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tamo3

Disk brake conversion: 280zx rear caliper bleeding problem

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Thanks Miles for pointing out for posting wrong forum.

 

create new topic here.

 

Hi,

 

I have a problem to find out right size bleeder nipple for 280zx rear caliper conversion.

I read several thread that I need to swap brake line and bleeder nipple in order to put nipple higher position than brake line for bleeding.

So, I swapped brake line and nipple input location.

 

However, the nipple won't stop bleeding.

I tried Russell's Speed Bleeder (6393630 10MM x 1.00) but result is same.

 

I changed caliper twice (purchased from rock auto) and still same issue.

 

Does anyone have clue?

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5 minutes ago, tamo3 said:

I have a problem to find out right size bleeder nipple for 280zx rear caliper conversion.

I read several thread that I need to swap brake line and bleeder nipple in order to put nipple higher position than brake line for bleeding.

So, I swapped brake line and nipple input location.

 

However, the nipple won't stop bleeding.

I tried Russell's Speed Bleeder (6393630 10MM x 1.00) but result is same.

 

I changed caliper twice (purchased from rock auto) and still same issue.

 

Does anyone have clue?

 

"the nipple won't stop bleeding" doesn't make sense.  What do you mean?  Maybe you could rephrase the question.

 

It does sound painful though...

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Hi Miles, 

 

Even though I tightened bleeder nipple as tight as I can, brake fluid keep coming out when I press brake pedal.

 

L_Bleeder_swapped_location.j.thumb.jpg.efc12c4d22fe4e081bd8bc833d6f052f.jpg

 

So, I swap back nipple and brake hose input to original location.

 

L_Bleeder_original_location.thumb.jpg.34479abd1318c5c1d680c7de3b5d47fd.jpg

 

I put brake caliper flat to make nipple facing up to bleed air, then mount it onto the maxima bracket now.

 

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The bleeder leaking and the position of the  caliper are not related.

 

Possible reasons a bleeder will leak after tightening it:

 

  • Wrong bleeder (but you have the correct bleeder)
  • Bleeder is damaged e.g., bent/smashed etc
  • Bleeder and or caliper threads are damaged
  • The seats are damaged or obstructed with dirt/metal/etc
  • Bleeder is in the wrong hole.

 

Post a clear sharp picture showing where the bleeder and brake line is installed on the caliper.

 

You do not have to over tighten a bleeder. Just close it and snug it down easy.

Edited by Miles

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It might help to get in to the details of how the bleeder screws work.  There's a narrow cone shaped seat on the bottom of the screw that plugs the hole in the caliper.  When you loosen the screw the fluid is released and flows in to the small hole next to the screw seat then up through the middle of the bleeder screw.  All that matters for stopping leaks is how the cone shaped seat fits in to the hole.  Reman calipers often have poor seats for the screw.  So inspect the hole carefully, and make sure that the seats are clean and smooth.  You should not have to tighten the screws very much if the sealing surfaces are in good shape.

 

Here's a picture I stole from the internet and where I got it.  I don't know if I agree with the guy but he takes a good picture.  I added some red lines to show the gouge in the screw from where it seats in the caliper.

 

http://www.eatsleeptinker.com/2014/05/15/brake-bleed-valves/

 

 

image.thumb.png.ee62751efea99b4d3327a99ef9928c4d.png

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Another view of how a bleeder seals when tightened. 

 

Note tapered portion of bleeder screw and the tapered seat inside the  bleeder passage.

 

When the tapered part of the bleeder and the seat mate and are tightened the bleeder is sealed.

 

If the mating surfaces are damaged,  or dirty , the seat and bleeder screw will not seal.

 

cimg7183_1024x768__e6bf1d225cd68d1b633d440fba03b2714c921bee.thumb.jpg.58f7024488f6b60c767dd0f78f6b2d31.jpg

Edited by Miles

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Thanks NewZed and Miles.

 

The speed bleeder nipple is so short. and DORMAN's OEM version is a bit longer than original.

I tried both to put it into the brake hose port. It looks like both bleeder nipples not even touching at the tapered section at all.

 

My guess is brake hose port does not have tapered port. I will check other 280zx caplier's brake hose port.

 

Thanks!

nipple.jpg

speedBleeder.jpg

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I made some notes on the  picture you posted.  The bleeder is pointing up as it should be.  Check the brake hose and make sure that  as the suspension moves the hose does not rub on the frame. 

 

It doesn't look like you have connected the parking brake cable to the caliper. Also, I don't see the parking brake bracket installed on  the caliper. 

 

Suggest that once the hose and parking brake cable are connected that you place a floor jack under the control arm (below the strut) and move the suspension up and down slowly checking for  the brake hose or parking bracket hitting the frame.

 

As far as the bleeder leaking issue goes,  check the internal bleeder mating surface in each caliper. If the mating surfaces are damaged or not machined correctly return both calipers and replace with  a different brand. 

 

Re-manufactured and even new  brake parts can be defective right out of the box. For example:

  • Maxima Calipers full of rust inside.
  • Caliper piston seals that leak the first time pressure is applied.
  • Wilwood brake master cylinders that leaked internally.
  • Wilwood master cylinder bleed screws that were deformed and wouldn't seal.

 

 

280zxCaliper.thumb.jpg.260f885cfb2a661a48e9d62b1196bda8.jpg.097700e32ecdc657cdfe5aec9024077c.jpg

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3 hours ago, tamo3 said:

Thanks NewZed and Miles.

 

The speed bleeder nipple is so short. and DORMAN's OEM version is a bit longer than original.

I tried both to put it into the brake hose port. It looks like both bleeder nipples not even touching at the tapered section at all.

 

My guess is brake hose port does not have tapered port. I will check other 280zx caplier's brake hose port.

 

Thanks!

nipple.jpg

speedBleeder.jpg

 

 

Did the bleeders come with the calipers? If so they should work unless the seats are damaged.

 

Where did you buy the calipers?

 

Did the calipers come with parking brake brackets?

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Thanks Miles.

The mystery is solved.

 

The bottom of the brake hose port is not tapered at all. I can see the brake piston.

990704151_Photo15-01-1991849AM.thumb.jpg.6e6b2ff0493a998a7049ab6ffc646fef.jpg

1929019211_Photo15-01-1991834AM.thumb.jpg.6414b9ba7cf8518d7573e3160a372f46.jpg

 

The nipple port has tapered end at the bottom.

406350852_Photo15-01-1991909AM.thumb.jpg.95c1bf05998d15ffb477eef12983190c.jpg

 

That's why no matter what nipple I use, no matter how hard I tightened in it did not stop bleeding when I swap nipple and brake hose port.

I thought I read somewhere internet someone suggest to swap ports in order to correctly bleeding....

 

Anyway, thanks a lot of your help!

 

By the way, I purchased rebuild caliper from RockAuto "A-1 CARDONE" brand. It's getting better quality compare to before. It's powder corted with shining silver and internal is also looks clean now.

 

R_Bleeder_original_location.j.thumb.jpg.93286754a914faeaaa457dc17f78cd8f.jpg

 

I haven't hooked up Ebrake cable yet. I replace original cable to 280zx cable since the e-brake cable end shape is different.

 

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If you are not experienced with brake work there will be more challenges ahead for you doing this brake swap.

 

In the interest of public safety and your own safety,  I suggest that you consult with an experienced brake mechanic before going any further. 

 

Also, before you put the car on the road you should have  a brake mechanic check the installation to make sure that the brake swap is safe.

Edited by Miles

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