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Discussion Starter #1
My issue is as follows:


  1. Brake bleeding issue with Hydraboost (shallow style master cylinder for 69 Camaro).
  2. Car is 69 Camaro, Hydroboost from Hydratech, C5 Front Disc/Rear Disc brakes from Touring Classics, CPP MCPV-1 master cylinder (with adapter for shallow M/S).
  3. Primary (closest to the Hydroboost) feeds the rear brake lines and secondaries (furthest from the hydroboost) feed the front brakes lines.
  4. Master cylinder bench bled, has good streams of brake fluid out the primary and secondary on the bench.
  5. Master Cylinder mounted to Hydroboost on car has no fluid coming out the primary, and very little coming out the secondary.
  6. Brake pedal travel is very limited 2-2-1/2". I think it should be almost double that.
  7. Pedal feels like it is stopping hard, there is no give nor does the pedal drop when a bleeder screw is opened.
  8. Pedal also sticks and sometimes does not want to come up. It isn't smooth on the return.
  9. Measured Hydroboost pushrod to M/C pushrod clearance running about 0.050" clearance (aimed for 0.030-0.060")

Seems like I can't depress my pedal enough to depress the M/S piston to push fluid down the lines (least the rear / primaries). Tried for over an hour to manually bleed (slowly push down pedal then open bleeder screw and close then slowly release pedal), no fluid was flowing down the primary to the rear lines. Tried gravity and vacuum bleeding as well no luck.



Thanks a bunch!
 

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Discussion Starter #2 (Edited)
Update:

Its completely new system. New Lines, Master and Hydroboost unit. P/S lines are not connected nor has the car been run and he PS purged of air.

I cracked each fitting on the rear line (I have a 2 piece rear line). I had a little fluid dribble out of the union at the frame rail, no fluid at the hump over to the diff.

I doubt any fluid is getting out there, I mounted the M/S up on the hydroboost but didn't connect the brake lines instead left the bench bleeder fittings in and the hoses up over to the reservoir. That way I could see what volume of fluid was being passed. There was 0 fluid going to the rears and very little fluid going to the front.

I think its either a pedal adjustment issue (wrong hole on the brake pedal, I used the lower one), or something with the pushrod in the Hydroboost not putting enough pressure on the M/S pushrod.

Any ideas or help would be appreciated.
 

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Typically, a band new master cylinder must be bench bled before installing it. It's nearly impossible to bleed a new MS in the vehicle.

Bench bleading requires connecting a tube to the discharge ports and routing them back into the resevoir. Then clamp the MS in a vice and use a screwdriver or other suitable tool to manually pump the MS until the air has been purged. Once the MS has been bench bled, you can install it in the system and perform a standard bleeding process.

It's a real PITA for sure.
 

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Discussion Starter #4
Thanks Dave for the response. The M/S was bled outside the vechile. The reason I kept the bleeder fittings and hoses on the M/S while mounted on the car was to see if I could get a steady stream of fluid out both the primary and secondary. Since I could on the bench I should be able to mounted in the car when the brake pedal is depressed. I couldn't on the car.

I believe I solved the problem. I had the clevis from the hydroboost mounted on the bottom hole on the brake pedal when it needed to be mounted on the top hole. My brake pedal switch was adjusted all the way out which made it difficult to mount. But once I adjusted the switch all the way out, I was able to mount the Hydroboost correctly.

Now I get full pedal travel and a steady stream of fluid out both the primary and secondaries.

Thanks!
 

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Hmmm. I had to fool with the mounting hole on my 68 which originally came with manual drums on the front. The previous owner swapped disks on the front from a Chevelle. Long story short, I found some of David Pozzi's info very helpful (try the brakes forum for a link). I thought the top hole was for manual brakes and the bottom hole was for boosted brakes. Anyway, glad you got it working. You might take a cruise through the Brakes forum looking for David Pozzi's links. He's has tons of useful info on brake systems.
 

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The clevis for hydroboost needs to have as straight of a travel as possible. This usually means that you need to install it in the manual brakes hole in the pedal.
 
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