412 master celinder

[eddydw_za]

Can you please help with the exploded view of the master cylinder.and the correct way the seals must be fitted

I had it received and the so-called professionals fit the seals ?
I think it was assembled wrong ? my problem is the brakes are very low and I can just about press it to the floor & if I open one of the brake bleeders there is no brakes at all. That doesn?t seem right, as it is suppose to be a dual system???

[ray greenwood]

Eddy....the correct seal poistions depend on who made the cylinder. FAG and Teves are the two main cylinders. Schafer made rebuild kits for both and each has differnt cups in the schafer kits. The main thing to remember is that the seal with the second set of lips is the outer most seal. This is call a shaft seal. Depending on which cylinder, there should be two cups on the outer piston and two on the inner piston. I believe they all face the same direction...inward. At the botom end (inner) of each piston ( I'll look in my books tonight), there should be a smooth brass shim under the seal...covering 3, 4 ,or 6 little holes. The shim must be smooth...no grooves or corrosion. You can clean it on a whetstone...or 2000 grit sandpaper. The area it sits on with the holes must be very smooth ...no pits, no corrosion. If any of the seals...other than the outer shaft seal, double lipped one, have shorter "skirts"...these seals go on top of the brass shims/valves. Also check under the grommets where the fluid resoivoir plumbs in. Make sure the very tiny holes (theres a large one and a small one under each grommet) have both been drilled through...full size ...into the new liner. If not, the master cylinder will not work. One is a replenisher...one is a metering port. If a long skirt seal is used in the wrong place, these orifices will be covered up by the "skirt" of the cup....and it will be difficult to bleed. If new pistons were used....they HAVE to be identical to the original in every respect....every measurement!!! Type 3 pistons will NOT work. They cover up the metering ports. The old pistons shoild have been re-used. You can use type 3 seal kit...no problem, but not the pistons. Check these things. It could simply be the bleeding process. Type 4's are hard to bleed from scratch. Lots of twists and turns. Ray