Sticking brakes - help needed before Sunday!

[Mutley00]

Intermittently SWMBOs brakes on her S1 are sticking on - all 4 judging by the heat in the wheels! The pedal goes rock hard when this happens, but will free off on its own. There was that much resistance the other day, I could barely reverse into the garage, but after 15 mins, they'd magically freed off again. Brake fluid is clean, the car never gets wet, so surely all 4 callipers cant be sticking at once? Putting my head into the footwell, I noticed there was some rust on the 'piston' as it disappeared through the grommet on the bulkhead.

I'm booked into my local Lotus expert next week, but want to ensure safe arrival at Bamford on Sunday, so if there's anything you could recommend me checking before then (preferably involving a Lump Hammer 😃 !) I'd apprecate hearing from you. I dont have the facility to take the trays off I'm afraid.

Thanks, Andrew

[duncx]

Can't image all four calipers are sticking so maybe the master cylinder is sticking? Won't take much stickiness on the master cylinder piston to stop the caliper pistons from freeing off properly. This can happen with time, particularly if the car isn't driven enough 

EDIT: The car hasn't been fitted with an aftermarket servo has it?

Edited June 28 by duncx

[Mutley00]

Defo not been driven enough matey, hence sadly Mandy has decided to sell her. If she makes it on Sunday, there will be a 'For Sale' sign in the window.

No aftermarket servo AFAIK. I presume the master cyllinder is inaccessible without a ramp/trays off - haven't had time to investigate today?

[duncx]

Sorry Andrew, no idea how to access the master cylinder - maybe though the front access hatch? DaveB will know!

[MrWill]

Bugger.

3 things.

1. Seized caplier. Least likely as all 4 at same time. No.

2. Brake hoses are old / original and have started to break down inside becoming a one way valve.  Again all 4 at same time. No.

3. Master cylinder is not releasing. Sounds most likely. This could be the master cylinder itself or the brake pedal pivot sticking. If you squeeze the brake pedal and you can move the pedal bake back up by slipping your toe underneath and pulling it back and it then there's space/free play to press back with no pressure then the master brake cylinder is sticking.

If this means you're not getting to LitP and you're near to Manchester I have a spare master cylinder and could do a swap if i moved some stuff around or you could get a local garage to do it if I got the part to you... It's just a common swap any decent garage could do in a couple of hours

Good luck

MrWill 👍

 

[winthattt]

I’d agree with the master cylinder being at fault, could be corrosion on the shaft of maybe just the pedal is stuck down? 

[Mutley00]

11 hours ago, MrWill said:

Bugger.

3 things.

1. Seized caplier. Least likely as all 4 at same time. No.

2. Brake hoses are old / original and have started to break down inside becoming a one way valve.  Again all 4 at same time. No.

3. Master cylinder is not releasing. Sounds most likely. This could be the master cylinder itself or the brake pedal pivot sticking. If you squeeze the brake pedal and you can move the pedal bake back up by slipping your toe underneath and pulling it back and it then there's space/free play to press back with no pressure then the master brake cylinder is sticking.

If this means you're not getting to LitP and you're near to Manchester I have a spare master cylinder and could do a swap if i moved some stuff around or you could get a local garage to do it if I got the part to you... It's just a common swap any decent garage could do in a couple of hours

Good luck

MrWill 👍

 

I tried a bit of vigorous depressing the brake pedal, and there is about an inch of 'play' when I get my toe under the pedal and pull back. The pedal then drops about an inch when I remove my toe. The brake lights stay on when I remove my toe from under the pedal and will only go off when I wedge a screwdriver under the pedal. I live West Sheffield only about 10 miles from Bamford so will probably limp to LiTP, if you wouldn't mind bringing your spare, I can either pay you by bank transfer or post the spare back to you if its just the pedal pivot. If you'd sooner hang on to it, I've just seen that they are only £65 new from Elise Parts. Thanks for your advice, Andrew

Edited June 29 by Mutley00

[Phil Hutchins]

Sticking brake master cylinder piston due to a small amount of corrosion/‘sticktion’ due to limited use over time. The internal return spring is relatively weak and doesn’t overcome the piston friction to release the pressure. Not really serviceable but as you’ve found out they’re cheap to replace  anyway. 
Before that you may want to try opening one bleed nipple and pumping some fresh fluid through thro’ several times which will move the piston more and free it off over a greater travel. 

[MrWill]

48 minutes ago, Mutley00 said:

I tried a bit of vigorous depressing the brake pedal, and there is about an inch of 'play' when I get my toe under the pedal and pull back. The pedal then drops about an inch when I remove my toe. The brake lights stay on when I remove my toe from under the pedal and will only go off when I wedge a screwdriver under the pedal. I live West Sheffield only about 10 miles from Bamford so will probably limp to LiTP, if you wouldn't mind bringing your spare, I can either pay you by bank transfer or post the spare back to you if its just the pedal pivot. If you'd sooner hang on to it, I've just seen that they are only £65 new from Elise Parts. Thanks for your advice, Andrew

No worries Mutley.  I'll put it in the boot now its up to you. Have a look at it and you can decide if you want it or would rather get a new one. Either way it's no trouble to bring it tomorrow. BtW its Free to a good mloc home 👍

[Mutley00]

Thanks for your help on this today Phil and Will. I think as you surmised it was lack of use and whatever was stuck, seems to have frred itself off. I now hane another problem........!

[Phil Hutchins]

On 30/06/2024 at 16:23, Mutley00 said:

Thanks for your help on this today Phil and Will. I think as you surmised it was lack of use and whatever was stuck, seems to have frred itself off. I now hane another problem........!

Hopefully you’ve now sorted the bonnet cable and master cylinder?! A mate had the same, just before your problem, on his S1 160. He’s swapped the master cylinder for new, but stripped the old one out of interest and found this…! God knows what the white stuff is but it certainly shouldn’t be there and wouldn’t have helped free-piston-return!!

[Mutley00]

Yes all sorted thanks Phil. The bonnet cable had become detached near the lock rather than broken and the master cyllinder has freed up with increased use. I wonder if that white stuff is some old grease that's crystallized? Seems to be traces of it on the coils of the left spring aswell 🤔