Dead brake boosters on my '74, rebuild?

[analogmike]

Hi,

I finally started driving my '74 Special and I'm really starting to like it, though it still needs sorting.

The brakes are very weak. I found the front calipers were stuck so I exercised them and flushed the brake fluid with Castrol and they are working now. Rears are working fine with new slave cylinders. But the pedal effort is still very high though I can lock up the brakes if I try hard.

I pulled the vaccuum line from the boosters and plugged it, with little change in pedal effort. So I guess the boosters need rebuilding. I'd rather do that and keep the car original than install a smaller master cylinder. Does that sound like an accurate assessment, is there something else that could be wrong (I am getting vacuum but have not measured it yet, parts stores don't carry vacuum gauges like they did in the old days!).

Should I attempt to rebuild them myself, and if so where do I get parts?

Or is there someone who will rebuild them for a decent price?

Or if I modify the brake lines around the boosters, will the brakes work better with them bypassed than dead? I am really good with older Porsches and they had no vacuum assist so I am not familiar with how they work.

Any help appreciated, happy new year!!!

(not enough room for my guitar gear, so I made two trips!!)

[BDA]

Europas are definitely not meant to haul bulky rigid containers!

I can't tell you about the difference the boosters make since I've only driven my car with boosters - the Girling when new and I used Lockheed when I rebuilt it. I suspect it makes a difference since I don't think Chunky would have added either the weight or the cost if he didn't think he had to, but YMMV. This might be helpful if you decide to go boosterless: http://gglotus.org/ggtech/europa-brakes/tcbrake1.htm. There may be more ideas here: http://lotus-europa.com/manuals/

If you do decide to keep them, rebuild kits are sometimes available on ebay. I just saw some that look like they are for the Europa boosters, but I don't know the actual designation for the Europa booster so those may not fit. While I've taken a booster apart, I've never rebuilt one so I can't speak authoritatively on it, but it didn't look that tricky.

If you would rather have them rebuilt, I would advise you to contact White Post Restorations (whitepost.com). They did a nice job on my rear calipers and M/C and they seem to be able to restore anything. They also have a fast turn-around.

Good luck and Happy New Year!!

[Grumblebuns]

With the cost of rebuilding the boosters running about $450 per unit (Apple Hydraulics), you may want to try to see if you can live with bypassing the boosters first. The alternative is finding some Lockheed replacements. I suspect they'll cost the same as the rebuilding the Girlings. This thread has some pictures of how to run the bypass lines.

http://www.lotuseuropa.org/LotusForum/index.php?topic=1069.0

[EuropaTC]

Hi Mike

The standard way a mechanic tests brake boosters (servo in UK) on our annual MoT test here is as follows;

Ignition off, car stationary & press the brake several times. This is to remove any residual vac. in the line & servo itself.
 
After 3-4 presses then press hard & hold the brake pedal down and whenever I've done the test I've used my left foot so I can blip the throttle with my right.

Start the engine. As the engine fires, revs rise and a vac. establishes which and then the servo kicks in and you can feel a slight downward movement on the brake pedal. It's not a lot and I couldn't even start to estimate how much but it is noticeable. 

No movement at all and your car fails the MoT because if a servo is fitted it must be working. Take it off completely and it doesn't matter how hard the brakes are to press, there's no problem with the test.....  it's a Brit thing 

Sticking servos were a regular feature of over winter storage on my cars. Once the above test failed I'd do the usual checks for hose connections and then move to the servo. 99 times out of 100 it was one of the small internal valves sticking and the servo cylinder seals themselves were ok and not leaking. Careful dismantling & cleaning usually got it working again without any problem and it would be fine until the next lay-up !

Brian

[analogmike]

Thanks for the replies!!!

I have been thinking I should pull one of the boosters apart and see what it looks like before I go much further. I think it has been sitting a while, maybe I can get it unstuck without a total rebuild. Or if I need parts, it looks like I can get rebuild kits / parts from Power Track Brakes in the UK. There is a great article about successfully rebuilding them here:

http://www.lotuselan.net/forums/lotus-suspension-f42/lockheed-brake-servo-rebuild-kits-t27431.html

And that article leads to some nice pictures here:

http://www.triumph-spitfire.nl/servoimages.htm

Maybe I can do some of this without even removing the boosters from the car.

[BDA]

Those are the Lockheed boosters. This video should be useful for rebuilding yours (https://www.youtube.com/watch?v=quRJ4_sqMYU).

[analogmike]

I thought we had Lockheed, mine look more like the Lockheed than the Girling. I can;t find decent pix of the boosters with Google, just this one which is nothing like mine



Here's a slight shot of mine:

[BDA]

Ok! The top picture has the stock Girling boosters. You have the Lockheed boosters like mine. Mine are probably 25 years old, but they have few miles on them, and they seem to be working fine so far. I'll have to print off those instructions for when I have to rebuild mine.

[CCM911]

Get in touch with R.D. Enterprises.  They have new sets available for about $500.  You may have to fiddle with the mounting, but they will definitely work.  Personally, I am removing mine altogether.  I plan on trying some different pad compounds if I do not like the feel.  I mean, a bunch of folks run without the boosters, and the car is only 1500 lbs or so, so I think it would be Ok to forgoe the boosters.  But we'll have to hear some opinions from folks more educated on this subject than I.

I also work on my 1984 911.  The Porsche is so easy to work on.  The Lotus is painful in comparison.   

[EuropaTC]

I also work on my 1984 911.  The Porsche is so easy to work on.  The Lotus is painful in comparison.   

   they have clearly changed since 1984 then......     

it took me two days (yes, two days     ) to change the serpentine drive belt on our Gen 2 Cayman last summer.  Ok, part of that was me going slowly because I didn't want to mark any of the trim, but even so getting the belt in place was a seriously hard job. 

I guess it's just what you're brought up on. I can think of a few awkward jobs on the Europa but mostly they are very simple and straightforward once you get to know the car.

Brian

[analogmike]

Thanks for the replies.

I did more digging, and found the boosters are fairly recent, though the PO had trouble with them too. The mechanic wrote him a note on the receipt:

"Poppet valves on the new boosters were stuck because you don't drive the car enough, drive it every week, it's fun!"

I got a vacuum gauge and tested the plumbing etc and after cleaning everything up, am getting about 10psi at idle. It's all PULSES though, I had to make a vacuum reservoir out of a small gas can to read the actual pressure. My boosters are not leaking vacuum, and those white round things on top are holding vacuum for a while after I turn off the car, I pulled them apart and they were pretty clean. I think those white things are servo (booster) air valves, and the poppet valves are inside, so I may need to disassemble the boosters to unstick them. I would think a vacuum reservoir with a one-way valve would help this brake system work better, to keep vacuum in the boosters. But maybe that's what these white air valves do?

The brakes are working a little better now, but I still don't think I am getting much boost. I will check out that video when I have time and see if he shows the poppet valves.

I did improve my shift linkage a lot, will post in another thread about that.

[EuropaTC]

If your servo is the same as I had fitted, mine came from an MGB. 

This page  http://www.mgb-stuff.org.uk/servo.htm  has a description of how it is supposed to work, plus some of the best cross sectional drawings I've seen in a while.  I used it when mine used to stick (before I junked them    )

Brian

[CCM911]

"1984" is the key phrase here, LOL.

I'll send you my 1984 for the Cayman?  I love those cars.  All my rich friends are now buying GT4 models.

I also work on my 1984 911.  The Porsche is so easy to work on.  The Lotus is painful in comparison.   

   they have clearly changed since 1984 then......     

it took me two days (yes, two days     ) to change the serpentine drive belt on our Gen 2 Cayman last summer.  Ok, part of that was me going slowly because I didn't want to mark any of the trim, but even so getting the belt in place was a seriously hard job. 

I guess it's just what you're brought up on. I can think of a few awkward jobs on the Europa but mostly they are very simple and straightforward once you get to know the car.

Brian

[analogmike]

OK I finally got my power brakes working!!

It was the poppet valve stuck, the thing that pushes up on the little white round thing on top of the booster, to release vacuum from one side of the booster to provide assist. There was always vacuum in my boosters as the poppet valves never released it so there was never any brake assist.

This is an easy job though I could not find a single explanation on the internet on how to fix a stuck poppet valve.

How to unstick a Lockheed Brake Booster

For diagrams and "how it works" see this link

http://www.mgb-stuff.org.uk/servo.htm

1) pop off the little top vent air valve cover, just snaps on and off, be careful not to lose the spring!

2) unscrew the 5 philips head screws that hold the round top of the white plastic air valve diaphragm assembly. 

3) carefully remove the cover, don't rip the diaphragm. Then you can pull it off the vacuum hose easily by rotating it up.

4) carefully remove the diaphragm.

5) There will be 3 larger philips screws holding the air valve diaphragm assembly bottom metal plate onto the brake booster. Remove these.

6) The bottom plate will pull off and you can see the air valve piston top in the middle. This is what's stuck. Clean it up and soak it with some PB Blaster. One of mine was VERY stuck, so I found a tapered EZ OUT with sharp splines and tapped it in gently, till it moved a bit, then turned the piston till it was free. Be careful you don't want to push it down too far. You may find a nicer way of freeing it. My second one was not stuck so bad, I was able to get it moving much more easily and lubed them both up.



7) Clean everything up well, lube the rubber parts a bit and put it together and you should be all set!

[3929R]

 
Thanks for posting the 411.
So how do you like stopping with the boosters as compared to without?