HELP! Brakes won't work after new calipers

[FiatJim]

Greetings,
The car is a '73 spider with the standard brake package.
I had been having a problem where the car would veer to the right under braking. The harder the braking, the greater the severity of veering. After a few minutes of driving at 30-45 mph the braking was even. After that it was variable: veering right OR left.

I gave the shop a print out (educational material) and the Haynes manual. The mechanic's diagnosis was a problem with the Brake Master Cylinder. So I purchased one and had them install it. No change in the symptoms. After the shop trying 2 or 3 tries, they suggested I replace both front calipers - then we'd know both were good.

I got a new set and had the shop install.
Now the problem: The brakes don't work at all!!!! They are stumped!!!
With the Freakout coming I am getting nervous, peeved,... !!

I really need some insight, wisdom & advice - - - HELP

Jim Herzog

[DieselSpider]

Did they replace the rubber hoses at each caliper? This is just about a must on old cars as the liners in the hoses start to fail and become one way valves either preventing the calipers from releasing or engaging depending on which way the liner has let loose.

Some of the rubber formulations used to make even new brake hoses and some of the rubber parts used in the calipers and master cylinders on our cars also do not hold up well to the newer brake fluids so its best to stick with old fashioned DOT3 brake fluid. If someone put DOT4 fully synthetic brake fluid in a system with incompatible rubber parts that will cause some of the rubber parts to fail in very short time.

On my car just before I purchased it someone put in DOT4 and that took out the Master Cylinder and all the rubber brake lines at the wheel positions. The liners turned to putty as did the piston cups in the new master cylinder that was only a few months old.

A brake shop that does not know how to verify rubber brake lines and understand their various signs of failure would leave me with great reservations about allowing them to service the brakes on any of my vehicles.

All said the brake systems on these cars are pretty simple. If you flush the old brake fluid out and renew the silicone brake grease on the caliper slides every 2 years you should get many years of trouble free operation from the hydraulics.

[FiatJim]

THANK YOU for the quick response. I will be heading to the shop when it opens (in 1 hr, 4 min)!

Jim

[18Fiatsandcounting]

Jim, let us know what you found out, and I agree with all that Diesel noted above. On other thought: If the car was veering left or right, the master cylinder is NOT the first place I would look, as it was more likely an issue with one of the front calipers or lines to them. If at all possible, I'd suggest another brake shop, as this one seems more of a "break" shop. (sorry, sorry...!!)

-Bryan

[FiatJim]

Yeah, "this one seems more of a "break" shop. (sorry, sorry...!!)"
That's why I went to the second shop. They put in the new calipers. Now, instead of veering (but stopping) I have NO stopping!

Welp - we will see what happens on Monday/Tuesday.

Gee, would it permissible to bring a small convertible from a different manufacturer to the Freakout!

[18Fiatsandcounting]

When you say the brakes don't work, what does that mean? Does the brake pedal go to the floor with no braking, or does the brake pedal feel relatively firm but you just don't have much braking power? If the former, it's almost certainly air in the lines and that should be easily fixable. If the latter, then there is something really wrong...

To get no braking on any wheel at all would be really odd, but if that's the case, the repair shop should have figured out what's going on. If your master cylinder still has a lot of air, then that would explain no brakes at all, but again, any good brake shop should be able to properly bleed the master cylinder.

-Bryan

[GeorgeT]

With all this work going on don't forget to support the rear axle when bleeding the rear brakes.

[FiatJim]

Well the saga continues. I printed out everyone's suggestions and he told me that he had bled the brakes with the rear axle being supported. The problem remains. Tomorrow he will change the master cylinder. He told me that there is a "portioning" valve,.. could that be the problem?

Jim

[18Fiatsandcounting]

Well, it's possible that the first master cylinder that was installed was bad, but it kinda sounds like "new parts in search of the problem."

Yes, there is a proportioning valve in the rear, and it's also known as the rear brake regulator or rear brake compensator. It's function is to limit the fluid pressure to the rear brakes during heavy braking, so that the rear wheels don't lock up. Sort of a poor man's Anti-Lock Brakes. However, it affects the rear brakes only, and the front brakes should still work fine even if this rear brake regulator is not working (unless it's leaking major amounts of brake fluid, of course).

I'm still thinking you've got significant air in the brake lines, but of course that's just my hunch from afar.

-Bryan

[DieselSpider]

Well the saga continues. I printed out everyone's suggestions and he told me that he had bled the brakes with the rear axle being supported. The problem remains. Tomorrow he will change the master cylinder. He told me that there is a "portioning" valve,.. could that be the problem?

Jim

It would not cause total brake failure but only impact the rear brakes.

They sound like parts changers and not brake mechanics.

How do you not know if the master cylinder is working or not after you install and bleed it when you are a trained and certified brake mechanic? It either pumps brake fluid and develops a firm pedal or it doesn't. If its doesn't work its pretty obvious when they bench bleed it or if they skip that part of the process when they test the feel of the brake pedal. A brake shop should have the primer lines, test plugs, gauges, etc to verify a master cylinder and should not just be spinning their wheels throwing parts and your money at this.

How are they bleeding the brakes anyway? Pressure pot, gravity, vacuum pump, pedal pushing or some other method? I use a simple MitiVac Vaccuum bleeder myself and have experienced a bad master cylinder, clogged brake hoses, etc and it was all fairly obvious what was going on and this was my first time working on a Fiats brakes.

There is nothing really that special about these brake systems to an old timer as they are fairly straight forward mechanical systems pretty common for the era.

[FiatJim]

Whew. What an ordeal!

The mechanic finally went back to the original master cylinder and was able to get the brakes bled and working!!

So, I can drive it to the Freakout! That's the good news. The bad is that it still veers under hard braking. I believe my next step is to get new brake lines. The ones in the car are only 6 years old,.. but if they were old-new stock, who really knows?

My wife an I are leaving Sunday & looking to have a great time.

Jim Herzog

[silvadw]

i found this as i had a pulling issue that went away.
i put it down to infrequent use and rust/dirt on discs that is removed by use.
Car does stop really well.
How are your discs?

https://www.brakebleeder.com/brake-pull-diagnosis/

[DieselSpider]

Uneven braking can also be due to wheel alignment issues, wheel bearings that need repacking/replacing or other worn suspension components along with uneven tire pressures, unevenly worn tires or mixing tire tread patterns on the same axle.

Rotors should be replaced as a pair as should calipers to ensure even braking. Calipers on the curb side of the vehicle can also have issues binding due to running through more standing water from the crown in the roadway causing it to accumulate there resulting in the calipers on that side rusting more so than on the other so cleaning and replenishing the silicone brake grease on the calipers, caliper brackets and sliding wedges is also critical for straight braking.

[aj81spider]

+1 on that. I had a problem where the car veered right under hard braking and it was worn suspension components. Fixing the suspension fixed the problem and it tracked straight.

[FiatJim]

We had a great time at the Freakout & visited my daughter (who left home 7 months ago ~ sniff).

The car worked great!
Interestingly, the pull/veer went away during the trip. So, perhaps Silvadw was right and the symptoms was due to a lack driving miles?

I believe the brakes still need a little work. It feels like it takes longer to stop than it did before and I haven't had them lock up yet, despite trying