The problem is fixed. After I swapped the front brake lines I was able to get fluid to the drums and pressure in the system. The brakes work great now!!!

This does beg the question of whether I’ve been driving the car without front brakes for some time or if I somehow caused this condition. Crazy.

Thanks to everyone for the assistance.

Good news! I think the problem must have existed before you changed your rear brake shoes. I can't see that changing the shoes caused the problem unless there was some sludge in the master cylinder that found its way into the brake lines when you started bleeding the system.

Richenrygarcia said:

None of the brakes are working. The pedal goes all that to the floor with no resistance. No amount of pumping changes this condition.

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I had no pressure after changing front cylinders and shoes. The only thing that worked was to use a lever to move the shoes on the self adjusters yo get them as close as possible to the drums. Only then did I get a pedal

Having worked on Fiats for a fair part of my youth, I have come to the conclusion that there 3 faults with the 'pattern' parts that we buy. (1) The return springs are too short, so when they are extended (by putting foot on brake pedal and operating the brakes) they are TOO powerful and pull the brake shoes too far back off the drum---hence long pedal movement before the pedal has any pressure. (2) the friction washers in the 'pattern' self adjusters don't seem to be as 'grippy' as the original Fiat ones were. This means that there is a lack of resistance against the spring which is trying to pull the shoes back off the drum, which again contributes to the long 'pedal' and, (3) some of the cheaper 'pattern' brake shoes have slightly thinner linings vis-a-vie the factory original.
The answer would seem to be (a) try and use the original springs if at all possible or, (b) if you have to use new springs, gently stretch them until they are the same length as the old springs.
The shoes that are bought for fitment will also have a bearing on the ability of the shoe to stay in the extended position. Middle Barton Garage have had shoes made by FERODO, to the original specifications---not the cheapest, but probably the best. Alternatively, I have had a lot of success with shoes made by:---METELLI

'Richenrygarcia' might dismantle the old master cylinder to see if there was any damage to the internal seals caused by possible corrosion in the section of the cylinder bore not normally traversed by the piston/seals except when bleeding the brakes.

Al.

Everyone, this problem has been resolved. Thanks for the assistance. I posted the solution above but I cannot figure out how to change the thread to note that it is fixed.

^^ I think Richenrygarcia misunderstood me.
I read all the posts and saw that the problem was eventually traced to faulty brake hoses.

The reason I suggested stripping the old master cylinder was to see what the internal condition was like - I know fitting a new master cylinder didn't cure the problem with bleeding the brakes so perhaps the OP assumed that there was nothing wrong with the original master cylinder. If he strips it, he might be glad he changed it.

Many people familiar with working on older cars, will not attempt bleeding brakes by the traditional pump the pedal to the floor method, instead using either pressure or vacuum bleeding equipment to avoid any risk of damaging seals should there be corrosion in the normally unused section of the master cylinder bore.

I always strip old components to see why/how they failed, plus it may help me understand how something works. I suspect that, nowadays, most people bin the old parts asap. I tend to hold onto old parts for some time - there may still be some life in the old part - might do as a spare - might get me or someone else out of a bind sometime. Might actually be better that modern replacements - e.g. ignition coils/ condensers :bang:. Might also serve as a pattern or template, even if just to photograph to show someone what you're looking for - much easier than trying to describe it.

As regards changing the thread to show that HIS problem has now been solved - no need, the thread will die a natural death. However, he shouldn't be surprised if some people continue to post suggestions or thoughts related to his original problem. We do this for the benefit of others not just the OP.
If in the future, someone does a search on a particular problem/topic, 'his' thread might be resurrected by them to ask for help with their similar/related problem. They will see all the info/suggestions posted on the original thread, PLUS any suggestions that were posted after the problem was solved, this might help them, as their problem might not be exactly the same as his or solved in the exact same way.

P.S. I wonder if 'Richenrygarcia' has cut open the faulty brake hoses to see what went wrong...… (we might all learn something ).

AL.

Al, thanks for the insight. I have not cut open the brake lines as I’ve been out of the country for work. I’ll take a look when I return home.

Richenrygarcia said:

Al, thanks for the insight. I have not cut open the brake lines as I’ve been out of the country for work. I’ll take a look when I return home.

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Do it mate, although you have solved the problem cutting open the lines will confirm that was the problem.


I for one would cut them open because if you do and they were ok alarm bells should ring as to what is actually happening with your braking system?!…...you have stated that potentially you had no front brakes for a while which is a scary thought in it's own right, these things aren't the best for crash test safety.....

Not sure if this thread has reached it natural end... but I'm having a similar problem...

I've a completely new brake system (restore) and I'm using a dual circuit master cylinder upgrade.

I am also using DOT5 brake fluid - which shouldn't be an issue with all new parts.

I've expelled the air out of the rear, but there's barely anything coming from the front nipples. In fact the small out amount of fluid that has come out of the front nipples seems to want to go in reverse, even with the pedal held down.

I have a Jago bleed kit (identical to the Sealey VS820), but unfortunately, the manufacturers seem to believe all reservoirs are the same :-(

I've tried to source a cap, correct size with a straight connector, but nobody seems to have the correct size...

Any ideas?

I feel your pain. I was at the pinnacle of frustration when I was dealing with this issue. The last thing I thought which would correct the problem was swapping the brake lines. It might be worth disconnecting your difficult to bleed brake lines upstream of the flex-lines, just to see if it makes a difference.

Best of luck and let us know how it goes.

Thanks for the suggestion... I'll give it ago & report back.

I was wondering if there might be a problem with the master cylinder? It wouldn't be the first failed new part.

I've undone the pipes upstream of the flexi hoses. There's a small amount of fluid that's run out but clearly no pressure.

I've made an adapter to the Sealey brake bleeding cap - The solution is to remove the reservoir and connect the Sealey pressured tank directly to the feed pipes that go down to the master cylinder. If I can pressure the system and then just deal with the problem of removing air bubbles from these feed pipes when I reinstall the reservoir, it should, in theory, get over the problem that I'm seeing.

https://i.vgy.me/GFSSAe.png

quick update... I've used the adaptor (pic above) and get absolutely no flow of fluid from front brake nipples.

Does anyone know how the 126 dual circuit master cylinder works?

Is it possible that the piston for the front brakes is stuck and failing to return whilst the piston for the rear circuit moves freely back and forth? I'm assuming that there are two pistons in line??

Yes, it's possible for the front piston (the one furthest from the pushrod) to stick in the forward position.

Iirc, there used to be a warning leaflet (which few bothered to read!) included with new Fiat dual type master cylinders which advised flushing out the cylinder with either clean brake fluid or it might have been (possibly?) isopropyl alcohol, before installation in the vehicle. I think the reason given was that the preservative used in the cylinder might cause a piston to stick if the new cylinder had been in storage for some time. I worked for a Fiat dealership and can recall a couple of instances where a piston stuck at the end of it's travel in the cylinder after installation. The customers (tradespeople), for some strange reason hadn't seen/read the leaflet.

Is there an end cap on your master cylinder that can be unscrewed with the m/cyl in situ to check if a piston has indeed stuck at the end of it's bore? This might save you from having to remove the m/cyl. and re-bleed the rear brakes.

Al.

Today, I removed the master cylinder to the End Cap and brake light switch off and put it onto another Dual Circuit Master Cylinder. The piston seems to be able to move from both ends. So I filled it to the extent that I could and blanked off the brake pipe ends with m8x1.5 bolts.

Installed everything, removed any signs of air on the feed side.

This time, I did manage to get a bit of air out after very long periods of brake pumping, but not enough to get pedal resistance - I think it's the DOT5 silicone fluid that is more viscous and doesn't let go of its bubbles.

I'm going to go down to the hydraulics place tomorrow and try to make a reverse bleeder, with an M8 x 1.5 hose connector that will screw directly into the wheel cylinder. I'll then pump fluid uphill back to the reservoir. After doing the first side, I'll clamp the flexi and do the other side. Etc. I'll post results.

nathanrobo said:

This time, I did manage to get a bit of air out after very long periods of brake pumping, but not enough to get pedal resistance - I think it's the DOT5 silicone fluid that is more viscous and doesn't let go of its bubbles.

Click to expand...

Are you using Automec silicone brake fluid? The one with the yellow and green label.

My car is only a single circuit but I used Automec and didn’t have any issues with it when filling and bleeding the system with all new components.