BRAKE HELP !!!!!

[narfire]

Gotta problem here folks. Took the car into Penticton about 15 ks and on the way home the car seemed to be loosing power,that is it was not accelerating when gas applied. Now what? When I took the foot off the pedal the car slowed down quickly. The smell tipped me off.. Brakes. The fronts(both sides) have not released or backed off after the last brake application. The rears are hot but managed to limp it into a friends front yard.
Wondering.....1: booster toasted
2: master cylinder pooched
3: booster hose kafuckeled
4: brake calipers snafu'd
5: all of above?
I have a new MC and the booster has the nut at the right distance from the mc I thought.
I have a couple of boosters from parts cars if needed but what a PITA to change.
Kind of hoping its the calipers. both have been re-done with new seals and have given about 1500 miles problem free.
Any help will of course be appreciated. I can fix tomorow as the weather will hold for another day (I think.)
Thanks
Chris

[ventura ace]

. . .I have a new MC and the booster has the nut at the right distance from the mc I thought.
. . .

I suggest you unbolt the MC, and pull it forward enough to adjust the rod. But before you do so, check to see if the brakes are still locked up. If yes, and if they unlock when you unbolt the MC, then you'll know that the rod adjustment was the likely problem.

A

[narfire]

Hi, thanks for the advice. I did have the car in a paint shop recently and am wondering now if,even though the brakes were wrapped up, there is an amount of dust in there that prevents the calipers from moving. Rading past threads they are supposed to move a bit I think,float? Going to try that first then the MC.

[ventura ace]

Not just Fiat, but any disc brake caliper should freely move back and forth along the rails. For the fronts, you should be able to use a screwdriver to pry the piston back in the retracted position a bit, and with the piston out of the way, you should be able to slide the caliper back and forth with ease. If not, it should be disassembled, cleaned, and reassembled with lube on the sliding parts.

You can do the same with the rears, but you can't collapse the piston by pushing it back. The caliper has to be removed and the piston rotated CW to collapse it, and when finished turning it, there is a groove in the piston that needs to be lined up a certain way with the brake pad.

A

[So Cal Mark]

only floating calipers should move. If the caliper has opposed pistons it will mount solid.

[ventura ace]

Thanks for the correction, Mark. I'm guessing that opposed pistons are not common. I've never seen or heard of them before. All the different types of cars that I've fiddled with the brakes have had the floating type with pistons on one side only.

The point is that the brake parts that are designed to move should move very freely.

A

[So Cal Mark]

much better braking with opposed piston calipers; that's why the WHOA kit uses them. Floating calipers are really only used for lightness

[narfire]

This morning the pass front wheel turned free,the driver was still sticky,but did turn but rubbing the pads.
Took the caliper off and took it to work. I have another set of calipers(clean & new seals) and tonight put the driver side on. Tried to bleed by vacume but no juice. Bled the pass. front and it had fluid. Had a friend pump the pedal and still nothing at the driver caliper. I went to the MC and cracked the rear supply,juice there. Cracked front pass and some fluid but with some air. Cracked the driver front and.... nothing no juice @ the MC while the friend pumped the brake pedal. Took the MC off and like many Fiat owners,dig out one of my spare MC's and will put it on tonight.
Would a pooched MC give the problems I had, that is siezed caliper/not retracting?
Chris

[So Cal Mark]

so you have no fluid coming from the mc to the front line? How would that cause the caliper to stick? It would cause it not to apply, but sticking is a different problem

[narfire]

Went out to look at the car tonight. What I did was put another MC(from parts car) on, got too dark to fiddle with bleeding the brakes. the MC I took off I put it in a vice and pushed the plunger in with a screw driver. I could feel air moving from the rear line hole but nothing from the front line holes. Its in the bin now. Same as a third MC I had...bined it as well.
Wondering if the piston siezed originally and some how screwed up the MC? I did manage to use a c-type clamp and get the piston to retract today after cooling down over night, and then with pliers on the edge of the piston, pull it partway out.
Last night after I limped the car to a friends place, the brake pedal had perhaps 1/4 inch travel before stop.
Looked at the booster hose to the intake did'nt notice anything amiss.
I am wondering if the booster has packed it in? What would the signs and symptoms of a nfg booster? but then the front brake/brakes were siezed last night after they worked fine for 20 minutes and 20kms.
The plunger in the booster is connected and moves with brake application. It got too dark to check the nut and MC set-up but the brakes have worked fine for the past 1200 miles or so, don't know if they go out of adjustment.
I'll order another MC tomorow just cause they are not going to break the bank,the booster?
Having a beer (love my M G D )

[mdrburchette]

I doubt it's the booster since it has nothing to do with the brake fluid. It also doesn't seem likely your master cylinder is at fault since you are getting fluid through one side of the front. What kind of shape are your brake lines? Have you replaced them recently? It sounds more like the fluid went to the caliper to activate it but it didn't go back into the reservoir to release it (make sense?) You may have an internally collapsed line.

[narfire]

Thanks Denise. When I re-built the car in the winter 07/08 I replaced all the steel lines and the flex hoses, as well as just about everything else that could be replaced with new stuff $$$. you are right in thinking the fluid went out but did not return (blockage?). At about 3 am I thought it could'nt be the booster as the rear brakes are fine.
Can the MC activate the rear but have something gibeled inside and not let fluid to the front discharge?
I've got one of those pressure brake bleeders,going to try that this am on the way to the shop. I'll also order a MC from one of the local parts stores. Teased them the other day saying they are going to have to expand to carry more Fiat parts with the Chrysler stuff.
Driving this car makes it all worth it.

[ventura ace]

Are you bench bleeding your MC before installing? If not, you may not ever get it to work right. You need to bench bleed the MC in order to get all the air out. You can still do a 'bench bleed' with it in the car, and might be the easiest thing for you to do right now. If you're not familiar with the term, 'bench bleeding' is merely using fittings and clear tubing to circulate the brake fluid from the master cylinder outlet ports directly to the reservoir, and pump again and again and again until you see no more air in the clear tubing. You should also orient the MC while doing so that the outlet ports are the highest point, to make sure there aren't any air pockets where the air will remain in the MC.

A

[narfire]

Ok got the car home. Some brake action but not untill the pedal is almost to the floor and then if I keep pushing then bottoms out. What I did was to pull the mc off and pull the booster plunger/rod out and back it in 1.5 turns.. Prior I was not getting juice to the front outlets but the rear was fine. Thought if the plunger was back a bit it might pick up from the inlet better. It worked, got juice out through the mc at the front outlets. Put the calipers back on and then started the bleeding process. Ace your right I should have bench bled the mc as I think there is air in the system still (duh..soft pedal). I have a pressure bleeder but still needs a slight mod. to make it work right. Wonder if this would help purge any air out of the mc?I would crack the lines at the mc. I just don't want to disconect the lines from the mc again as it has been a royal PITA to get them threaded again.
I'll spend a bit of time tomorow.
Now I smell warm/hot coolant. Hope it is just burning off some drips when I disconected the heater hard line when installing some headers.
Never ends eh!
Thanks for the insights/suggestions
Chris

[narfire]

Think I found the problem. Put another caliper on with new seals, also turned the nut on the booster in one turn,got juice to the mc and all the lines. Changed all the copper washers on the hoses,tight now. The siezing was from a piece of crap of some sort in the caliper. Popped the piston with air (did'nt have my thumb out of the way,had to drill a hole in the nail to let the blood out) and inside was a piece of something about 1/4cm long 2mm wide and .5mm thick.although soft I'm sure it was the cause of this grief. Got to make sure the fluid is clean and a screen in place before the MC.
Now I'm waiting for the next issue,hope it's a while
Thanks for the suggestions
Chris