XK-120 Front Brakes Grabbing

We had a brake cylinder leaking on my Wife’s treasured 120 FHC. Of course the linings were saturated with brake fluid. I cleaned them with acetone and alcohol but still have violently grabbing brakes. Any thoughts how to clean the linings or any other BTDT. Of course I can replace the shoes but those on the car are near-new.

TIA

Take a second look at them. The acetone may have been a bit too aggressive. I would think more alcohol, give them a good soak and let them drain off and dry well before putting the drum back on.

I would be interested in how the additional alcohol wash works out. I had a similar problem with my XK120, a leaking wheel cylinder, and was informed by a local chap who runs an MGA that a soak of the shoes in soap and water would do the job. After getting the offending cylinders sleeved and following his instructions I replaced the shoes. On a drive shortly after when the woman in front braked heavily I experienced that particular wheel lock up under hard braking. At that point I opted to get the shoes re-lined. I have also tried brake clean fluid, but once the shoes become impregnated it seems very difficult to get rid of the fluid.

Chris.

If not akready done, it helps to avoid grabbing if you chamfer the leading edge of brake shoe friction material.

Hi Eric,
I would think the soap and water would be a good idea as brake fluid is hydroscopic, and would bond with the water (Assuming you are not running Silicone BF)

Although as per Rob’s comments

…tends to fix most problems, :slight_smile:

I made the assumption that Eric was using isopropyl alcohol. My lab technicians use it for cleaning high vacuum components because it does not leave any residue.

From Wikipedia: [Isopropyl alcohol is also used to remove brake fluid traces from hydraulic braking systems, so that the brake fluid (usually DOT 3, DOT 4, or mineral oil) does not contaminate the brake pads, which would result in poor braking.]

Using it in other ways might cause more problems. :stuck_out_tongue_closed_eyes:

I cleaned the shoes with brake cleaner and alcohol. I am not sure how effective that was, however. Ultimately I boiled the shoes in water and dish soap for about an hour and a half, then dried them in the oven at 150 def F for an hour and a half, then let them set over night. Results, so far are good. I can apply the brakes and take my hands off the wheel and it stops straight.

I had some problem bleeding the brakes (dual master) but it has always been a chore. I ultimately pressure bled. It takes about 30 psi to get flow thru the master, the lines and out the bleeder. Ten psi was not enough.

Many thanks to all for the advice and encouragement here. (smile)

Eric