changing from dunlop to girling
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william vd Sman
changing from dunlop to girling
I'm thinking of changing the front brakes on my S1 zagato to girlings. what parts besides the calipers do i need? Like a different master cilinder (I prefer to remain servoless)
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Huib
Re: changing from dunlop to girling
I assume you mean the Fulvia S2 Girlings.
In hydraulic systems the surface area of the pistons is important. The combined surface area of the small and the large piston in the Girling calliper is exactly the same as the surface area of the single 2 1/8" Dunlop piston.
As far as the hydraulic part goes you can just interchange the two if you connect the small and the big cilinders to the same brake line. You can thus keep the 18mm master brake cilinder and avoid a servo
Mechanically it is a different affair. You need an upright with the bent steering arm. This has to be an early S2 upright where the upper wishbone was still the tubular one otherwise the top hole does not match the cone of the upper suspension ball joint. I don't know if the hole for the S2 track rod end matches the cone of the S1 track rod end. If not you also have to change the Pitman arms and the track rods.
It is wise to also change the discs to S2 discs.
Personally I would never consider to replace the Dunlop brakes by an S2/3 Girling system as I find the Dunlop brakes far superior in braking performance. They have to be in order of course and the retraction mechanism in the pistons has to be reset to the correct value.
In hydraulic systems the surface area of the pistons is important. The combined surface area of the small and the large piston in the Girling calliper is exactly the same as the surface area of the single 2 1/8" Dunlop piston.
As far as the hydraulic part goes you can just interchange the two if you connect the small and the big cilinders to the same brake line. You can thus keep the 18mm master brake cilinder and avoid a servo
Mechanically it is a different affair. You need an upright with the bent steering arm. This has to be an early S2 upright where the upper wishbone was still the tubular one otherwise the top hole does not match the cone of the upper suspension ball joint. I don't know if the hole for the S2 track rod end matches the cone of the S1 track rod end. If not you also have to change the Pitman arms and the track rods.
It is wise to also change the discs to S2 discs.
Personally I would never consider to replace the Dunlop brakes by an S2/3 Girling system as I find the Dunlop brakes far superior in braking performance. They have to be in order of course and the retraction mechanism in the pistons has to be reset to the correct value.
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P. de R. Leclercq
Re: changing from dunlop to girling
Huib rightly points out that you need the curved steering arms. These can be found on early S 11/2 cars. These had the curved arms but with S1 ball joints. In fact there is one about 50 yds from me as I write this, but it isn't mine...
In fact I fitted S2 calipers to a S1 car with the straight arms. I had to do some grinding on the calipers and in addition, bore into the rear of the larger of the two cylinders on each caliper, spot face the hole and use a banjo fitting, as the top inlet is unusable with the straight arms. Additionally, it is necessary to fit approx 2mm spacers to centralise the calipers on the discs. There was no problem with the S1 (Fanalone discs) that is until they cracked. We replaced them with the normal 1/2" thick S1 discs. Oh yes, bleeding ts tricky, but possible. EBC yellow stuff pads are used (as I do on my special). They are superb. I know Huib likes the Dunlop brakes, but these really improved the car.
This conversion was done on a Fanalone which has just enjoyed a champagne celebration; 20 rallies completed without major problems - apart from two broken rockers - caused by a hardening failure on the inlet camshaft.
I recommend that you throw away the original Fulvia master cylinder. Good ones are very rare these days - unless of course you are prepared to have the cylinder bored and lined with stainless steel - we did a number of these at Evolution Engineering with good results, but we were probably making a big loss on the work. On my car I use a FIAT Regata master cylinder, bought new on ebay for £15. I had an adaptor plate made and a longer push rod. Again, this was a vast improvement on the original which had been rebuilt at least four times to no avail.
Paul
In fact I fitted S2 calipers to a S1 car with the straight arms. I had to do some grinding on the calipers and in addition, bore into the rear of the larger of the two cylinders on each caliper, spot face the hole and use a banjo fitting, as the top inlet is unusable with the straight arms. Additionally, it is necessary to fit approx 2mm spacers to centralise the calipers on the discs. There was no problem with the S1 (Fanalone discs) that is until they cracked. We replaced them with the normal 1/2" thick S1 discs. Oh yes, bleeding ts tricky, but possible. EBC yellow stuff pads are used (as I do on my special). They are superb. I know Huib likes the Dunlop brakes, but these really improved the car.
This conversion was done on a Fanalone which has just enjoyed a champagne celebration; 20 rallies completed without major problems - apart from two broken rockers - caused by a hardening failure on the inlet camshaft.
I recommend that you throw away the original Fulvia master cylinder. Good ones are very rare these days - unless of course you are prepared to have the cylinder bored and lined with stainless steel - we did a number of these at Evolution Engineering with good results, but we were probably making a big loss on the work. On my car I use a FIAT Regata master cylinder, bought new on ebay for £15. I had an adaptor plate made and a longer push rod. Again, this was a vast improvement on the original which had been rebuilt at least four times to no avail.
Paul
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william vd Sman
Re: changing from dunlop to girling
The thing with the dunlops is the size of the pads. they are very small. Even if the pistons are rather big the pad is moped like. I sourced 'competition' pads as I suspected should be easy to find as 50's and 60's Jaguars have the same and are still frequently used for historic competition. This was not so easy as it sounded though as I was only able to find Mintex as a supplier. They suggest their compound M1144 for fast road use. price is 77pound plus vat per axle set. Which for these pad s works out to something like 10 pounds per square cm! I cannot belive that these pads in any compound will transform the brakes.
The girlings have 4 modern pistons of uneven diameter. Used in the early ninethies for the first time on motorcycles. have big pads available in many competition compounds. This must, I repeat must be better than the Dunlop system which dates from the early 50's.
Currently I have Ferodo compound 300 pads on the front and normal budget pads on the not so critical rear axle. master cylinder is NOS 18mm which works fine. Breaded brakelines finish it off. In my oppinion the system is as good as it could be but still I miss initial bite and good braking power at high speeds.
So: Uprights from early SII (berlina 818.610?). Do they take SI trackrods besides SI balljoints?
And probably a 19mm GTE or 1.3S SI mastercilinder or the SII mastercylinder with rearbalance limiter (cut the pad area). Calipers with two lines connected and EBC yellow stuff.
The girlings have 4 modern pistons of uneven diameter. Used in the early ninethies for the first time on motorcycles. have big pads available in many competition compounds. This must, I repeat must be better than the Dunlop system which dates from the early 50's.
Currently I have Ferodo compound 300 pads on the front and normal budget pads on the not so critical rear axle. master cylinder is NOS 18mm which works fine. Breaded brakelines finish it off. In my oppinion the system is as good as it could be but still I miss initial bite and good braking power at high speeds.
So: Uprights from early SII (berlina 818.610?). Do they take SI trackrods besides SI balljoints?
And probably a 19mm GTE or 1.3S SI mastercilinder or the SII mastercylinder with rearbalance limiter (cut the pad area). Calipers with two lines connected and EBC yellow stuff.
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Michael Beattie
Re: changing from dunlop to girling
I am no expert on the various options and advantages of Dunlop vs Girling.
However, I have just fitted a set of EBC Green Stuff pads to the front of my S2 1600. These pads while being mounted on the std size pad base, are tapered in from the base to the pad face at the top and bottom edges, giving a much smaller pad area on the disc. I assume this increases the pressure on the disc ( same force over a smaller applied area). The improvement I have experienced that these pads have made over the std road pad is dramatic, it really does stand on its nose. So a smaller pad area doesn't, in this case, seem to have had an adverse effect.
However, I have just fitted a set of EBC Green Stuff pads to the front of my S2 1600. These pads while being mounted on the std size pad base, are tapered in from the base to the pad face at the top and bottom edges, giving a much smaller pad area on the disc. I assume this increases the pressure on the disc ( same force over a smaller applied area). The improvement I have experienced that these pads have made over the std road pad is dramatic, it really does stand on its nose. So a smaller pad area doesn't, in this case, seem to have had an adverse effect.
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shaun pond
Re: changing from dunlop to girling
Paul,
What's the nature of the improvement in using the Regata master cylinder? Is it a matter of stopping power, or ease of bleeding, or better modulation, or all of the above?
We don't get Regatas over here, so I have no notion of the size and features of the Regata's master cylinder relative to that of the Fulvia.
I have learned that bleeding an S1 master cylinder seems to be inordinately difficult, at least for a neophyte like myself.
Regards
Shaun Pond
What's the nature of the improvement in using the Regata master cylinder? Is it a matter of stopping power, or ease of bleeding, or better modulation, or all of the above?
We don't get Regatas over here, so I have no notion of the size and features of the Regata's master cylinder relative to that of the Fulvia.
I have learned that bleeding an S1 master cylinder seems to be inordinately difficult, at least for a neophyte like myself.
Regards
Shaun Pond
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william vd Sman
Re: changing from dunlop to girling
Has anyone experienced with competition pads fitted to a Dunlop system? Are there more brands available than Mintex M1144?
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Tony Kovacevic
Re: changing from dunlop to girling
Back to the original question. I fitted Ser 2 Girling front calipers to my HF around 10 years ago using the original steering arms and the modifications as quoted by Paul. Wanting to replicate the factory set up, I bored the original master cylinder to 21mm, had it resleeved and then used suitably modified Ser2 innards to end up with a standard looking 18mm Ser1 master cylinder with Ser2 performance. I fitted a set of braided brake hoses and a set of semi competition pads.
Was it worth it? Absolutely, I have raced the car a number of times and my cars brake performance is far superior to the standard Fulvias I have owned and customers cars that I have driven. Other than regular brake fluid changes, I have not touched my brake system since.By the way, did you know that that the Ser 2 caliper overhaul seals are the same as early Toyota Landcruiser?
Was it worth it? Absolutely, I have raced the car a number of times and my cars brake performance is far superior to the standard Fulvias I have owned and customers cars that I have driven. Other than regular brake fluid changes, I have not touched my brake system since.By the way, did you know that that the Ser 2 caliper overhaul seals are the same as early Toyota Landcruiser?
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Huib
Re: changing from dunlop to girling
The size of the pads is not important as Michael points out.
Total friction, whether tires or brake pads is the friction coefficient multiplied by pressure multiplied by surface area. The product of pressure and surface area is also called force. It is the force that is important.
The force equals the hydraulic pressure multiplied by the surface area of the piston(s) in the wheel brake cilinder.
The hydraulic pressure is the force applied by your foot multiplied by the leverage of the pedal and divided by the surface area of the plunger in the master brake cilinder. It thus follows that the smaller the diameter of the master brake cilinder the higher the hydraulic pressure.
The reason for the Dunlop pads being small and thick is thermal insulation. At the time the philosophy was to insulate the heat from the liquid. This worked reasonably well with the small thick pads containing asbestos. When asbestos was banned the philosophy changed to dissipating the heat quickly which resulted in large thinner pads with steel backing.
For many years the pads for the Dunlop system made from asbestos free friction material did not give the required thermal insulation. It is only since a few years that it is possible to make friction material with thermal properties coming very very close to the old pads containing asbestos. I stock these pads in relatively large quantities as one never knows what the material is of the pads which are being sold by car parts dealers.
I do also still have a stock of the old asbestos rally pads made of M68FF material of M57FG. The difference with the new asbestos free pads with the correct thermal properties can be neglected. The latter cost 45 euro per set.
Note that although the Dunlop pads are made completely of friction material they are to be divided in three functional sections. You need a few mm to stick in the calliper. Then a section to bridge the gap between calliper and disc. And then on the business end a section to cover wear.
The book specifies a total minimum thickness of 8 mm for the Dunlop pads This is of course when the callipers are in good condition and properly centered and when the thickness of the disc is within limits. When rallying or racing one does of course appear at the start with new pads so that thermal insulation is optimal.
From physics class some may remember that cooling is proportional to temperature difference. The higher the temperature, the better the heat transfer. If the stage requires a lot of braking it is thus best to brake short and hard instead of long soft braking as the temperature rises quickly resulting in better cooling and the time between braking is longer so that more time is available for cooling.
Total friction, whether tires or brake pads is the friction coefficient multiplied by pressure multiplied by surface area. The product of pressure and surface area is also called force. It is the force that is important.
The force equals the hydraulic pressure multiplied by the surface area of the piston(s) in the wheel brake cilinder.
The hydraulic pressure is the force applied by your foot multiplied by the leverage of the pedal and divided by the surface area of the plunger in the master brake cilinder. It thus follows that the smaller the diameter of the master brake cilinder the higher the hydraulic pressure.
The reason for the Dunlop pads being small and thick is thermal insulation. At the time the philosophy was to insulate the heat from the liquid. This worked reasonably well with the small thick pads containing asbestos. When asbestos was banned the philosophy changed to dissipating the heat quickly which resulted in large thinner pads with steel backing.
For many years the pads for the Dunlop system made from asbestos free friction material did not give the required thermal insulation. It is only since a few years that it is possible to make friction material with thermal properties coming very very close to the old pads containing asbestos. I stock these pads in relatively large quantities as one never knows what the material is of the pads which are being sold by car parts dealers.
I do also still have a stock of the old asbestos rally pads made of M68FF material of M57FG. The difference with the new asbestos free pads with the correct thermal properties can be neglected. The latter cost 45 euro per set.
Note that although the Dunlop pads are made completely of friction material they are to be divided in three functional sections. You need a few mm to stick in the calliper. Then a section to bridge the gap between calliper and disc. And then on the business end a section to cover wear.
The book specifies a total minimum thickness of 8 mm for the Dunlop pads This is of course when the callipers are in good condition and properly centered and when the thickness of the disc is within limits. When rallying or racing one does of course appear at the start with new pads so that thermal insulation is optimal.
From physics class some may remember that cooling is proportional to temperature difference. The higher the temperature, the better the heat transfer. If the stage requires a lot of braking it is thus best to brake short and hard instead of long soft braking as the temperature rises quickly resulting in better cooling and the time between braking is longer so that more time is available for cooling.
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P. de R. Leclercq
Re: changing from dunlop to girling
Ha-ha! Well it's 19mm diameter and was easily available. There are many of this type that were fitted to FIAT group vehicles; if you buy one you will need the plastic reservoir e.g. from a Beta or similar. This "plugs in" to the top of the cylinder.
I bought it because it was the right diameter, and most important, new and replaceable.
The trick with S1 master cylinders is to pump fluid through on the bench. Mount the cylinder in the vice, fill with fluid and pump by hand, bllocking the outlets one at a time. Sometimes we had to block one with a plug and ball bearing before the second circuit would pressurise. They are funny things!
Paul
I bought it because it was the right diameter, and most important, new and replaceable.
The trick with S1 master cylinders is to pump fluid through on the bench. Mount the cylinder in the vice, fill with fluid and pump by hand, bllocking the outlets one at a time. Sometimes we had to block one with a plug and ball bearing before the second circuit would pressurise. They are funny things!
Paul