Technical No Brakes

[GBGraham]

Hoping for a bit of guidance please, I bought the 124 coupe with no brakes and the pedal goes to the floor so I started at the furthest from the master cylinder. At the RH rear I loosened the bleed nipple and I have fluid flowing regardless of pumping the pedal. With the same process on the LH rear I have no fluid at all no matter what I do, pump the pedal or under gravity. I have not gone and further as looking at the fronts. Any ideas guys

 

[puntodad19]

Why not start at the master cylinder.

Is there any fluid in the resevoir at all and what colour is it ?

What did the previous owner say about the brakes ?

To save buying a wig, start at the master cylinder resevoir screw top and logically work your way to each wheel checking every pipe, union, hose and haudraulic unit not to mention every friction component etc..

Brakes are very safety critical.

You have an assistant, a manual, know and understand the braking system...split diagonally, front to back, or not split at all ?

How long has this vehicle been asleep ?

Enjoy.

 

[124BC1]

Braking system, except on the very early 1st series approx. 1968-'70? (AC) Coupes, is dual circuit, split into separate front and rear circuits.
So if you have fluid being expelled from one rear wheel, fluid should also come from the other rear wheel - so possibly a blocked bleed screw, blocked hose or pipe or just out of fluid?
Note:- Because of the pressure limiting valve fitted on the rear brakes, the rear brakes can only be bled if the car is either on it's wheels or if the car is raised with the axle supported - allowing the axle to hang (e.g. by supporting the body instead of the axle) will close off the valve and prevent fluid flow to the rear brakes.

 

[124BC1]

----------------
To save buying a wig,

.......

 

[puntodad19]

I am solar powered these days....

Some of you out there have vehicle problems that drive you insane, round and round in circles and you end up pulling out your hair, hence the wig

Mind you, computers..........

 

[GBGraham]

No wig pulling from as I haven't got much to pull

The car is a nut and bolt restoration that once finished has been parked for 4/5 years so I'm expecting seizures so today I will removed the master cylinder and start there with the pedal being so free.
As for the rear callipers, it is a single line the rear brakes that goes through a compensator so I suppose there could be a problem there in not letting fluid to the LH rear, any thoughts from anyone familiar with the 124 ?

 

[puntodad19]

You know of Bigg Red....

 

[puntodad19]

You know of Bigg Red...?

 

[GBGraham]

If it's me you are asking, sorry I don't . . should I?

 

[puntodad19]

May prove usefull.

 

[124BC1]

No wig pulling from as I haven't got much to pull

The car is a nut and bolt restoration that once finished has been parked for 4/5 years so I'm expecting seizures so today I will removed the master cylinder and start there with the pedal being so free.
As for the rear callipers, it is a single line the rear brakes that goes through a compensator so I suppose there could be a problem there in not letting fluid to the LH rear, any thoughts from anyone familiar with the 124 ?

There is one hard brake line to the rear brakes, this goes from the master cylinder to the brake pressure regulator valve (aka a compensator) , another pipe exits the brake press. regulator. and goes to a flexible hose and this goes to a 3 way union on the rear axle, 2 hard lines exit the 3 way union, 1 goes the left rear brake, the other goes to the right rear brake. The br. press. reg. valve is mounted above the rear axle and is connected to the rear axle by a linkage - as the axle is loaded the valve is held open, as the axle drops (e.g. if you jack up the car or go over a sharp rise and 'get some air') the valve closes - this is designed to prevent the rear brakes locking if you brake very hard. The flexible hose is there to allow for rear axle movement. The br. press. reg. valve is a small alloy housing, it has 2 metal (hard) lines going to it and has a rubber boot covering the end of the linkage, it's attached to the bodyshell by 2 x 13mm headed bolts. I'd leave this alone if it's working ok.

So, in summary, the br. press. reg. valve (or compensator) supplies fluid to both rear brakes so it is highly unlikely that it's a problem.
Also, if you can pump fluid from either of the rear brakes, it's unlikely that there's anything wrong with the master cylinder or the rear brake line or the compensator.

I'd check for a blockage to the LH rear brake, possible the bleed screw or the flexible hose. You might loosen the 2 rear brake pipes where they attach to the 3 way union and see if you're getting fluid from both pipes .If ok, LH loosen pipe where it attaches to the LH caliper flexible hose and see if you have fluid, if ok, loosen hose to caliper (iirc, you'll have to remove the rear caliper to do this as the hose screws into the caliper body) and see if you have fluid. If you still have fluid, proceed:-

Remove the LH rear caliper (4 little spring clips plus 2 wedges) and examine the orientation of the caliper piston - there's a deep groove that fits over a projecting pin on the back of the brake pad but there's also a small line, like a deep scratch - this scratched line should be above the deep groove when the caliper is fitted to the brake.
Reason:- there's a bleed channel inside the caliper, the scratched line indicates when the piston is correctly positioned, if the scratched line is under the deep groove, it won't be possible to properly bleed air from the caliper (I can't remember if it will also prevent fluid flowing from the bleed screw).

P.S. it would be helpful if you could indicate which model of 124 Coupe you have (AC, BC or CC) or the year of manufacture, also supply engine size (1438, 1608, `1592, 1756cc) if you want to ask any engine related questions. (on the Coupes, there should be a little al. plate on the rear of the firewall which shows the model plus other info).

 

[124BC1]

You know of Bigg Red....

Bigg Red are in the U.K. , OP is in Greece...

And should he find he needs calipers, both seals and new calipers are still available from a number of suppliers at reasonable cost.

 

[GBGraham]

There is one hard brake line to the rear brakes, this goes from the master cylinder to the brake pressure regulator valve (aka a compensator) , another pipe exits the brake press. regulator. and goes to a flexible hose and this goes to a 3 way union on the rear axle, 2 hard lines exit the 3 way union, 1 goes the left rear brake, the other goes to the right rear brake. The br. press. reg. valve is mounted above the rear axle and is connected to the rear axle by a linkage - as the axle is loaded the valve is held open, as the axle drops (e.g. if you jack up the car or go over a sharp rise and 'get some air') the valve closes - this is designed to prevent the rear brakes locking if you brake very hard. The flexible hose is there to allow for rear axle movement. The br. press. reg. valve is a small alloy housing, it has 2 metal (hard) lines going to it and has a rubber boot covering the end of the linkage, it's attached to the bodyshell by 2 x 13mm headed bolts. I'd leave this alone if it's working ok.

So, in summary, the br. press. reg. valve (or compensator) supplies fluid to both rear brakes so it is highly unlikely that it's a problem.
Also, if you can pump fluid from either of the rear brakes, it's unlikely that there's anything wrong with the master cylinder or the rear brake line or the compensator.

I'd check for a blockage to the LH rear brake, possible the bleed screw or the flexible hose. You might loosen the 2 rear brake pipes where they attach to the 3 way union and see if you're getting fluid from both pipes .If ok, LH loosen pipe where it attaches to the LH caliper flexible hose and see if you have fluid, if ok, loosen hose to caliper (iirc, you'll have to remove the rear caliper to do this as the hose screws into the caliper body) and see if you have fluid. If you still have fluid, proceed:-

Remove the LH rear caliper (4 little spring clips plus 2 wedges) and examine the orientation of the caliper piston - there's a deep groove that fits over a projecting pin on the back of the brake pad but there's also a small line, like a deep scratch - this scratched line should be above the deep groove when the caliper is fitted to the brake.
Reason:- there's a bleed channel inside the caliper, the scratched line indicates when the piston is correctly positioned, if the scratched line is under the deep groove, it won't be possible to properly bleed air from the caliper (I can't remember if it will also prevent fluid flowing from the bleed screw).

P.S. it would be helpful if you could indicate which model of 124 Coupe you have (AC, BC or CC) or the year of manufacture, also supply engine size (1438, 1608, `1592, 1756cc) if you want to ask any engine related questions. (on the Coupes, there should be a little al. plate on the rear of the firewall which shows the model plus other info).

Thank you ever so much for your comprehensive information, much appreciated. I have removed and refitted the master cylinder and I am quite happy this is functioning correctly. I have now got the car well off the ground on axle stands and wheels off and I will follow your advice. The car is a 1973 CC 1600cc, I'm not sure on the precise cc as the registration paper says 1598 but this could be to keep it under 1600 for tax purposes. Maybe the powers at be could give a slot for this to be entered on the personnel banner ?

 

[124BC1]

---------------- I have now got the car well off the ground on axle stands and wheels off and I will follow your advice. The car is a 1973 CC 1600cc, I'm not sure on the precise cc as the registration paper says 1598 but this could be to keep it under 1600 for tax purposes. Maybe the powers at be could give a slot for this to be entered on the personnel banner ?

I trust you have the axle stands under the rear axle not under the bodyshell, as per my earlier advice, re. bleeding air from the brakes?

Your engine should be 1592cc and is very similar to the 1600cc Fiat 132, in fact you may find the engine number begins with 132AB (the engine no. is located on a flat surface just above the alloy oil filter housing, left (carb.) side of engine.

The 124 Coupe is mechanically/electrically very similar to the 124 Spider so lots of parts suppliers, just about everything is still available (except body panels).

 

[GBGraham]

I trust you have the axle stands under the rear axle not under the bodyshell, as per my earlier advice, re. bleeding air from the brakes?

Your engine should be 1592cc and is very similar to the 1600cc Fiat 132, in fact you may find the engine number begins with 132AB (the engine no. is located on a flat surface just above the alloy oil filter housing, left (carb.) side of engine.

The 124 Coupe is mechanically/electrically very similar to the 124 Spider so lots of parts suppliers, just about everything is still available (except body panels).

 

[GBGraham]

Thanks and no fears, the stands are under the axle. The body VIN plate says for the engine as 132AC000 but the engine block number is 125BC000 so it is a 1608cc by my investigation

 

[124BC1]

Thanks and no fears, the stands are under the axle. The body VIN plate says for the engine as 132AC000 but the engine block number is 125BC000 so it is a 1608cc by my investigation

Yep, your engine is a 1608cc.
I thought all the CC models had the later type1592 or 1756cc engines, as evidenced by the engine number on your car's chassis/VIN plate, presumably someone fitted an earlier 1608cc engine for some reason.
The 1608cc engine (125BC) when used in the Sport Coupe destined for European markets was fitted with 2 x twin downdraft carbs (either 2 x Weber 40IDF or 2 x equivalent Solex carbs) and developed 110 bhp, and because of the fitment of these carbs, the distributor was driven off the exhaust cam(these BC Coupes had a revcounter that read to 9000 rpm instead of 8000 rpm as on all other Sport Coupes).

I'm curious as to what carb/carbs are fitted to your engine? Many of the BC, 1608cc engines were converted to a single twin choke downdraft carb but left the distributor driven by the exhaust cam (as per on many U.S. models of 124 Spider).

 

[GBGraham]

Yes it's obviously have an engine change and it must have been done before the previous owner as he knows nothing of a change.
Here's showing it has Twin Dellorto DRLA 40's and it has a 8k rev counter

 

[124BC1]

Very tidy engine bay

A couple of polite observations, if I may?

I'd prefer to see a timing belt cover fitted but have heard some owners prefer to leave it off. The original 125 T/C engines (earlier version of the 125BC engine) and the 124 AC engines had an cast al. alloy t/b cover, 125 BC engines had a type of hard plastic, later 132 type engines had a softer yellow plastic cover - my preference was always a nicely polished alloy cover (I'm a great fan of Solvol Autosol ) These covers are not necessarily all interchangeable, the cyl. block can vary in height as can the mounting points.

The inlets to those twin carbs would normally be covered by an air cleaner, the current installation leaves the air corrector and idle air jets potentially exposed to dust/grit, I think I'd shield them perhaps using some fine mesh, even women's nylon tights type material (I've seen such material used as a basic dust 'filter' on carb inlet trumpets (I think 'velocity stacks' used to be the old term?).

 

[GBGraham]

You may, certainly. As for the t/b cover I'm already on this and it will be dealt with because my feelings are the same.
Thanks for the heads up on the carbs, I will tend to this and I'm thinking scotch pad will do the job.