When I bought my 1970 1.3 Rally S, it was disclosed that the "brakes" were from a S2. The problem is I do not like the feel of the brakes. The system is fine (no air) but it feels over boosted and the pedal is too sensitive. I believe the S1 did not come with a brake booster. Several other vintage Italian cars I've owned did not have boosters and I like the direct feel, so I would like to go back to original. What reasons are there for changing to S2 brakes? (parts avail.?) Are the master cylinders interchangeable or are other modifications necessary?
Thanks
Stephan
Brake boost
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Peter Cripps
Re: Brake boost
Stephan,
There's an extensive discussion of S1 vs S2 brakes here:
brakes
My Fulvia has S2 front brakes and S1 rear.
I can't comment from direct experience on the S1 front brakes, but I find the S2 system very good, especially for a car that's almost 40 years old. The S1 rears are also good, with a handbrake that actually works!
Peter
There's an extensive discussion of S1 vs S2 brakes here:
brakes
My Fulvia has S2 front brakes and S1 rear.
I can't comment from direct experience on the S1 front brakes, but I find the S2 system very good, especially for a car that's almost 40 years old. The S1 rears are also good, with a handbrake that actually works!
Peter
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Huib Geurink
Re: Brake boost
The S1 has the so called Dunlop brakes. This is a first generation system. It is complex and requires attention and service. It consists of callipers with bolted on wheel brake cilinders. The diameter of the wheel brake cilinders at the front is always 2 1/8 inch whether on Fulvia, Flavia, Flaminia, Jaguars or Ferrari's. The diameter at the rear depends on the weight, size and top speed of the car and is selected for best balance between front and rear braking for the model. The earlier Fulvia coupe's and Zagato's (1200 and 1.3 without S) have 1 5/16 inch at the rear. These are marked 21 as 1 5/16 = 21/16. The master brake cilinder is a two chamber, straightforward thing with a diameter of 18 mm. There is no booster. I prefer this Dunlop system without the booster any time but it costs a lot to put it back in new condition.
Note that the Flavia and Flaminia have a two chamber proportional Lockheed booster which is or rather was a very beautiful thing. Today it is a pain in the exhaust to get it to work properly.
The GTE and the Rally 1.3S have a single chamber booster on the front wheels only. This booster is seperate from the master cilinder and is also proportional. These models also have a brake pressure limiter for the rear wheels. It is mounted in the engine bay against the passengers foot well. The diameter of the master cilinder is increased to 19 mm. On the coupe's the diameter of the rear wheel brake cilinders was increased from 1 5/16 inch to 1 3/8 inch to get more force from the same pressure to compensate for the fact that the front wheels also got more force from the same pressure through the booster.
I can understand the addition of the booster for the GTE. My wild guess is that the single booster on the front wheels of the Rally 1.3S may have to do something with the fact that 1 5/16 inch, which was the smallest size available, is still a bit too large to prevent the rear wheels from locking before the front wheels under all circumstances.
When asbestos was banned we had a problem for many years to get good pads. However, since a few years Mintex makes pads with material which all but equals top quality asbestos pads. The EBC Green Stuff pads are even slightly better than top quality asbestos pads.
The construction of the Dunlop brakes is such that the wheel brake clinders corrode easily if not properly looked after. Also there is some wear on the retraction mechanism which is in the pistons of the wheel brake cilinders. People who do not properly understand the Dunlop brakes and / or lack the resources to restore the system to new condition often resorted to replacing the brakes with the S2 brakes which are of more modern design and can better withstand neglect. It is not easy to do the conversion properly. At the rear the complete axle has to be changed. At the front the swivel has to be changed to an early S2 one. S1 swivels have a straight steering arm. S2 swivels have a curved steering arm. You cannot use later S2/S3 swivels as the hole for the suspension ball joints is wrong.
In addition some change the master brake cilinder also to the S2 set up of combined brake servo and 21 mm master brake cilinder. As a result it becomes impossible to adjust the steering box and nearly impossible to fill up the steering box with oil. I can understand the need to increase the diameter because there are five hoses to inflate instead of three. If the diameter of the master brake cilinders is increased your foot has to push harder on the pedal. There is a point where you can no longer do without a booster.
Some people do the modification because they think the larger pads of the S2 give better braking performance than the rather small Dunlop pads. They are misguided. The friction between pad and disc depends on the force and the friction coefficient. The surface area of the pads drops from all equations. The friction coefficient depends on the material. The force equals the pressure in the hydraulic system multiplied by the surface area of the wheel brake pistons, not the surface area of the pads.
If you have an S2 booster and 21 mm master brake cilinder sitting on your S1 steering column, you need the pin and a 18 or 19 mm S1 master brake cilinder. 18 mm of you do not install a booster on the front wheels. 19 mm if you install a booster on the front wheels.
Note that the Flavia and Flaminia have a two chamber proportional Lockheed booster which is or rather was a very beautiful thing. Today it is a pain in the exhaust to get it to work properly.
The GTE and the Rally 1.3S have a single chamber booster on the front wheels only. This booster is seperate from the master cilinder and is also proportional. These models also have a brake pressure limiter for the rear wheels. It is mounted in the engine bay against the passengers foot well. The diameter of the master cilinder is increased to 19 mm. On the coupe's the diameter of the rear wheel brake cilinders was increased from 1 5/16 inch to 1 3/8 inch to get more force from the same pressure to compensate for the fact that the front wheels also got more force from the same pressure through the booster.
I can understand the addition of the booster for the GTE. My wild guess is that the single booster on the front wheels of the Rally 1.3S may have to do something with the fact that 1 5/16 inch, which was the smallest size available, is still a bit too large to prevent the rear wheels from locking before the front wheels under all circumstances.
When asbestos was banned we had a problem for many years to get good pads. However, since a few years Mintex makes pads with material which all but equals top quality asbestos pads. The EBC Green Stuff pads are even slightly better than top quality asbestos pads.
The construction of the Dunlop brakes is such that the wheel brake clinders corrode easily if not properly looked after. Also there is some wear on the retraction mechanism which is in the pistons of the wheel brake cilinders. People who do not properly understand the Dunlop brakes and / or lack the resources to restore the system to new condition often resorted to replacing the brakes with the S2 brakes which are of more modern design and can better withstand neglect. It is not easy to do the conversion properly. At the rear the complete axle has to be changed. At the front the swivel has to be changed to an early S2 one. S1 swivels have a straight steering arm. S2 swivels have a curved steering arm. You cannot use later S2/S3 swivels as the hole for the suspension ball joints is wrong.
In addition some change the master brake cilinder also to the S2 set up of combined brake servo and 21 mm master brake cilinder. As a result it becomes impossible to adjust the steering box and nearly impossible to fill up the steering box with oil. I can understand the need to increase the diameter because there are five hoses to inflate instead of three. If the diameter of the master brake cilinders is increased your foot has to push harder on the pedal. There is a point where you can no longer do without a booster.
Some people do the modification because they think the larger pads of the S2 give better braking performance than the rather small Dunlop pads. They are misguided. The friction between pad and disc depends on the force and the friction coefficient. The surface area of the pads drops from all equations. The friction coefficient depends on the material. The force equals the pressure in the hydraulic system multiplied by the surface area of the wheel brake pistons, not the surface area of the pads.
If you have an S2 booster and 21 mm master brake cilinder sitting on your S1 steering column, you need the pin and a 18 or 19 mm S1 master brake cilinder. 18 mm of you do not install a booster on the front wheels. 19 mm if you install a booster on the front wheels.
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Stephan Protzen
Re: Brake boost
Thank you.
Now I will investigate what changes were really made. At this point I think only the master was changed. How do you know which master is there with out disassembling the system? Are there part numbers visible on the master cylinder? I will check the clearance to the steering box and also if the calipers have bolted on wheel cylinders.
Stephan
Now I will investigate what changes were really made. At this point I think only the master was changed. How do you know which master is there with out disassembling the system? Are there part numbers visible on the master cylinder? I will check the clearance to the steering box and also if the calipers have bolted on wheel cylinders.
Stephan
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Stephan Protzen
Re: Brake boost
I spent some time in the garage today.
Following Huib's description I was quickly able to determine that I have the Dunlop brakes. The fact that the kind folks in Britian cast their name on the brakes helped confirm this. As Huib said the master cylinder/booster is now over the steering box.
The three brake lines have unions near the master cylinder(effectively lengthening the lines) I would assume Lancia made the brake lines to the correct lenght and this is where the S2 cylinder was put in.
Taking advice from this forum I am driving the Lancia more often ( at least once per week) so even though the brakes work fine I would like to correct the feel instead of getting used to what I have.
I think I would go with no booster (Huibs post suggests all??? Rally1.3s had a front booster, ) so 18mm master. By pin I think you mean the pin between the pedal and the master, correct??.
One final question for Huib, apart from flushing the system with DOT 4 (my next project) what kind of maintenace do the Dunlops require? My wheel cylinders all look good with no leaks.
Stephan
Following Huib's description I was quickly able to determine that I have the Dunlop brakes. The fact that the kind folks in Britian cast their name on the brakes helped confirm this. As Huib said the master cylinder/booster is now over the steering box.
The three brake lines have unions near the master cylinder(effectively lengthening the lines) I would assume Lancia made the brake lines to the correct lenght and this is where the S2 cylinder was put in.
Taking advice from this forum I am driving the Lancia more often ( at least once per week) so even though the brakes work fine I would like to correct the feel instead of getting used to what I have.
I think I would go with no booster (Huibs post suggests all??? Rally1.3s had a front booster, ) so 18mm master. By pin I think you mean the pin between the pedal and the master, correct??.
One final question for Huib, apart from flushing the system with DOT 4 (my next project) what kind of maintenace do the Dunlops require? My wheel cylinders all look good with no leaks.
Stephan
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Huib Geurink
Re: Brake boost
First of all, to cover the legal angle, my advice is to re install original parts for the rallye 1.3S.
If you want instead to go back to the braking system of the earlier coupe's (1200 and rallye 1.3) it looks like a good idea to do it completely and properly. One of the reasons I personally prefer the 1200 or rallye 1.3 over the rallye 1.3S is the simplicity of the braking system and its excellent feel.
This change would then mean:
1) install an original 18 mm master brake cilinder
2) install 1 5/16 wheel brake cilinders at the rear
3) remove the brake pressure limiter
Whether your wheel brake cilinders are good or not is impossible to see from the outside. This is exactly the weak point of the Dunlop system. On modern brakes (starting with the Girling brakes of the S2) the seal is in the cilinder near the top. No water can go into the gap between cilinder and piston. On the Dunlop brakes the seal is at the bottom of the piston. If you put in new pads the piston is pushed all the way back. The seal is now near the bottom of the cilinder. Brakes are known to heat up and cool down. This means air is pumped into and out of the gap. If there is air there is moisture. If it cools down there is condensation. If there is condensation there is rust. The rust is on the wall of the cilinder near the top. When the pads wear the piston moves out and the seal moves towards the top of the cilinder where there may be rust. At any moment the thing may then start to leak. You have to open the wheel brake cilinders for inspection to tell whether they are good or not.
My advice is:
1) make sure the rubber dust covers are in top condition
2) massage some silicone brake grease into the gap. Not too much other wise it will leak onto pads or discs when it heats up.
3) use the brakes frequently
4) when you replace pads (the book says minimum thickness 7 mm, I use 8 mm) open the wheel brake cilinders. Clean. Inspect. Assemble with new silicone grease.
5) ALWAYS carry a set of spare pads in the boot. If a wheel brake cilinder starts to leak, the solution is to push the piston back in to get the seal back onto a clean section of the cilinder wall. This means inserting a new pad.
If you want instead to go back to the braking system of the earlier coupe's (1200 and rallye 1.3) it looks like a good idea to do it completely and properly. One of the reasons I personally prefer the 1200 or rallye 1.3 over the rallye 1.3S is the simplicity of the braking system and its excellent feel.
This change would then mean:
1) install an original 18 mm master brake cilinder
2) install 1 5/16 wheel brake cilinders at the rear
3) remove the brake pressure limiter
Whether your wheel brake cilinders are good or not is impossible to see from the outside. This is exactly the weak point of the Dunlop system. On modern brakes (starting with the Girling brakes of the S2) the seal is in the cilinder near the top. No water can go into the gap between cilinder and piston. On the Dunlop brakes the seal is at the bottom of the piston. If you put in new pads the piston is pushed all the way back. The seal is now near the bottom of the cilinder. Brakes are known to heat up and cool down. This means air is pumped into and out of the gap. If there is air there is moisture. If it cools down there is condensation. If there is condensation there is rust. The rust is on the wall of the cilinder near the top. When the pads wear the piston moves out and the seal moves towards the top of the cilinder where there may be rust. At any moment the thing may then start to leak. You have to open the wheel brake cilinders for inspection to tell whether they are good or not.
My advice is:
1) make sure the rubber dust covers are in top condition
2) massage some silicone brake grease into the gap. Not too much other wise it will leak onto pads or discs when it heats up.
3) use the brakes frequently
4) when you replace pads (the book says minimum thickness 7 mm, I use 8 mm) open the wheel brake cilinders. Clean. Inspect. Assemble with new silicone grease.
5) ALWAYS carry a set of spare pads in the boot. If a wheel brake cilinder starts to leak, the solution is to push the piston back in to get the seal back onto a clean section of the cilinder wall. This means inserting a new pad.
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Stephan Protzen
Re: Brake boost
It,s a shame that the legal angle needs to be covered, I thought we only had those issues here in the USA.
Thank you very much for the advice. While there may be specialists on either coast I am pretty much on my own out here in the Southwest. Of course there are good mechanics but they do not have the knowledge of Lancias like you do. I do enjoy doing the mechanicl work myself and it is very generous of you to give advice.
I think I will chage to the non boosted master and rebuild the entire brake system at the same time.
Regards Stephan
Thank you very much for the advice. While there may be specialists on either coast I am pretty much on my own out here in the Southwest. Of course there are good mechanics but they do not have the knowledge of Lancias like you do. I do enjoy doing the mechanicl work myself and it is very generous of you to give advice.
I think I will chage to the non boosted master and rebuild the entire brake system at the same time.
Regards Stephan
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jogo48
Re: Brake boost - simple solution
Stephen,
not so simple Solution 1: drive to E. Coast, ship car to Huib; take long vacation; bring work clothes, pup-tent, sleeping bag, patience. All problems will be solved, "in time".
Return to USA & wait for car to return. No doubt it will return, but 'Lard Nose When' !
simple Solution 2: locate best W. Coast Fulvia expert & drive there. Return Home, knowing that it is in good hands, sleep well. . All problems will be solved, "in time". Return some time "down-the-road" & drive back home, safely.
Sol 3: do it yourself & 'go crazy' ! Risk your sanity & potentially your own / others safety. All problems may not be solved, "in time". More harm may be done than good.
But you already know this..........
not so simple Solution 1: drive to E. Coast, ship car to Huib; take long vacation; bring work clothes, pup-tent, sleeping bag, patience. All problems will be solved, "in time".
Return to USA & wait for car to return. No doubt it will return, but 'Lard Nose When' !
simple Solution 2: locate best W. Coast Fulvia expert & drive there. Return Home, knowing that it is in good hands, sleep well. . All problems will be solved, "in time". Return some time "down-the-road" & drive back home, safely.
Sol 3: do it yourself & 'go crazy' ! Risk your sanity & potentially your own / others safety. All problems may not be solved, "in time". More harm may be done than good.
But you already know this..........
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Stephan Protzen
Re: Brake boost - simple solution
Solution 1, I could fullfill missed opportunity of youth and backpack around europe with pup tent while Huib gives my Fulvia the "Lexus" treatment. Oh I no longer have the time I had in my carefree youth.
Solution 2, simple yes but what a boring drive through the desert. Also coventional wisdom says its better to just buy a car some else already paid to restore.
So it has to be #3. While there are times when some profanity escapes the garage, I find working on my cars therapeutic, actually preserving my sanity. Most importantly I get to keep driving the Fulvia!
Solution 2, simple yes but what a boring drive through the desert. Also coventional wisdom says its better to just buy a car some else already paid to restore.
So it has to be #3. While there are times when some profanity escapes the garage, I find working on my cars therapeutic, actually preserving my sanity. Most importantly I get to keep driving the Fulvia!
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tim
Re: Brake boost - simple solution
Stephan
I'm with you on the therapy! Also good for the waistline - not sat in front of TV with donuts and beer!! Also believe if you take your time, buy the right parts and use good specialists you get a better job than leaving to unknowledgable folk in a motor repair shop (I definately do not include Huib or other Lancia specialists in that group!).
Tim
I'm with you on the therapy! Also good for the waistline - not sat in front of TV with donuts and beer!! Also believe if you take your time, buy the right parts and use good specialists you get a better job than leaving to unknowledgable folk in a motor repair shop (I definately do not include Huib or other Lancia specialists in that group!).
Tim