Larger disc brakes

[burgoyne 69]

Has anyone tried larger discs on their Marlin?

I have replaced the rear shoes with standard new ones.
Replaced the rear brake pistons.
I have replaced the rear front pads with new standard ones.
I have bleed the whole system
The servo seems okay.......... the servo pipe is not leaking. the non return valve holds vacuum for a few minutes with the engine stopped. After pressing the brake several times with the engine stopped, then holding it down hard and starting the engine the pedal moves down. I don't know if there is any other tests that can be done.

I have 195 65 15 tyres on the front, 215 65 15 at the rear.
I have the 1600 koln back axle . with the 2l pinto

Although the car does stop okay, doesn't pull the side, or have uneven brake wear.
It doesn't stop like a modern car. I realize it can only be as good as a Cortina as it shares the same parts. but I would like something better.

I am toying with the Idea of either 260mm discs with 4 pot calipers or 280mm discs with 4 pot calipers...... standard is 247 with 2 pot calipers
I have calculated the piston sizes for 4 pots to give the same area/ force/ movement as the old calipers.

I am thinking 10 % bigger wheels than a Cortina deserve 10 % bigger brakes.
I realize most of the braking on a car is on the front. but don't want to overdo things.

Any thoughts any one?

[milliemarlin]

Re: Larger disc brakes

I have certainly noticed the difference in braking with a modern car and my Sierra based Cabrio. I think the problem is the weight of the car. I have approached a roundabout at about the same speed but the Cabrio will lock the front wheels much more readily than the modern car. The lighter car does have less momentum so should not be a problem for the brakes. I have found getting the steering geometry right makes the biggest difference.

Larger disks will make the wheels lock even more easily but I doubt it will help you stop quicker without changes to the tyres.

On the whole I find the stopping distance is a function of the pleasure of driving with gusto.
Paul

[Ye Ol Ripper]

Re: Larger disc brakes

Hi
1) Which model Marlin do you have is it a Roadster, YKC,Hunter or Cabriolet, as I cannot see any mention of this?

2) What's the approx BHP of your engine , is it a standard spec Pinto?

3) Are your current discs vented, as I seem to recall that the change from Cortina to Sierra had a completely different Calliper & disc combination?

The following may be of use:
https://www.rodsnsods.co.uk/threads/...7/#post-128692

[boustrophedon]

Re: Larger disc brakes

My Sierra based YKC roadster stops much better than any saloon car and that only has solid Sierra disks. Yes you can lock the front wheels up but then it does not have ABS.

With a Ford setup there is a huge range of suppliers out there to supply bigger discs and callipers.

[burgoyne 69]

Re: Larger disc brakes

Hi
1) Which model Marlin do you have is it a Roadster, YKC,Hunter or Cabriolet, as I cannot see any mention of this?

2) What's the approx BHP of your engine , is it a standard spec Pinto?

3) Are your current discs vented, as I seem to recall that the change from Cortina to Sierra had a completely different Calliper & disc combination?

The following may be of use:
https://www.rodsnsods.co.uk/threads/...7/#post-128692

Thank you for responding.
I have a Berlinetta with a modified pinto . It has been in a rolling road and made140bhp at the wheels .
The disks are not vented and I have never ran into poor braking due to to overheating.

[Ye Ol Ripper]

Re: Larger disc brakes

I am guessing that the brake set up will be adequate because your car weighs less than the Cortina. If you haven't had any brake fade, have you looked at the possibility of trying a larger servo and brake master combination?

Perhaps there is some info within this forum or from a Pitstop article from the past?

I don't have a Berlinetta , however if you check the build documents there may or may not have been a shortened pedal arrangement compared to the original Cortina pedals?

That was the case with the Roadsters , as a result you have less leverage on the pedal when you press the brake. The result is the need to press it harder than a modern car . It is something that you will get used to.

The Rear Shoes

Historically most auto rear shoe brake adjusters don't work properly for the full life of the shoes. So when you set up the rear brakes, did you slacken off the handbrake fully first before adjusting the rear brake shoes with a screwdriver manually?

The hand brake cable slack should always be adjusted last.

This will reduce your brake pedal travel , if you haven't already done it that way.

[burgoyne 69]

Re: Larger disc brakes

for £ 175 For 2 new calipers and pads has and one tried the Austin princess calipers . on eBay. I believe people used these years ago on escorts, cortinas and capris has anybody tried these and what would be needed to fit them ? , it says m12 so would you need to drill them out to m16?. Is that safe? . tried to see these at the place selling them, they had non in stock and I was told they came direct from the manufacturers so I would have to purchase first.

[HairyDave]

Re: Larger disc brakes

If the front brakes lock easily, possibly a brake proportion valve eg CBS. BRKPROP2 or3 would be the answer. Reducing the front effort and transferring it to the rear. Bigger disks will just make locking up worse.

[milliemarlin]

Re: Larger disc brakes

I would have thought, if you are sure bigger disks will help, that one of the established kits would be the safest option. Burton Power has a range of Cortina based options:

https://www.burtonpower.com/parts-by-category/brakes/brake-kits/ford-cortina-mk3-mk4-mk5-brake-kits.html

I was the first to suggest that locking the wheels was the limitation but you haven’t actually described the symptoms you are experiencing. The standard Cortina brakes ought to be more than good enough for everyday use. Can you describe the problem in more detail?
Paul

[burgoyne 69]

Re: Larger disc brakes

I would have thought, if you are sure bigger disks will help, that one of the established kits would be the safest option. Burton Power has a range of Cortina based options:

https://www.burtonpower.com/parts-by-category/brakes/brake-kits/ford-cortina-mk3-mk4-mk5-brake-kits.html

I was the first to suggest that locking the wheels was the limitation but you haven’t actually described the symptoms you are experiencing. The standard Cortina brakes ought to be more than good enough for everyday use. Can you describe the problem in more detail?
Paul

Not a problem as such.I can still lock the front wheels as an emergency stop but it takes much more effort than my car.... mini countryman, BMW version and my works van which is mostly loaded with tools and tackle.......ford transit connect.. I just wanted something a little better, but not that good, that the wheels lock up. My daughter has a standard Hyundai i10. The braking is unbelievable , If I drive it, at takes a few miles to get used to as I almost lock the brakes under normal conditions.

Drove the Marlin down hill with no servo yesterday........ the force I needed to slow the car was the same as an emergency stop with the servo on. So I presume the servo is working okay, and the brakes are okay. Perhaps a larger servo is the answer, I know people have fitted a land rover one as the Cortina servo is obsolete,but I think this would present further challengers.

[milliemarlin]

Re: Larger disc brakes

I recently hired a car in Spain. It had lots “safety” systems. I applied the brakes as I approached the exit barrier and nearly hit the windscreen. It was like an on off switch. It took me quite a while to get used to it; at least to the point where it wasn’t feeling like I hit a brick wall at every junction.

In the city it beeped at me as I drove past parked cars and cars passed me in another lane, flashing up a video of the appropriate corner on its large central screen. The distraction almost made me crash a couple of times.

I naturally tend to try to straighten out curves to reduce tyre wear. On the autopista the car shook the steering wheel every time I approached the white line marking the edge of my lane. But worst of all as I smoothly changed lanes to overtake a camión the car decided I was too close and reduced my speed. That I found alarming, in fact I thought it was darned right dangerous.

I can’t remember ever driving a car without a servo. It must have been quite different. I have been caught out coasting with the engine off on occasion. Quite a thrill.

I do know after driving my Cabrio for a few hours it feels like my arms and right foot have had a workout. There’s no power steering or cruise control. I rather like that.

Some of the systems on my car are simply there because I enjoy them. I enjoy the challenge of making and fitting them as well as the joy of using them. So I wish you well with your project. I have certainly considered how good a set of multi-pot Brembos would look on the Sportster I am building.
Paul

[burgoyne 69]

Re: Larger disc brakes

I recently hired a car in Spain. It had lots “safety” systems. I applied the brakes as I approached the exit barrier and nearly hit the windscreen. It was like an on off switch. It took me quite a while to get used to it; at least to the point where it wasn’t feeling like I hit a brick wall at every junction.

In the city it beeped at me as I drove past parked cars and cars passed me in another lane, flashing up a video of the appropriate corner on its large central screen. The distraction almost made me crash a couple of times.

I naturally tend to try to straighten out curves to reduce tyre wear. On the autopista the car shook the steering wheel every time I approached the white line marking the edge of my lane. But worst of all as I smoothly changed lanes to overtake a camión the car decided I was too close and reduced my speed. That I found alarming, in fact I thought it was darned right dangerous.

I can’t remember ever driving a car without a servo. It must have been quite different. I have been caught out coasting with the engine off on occasion. Quite a thrill.

I do know after driving my Cabrio for a few hours it feels like my arms and right foot have had a workout. There’s no power steering or cruise control. I rather like that.

Some of the systems on my car are simply there because I enjoy them. I enjoy the challenge of making and fitting them as well as the joy of using them. So I wish you well with your project. I have certainly considered how good a set of multi-pot Brembos would look on the Sportster I am building.
Paul

If it was as easy as buying a larger Cortina servo, say with a ratio of 1:3 instead of 1:9 , for me that would be the answer. But it isn't a option, getting even a new standard Cortina servo is near impossible,good job they are reliable.

Just wondering If anybody has tried an alternative .I hear a land rover servo is a good match and available but don't think it has a larger ratio.