DSE Brake booster

[RamAir]

Thanks Tobin for sharing your expertise.
The video shows the behavior of the MC when the outlets are not connected to brake pipes (tubing direct to the reservoir). With it connected to the brake pipes I could press the pedal almost to floor
With the engine off the pedal also moving slowly but not as slow as with the engine on. I appreciate the Bendix document that you added. I will do the bleeding procedure tomorrow.
Since you are on this thread I have a question. I will order brakes from you soon (325 mm GMSS or AFX-kit) but I observed that the KORE3-Logo C6 std caliper are no longer available (according to your website). Should I go with Corvette C6 or are the C5 Kore3-logo strong enough.

[Apogee]

Okay, that explains the stroke versus effort on the master cylinder.

PBR discontinued the C6 2-piston front calipers for the aftermarket without any notification when they shifted production of these part numbers to the US under Akebono's direction. I've been told that they didn't include the tooling for the "generic" calipers when they moved these production lines from Australia, however they machined the faces of the C5 calipers for years without any issues as they did not have dedicated tooling for the non-logo versions, so I'm not sure why they can't or won't do the same with the C6 variants now. The best way at this time to get the C6 calipers is to opt for the GM "Corvette" logo'd option if you want the added 25% to 30% rigidity over the C5 calipers. That said, the C5 calipers are still excellent calipers and are more than strong/rigid enough for all but the most severe-duty applications.

Tobin
KORE3

[andrewb70]

Tobin,

Are you aware of any quick take-up MC that has a deep hole in the back of the piston for use in a manual set-up?



Andrew

[Apogee]

Tobin,

Are you aware of any quick take-up MC that has a deep hole in the back of the piston for use in a manual set-up?

Andrew

I am not, but have had the same thought and done some research without any success. Machining the piston wouldn't be all that difficult, although it would require disassembly of the unit and there's always a risk associated with such operations. An alternative might be to make some sort of spacer/guide to be mounted between the firewall and MC and then run a longer pushrod...it seems like it could work in my head anyway.

Tobin
KORE3

[TnBlkC230WZ]

Bench bleeding is just that, bleeding on the bench. You need to have the master cylinder level to get all the air out. You can do it in the car with manual brakes, but not power.

I have one in my Nova and it works very nicely on the road and track.

[JD'sTT55]

I second Tobins post. The quick take up cylinders can be a bear to bleed sometimes. Once you've bled in the vice w the tubes. Blocking the ports w plugs further confirms all the air is out of the quick take up valve. Upon pushing the piston it should only move slightly with a little fluid flow into the reservoir and firmly stopping. Any sign of air bubbles into reservoir or spongyness indicates some air is still trapped in cylinder.

[RamAir]

So I have not been successful with my new MC/BB. I Have done the bench bleeding according to the Bendix procedure that Tobin provided me with (Thanks !). The pedal is firm, but it will still not release instant. I have now mounted the brake booster in the vise without the MC attached to the BB. If you look at the the video on youtube, http://www.youtube.com/watch?v=y1fAzOc5Fdw as you can see the push-rod will return somewhat slow to its default position. Is this normal or is something wrong with the BB.

[JD'sTT55]

The video of the booster action appears normal to me. Compared to the many I have replaced. Also one other thing to check would be your rear shoe adjustment excessive clearance could cause a low pedal.

[JD'sTT55]

I am unsure of the method you are using to bleed your brakes but I have found that sometimes the pumping the pedal method causes the air to break up in smaller bubbles and harder to get out. What has worked for me was to have a buddy help. I would open the furthest bleeder from the master cylinder first and have my buddy slowly depress the pedal to the floor and I would close the bleeder when he hollered that it was at the floor. Then he would allow the pedal up slowly and repeat at each cylinder Until no air bubbles were seen and a firm pedal was obtained. Which with no vacuum from the engine should usually be just a small amount of pedal travel. And when the engine is started should only drop a little with the assist. Sometimes I would leave the cylinder cap off as to not create a suction on the reservoir side as I was displacing so much fluid. Just dont push the pedal fast or hard with the cap off or it will make a mess. Been there done that. Hope this helps.

[RamAir]

Since it so difficult to bleed the system should I invest in a power bleeder just to be sure that no air are trapped.

[TnBlkC230WZ]

Since it so difficult to bleed the system should I invest in a power bleeder just to be sure that no air are trapped.

They do make the job much easier.