Caterham Brake Problem - Fronts Jamming then foot to floor

[terryp]

OK I know its not a Caterham forum, but this is the Free Parking area!

Today I noticed the car getting hotter than normal and the brakes seemed to be binding a little. Anyway it got worse and worse, and then suddenly my foot went to the floor. The front callipers jammed on and the rear wheels spinning trying to reverse it in the drive!
I released the pressure from the bleed screw and the wheels released so I could park.

The car is a 1984 and has a tandem dual circuit master cylinder. I have ordered a car set of seals with Redline but wonder what the problem actually is?
Master Cylinder?

Any ideas anyone

Thanks
Terry
S4 Federal Lotus Elan Honest!

[nebogipfel]

Servo

[terryp]

Yes if it had one!

Terry

[nebogipfel]

Yes if it had one!

Terry

B*gger Master cylinder

[Jason1]

Hi

My first thoughts were servo. What else is in the system?
Do you have a pressure regulating valve?

Jason

[terryp]

Jason
System is Dual Circuit master + Spitfire front callipers + Ital rear drums , no other bits so completely simple.
??????
I wonder if its something to do with the valve within the master cylinder

Thanks
Terry

[nebogipfel]

Jason
System is Dual Circuit master + Spitfire front callipers + Ital rear drums , no other bits so completely simple.
??????
I wonder if its something to do with the valve within the master cylinder

Thanks
Terry

Was it both sides locked for sure? If one it could be a flexy hose acting as a one way valve. Did it lock the rears?

[elansprint71]

Flexible hoses collapsed internally thereby, as my learned friend suggested, becoming one-way valves. Been there, done that.

[terryp]

It appeared to lock both fronts, both discs were very very hot, with the rears I can't be sure but the wheels were spinning, and the handbrake was working!

Flexible hoses are aeroquip all round, do these act the same?

Thanks
Terry

[terryp]

I just thought , when I released the pressure , I did it on one side only but both released so I would say that the hoses are OK?

Terry

[cal44]

If I understand this, you do not have proportioning valve in the system........right?


I reckon it is the master that is causing the issue............no proportioning valve? when you brake hard do all lock up, some, back, front?

Mike

[terryp]

No proportioning valve.

I have also remembered that I felt the rear drums and they were cool .....

So either master cylinder or front flexible hoses ?

Does anyone know how the dual circuit master cylinder works?

Thanks
Terry

[elansprint71]

I just thought , when I released the pressure , I did it on one side only but both released so I would say that the hoses are OK?

Terry

Not the hoses then; and Aeroquips will eventually degrade too.

[dpo#4]

Hi, Terrry-

While I am not familiar with the details of a Spitfire dual master cylinder, your experience sometimes occurs in other vehicles if the brake pedal pushrod is slightly pressing the piston. Fluid is blocked from venting to the reservoir and pressure progressively builds with each brake application. The heat boils the fluid, resulting in pedal-to-floor/heart-in-throat. My guess is insufficient pushrod freeplay, or perhaps a sticky piston on the return stroke at the front brakes half of the master. Hose constriction is also common, though, as pointed out, usually on one side. You might try applying the brakes a number of times with the wheels up off the ground until rotation by hand shows drag. Momentarily loosen a connection a quarter turn to release any trapped pressure, starting from the master, and try rotating the tire after doing each connection. When fluid gushes and the drag eases, the blockage is between the last two connections.
With no proportioning/metering valves, you won't have many to do. Hope this helps.
Ray

[terryp]

Thanks Ray, I will give that a go.

Cheers

Terry