Hey Guys,

So I hate to ask this as I know there are MANY threads about it. I have read them but I am still having trouble bleeding the brakes on my FD.

Front brakes were replaced with Wilwood Kit from SBG with SS lines. Rear brake calipers were rebuilt and SS lines installed. My car is a RHD so I assume the correct order is RL, RR, FL, FR (furthest to closest from MC)?

I have tried to bleed the system twice. First attempt yielded lots of bubbles but still a soft pedal. Second attempt yielded no bubbles but I did hear ”gurgling” around the ABS area. But no improvement in pedal feel.

I have now pushed about 1.5 litres of clean fluid through the system. I tried a mityvac but the false bubbles caused by seepage at the nipple frustrated me. So I went back to the simple method with a friend pumping the pedal.

Do I just keep bleeding? Or does anyone have any advice?

The master cylinder was working fine before the winter and I did not work on it. I have had back luck with them in the past so I intentionally left it alone to avoid bleeding headaches. However as my lines emptied via gravity whilst working on the car, could it have gotten air stuck in it and thus require bench bleeding? Or is the fact I am pushing fluid a sign that it is fine?

All I need is enough braking capacity to get to my local shop and have them pressure bleed it. But right now I have no brake when the power assist comes on with the motor.

Also, I checked thoroughly for leaks but found none. I also expect a leak would result in endless air bubbles when bleeding.

Any advice would be appreciated!

Thanks in advance, Tom

 

Leaks usually aren't too bad to find. Best method is have the bleeder screws closed and have a friend push down the brake pedal to pressurize the system. Any spot that leaks you will see and feel brake fluid seeping out.

It's possible your master cylinder has a sticking valve - I ran into that myself. There's a post I made a month or two back about it with some good input on how to take apart the master and check things. It wasn't too bad to take the master off the car but be careful about dripping brake fluid on paint.

Right now what are the brakes like? Is it just soft, do they lock up or move the calipers at all? With the brakes down can you still spin the wheels?

Dale

 

Sounds like, from your description, the ABS unit has air in it. Depending on where the air is trapped in the ABS that thing can be difficult to bleed in the car. I have had best luck using a pressure bleeder. Works way better than any other method. The least efficient method is pumping the pedal.
As far as pressure bleeders there are many brands available, However from my point of view the problem with most of these home mechanic pressure bleeders you are pressurizing the system with moisture laden air (at least here in San Diego). That's probably fine if you're using O'Reilly Auto Parts brake, fluid, but the idea that my $50/liter AP Racing Radi-CAL R4 brake fluid's boiling point is now 40% lower because I kept pumping damp air in with each refill of the bleeder just rubs me the wrong way. So, for home use I use a Eezibleed brake bleeder and an air supply dryer to pressurize it with:


This drying filter is attached to my air compressor line that feeds the Eezibleed:

 

I've used this with great success -

https://www.motiveproducts.com/colle...t-bleeder-kits

That's a link to the Miata kit I think but they have one that screws right to the FD's brake master.

Pump it up with the pump on the bleeder to about 10-15 psi and it pressurizes the tank full of brake fluid. It pushes fluid through, just crack the bleed nipple and there you go.

Since OP is in Canada I wasn't going to throw a lot of specialized tools since shipping can be a killer. But I think this is a better alternative to pressurizing with shop air. It's also nice because it keeps the master topped off so you don't run dry.


Dale

 

On a RHD, the correct bleed is RR > LR > RF > LF. Even though the master is closer to the RF, the line travels from one side of the car to the pump then back.....having said that, not likely to be a big issue!

If there's no problem in fluid tightness, a gravity bleed is probably the best bleed - if you have time and patience. Vacuum bleed using a mityvac is near useless, easy enough to make a pressure bleed.... shrader valve from a tyre place drilled into another mazda cap you picked up from a wrecker and bob's your uncle. Simply a foot or hand pump to put 5 or 6 lb into the system should get you there.

 

Everyone who has replied so far - thank you for all the suggestions and advice!

i actually have a spare brake master cylinder cap, so I am going to have a go at "MacGyvering" a pressure bleeder system this weekend - I will report back on my progress

 

I'm with Dale on this. I have one that I use on all my cars. I started using a PowerBleeder when I was racing 24 Hr. of LeMons. Even tired brake systems get a new lease on life when they have fresh fluids with no bubbles.
Haven't looked back since.

 

Agreed, I will very likely be ordering one.

Only reason for trying to build my own this time is because I don't want to wait 2 more weeks for shipping.......summer is so short here and I haven't driven the car since September

 

Word of warning, that technique with putting the valve stem in the cap can be tricky - air leaks and whatnot. Keep the pressure LOW in there, like 10-15psi.

Did you see my question on what exactly is going on with your brakes?

Dale

 

Yep I did see your question, not trying to be rude or ignore you - I wanted to lift the car and check before I replied, but work gets in the way.......

Will check tonight and test my bleeder and report back....assuming the wife doesn't have other plans.....

 

By the way, the schrader you best use, is the type with two nuts and rubber seals each side, rather than one relying on threads - or rubber bung type, which probably wouldn't work/fit. Mostly seen them used on 3 piece wheels in the past.

 

So over the weekend I spent two full days on the brakes - still no luck:

• I built a pressure bleeder using a spare cap and my mityvac. I pushed another litre of brake fluid through (~1/4 at each bleeder). No bubbles and no change.
• I then left the tool applying pressure to the brake reservoir for several hours (~15psi) and saw no drop. I looked again for leaks - nothing.
• Based on the above I decided to eliminate the master cylinder as an issue. I just so happen to have a brand new Chips 929 at home. So I installed that and I bled the master on car by installing short pipes to recirculate back to the reservoir until no bubbles appeared. I then re bled the system and got some bubbles at the bleeders. There was an improvement and I figured problem solved. The next morning I checked the pedal and it felt softer then the previous night.
• I figured I would try to bleed again. However I first wanted to check the rear calipers I rebuilt. I checked them both for leaks around the dust boot and they were clean and dry (except the pad backing grease). I also checked the point the lines connect.They seemed clean but I had painted that area and was worried they might not have seated properly. So i removed the lines, sanded off the paint and re attached the lines.
• I then re bled the whole system, but this time with the key in the 'on' position, just in case that opens anything in the ABS system. During bleeding I spent time with a rubber mallet tapping the calipers and the ABS unit. I noted bubbles at both rear brakes (not surprising as I disconnected the lines). I also noted bubbles at the front right caliper, but I think that may have been from the connection of my tubing. No bubbles noted at the front left side.

The pedal has resistance throughout the range of motion, but only gets hard at the bottom. I spun the wheels while my wife pressed the pedal. The calipers engage and add drag to the brakes about 1/2 depressed but only lock them to the point i cannot turn the wheels at the bottom of the pedal travel. I assume once the engine is on the pedal will go right to the floor with ease.

Any one have any ideas? I am totally stumped and exhausted.

Could the rear calipers be leaking behind the dust boots without leaking out?

I am going to fire up the car when the weather improves to see if the changes made provide enough braking to limp the car to a local shop. Hopefully they can sort it out. I guess the best outcome is stubborn bubbles. But any ideas to avoid a dodgy ride would be appreciated.

Thanks, Tom

 

Unfortunately the the local shop can't fit me in for two weeks - I guess that's what happens when he is the only decent mechanic in town.

Any ideas for me to test in the interim will be greatly appreciated.

I will fire up the car tonight and see how the pedal feels with the power assist. If not too dodgy I will take the car for a short lap round the block and try another bleed, just in case that dislodges anything in the system.

Otherwise I am totally out of ideas

 

Is the pedal going all the way to the floor or is it going down about halfway then hitting a wall?

Did you go through my recent thread on the issue I had?

https://www.rx7club.com/3rd-generati...ekend-1124717/

Dale

 

Yep I read your thread and I replaced with a brand new master to eliminate that as an issue. Is there another discussion in there I totally missed?

As above - The pedal has resistance throughout the range of motion, but only gets hard at the bottom. I spun the wheels while my wife pressed the pedal. The calipers engage and add drag to the brakes about 1/2 depressed but only lock them to the point i cannot turn the wheels at the bottom of the pedal travel.

When it gets hard at the bottom I am not sure if it is hard because it cannot compress the pistons any further, or if it has reached the bottom of its range of motion.

When I installed the rear pads i had to screw in the pistons. How do i trigger them to self adjust? Could they be causing the issue in the same way poorly adjusted drum brakes would?

FYI - I appreciate you sticking with me on this Dale

 

So tonight I re bled my master cylinder again just in case.

I hooked up tubes to bleed in car, I spent ages bleeding it at every conceivable angle from front end high to rear high as I jacked up the car. Probably spent a good 30 minutes doing this. Tapping the caliper in between bleeds and waiting for any magical bubbles to appear. I carefully checked for leaks at all connections and gave everything a fraction of a turn tighter just in case.

I then proceeded to bleed each corner, pushing another litre of fluid through. I think I am over 4 litres now in total. I got bubbles at the RR caliper some small ones at the RL but none in the front.

The pedal is hard close to the floor, with a couple of quick pumps it gets hard an inch or so higher.

Weather permitting i will fire the car up tomorrow and see what the pedal feel is like with the engine on. Fingers crossed it is enough to limp to the local shop where I have an appointment late next week.

I have to admit this is really making me second guess my mechanical skills.......

 

Sounds quite the conundrum.

If you're worried about the ABS, you could crack the 2 front and the single rear line outlets to see if you get anything beyond fluid....10mm flare nut spanner to avoid vice grips when the nuts are rounded! Last year was the last time I rebuilt rear calipers, vaguely remember O rings seal the handbrake mechanism from the piston area, I guess there's a possibility of pinching something there? You'd think several hundred pounds of pressure, even without booster assist, would deliver a weep at least with that volume of fluid put through the system.

I can't see how it would be as troublesome as something like an openwheeler, maybe removing the front calipers, blocking the pads with a bit of wood or similar to get the bleed directly vertical might be a final desperate attempt - assume there's an inner and outer nipple on the Wilwoods?

 

There was some comments in my thread about master cylinders sitting for a while and one of the valves inside gets stuck. It could be a possibility with the new 929 cylinder.

May be worth opening up your old cylinder and having a look around.

I've found sometimes it helps to have all the bleeders closed and just mash on the brake pedal a bunch, rapid pumps. Sometimes that can shock loose an air bubble or just get the system to pressurize.

Dale

 

I am an idiot

I apologize for wasting everyone's time - I will report back tonight, but I expect to have a fully functional brake system very soon.......

On a positive note, I probably have the cleanest brake system of any RX7 due to the amount of fluid I have pushed through......

 

Brakes bled at ALL nipples last night........

Pedal has a small amount of free play then is ROCK hard

Hoping to get a break in the weather soon so that I can fire it up and see how the pedal feel is with power assist. But I am pretty confident it will be good.

Thank you all for your help and patience, now all I need is an alignment and I am on the road

 

Thanks for the update! Your post is a good reminder to us all not to overlook the obvious.

 

Yes it's amazing how easily when faced with an issue, we automatically overlook the simple stuff and start diving down the complicated rabbit hole. Also I am happy to admit to my stupid mistakes as it means I should never forget what I learned.

It worked out well in the end - I installed the 929 master that I was putting off, meaning my whole braking system is like new or perhaps better. Also I now have much more confidence in my knowledge of the braking system.

 

Good to hear, was thinking there was some sort of weird static camber issue. I think we've all been there at some stage!

 

Thank you for your help - you definitely sparked my eureka moment!

 

I just bled the brakes on my FD. Since I'm finally going autocrossing again and I know the fluid hasn't been changed in two years, time to do the needful. While I had the car in the air I thought I'd go ahead and bleed the clutch slave as well. Holy crap. I don't think I've ever seen brake fluid that dark in my life. I'd be willing to bet that the stuff that came out was 15 old if it was a day. Turned my Aquafina catch bottle a lovely forest green. Filthy. I haven't been able to drive it yet but that will happen in the morning. Some time after Le Mans is over.

P.S. If at all possible, addict your SO to watching motorsports. It's awesome!