Bench Bleeding New Calipers Before Installation

[Miles]

Had to replace the 240SX rear calipers on my 240Z this week.  Had a brain fart idea that worked.

 

Bench bleed caliper method:

 

Bench bleed the calipers before installing them:  While prepping the new calipers I noticed my MC bench bleeding kit on the bench. The fittings used for the MC will also fit the caliper. I used the fittings/hoses  from my MC bench bleeding kit (O'reilley's)  plus a huge syringe I found at a grocery store. Connect the syringe with hose to the speed bleeder. Screw in  a plastic push-on hose fitting (from a bench bleeding kit) into the inlet of the caliper with a hose to a bottle to catch the fluid. Push fluid into the caliper with the syringe being careful not to push any bubbles in the hose into the caliper. Once the caliper is full, and no bubbles are seen, close the speed bleeder and plug the inlet with a M10 x 1.0 bolt. I was amazed at how much air flowed out of the caliper. It took about three full syringes of fluid to get all of the fine bubbles out. After installing the calipers (see procedure below), and doing one side at a time, it only took three pumps to get a firm  pedal for each caliper.

 

Steps:

• Bench bleed calipers being sure to tighten the speed bleeder and install a M10x1.0 bolt in the  caliper inlet when done  to keep the caliper sealed.
• Fill MC reservoir with fluid.
• Push brake pedal with your hand and block it in place with a stick between the seat  and the pedal. This blocks the fluid return port in the MC so fluid will not flow out of the MC.
• Remove old caliper leaving the flex line attached and hang it from the spring with some wire. This keeps the brake line sealed and prevents any fluid loss while installing the new caliper.
• Install new caliper and pads.
• Move the flex line from the old caliper to the new caliper. Since you blocked the return port in the MC there should be almost no fluid drips from the open flex line.
• Attach hose and catch bottle to the speed bleeder. Open the speed bleeder and pump. The first pump will go to the floor because the piston will move out taking up the slack between the piston and the brake pad/rotor. The second and third pump will firm up the pedal.

 

I just did this this week. It was the quickest brake bleed I have done with Maxima/240SX calipers. No wasted fluid too.

 

MC bleeder kits are available from O'reilley's. They contain a variety of plastic MC outlet fittings, but for some reason only one M10 x 1.0 fitting so I buy two.

Edited July 25, 2020 by Miles
addingpictures

[Twisted46]

Good to know! I just got my Wilwoods in and will be putting them on next week.

Edited July 25, 2020 by Twisted46