Front Brake Issue, 914 Pulls right when stopping Options

[PDXBob]

So, an update:
Had my front calipers just rebuilt by PMB. This solved my problem with pulling to the right. However I still don’t have good brakes, i.e., pedal goes nearly to floor before the car stops. Can’t come close to locking up wheels.

So far, I’ve had front and back calipers rebuilt by PMB. Also, replaced rubber brake lines with PMB braided steel. Bought 4 new Textar pads. Adjusted (vented) the back brakes to within specs. I have a Motive Pressure Bleeder and have bleed brakes using it at least 3 times. Just today did the 2-person brake bleed procedure on back brakes. Will do 2-person brake bleed of front’s tomorrow. Master cylinder only about 3 years old. I’ve pumped about 2 quarts of fluid through system and each time get pure, clean fluid and virtually no air bubbles. I’m Running out of ideas on what else to do.

Any thoughts or wild-a$$ guesses greatly appreciated.
PDXBob (1975 914)

Virtually no air bubbles isn't good enough. You need to bleed them until all of the air is out of the system. Try the long hose method (bonus, only 1 person is needed). I couldn't get mine properly bled until I switch to speed bleeders. Good luck!

I’m not familiar with the “long hose method”. Can you describe.
Thx
(No Brakes) Bob

[rhodyguy]

Long hose=speed bleeders in the top caliper bleeder holes on all 4 corners, enough clear hose/tubing to fit the bleeders and stretch from the R rear caliper to the catch jar that will be on the floor next to the drivers door. RR, LR, RF, LF. Buy some extra fluid as this method really flushes the system and the tubing holds a bit of BF. Take care to keep the reservoir full. You don’t need anyone to pump the pedal and HOLD! relax.

[PDXBob]

Long hose=speed bleeders in the top caliper bleeder holes on all 4 corners, enough clear hose/tubing to fit the bleeders and stretch from the R rear caliper to the catch jar that will be on the floor next to the drivers door. RR, LR, RF, LF. Buy some extra fluid as this method really flushes the system and the tubing holds a bit of BF. Take care to keep the reservoir full. You don’t need anyone to pump the pedal and HOLD! relax.

So, if I understand this correctly, after I have opened a speed bleeder (say RR) I just sit in drivers seat and pump out the fluid (and any air). Speed bleeders keep air from sucking back into caliper. Correct?

[brubou]

Correct, there is a one way valve mechanism in them, probably using a spring and either a ball or something to block reverse flow.

[rjames]

When I had my brakes refurbished they came with refurbished bleeders. I suspect they had pitting that was hard to see. One of them leaked from the threads until in frustration I tightened way past spec and it snapped off. Luckily it was a lower bleeder and it stopped leaking after it snapped.

I spent days trying to get all of the air out of the system and couldn't do it. But I after swapping over to speed bleeders I was done in less than 30 minutes.

YMMV

[rhodyguy]

You will see the bubbles traveling thru the tube with the door open. I used a large canning, glass quart size, jar for the catch. Going thru twice worked best for me. The 2nd time it goes pretty fast. I think they spare the master cyl some abuse too. You’re not under the car forever opening and closing valves. Then I put a lid on the jar and take the spent fluid to recycle.

[76-914]

I run the hose all the way to the reservoir. That way I don't need to keep refilling the reservoir while I'm pumping. You'll need to fashion some wire to hold the end of the hose over the neck of the reservoir. (IMG:style_emoticons/default/beerchug.gif) It will take 100+ pumps on the brake pedal at each caliper. Start with the right rear. then left rear, then right front, finally left front. If re-using the old MC don't push the pedal past the point it is used to stopping at. An easy way to do this is to cut a 3" long piece of 2" PVC then cut it length wise on one side, pull it apart until it will slip over the brake pedal. This will keep you from pumping the pedal too far. If you installed a new MC bleed it before you do any thing. (IMG:style_emoticons/default/beerchug.gif)

[rhodyguy]

Return to reservoir….I’m going to get new longer tubing. The pedal block is a good trick too. THX.

[emerygt350]

Interesting. How do you seal the line at the bleeder?

[rhodyguy]

You get tubing that’s a snug fit. The fluid is not under pressure. Just flowing. With the jar on the floor gravity does most of the work. I put the jar in a small plastic tub. No concrete mess to wipe down.

[emerygt350]

I figured if you are running it all the way back it's gonna have a little more pressure. Wonder about leaks at the bleeder.

[rjames]

I figured if you are running it all the way back it's gonna have a little more pressure. Wonder about leaks at the bleeder.

No leaks if your tubing fits snuggly over the bleeder and your bleeders are in good shape. Mine allowed air to go back in, which is why I switched to the speed bleeders.

After you've removed all of the old fluid, have other end of the tube go to the reservoir so you're not wasting fluid or constantly having to refill the reservoir.

[emerygt350]

The rear adjustment can be difficult to gauge.
Just for testing adjust the rears until you have no clearance and see if that helps.
Don't drive the car like this but by taking all of the adjustment out you eliminate one variable.
If this works, then back the adjustment off just a bit. .004 is maybe 10-15 degrees of swing from contact.

I recently rebuilt a MSM Miata rear caliper set. It has one adjuster exactly like the 914 on the inside. Set it up as Mazda suggested and had low pedal. Adjusted the clearance more by "feel" than with gauges the second time. Worked fine after a much tighter adjustment than the service manual suggested.

I just went back and tried this (PMB calipers just installed on the back) and I have to say I am pretty impressed. My brakes (after I installed the new rears) were ok to start with but this gave them quite a nudge. Much more confident in the stop. I could lock them up before but the pedal was getting pretty low. Now it is not even going down half way before we are into a "scare the neighbors" stop.

I do notice a little variability from stop to stop. I always give it a little double tap so it isn't that the brakes are pumped up sometimes and sometimes not. I suspect I still have some air in the fronts that needs to be worked out.

[PDXBob]

I’m going to try the long hose bleeding method suggested by rJames and others. Just ordered speed bleeders from Pelican. I think I’ll route the hose from bleeder valve to reservoir and get some kind of mesh to use as filter; however the fluid looks super clean since I’ve been working on brakes for some time and pumped a lot of new fluid through system.

[emerygt350]

I am not there yet. I have been bleeding crappy old brakes for 35 years now and I just don't buy you have to go to that crazy extent if you have a friend. The only thing that makes me question that is the weird valve on the rear system after the firewall. That may require something extra but so far my rear brakes (after setting the venting as metioned) are great. For the fronts, a good old pump, pump, pump, hold, bleed should be enough (if you have a friend).