Final Brake Bleeding and adjustments

FWIW, I've been told to generally bleed from longest to shortest, and that has worked successfully for me on Panteras.  Technically my current JFZ system does revert back to a spongy pedal a few minutes later, but those JFZ systems are notoriously that way--I need to re-research the best way to get those to a hard pedal, as I recall that involves something like rotating the calipers, wood blocks and such while bleeding.

It might be helpful to temporarily install a known working master cylinder.  If you do not have one, send me a PM and I might be able to help with one that includes the hard lines.

Hello,

I had the same kind of problem as you. I had reversed the 2 rear calipers.........

Make sure you don't have any residual assembly grease from the caliper rebuild gunking up the bleeders. That was my problem, I thought all air was out, but the pedal was soft. I used a pressure bleeder and whilst under pressure, took out each bleeder, gave the caliper a quick clean with a Q-tip where the bleeder screws in, and then put it back in, and changed bleeders for new ones in some cases when there was greeae inside. Messy, but solved my problems. Watch the reservoir if you use a simple pressure system, so you don't run it out of fluid...

Cheers, Tim.

After sitting for 30 years I expect a few solidly plugged areas. I have had to DRILL out some bleeders and ports to remove solidified varnish. Check visually and with wire probes for clear areas. I've also had to do this to the cam bearing oil feeds on older engines, especially those with oil feed restrictors.This in spite of boiling blocks out in very hot solvent washers. Age hardened varnish is very tough stuff!

With the movable shuttle valve and the movable non-adjustable stock proportioning valve, I doubt if a rock-hard brake pedal is possible even if perfectly bled. Thats one reason why I deleted both in my Pantera back in the last century. Others gut those parts for a more stable platform with the stock look. You will almost always feel moving parts inside any hydraulic system. Manual adjust proportioning valves have no spring-controlled movable parts, and all the shuttle valve does is turn on a red dash light if one caliper somehow develops a leak.. Which a perceptive driver will see in low fluid level during "preflight" look-overs anyway.

+1 on reversed calipers. I know it sounds  so unlikely that it can't happen but I have seen it done twice with a lot of red faces shortly afterwards. Easy check is that nipples are at the top.

Did u bleed both bleeders on the front calipers?

Yes.  The bottom ones first and then the top ones.

I put completely new front and rear calipers on. It took just over 1 quart of Dot 5 fluid to get the purple out of the bleeders.

I'm not entirely certain that you can get a rock hard pedal with rubber hoses?

In my experience you need to go to -3 braided teflon hoses to achieve that. Is that what the Goodrich hoses are? Teflon?

If you are going to this extent to analise the system, I think that you need to put a pressure gauge in line, possibly on T fittings to see what the master is putting out and then what the calipers are receiving.

Thanks so much for all of the informed and detailed comments.

For the record - the caliper positions are checked as  correct. The lower and upper bleed points on the front were done. The goodrich lines are 3- braided high pressure. The calipers were detailed cleaned before reassembly and there is no residual gum anywhere in the system. The bleeders are free flowing.

I wanted to keep all the brake system parts stock to keep the car close to original so replaced both the in line brake valve and shuttle with the original parts.

Feedback from others I have now received  are the same as Bosswenches comments - that it is likely with the movable shuttle valve and the movable  stock proportioning valve, a rock-hard brake pedal is unlikely.

A tentative shakedown drive has been suggested , then a final re-beed following the action of the booster and the system in general. I will get this done and give some feedback after that.

Thank you to everyone.

Decades ago (when I still had OEM calipers), I recall being frustrated by a mushy brake pedal. I decided to try bleeding the front calipers off of the car. I removed the caliper mounting bolts, put a 3/4" piece of plywood between the pads and moved the calipers around into different positions while tapping them with a mallet and bleeding. To my amazement, I got air bubbles...and a hard pedal.

Might be worth a try. 

That’s interesting David.  Hmm

Thanks David. I am going down to the dungeon to give that suggestion a red hot try !

Try bleeding the bottom bleeder with the caliper upside down and the bleed screw pointing “up”.

Doug's suggestion about rubber hoses is a good thought. Under the pressures used in max braking, rubber hoses swell. I use AN braided-stainless which helps, and going to dash-3 in place of the commonly used dash-4 size helps more. That's old-tech from the Korean war, though. Nowadays, serious go-fasters use lighter weight braided-kevlar hoses, still in dash-3 size. And (personal preference)- I discard any 'residual pressure valves' found in some aftermarket and even performance production master cylinders. Owners install them in (usually front) brake lines for slightly quicker response and also slightly more pad-drag & wear..

Result was some small further amount of entrained air came out of the LH caliper . Pedal feels improved but still not rock hard - but certainly ready for a test drive !

Thanks again.

Bosswrench - these are the braided lines I had installed to replace the rubber lines. I am not sure what category they would fall into. They are stainless braided and sealed .

I have Goodrich lines as well.  That is not the problem. They produce a firm pedal.  I  bleed from back to front - rear left, right, then fronts.  Stock calipers and master.  Also, I was never told to put sealing tape on bleeder screws.  

+1 for no Teflon tape on any brake system threads.