Removing Master Brake Cylinder on 1990 Jeep Cherokee (with ABS)

Hmm.... Well both of my XJ's are clear to get at with a socket wrench and an extension from the bottom side or with a box end wrench from the top which would be a PITA but is feasible.

What about a socket, then a universal joint, then an extension?

If worse came to worse, you could maybe go inside and unbolt the power booster from the firewall, unhook the brake rod from the pedal then put the whole works on the bench to remove the MC from the power booster?

Just a couple ideas for you.

Mike

Thanks Mike, but the problem is that this car has the Bendix 9 ABS system. There is no booster. Where the booster normaly sits the actuators for the ABS system sits on my car.

On a car with regular brakes I can see i pictures that sockets or wrenches can be used. But here there simply is no space. I can reach the nut fine ant have tried both an open and a closed wrench. Also tried a socket. But to no avail. No room between the nut and body of actuator assembly.

Have in mind to loosen the bolts from the inside under the dash. I think that the bolt possibly have a nut also on the inside. Can feel something on both sides of the brake pedal that I think is the same two bolts that holds the MC and it feels like there is nuts on that side to. Cant say I look forward to the yoga sessin reaching then.... :-)

But I am sure there is a procedure for this job. But my Alldata CD and my Haynes does not cover that in detail.

regards Odd-Inge Larsen

Well, I have checked further.

a) the Master Cylinder is fastened with two bolts to a golden colored plate in engine compartment. b) Plate is fastened to torpedo-wall by maybe 4 bolts with nuts inside under dash. Theese bolts also holds the pedal assembly under the dash. c) Dont see it as reasonable that whole plate, pedal etc should have to be removed. And according to manual it should not be nessecary. d) The two nuts holding the MC is plenty reachable. One of the nuts is OK to unfasten. No problem. But an open ended spanner can not fit on nut closest to fender because it is to bulky in the end bit. It buts against MC body on one side and actuator assembly on other side. e) A ring spanner will not fit because the gap between the bolt sticking out of the nut and the actuator assembly is to small. f) A possible solution could be to destroy a ring spanner, making it sort of open ended. The type you normaly should use on brake lines. It could fit and if it still is strong enough to loosen the nut it should give me room for unfastening the nut, but I probably cant turn it more than 1/8 of a turn with each take... The ring spanner is much slimmer than a normal open ended (box?) spanner.

regards Odd-Inge Larsen

A new update. On closer inspection my f) solution can not be used. This is because the nut itself is to thick to pass between the bolt and the actuator assembly. And even worse the MC itself cant be threaded of the bolt end because it will not pass the actuator assembly.

My guess then is that step 1 must be to loosen the actuator assembly. But I cant see any bolts holding that on.

Much appreciated if anybody with a Jeep service book could look up this procedure for a Jeep Cherokee 1990 with Bendix 9 ABS brakes (fingers crossed).

regards Odd-Inge Larsen

It seems that Mike's solution, removing the four nuts inside under the dash could be the only way forward. Assuming that the actuator assembly and the MC is fastened to the golden plate inside engine compartment and this plate is hold in place by the before mentioned 4 bolts. There is no obvious way of doing this as far as I can see other than removing the whole lump og MC+Master Cylinder, proportioning valve, accumulator and so on so one could disassemble it on a workbench.

Odd-Inge Larsen

The best description I could find in my 91 pdf says you have to remove the combination or proportioning valve 'before' you can remove the MC.

Mike

Odd->

Just for info. Got it changed. Had two loosen the four nuts under the dash, the three brakelines (FL, FR, R), the elecric connectors and the punmp and pump return line. Also the bolt that connects the brake pedal to the MC rod. Removed the water tank for the wiper washer system for better access.

When all this was removed the whole assembly could slide out (bearly) and be worked on on the workbench. Then one had to loosen and push away the actuator assemblu to get the MC loose. A good 8 hour work in total but much of this scratching my head :-)

Odd-Inge Larsen

Thanks for the follow up. I kinda had the feeling the whole works had to come out.

Mike

Odd->