Please help me with my brakes

[manoa matt]

The 124 has 4 mounting studs on the back of the booster, while the pictured booster for the 131 only shows 3. Of couse that could be a "representative" picture of the part and not a picture of the actual part. The booster mounts to a plate via 4 studs on the booster. Then the plate in turn is mounted to the firewall with 4 studs that protrude through and secure the pedal box assembily. It may be possible to mount that 131 booster to the intermediate plate. The critical part is the length of the rod that connects to the brake pedal. The "new" boosters offered by the vendors have an adjustable length connection to the pedal.

[katsi]

Sorry to be so crude but - FUCK IT! For the life of me, I can NOT figure out why the system won't build pressure. I fucked with the acorn bolt, taking carefull meansurments and then just plain old fucked with it. I had the fucking MC off 5 times, spilled god knows how much brake fluid over the garage and bled each line 5 times each. IF I COULD GET AN AIR BUBBLE THAT WOULD BE NICE. Fuck the whole thing. I can not figure it out. I have brought 3 cars back from the dead and each needed some brake work form one end of the spectrum to the other. I have rebuilt MC's multiple times and NEVER had any problem building pressure in the system. I am truely Pissed off and at a loss. ANY HELP??????

[kilrwail]

I sense a certain amount of frustration in your post Hopefully a good night's sleep will permit you to tackle the problem calmly.

I am still chasing the last bubble in my system, although I do have pressure. Here are a couple of things I have learned, having passed the point you're at:
1. My brakes were excellent before I started - my original objective was simply to change the fluid. Life got complicated when I broke two bleeder screws. After replacing the two front calipers and freeing up the two rear bleeders, all the lines were empty and the reservoir was empty, having sucked out the fluid at the outset.
2. I used a MityVac to suck new fluid through the lines, then I pumped several times at each wheel to remove the air from the lines. Then I pumped a couple more times per wheel until I got pressure in the system, which was much more apparent in the rear lines than the front. The car was on jackstands, approximately level with the ground.
3. Without the motor running, the pedal is quite firm. But with the motor running and the booster working (remember, I know it was good when I started), the pedal goes down about an inch before engaging.
4. I conclude there's still air in the master cylinder. The brakes work, but pull the car to the right. Looking at the master cylinder and the drawings of it, I know there are two pistons and multiple springs inside - lots of nooks and crannies where air could be trapped. Also, the front piston seems to apply only to the front left wheel, since that's the only line ahead of the front piston.
5. This morning, I intend to elevate all four wheels, with the rears significantly above the fronts. I believe my air bubble is trapped in the nose of the master cylinder, ahead of the forward piston, because the car pulls to the right. I will have my son pump the pedal with the motor running, while I watch the fluid coming out of the left front. I will also tap the master cylinder during the pumping, to try to dislodge the bubble and cause it to move backwards into the path of the piston (Matt's suggestion). If necessary, I will repeat this process with the other wheels.
6. If you can't get pressure with the motor off, your booster's condition is not relevant. I suggest you orient the car so that the rear is a few inches higher than the front. Focus on the left front, since it has a dedicated line and piston, and tap the front of the m/c to try to dislodge the air. Then move on to the other wheels. I believe that an assistant is vital to this process.
7. If it's of any comfort, I do not have any of these problems with my other cars, each of which has a single piston m/c. I change the fluid annually or more often in both of them, in under an hour from beginning to end. The Fiat dual-piston m/c adds significant complexity, in my opinion, if you take too much fluid from the m/c before beginning to add new fluid.
8. Now the purists here will be aghast at this: I used ATE Super Blue fluid for my new fluid, so I know that all the fluid I'm bleeding is clean and new, by the colour change. I have not bought gallons of additional fluid for this long bleeding process, since I'm using only new fluid. I simply re-use it. There, I've confessed.

If you have no fluid leaks and you had good brakes before you started, then your problem is unlikely to be either the m/c or the booster. I believe the focus should be on orienting the m/c at different angles - particularly nose down - so the air can escape when you tap on it. Good luck with your challenge and remember, they're still great little cars!

[So Cal Mark]

after all this, it sounds like you have a defective master cylinder. New parts do not guarantee good working parts

[narfire]

Hi Katsi. I feel your frustration,had a few "rigging fits" at my car as well. Today I jacked up the rear end while on a downhill slope,kinda looked like a rock cod held up by the tail. Put the pressure bleeder on and pumped to 10 lbs,cracked the rear driver side and after whacking the MC a few times(as per suggestions).... air, after pumping the bleeder and whacking the MC a few more times and filling the bleeder with juice and me sipping Guiness or two, started to get a steady flow of fluid. Did the same with the pass. side but no air. Buttoned it up and went for a quick spin and way better brake feel but still not great. I broke the cap for the bleeder to res. so I have to make another before repeating the process.
If you can get a pressure bleeder,it sure made the initial bleeding process easy,also being the driver side I used a long stick & with the door open you can pump the pedal as well. This seemed to chase the air from the rear lines.
As Mark said a new MC can be a pain. I'm on my third new MC and seems to have some hope of getting the brakes right.
Not sure if the guiness helped though.
Chris

[So Cal Mark]

Guiness always helps.

[halg]

Remember it is just a car, frustrating at times but nothing to get blown away by. My 1956 Moretti refused all normal attempts at bleeding. I finally had to make a cap for the reservoir where I could hook up a low pressure regulator and pressure bleed thru the master cylinder, it worked. Don't know if it will help but it worked for me.
Hal

[emosfiat]

Hey, Katsi. I feel for you. I have a 1981 FI that has frustrated me for months and a few dollars later I still have thee same fuel problem. These cars can be a challenge but all can be worked through. My friend and I have done two sets of brakes from a frozen state to well working. Sometimes had to stop and start over with the rebuild and make sure all is right. My suggestion is to order a full set of rebuild kits just in case a seal is bad and bleeding back through the caliper. Fill the MC with fluid after you bench bleed it. Fill each caliper with floid prior to reinstalling it. Start the bleeding process again. The system is simple hydrolics. If you can not build pressure then there is a leak or bleed back. My friend and I are close to you here in League City. Frustrating I know but stick with it. It will work out. Call Vick. They have techs available to help. Tell them what you have done to this point. Could be a defective MC. Rebuilds sometimes do this. I am out of town this week but maybe when I get back we can hook up we can try again. Emo. Call me 281-788-1963.

[VAS]

I came by this thread this weekend and if the car is on jacks, the rear must be supported by the differential. If the rear of the car is supported by the body and the differential allowed to drop, the brake compensator car will not allow the brake system to be properly bled.

The master cylinders stocked at Vick's are name brand.

-Jerry Lee Phillips
owner, Vick AutoSports

[katsi]

Thanks again for the good advice. sorry about getting so worked up the other night . I just needed to let off a little steam. Personally, I think the MC is faulty . I'm going to get some help and work through it the old fashoned 2 person way . If I can't get any pressure, I'll rebuild the MC. It's supposed to be NEW and not Remanufactured. I rented a pressure gun or whatever and that did not seem to help either. I know it's something and that it CAN be fixed, I just need to figure it out. Anyway, I will keep you all posted.

[jwhite]

The booster can be repaired if it is a simple seal and the unit need not be split. The bladder replacement is more difficult.
It is a rubber disk and has one side that seals. You will see the mark. Flip it over and it is refreshed or buy the repair kit.

http://www.fiat-spider.net/servicemanua ... erhaul.htm

[joshuagore]

I am having this same problem, my brakes went completely dry, sat for atleast a week. I have pressurized the system using a tool, at 25psi. It works great for bleeding, but I still can't build pressure.

Frustrating, I am livid.
Josh

[narfire]

I had three different MC's before i pulled the plunger out of the booster and unscrewed the acorn a turn. that helped and after a couple of times of pulling the MC and unscrewing the acorn on the booster plunger 1/2 turn each time, got good pedal and to date seems to be working just fine. I'm not sure,but perhaps there might be a difference in the clearance between different MC brands. I would like to thing they would be the same though.
I also used the "mark 1" manual brake pedal pump system (wife) to help.

[joshuagore]

I am having this same problem, my brakes went completely dry, sat for atleast a week. I have pressurized the system using a tool, at 25psi. It works great for bleeding, but I still can't build pressure.

Frustrating, I am livid.
Josh

I have now removed all 3 fittings on the master cylinder and bled it. Very little or no bubbles. It is getting very frustrating, before this I had no braking problems. It seems either my master failed, or I am doing something hugely wrong.

Any clues?
Josh

[htchevyii]

You guys are making me nervous, I have yet to bleed the new brakes on my '72. I don't remember having any issues when I rebuilt the brake system on my '82.