...
Its hard to find a 0.5 master in here, and it seems like the 0.625 is doing it for everybody else so there has to be something that im missing.
I put in new pads and it really didnt do that much, it locks on wet with decent pull but still not locking on dry
 
Well it's an amazingly simple problem of hydraulics and lever force, there is no mystery.
If your handbrake lever is 3 inches long.. that'll do it.
If your handbrake lever is 6ft long the problem is not there.
If the pivot points are 8 inches apart that'll do it too, especially if your handbrake lever is 3 inches long.
If your pivot points are 3mm apart look elsewhere.
If the master cylinder is 0.625" and your wheel cylinders are 0.150" that'll do it.

So...
l'd be looking closely at lever length vs pivot points.
 
oscar said:
Well it's an amazingly simple problem of hydraulics and lever force, there is no mystery.
If your handbrake lever is 3 inches long.. that'll do it.
If your handbrake lever is 6ft long the problem is not there.
If the pivot points are 8 inches apart that'll do it too, especially if your handbrake lever is 3 inches long.
If your pivot points are 3mm apart look elsewhere.
If the master cylinder is 0.625" and your wheel cylinders are 0.150" that'll do it.

So...
l'd be looking closely at lever length vs pivot points.
Click to expand...
The lever is 490mm? long and the pivot points are about 50mm apart,maybe a bit more.
Master is 0.625 and the rear brake cylinder is 36mm.
Now the handle feels rock solid,maybe too rock solid and the travel is quite short imho.
Maybe its a kinked line. You can still feel the pedal rise when pulling the handbrake
 
Thanks for posting up the specs. Master cylinder vs wheel cylinder size will work but the pivot points must be much closer together for them to do so, probably half the distance you already have, depending on how you like it. If changing the pivot points is not possible it is a longer handle or smaller (0.5") master or bigger brake pistons (40+mm)
 
Be very careful to ensure that the handbrake piston cannot be pushed out by footbrake hydraulic pressure, it is only a circlip that holds it in and it was not designed to have pressure against it.
The safest way is to install dedicated rear calipers with a separate handbrake/master cylinder with integral reservoir.
 
oscar said:
Thanks for posting up the specs. Master cylinder vs wheel cylinder size will work but the pivot points must be much closer together for them to do so, probably half the distance you already have, depending on how you like it. If changing the pivot points is not possible it is a longer handle or smaller (0.5") master or bigger brake pistons (40+mm)
Click to expand...
Ill try with a different pivot point, i can always drill a new one! Thanks!
 
oscar said:
Be very careful to ensure that the handbrake piston cannot be pushed out by footbrake hydraulic pressure, it is only a circlip that holds it in and it was not designed to have pressure against it.
The safest way is to install dedicated rear calipers with a separate handbrake/master cylinder with integral reservoir.
Click to expand...
What confuses me the most is that a friend has exactly the same setup,same master, handle and brakes but his hydro works like a charm.
 
Ippeex said:
Ill try with a different pivot point, i can always drill a new one! Thanks!
Click to expand...
I shortened the pivot to master length by 2cm and the travel is much nicer and it seems to grab better but the brakes tend to get stuck on.
Adjusted the rod length and now the handle occasionally stays rock solid and there is no braking power. So maybe all the air is not out, but wouldnt that make the handle and pedal soft?
 
It is important to remember that fluid flows both ways through the master cylinder.
If the cylinder cannot fully open (rod length too long) it blocks the fluid return hole and the brakes remain pressurised.
The other reason maybe that the lever ratio is now such that it is going 'over centre'
You can tell if this is happening by feel.
The lever will have consistent resistance and then suddenly it will get very easy.
 
oscar said:
It is important to remember that fluid flows both ways through the master cylinder.
If the cylinder cannot fully open (rod length too long) it blocks the fluid return hole and the brakes remain pressurised.
The other reason maybe that the lever ratio is now such that it is going 'over centre'
You can tell if this is happening by feel.
The lever will have consistent resistance and then suddenly it will get very easy.
Click to expand...
Yeah if i calculated correctly the ratio now is 14:1. Ill try something like 11 or 12:1. The feeling was way nicer now but it was really picky about the rod length. It either locked the brakes and stayed on or it was weak and a lot stiffer
 
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