Another brake bleeding question

[87-WE2]

OK - so I've replaced rear shoes, hardware, wheel cylinders, and an axle seal. Thanks to all for all the advice. I'm surprised I've gotten this far.

The car is all back together now and I've bled the brakes with the mityvac? vacuum pump. I thought I sucked out all the air with it, but I still have a mushy pedal. The brakes work, but the pedal is REALLY mushy.

Since the rear brake lines were off, do I need to bleed the FRONT brakes, too?? I'm pretty sure I followed the bleeding procedure to a T, but I didn't bleed the fronts since I didn't crack them open.

Any help?

 

[pacecarta]

dont forget the rubber lines also need replacing
the line above the axle and the lines to the front calipers

 

[87-WE2]

???

The brakes were fine before. I thought I had a leaky wheel cylinder, but it turned out to be a bad axle seal. I didn't figure this out until I had already changed both wheel cylinders.

My lines on top of the axle are metal. I changed one of them out because I boogered up the flare nut trying to get it off.

Do you have to change these lines every time you bust into the brake system?? Like I said, everything was working OK before, I had just mis-diagnosed a bad axle seal as a wheel cylinder. If I had been smart enough to figure out the bad axle seal in the first place, I never would have done anything to the brakes or the lines.

I'm just a little thrown off by your response pacecarta.

If I break the seal on the rear brakes, do I need to bleed the fronts also?

 

[pacecarta]

if you had a pedal before and all you did was replace the line and the wheel cylinders its a bleeding issue or you have a leak

if you had a soft pedal before and replaced the cylinders and such and didnt do the rubber than i'm saying those 25yr old rubber lines are due for replacement because they can be the cause of a soft pedal because they breakdown with all the flexing over the years can swell up causing a soft pedal that no amount of bleeding will fix

if you didnt break open the front system you dont need to touch the front

 

[87-WE2]

Thanks for the info!!

Sweet. Brakes were fine before. the only leak i had was the axle seal. (thought it was the wheel cylinder).

Glad I don't have to bleed the front!!

I've searched and searched about bleeding and the general idea i get is that when you think you've bled too much, you need to bleed about 10-15 more times - then you're halfway there!!!

Off I go to bleed!!!!

Thanks pacecarta - I'll check for any leaks from anywhere else, but she's pretty dry underneath now.

 

[1quick6]

Mity vacs aren't that great for bleeding brakes. Unless you teflon tape the bleeders, the will often suck air into the system through the threads.

 

[RmvBfrFlght]

Mity vacs aren't that great for bleeding brakes. Unless you teflon tape the bleeders, the will often suck air into the system through the threads.

Uh, no, can't pull air into the system backwards. All I do any more is the Mity-Vac bleed process. Works great. And the 'missus (or kids) really appreciates it as I'm not having her (them) do the pedal thing.

87-WE2, if the pedal is mushy then there is still air in the system. If the rear circuit leaked dry while the wheel cylinder was off, need to start by bench bleeding the M/C. When doing the vacuum bled I pull a good vacuum for a strong stream of fluid.

IOW, keep it moving to pull the air through with the fluid.

RemoveBeforeFlight

 

[87-WE2]

well i'm tired of bleeding. it still isn't right.

as far as the mityvac goes, i taped the bleeders just to be sure. one leaked a little air (lots of tiny bubbles), but one didn't leak at all.

Seem as if I got all the air out though, but I don't think i did.

I'm inclined to agree with remove before flight. I didn't think about air goinng all the way back up the line to the master, but when I replaced that one line, I remember there was no fluid that came out when I disconnected from the rubber line above the axle. I'll try bench bleeding tomorrow. going to go study up on bleeding to make sure I covered everything.

i put s-10 manual cylinders on both wheels and hoped to be able to hold better, but I can still only hold 3# before spinning. Brand spanking new bfg dr's also. will post up tomorrow after benching the mc.

thanks folks.

 

[steve hughes]

Silly question, but did you adjust the rear brakes after replaceing everthing? If you hit the brake pedal a second or third time does the pedal come up higher? Pump the pedal afew times and hold pressure on it. Does it blead down?

 

[87-WE2]

thanks for the response steve. you have my attention - i did not adjust rears after. I figured with new shoes, hardware, and cylinders, everything should be fat enough.

I'm going to go search how to adjust the rear brakes. If you can post a link, it would be much appreciated.

I felt pretty brave and took it for a drive because the brakes felt good, but with the pedal closer to the floor than before all the brake work. The brakes seem to work pretty well, but there quite a bit of pedal travel before they kick in. I'll probably still bench bleed the M/C because i have 2 quarts of brake fluid (one barely any used, and one unopened).

I tried a power brake, and it held, but to the same old 3# as before. I was hoping for quite a bit more with the s10 cylinders, PLUS not having gear oil all over the drum and shoes.

maybe if I adjust them right, they will! I did hammer down on the brakes and they locked up, but when the pedal was flat on the floor.

 

[steve hughes]

Adjusting the brakes will probably fix your problem .

 

[1quick6]

Uh, no, can't pull air into the system backwards.

Ok, not sucking it IN the system per se, but they can suck air into the bleed tube through the threads, thus pulling less fluid through and giving you the illusion that you aren't getting a good bleed.

I agree with the above. Get a brake spoon and adjust the rears and you may have your pedal height problem fixed. Good luck.

 

[TR Custom Parts]

Like previously posted if you ran the mc dry when you opened up the lines you will have to bench bleed it. Just run a short length of brake line so it goes into the chamber of the mc, fill with fluid and gently push the brake pedal until no more air bubbles come out of the line that is submerged in the mc. You won't have to do it to both chambers as you only opened the line to the rears. Just make sure you bench bleed the correct chamber!

Tell you the truth, I have always had the best luck with bleeding using the gravity method. Length of vacuum line from the bleeder submerged in a glass jar of brake fluid. Crack the bleeder open and let gravity do the work. Takes a lot longer and you have to keep an eye on your mc so it doesn't go dry.

 

[87-WE2]

brakes OK - thanks guys!

Thanks Steve Hughes and Mark Hueffmann. Adjusted the rear brakes and they are as they were before. Only held one more # of boost with the S-10 cylinders, but at least the thing slows down when I push my left foot down.

And for some curious reason when the rear brakes are adjusted properly, the parking brake is adjusted properly.

Thanks for everyone's help!!

 

[RmvBfrFlght]

Thanks Steve Hughes and Mark Hueffmann. Adjusted the rear brakes and they are as they were before. Only held one more # of boost with the S-10 cylinders, but at least the thing slows down when I push my left foot down.

And for some curious reason when the rear brakes are adjusted properly, the parking brake is adjusted properly.

Thanks for everyone's help!!

Is the pedal still mushy?

Can do a final rear brake adjustment by backing up and aggressively pumping the brake pedal while coming to a stop. This needs to be done while the brakes are cold. Otherwise they can be over adjusted, when hot the drums expand and are larger in diameter.

RemoveBeforeFlight