I give up with brake bleeding

[GregWeld]

7/8th MC is just about all I've ever used... and the brakes have always been stellar! I've put on Baers - Wilwoods - and any number of other combinations.

Did you check the Wilwood MC to see if it's one of their recalled versions??

[vstol]

Originally Posted by GregWeld

7/8th MC is just about all I've ever used... and the brakes have always been stellar! I've put on Baers - Wilwoods - and any number of other combinations.

Did you check the Wilwood MC to see if it's one of their recalled versions??

I will call them tomorrow. So what I am hearing is 7/8ths more pressure than 15/16ths but softer pedal?

[Vegas69]

I'd stick with the 15/16t until you verify it's not a math problem or air. I personally didn't like the 7/8 due to pedal travel.

[vstol]

After I bled the MC I put caps in and checked for air. I could not push the pedal and it did not move after holding it for a while so I feel pretty darn sure the MC is bled correctly. I might re-bleed the system one more time. From what I have learned dropping down to 7/8ths the pedal would be softer.

[vstol]

Anyone heard that the E-brake should be engaged before bleeding the rear brakes. On the C4 it is just using the piston vice a rear drum unit.

[dhutton]

I seem to recall that it needs to be properly adjusted. When they use that style caliper on some swaps you have to unbolt the caliper and rotate it so the bleeder is at the top to get all the air out. Not sure if that applies here.

Don

[vstol]

Just went Tobin (Kore3) suggestion and bought the CPP 15/16ths MC to fit my car then I might go with it boosted if this is not enough which should be fine. Std setup for manual is 1 inch bore. Thanks for all your help, I will let you know how it goes. This retired Marine has had enough.

[rustomatic]

It might be a dumb theory, but I get the sense that adjustable proportioning valves make effective bleeding much more difficult, especially if the valve is set to close off one end of the system when you're bleeding. I say this because I've only had problems bleeding systems that have adjustable proportioning valves. With my current system (mostly new steel lines/bends/masters/pedal), which has no adjustable valve (dual masters with balance bar instead), basic gravity bleeding actually worked the first time (as far as I can tell at this point). I was so happy to avoid that stupid compressor suction setup . . .

[Hydratech®]

FYI - I see people spending all kinds of money on expensive master cylinders, swapping them out for different bore sizes for test purposes to see what / if any improvements are to be had (brake feel tuning purposes). Here are some super low cost OE GM MC's that you should be aware of to use for initial bore size swap out test purposes:

7/8" bore manual brake: RAYBESTOS MC39027
(1977 Chevy Monza)
WARNING: This MC does NOT have the deep MC pushrod hole. You CAN drill the piston for a deeper pushrod hole, use a rubber boot to make sure the brake pedal rod doesn't accidentally fall out, or rig up a brake pedal rod retainer of sorts.

http://piratejack.net/master-cylinder-manual-rod-boot/

Here you can see how www.mpbrakes.com (Master Power Brake Company) takes late model MC's that are equipped with the short rod / shallow MC pushrod and then drills them for the deep pushrod hole for manual brake usage:

https://www.mpbrakes.com/images/MC39...earM-Large.jpg

BTW - You are looking at a 2000 +/- model year US S-10 MC that has been drilled for manual brake usage in the image link above.

15/16" bore manual brake: CARDONE SELECT 131639
(1977 Chevy Malibu - deep MC pushrod hole)
(Baer used to supply these with their braking systems years ago)

1" bore manual brake: CARDONE SELECT 131371
(1968 - 1976 C3 Corvette - deep MC pushrod hole)

Once you prove out what MC bore size you may like best, THEN spend the money on a "bling" MC if desired.

Oh, and the general rule with GM MC's is the 1/2" port is for the front brakes, and the 9/16" port is for the rear brakes (mentioning this because some MC's are reversed from others as far as which port is which). There are some exceptions...

[vstol]

If I keep the push rod in the manual position vice pwr on the stock pedal it will just make the brakes very sensitive correct? So 5.7:1 vice 3.5/4:1?