Girling Mk2B Brake Servo Issue

[RAJ2628]

This post is intended to help and prevent future buyers of this type of servo from making the same mistake as me. This is my first Elan project and I was unaware of potential issues with the Girling Mk2B Brake Servo.
Since retirement in June 2019 I have been refurbishing a Lotus Elan S4. Early on in the build I bought a load of parts from one of our favourite suppliers. One of the parts was a replacement, refurbished Girling Mk2B Brake Servo.
Just before I fitted the servo, someone told me that these things don't store well.
As I bought this part over 2 years earlier, I took his advice and got it checked at a well known brake servicer near me. It passed.
In September 2023 I fitted the Brake Servo and filled and bled the system to check for leaks. For several reasons I didn't check the brakes until June of this year. I was unimpressed with the car under braking. After a couple of re-bleeds and using the hints and tips for checking servo function, I decided to get it re-checked. This time there was an intermittent issue discovered, so I asked if it could be re-built. The rebuild discovered that the previous refurbisher applied too much grease around the piston area.
My recommendation from my experience is hold off from buying the Girling Mk2B until you really need it and choose your supplier wisely.
These things are around £250+ to buy and a full investigation, strip down and rebuild cost is about £250.
On a positive note, the guy who refurbished the servo was very helpful and turned the re-build around really quickly. From his description of what he found and how he repaired it I expect no issues when I fit it.

[Hawksfield]

RAJ
Could be more explicit around the statement of to much grease around the piston.
My experience with mk2b is no grease at all only fresh fluid. Even the rubber diaphragm should be dry..
Your builders statement is that he would use grease but not to much.

Hope it works ok for you. The only problem I have experienced is the poor replacement primary control valve seals
Which cause brakes to lock up or push back.
Plenty of posts on here.

John

[JonB]

Quite a few people suggest the car is better off without a servo. They point to better brake feel and less tendency to lock under hard braking. My Plus 2 , now sold, certainly locked up easily, especially in the wet. Don’t forget it’s a very light car.

Accordingly, my servo is still in a box, unrestored. Like you I am restoring an S4, but I will try it without a servo first, to see if what I’ve been told is true. I figure the servo is easy enough to retrofit if I don’t like the car without.

[RAJ2628]

Hawksfield
You are correct, the chap I sent the servo to did say there should be no grease.

[RAJ2628]

JonB
I took the servo off and made a bypass link to see how it felt. I did not get a feeling of confidence under braking. I thought (as others have posted) that better brake pad material and a larger bore master cylinder was needed. I just wanted to get the brake system working as designed.
As I said, I simply don't want people to make my mistake. For all the good info presented on the forum, there is nothing that says the expensive "brand new to me" servo can degrade just sat in a box.
It could be in a couple of years, I do change my mind and do as you, and others suggest.
How long have you had your servo in the box.

[JonB]

Hi RAJ

No criticism intended. My servo has not been used for over 30 years, the car is a so-called “garage find” and I am restoring it. I took it off the car 18 months ago, it’s rusty and in need of TLC. For all I know it works properly. I suppose I will have to recommission it.

Now your comment about a larger bore master cylinder doesn’t make sense. Doing that would mean greater pressure needed at the pedal. I think slightly smaller is what you need in order to gain hydraulic advantage.

That said I think sorting your servo is going to be your best bet.

Best
JonB