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Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Fri May 06, 2011 10:19 am
by john.p.clegg

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Fri May 06, 2011 10:23 am
by paddy
Quite right, I completely forgot to ask if you have a servo.

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Sun May 08, 2011 12:04 pm
by Steve G
john.p.clegg wrote:Also

elan-f14/brakes-binding-t22035.html

John :wink:


Thanks for that link John. I have read through most of those threads now.

paddy wrote:Quite right, I completely forgot to ask if you have a servo.


I don't have a servo, there was one in the car but it was leaking so I recently removed it and rerouted the brake line going to the servo straight to the union from the m/c.

I have done what you said Paddy and started by checking the pedal assembly. At first I thought it might have been fouling the Steering clamp but it isn't, touching slightly on occasion but not obstructing the return of the push rod. I disconnected the pedal from the push rod and there was no further movement of the push rod, the brakes were still binding. It seems to be set up correctly here although I now note (after reading the linked threads) that there is little to no play in the assembly, touch the brake pedal and the push rod starts moving.

So I removed one front wheel and using a wrench just about managed to push one pad back from the disc, the other pad was still stuck fast against the disc and the wheel the other side was still 'bound'. To give an idea of the degree of binding, I could turn the wheel with wheel still on but with wheel off couldn't turn the disc/hub until releasing one pad then it was still very difficult by hand. It seems as though the pistons are not returning at all.

I don't know where to go from here, I have the caliper rebuilding kits for the fronts but I don't want to start rebuilding the calipers when they might not be the problem, the pads and discs look hardly worn at all and I doubt that the calipers can be in too bad a state when they worked perfectly before the car was taken off the road and garaged a year ago. The fact that all four brakes are binding makes it seem clear that it is a hydraulic problem and not four seized calipers.

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Sun May 08, 2011 3:14 pm
by Tonyw
You could try loosening the pipe leading from the master cylinder and see if the system is holding a bit of pressure, you have a center valve master cylinder and it may just be that the center valve is holding to much pressure and causing binding.

Tonyw

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Mon May 09, 2011 10:57 am
by Steve G
Thanks Tony, I will try that tonight. Meeting a client this afternoon who I've just found out is a petrolhead of the highest order, has an old Alfa and used to run Lotuses. He likes nothing more than fettling with old cars so he may be of some help.

In my trawling of the internet for possible causes of brake binding, I came across an Austin Healey site that has a support article that suggests flexible brake hoses as a likely candidate for brake binding when all other avenues have been explored/rectified. Apparently they can collapse internally forming a kind of one way valve (i.e. the significant pressure from the master cylinder will allow passage of brake fluid but the lower return pressure will not). They will show no external signs of the internal collapse either.

When I upgraded the discs and pads of my Clio Trophy for trackday use I replaced all the hoses with stainless steel braided lines as they resist this degradation and collapse. If it turns out to be the hoses causing my brake binding I think I may do the same for the Elan.

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Mon May 09, 2011 11:33 am
by twincamman
to return the calliper pistons on disc brakes I use a dirty great 'C' clamp ---ed

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Mon May 09, 2011 12:43 pm
by Steve G
Thanks, I need to get one of those.

Is this the master cylinder I need?;
http://cgi.ebay.co.uk/MASTER-CYLINDER-L ... b8f40#shId

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Mon May 09, 2011 1:17 pm
by bcmc33
Steve G wrote:Is this the master cylinder I need?;
http://cgi.ebay.co.uk/MASTER-CYLINDER-L ... b8f40#shId

It looks like a small reservoir clutch M/C to me. You need the large reservoir version for the brakes.
Make sure you get the correct size - probably 0.625" diameter if you're not using a servo.

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Mon May 09, 2011 1:33 pm
by Steve G
Ummm...when you say 'not using a servo', what do you mean? Should I have a different master cylinder if I have removed the servo? Could this be the cause of my brake binding issue?

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Mon May 09, 2011 1:57 pm
by paddy
No, it wouldn't cause the brakes to bind. But it would be usual to use a master cylinder with a smaller bore, which reduces the pedal effort (to compensate for not having a servo). It will mean longer pedal travel than if you retained the original cylinder and servo.

Paddy

Re: MOT booked for Thursday, a bit of guidance needed...

PostPosted: Mon May 16, 2011 9:53 am
by Steve G
It passed! And with not a single advisory! Even my Honda used to get one or two advisories. I got the garage to sort the brakes in the end as I ran out of time and also wanted to make sure the brakes were done properly. I'm very glad I did as they found the two front pistons to be rusty and black sludge in the m/c. So they cleaned up and rebuilt the front calipers, drained and cleaned out the master cylinder, refilled and bled the brake system and also lubricated and adjusted the handbrake system so that passed too. Even though I'm not going to use it it's nice to have a working handbrake. Since removing the servo the brakes require a firm shove to stop quickly. No extra effort is required to slow the car normally, as you would approaching a junction for instance, and the braking has a very natural, linear feel, I prefer it.

I can't recommend the garage more highly if you have an Elan, or other classic car, that needs an MOT. They are Fairlight Garage in Saltdean (01273 303020). A very understanding and sympathetic MOT tester, which I've heard is a rare thing these days. Have it done on a Saturday and you can even pop round mine for a cup of tea while you wait!

The brakes binding were obviously holding the car back quite a bit as I was pleasantly surprised by the acceleration driving it home, I love the combination of immediate throttle response followed by an elastic delay in the driveline as the donuts wind up. Can't wait to get it taxed and insured and go for a proper drive.

Thanks to everyone for their very helpful advice.