I’ve recently recommissioned a 1970 series 1 Fulvia after 7 years in a shed. A previous owner had fitted a brake booster and Girling front calipers from a series 2.
I’ve had the master cylinder and callipers rebuilt, and fitted new hoses.
I’ve recently started to drive the car a bit further than around the block, and have now noticed that after around 20 minutes of driving, the front calipers start to bind and drag.
Unsure why this issue would only appear after a period of driving - happy to receive advice if a) anyone else has experienced a similar issue on a refurbished brake system, and b) can suggest a fix!
Photo for interest.
Curious brake issues Series 1/2 Fulvia
Curious brake issues Series 1/2 Fulvia
- Attachments
-
Re: Curious brake issues Series 1/2 Fulvia
The usual cause is not enough free play between the pin of the pedal, in your case the pin of the S2 servo, and the plunger of the master brake cylinder. If the plungers inside the master brake cylinder are not allowed to go fully back to their rest position, the compensation hole will not open.
The brake fluid in the lines under the bonnet heats up and expands. Fluid should flow back into the master brake cylinder. If the hole is closed the expansion of the fluid will push the pads against the discs.
If it were my car I would bring it back to original.
Is it a Rallye 1.3 or Rallye 1.3S?
What is the VIN?
The brake fluid in the lines under the bonnet heats up and expands. Fluid should flow back into the master brake cylinder. If the hole is closed the expansion of the fluid will push the pads against the discs.
If it were my car I would bring it back to original.
Is it a Rallye 1.3 or Rallye 1.3S?
What is the VIN?
Re: Curious brake issues Series 1/2 Fulvia
The change to S2 front brakes was done around 30 years ago; the effort to revert back to frankly average Dunlop front calipers is not one I’m considering at this point.
Sounds like I need to split the booster off and check actuating rod lengths…
It’s a 1.3s Rallye, VIN 818.361 010732.
Was originally burgundy with cream seats and green carpets.
Sounds like I need to split the booster off and check actuating rod lengths…
It’s a 1.3s Rallye, VIN 818.361 010732.
Was originally burgundy with cream seats and green carpets.
- Attachments
-
-
lancia7550
- Posts: 76
- Joined: 10 Nov 2012, 22:26
Re: Curious brake issues Series 1/2 Fulvia
Dunlop brakes on an S1, when everything is in good condition, work superbly and probably better than most cars of the time. If anyone finds theirs to be not good, there is definitely a problem somewhere.
I'd be suspicious of a S1 system converted to S2, that the front/ rear brake balance won't be right unless the the S2 rear balancer and calipers could also successfully be transplanted.
I'd be suspicious of a S1 system converted to S2, that the front/ rear brake balance won't be right unless the the S2 rear balancer and calipers could also successfully be transplanted.
Re: Curious brake issues Series 1/2 Fulvia
I agree. And with the new style brake cylinders the S1 system is superior to the S2 system.
The trapezium seal in the cylinder wall of the new style cylinders is less trapezium than the seal in the Girling brakes. Retraction is less. The pads are pushed back by the discs. If the discs are straight and don't wobble it means that dust and water is removed from the disc as pads are only a molecule size away from the discs.. Response is much faster , specially in rainy circumstances. The book specifies a maximum wobble of 150 micron. We bring it down to 30 micron. A world of difference.
In hydraulics one calculates with surface area's. The surface area of the 2 1/8 Dunlop style cylinder is exactly equal to the surface area's of the medium size and small size pistons in the Girling callipers.
The non servo brakes of the S1 do have 18mm master brake cylinders. This means they displace less fluid per mm movement. Make sure everything is perfect, which is advisable for all parts of a Fulvia or any other Lancia of the era or before. If it is not perfect it is not Lancia.
The S1 system is Duplex. That means front and rear circuits are seperated. If the front circuit loses fluid the rear brakes will still brake and the other way around.
The S2 system is Super Duplex. One circuit operates on the 4 small cylinders of the front callipers as well as on the cylinders at the rear. The other circuit operates on the medium sized cylinders of the front callipers. There are two rubber hoses to each of the front callipers. One of the causes of loosing fluid is rubber hoses being cut by a piece of steel wire wrapping itself around one of the front wheels. In this case both circuits loose their fluid and there is no braking action at all. Fortunately the S2 had a much better hand brake. Was the rear axle swapped too? So that you have a good hand brake.
The volume of the two chambers in the master brake cylinder are different for Duplex and Super Duplex systems. Was the braking tested with one circuit empty and with the other circuit empty?
Now the Rallye 1.3S had a very advanced and brilliant brake system. It used a proportional brake servo. Very complicated but brilliant performance. The servo only works on the front brakes. So for a given pedal force the brake force on the front brakes was increased. The force on the rear brakes was increased by mounting slightly larger wheel brake cylinders. At the rear there are 1 5/16" cylinders on coupé's without servo and 1 3/8"cylinders on cars with servo. Also the diameter of the master brake cylinder went from 18mm to 19m
And a high tech brake force limiter was introduced. It is driven by the attitude of the car as well as pressure of the fluid in the line going to the rear.
30 years ago parts were not available. Today they are.
The trapezium seal in the cylinder wall of the new style cylinders is less trapezium than the seal in the Girling brakes. Retraction is less. The pads are pushed back by the discs. If the discs are straight and don't wobble it means that dust and water is removed from the disc as pads are only a molecule size away from the discs.. Response is much faster , specially in rainy circumstances. The book specifies a maximum wobble of 150 micron. We bring it down to 30 micron. A world of difference.
In hydraulics one calculates with surface area's. The surface area of the 2 1/8 Dunlop style cylinder is exactly equal to the surface area's of the medium size and small size pistons in the Girling callipers.
The non servo brakes of the S1 do have 18mm master brake cylinders. This means they displace less fluid per mm movement. Make sure everything is perfect, which is advisable for all parts of a Fulvia or any other Lancia of the era or before. If it is not perfect it is not Lancia.
The S1 system is Duplex. That means front and rear circuits are seperated. If the front circuit loses fluid the rear brakes will still brake and the other way around.
The S2 system is Super Duplex. One circuit operates on the 4 small cylinders of the front callipers as well as on the cylinders at the rear. The other circuit operates on the medium sized cylinders of the front callipers. There are two rubber hoses to each of the front callipers. One of the causes of loosing fluid is rubber hoses being cut by a piece of steel wire wrapping itself around one of the front wheels. In this case both circuits loose their fluid and there is no braking action at all. Fortunately the S2 had a much better hand brake. Was the rear axle swapped too? So that you have a good hand brake.
The volume of the two chambers in the master brake cylinder are different for Duplex and Super Duplex systems. Was the braking tested with one circuit empty and with the other circuit empty?
Now the Rallye 1.3S had a very advanced and brilliant brake system. It used a proportional brake servo. Very complicated but brilliant performance. The servo only works on the front brakes. So for a given pedal force the brake force on the front brakes was increased. The force on the rear brakes was increased by mounting slightly larger wheel brake cylinders. At the rear there are 1 5/16" cylinders on coupé's without servo and 1 3/8"cylinders on cars with servo. Also the diameter of the master brake cylinder went from 18mm to 19m
And a high tech brake force limiter was introduced. It is driven by the attitude of the car as well as pressure of the fluid in the line going to the rear.
30 years ago parts were not available. Today they are.
Re: Curious brake issues Series 1/2 Fulvia
Yes opinion noted on the above. This is the way I acquired the car, and the car operated with this setup for 25+ years.
The S1 master cylinder has been replaced with a (freshly overhauled) S2 MC and the addition of the brake booster.
Braking performance has been satisfactory (and, by the look of the removed corrosion from the discs now back in use, comparatively even front and rear). The only concern has been the front brakes starting to drag/lock on after 20 minutes or so of driving.
I will report back after adjusting the reaction rod by a millimetre or two.
The S1 master cylinder has been replaced with a (freshly overhauled) S2 MC and the addition of the brake booster.
Braking performance has been satisfactory (and, by the look of the removed corrosion from the discs now back in use, comparatively even front and rear). The only concern has been the front brakes starting to drag/lock on after 20 minutes or so of driving.
I will report back after adjusting the reaction rod by a millimetre or two.
Re: Curious brake issues Series 1/2 Fulvia
Further to your description Huib, my setup currently only has one hose to each of the front Girling calipers.
All the brake components are overhauled or replaced, apart from the discs and pads which had plenty of life in them.
No, the rear axle etc was not replaced or changed, the rear brakes still have the separate handbrake pads etc, and overhauled Dunlop hydraulic cylinders.
No, braking hasn't been tested with one or other circuit 'empty'.
All the brake components are overhauled or replaced, apart from the discs and pads which had plenty of life in them.
No, the rear axle etc was not replaced or changed, the rear brakes still have the separate handbrake pads etc, and overhauled Dunlop hydraulic cylinders.
No, braking hasn't been tested with one or other circuit 'empty'.