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jersey280

Brake bleed HELP PLZ?!

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Hey guys,

 

Own a 76 280z which I recently competed the Toyota 4x4 brake swap on. Additionally, I swapped the master cylinder with a 280zx for better pedal feel. All items are new refurbished from Rockauto. It was my first time "bench bleeding" a master cylinder, didn't seem too difficult and I did my best. I reinstalled the MC and for some reason I cannot seem to bleed these brakes. I have used the 2 person technique and I have the 1 person hand suction pump. I slowly move fluid from the MC reservoirs using the hand pump but I cannot get it to go to solid fluid, its always an air fluid mix and unable to get a pedal.

 

I have read online that just incase I had completed the bench bleed of the MC incorrectly, that I would still be able to bleed the brakes. Is this not the case with our car? Am I missing something here? Did I get trash parts from Rockauto? Any help or ideas I appreciate, Thanks so much!

 

-Jersey280

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Describe the procedure you used to bench bleed the MC.

 

What is the brake set up on the rear?  Some rear brake "upgrades" place the bleed screw at an angle making it impossible for  air to escape the caliper.

Edited by Miles

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This is the last refurbished caliper I got from Rockauto,  it's always worth dismantling their stuff to find out what you really bought.

attachicon.gifDSCN0467.JPGattachicon.gifDSCN0469.JPG

 

Same thing happened to me. I bought rebuilt Cardone 240SX rear calipers from O'Reily's. They were both filled with rust as if they had been submerged in water for a long time.

Edited by Miles

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If you are continually getting air and it never purges there is an air leak somewhere. Does the brake pedal pump up at all? If so, pump it up and hold it down whith pressure in the line and see it if sinks slowly. This indicates a leak. Next, inspect the enitre brake system for leaks at each joint and compoment. If there are no fluid leaks the master is bad.

 

As mentioned, caliper mounting with caliper swaps sometimes leads to an arrangement that requires taking the calipers off and holding them with the bleered at the top to properly bleed them. Also, on occassion the left and right calipers get installed on the oppsosite side which places the bleeders at the bottom causing air to get trapped in the calipers.

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Also don't use the one hand bleeder pumps, if you have a leak in the system it will just pull air in through the leak, alternatively it can pull fluid from another line with the Tees if the route to the master is really long. 

 

Once you get the system setup again do the double bleed. Get two containers, fill the bottom by an inch or so of clean brake fluid and put it on a box so your hose isn't super long, make sure your hose is fully submerged in the fluid. Crack open both lines either both fronts or both backs and keep pumping. If you do it correctly any bubble gets pushed through the line and bubbles into the reservoir, then when you let off the brake it pulls non bubbled fluid from the bottom of the reservoir. Keep doing this until you don't see any bubbles come up. I use some cut water bottles and just put one foot in the car so I can monitor one side. Once you have successfully purged the system you can bleed the system one side at a time to get good clean fluid in there. Repeat for the other circuit.

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If the reaction disk fell out of the booster, that will leave you with no pedal. It's a little rubber disk that fits in the booster. Search for more info if needed.

 

A different way to bleed is to push fluid through the system backwards. I recently used a 50cc syringe with a bit of bleeder hose on it and opened the bleeder on the master and pushed fluid into it to fix my clutch which wouldn't bleed correctly the normal way. Used same method to bleed an entirely new system (masters, hard lines, SS lines, and calipers) when regular method and mityvac weren't cutting it.  Pushed fluid into the calipers, then did the masters last.

Edited by JMortensen

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This Motive Power bleeder is what I have been using to bleed brakes for about 12 years.  Works good. 

 

I use the 0251 model  kit that has the universal MC cap, but one of the other kits may have a cap that fits 240Z, 280Z, 280ZX and Wilwood MCs.

 

https://www.motiveproducts.com/collections/import-power-bleeder-kits

 

 

 



  Edited by Miles

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Interesting, I've never had to do that with my brakes, but have had to do that with my clutch slave. Is 50cc enough to push air all the way back to the master? Or do you have to rebuild part way through?

I just pushed fluid back on each bleeder and kept filling the syringe as necessary. You can just pull fluid out of the master so it doesn't overfill. I think 50cc probably is enough to push air all the way back if you have some fluid in the calipers already. I didn't do this dry, I did it after the normal method and the mityvac failed to solve the problem.

 

I think sometimes you get a bubble that just won't move when you push the fluid through in the normal direction. Doing it backwards can get the bubble moving in that situation.

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