5 replies to this topic

[leyland73]

My 89 Thirty has been sitting unused in the garage for 14 years, now being brought back to life. Brake hoses, calipers and wheel cylinders all replaced along with a new brake master cylinder; 13k miles from new.

Brake pedal, without master cylinder attached was sticking and would not return correctly. All linkages have been lightly oiled and pedal return improved. Decided to replace servo to be on the safe side. brakes bled several times, 1 litre of fluid flushed through, and pedal firm before starting engine, the pedal drops almost to the bottom of its travel once engine starts. Pedal then relatively firm again, servo seems to make no difference.

Completely at odds as to why the brake pedal would be behaving like this?

Considering replacing the new servo with the old one to see if this improves things.

Has anyone any thoughts as to what is going on here?

[leyland73]

Have bled brakes again using a vacuum bleeder and checked all pipe connections, still the same. Front calipers on the right way up and rear brakes adjusted up tight.

Would a faulty non return valve cause problems like this?

[Spider]

It is normal for the pedal to drop a little if you have your foot on the pedal and then start it.

 

That it's dropping to the floor is of concern, it won't be the non-return valve I'm sorry. You may need to have the Servo overhauled.

[Junior Mini]

It does sound like the servo diaphragm I'm afraid. You could get a rebuild kit and overhaul you're old one maybe?

[cal844]

Could it be the set up of the bell crank?

[leyland73]

It does sound like the servo diaphragm I'm afraid. You could get a rebuild kit and overhaul you're old one maybe?

It’s a new servo just fitted, will try the old one again then if that works, it’s a refund from minispares for the new servo!