Hi,
Maybe Brake master cylinder differences has been discussed before in various posts..
My 2008 Territory had developed that 'sinking feeling' of the pedal slowly sinking to the floor, (without fluid leaking out anywhere), so I desperately had to repair it today. It isn't so cool to drive with barely any brakes
I knew there were some differences, between BA, BF, SY, SZ and FG, but I thought I would have something in my collection to swap over, that would work, but guess what: I was wrong! ... and I wasted half my day on it too.
Type 1: Angled bolt pattern onto the brake booster. Small fitting for the tube closest to the booster. (Found on BF year 2006, incl. F6 Typhoon)
Shaft from booster goes about 15mm deeper into this master cylinder than type 2 below.
Type 2: Angled bolt pattern onto the brake booster. Identical larger tube fitting for both connections. ( Found on my SY 2008 ). Has a bras nut on the side near the brake booster,
Type 3: Horizontal bolt pattern onto the brake booster. Identical large tube fittings for both connections. Found on 2010 FG, an Territory SZ. (Probably all the FG range and SZ range).
Note: There may be other important differences that I'm not aware of, for example different pressure ratio for the rear, so please be careful when ordering brake parts for your car, The lesson is: Don't mix and match like I tried today..
This is how I wasted my afternoon, without too much luck:
My first attempt: Grabbed both the Booster and Master from FG, (Type 3 above), and tried to install it in my SY Terri. I though this should work since both have DSC, and both have the same sizes tube connections.. Nah, pedal was a little lower positioned, but shaft from booster returned to end position, so I thought it would be ok, Swapped the sensor on the reservoir, and attempted a test run: No luck, brakes remained on quite stiff after braking, so that unless my master cylinder was faulty, that does not work!!
Second attempt: Swap back to the original SY booster with angled bolt interface, (described as Type2 above), but I grabbed just the master cylinder from a BF F6, No luck, the rear tube didn't fit.
Third attempt: Desperately wanted this back together and working today, so I thought: Let's dismantle both the Type1 and Type2 master cylinders, find the fault and possibly swap some seals or parts over, since both are PBR make, and both looks same size.. I thought there can't be that many differences inside. How wrong I was! After removing the reservoir and pulling the 'pin' out from one of them from the hole where the reservoir sat, the thing popped apart and splatted brake fluid all over my clothes, so I had to quickly wash and change. Not a good start. That master was clean and nice, couldn't see any wear or problems. Got the next one, my original 'problem' master cylinder apart also. All the pistons and springs were totally different. The only thing in common is that they fit in the same housing, except the depth of the rod from the booster goes deeper into the piston, so it wouldn't work to swap internals around. Besides the type with small brass screw cap near the booster has two pins holding it together, and two bleed valves, (one for each circuit). The 'problem' master had quite dirty fluid, some small dirt particles in it, so I recon that was the problem that the dirt had caused the small 'bleed' valves that open when you return the pedal to neutral didn't seal. These sit in the center of each of the two circuit pistons.
I had in a way given up at that point, so I re-assembled it, and put back the original one, as I thought I had to order a new one, and wait for that, but wanted to be able to slowly move the car around at least while waiting for parts.
I topped up fluid and did a few pumps, and suddenly it seems to not 'sink' anymore. Then I thought: This is going surprisingly well, so let's drive from A to B, no problems, 'fixed'.. I hooked up the trailer and started driving, I thought, much better than before.. However, not far from my house, empty road, I did a test to see how well it would stop. Crap.. It braked mostly on the back so I could feel the rear end lowering down while braking, way to little breaking at the front.. Hmm.. In the rush I had swapped the two tubes around. On Territory the both tubes reach each position, and they are the same size. I assume the 'thing' next to the master pistons is a pressure regulator for the rear circuit.
So the lesson is: Next time I will order a new part exactly for the model.
Interesting if any of you can confirm how many types of brake master cylinders there are, and if you have done similar swaps that actually worked.
Cheers,