I need to replace my brake booster (disappearing brake fluid....). SNG Barratt has two different Lockheed units. One is 3:1 and the other is 4.25:1. Is there a way I can tell what my car currently has (Preferably by not taking it out))? If I cannot determine, is there a difference in quality between the two models? The 3:1 is about $80 more. If I can save some money for other parts...great, but I do not want to be cheap on an important braking part.
thanks,
JR

 

I've recently had to get my booster replaced so I've done a little research on the matter. You have disc brakes on your car as I do. I got the LE 10117. the larger boost is no good as it's likely to lock up the rear brakes. There was a forum discussion about this in the last year. Good Luck ! Before spending the money, I'd make sure to first check that you don't have a leak from the MC , a caliper, or a in a brake line. More knowedgeable members may have different advise !
Schmitty.

 

Schmitty - Thanks....I already checked master, each wheel caliper and the brake lines.

 

The boosters leak internally into the main vacuum chamber.
Eventually the fluid will work its way into the intake manifold and be burned with clouds of billowing white smoke.
If you're running DOT 5 (silicone) brake fluid, do not drive the car until the booster is replaced or repaired.

If the silicone brake fluid is burned in the engine, it turns into a sandy mess and destroys the engine.

 

I do not use DOT5 in my cars. Have not noticed any exhaust smoke but 3 reservoir bottles of brake fluid are “missing”

 

It takes a while, it has to fill up the vacuum tank first, that's a lot of brake fluid !
The fluid is in the large piston chamber, it leaks past the seal of the slave cylinder, that's shot.

I rebuilt mine a while ago now, it's up to you what you want to do.

 

Another option is to have the booster sent out and rebuilt. I had mine done by White Post Restorations in White Post, Virginia a couple of years ago for $500. It's probably more now. On the plus side you get the same unit back so you know it will perform as OE and it will fit without extra brackets. They re-plate the housing so it looks 100% OEM if that is important to you.
As an aside, I also have an E-Type and I had disappearing brake fluid and brakes that were slow to release. When I took the old booster out I must have poured a pint of nasty, rusty old brake fluid out of the vacuum chamber. Its a wonder it worked at all.

 

JeffR1. - I already opened up the vacuum reservoir…and it was EMPTY.

 

If White Post can rebuild your servo ( booster) that is the way to go !!! the after market unit your looking at on SNG will require some "fiddling" to fit on the car. My mechanic said that installing the aftermarket servo on my car was a "nightmare". I believe him. He needed to find new mounting position ( requiring cutting the metal in the engine compartment), needing to replace the main brake line to the new servo, etc. not an easy job - but doable yourself if you are very mechanical. a White Post servo rebuild would be so much simpler. Just drop it in and hook it back up. I'd call them before ordering the new part. I sent mine to WP, they sent if back..."no can do".. Thus I had no choice but to get the new servo.
The vacuum reservoir doesn't actually hold brake fluid - it holds air - a vacuum from the intake manifold -when the engine is running - goes into a "reservoir" - that supplies air to the servo if the engine should stop operating and not produce vacuum from the intake manifold. kinda of a short period safety meausure should your engine fail while going down a steep grade. Not really needed, IMHO. brakes will work without the vacuum component - just will require a lot more brake pedal pressure. Good Luck !

 

Schmitty ~ All the pipework is wrong with the aftermarket boosters, from vacuum to fluid. They are frustratingly close but won't make it. (S Type)

I sent my booster/servo to Barratts UK for rebuild and back came a masterpiece as new. This picture is no scam. it is exactly as you get them back.

 

Refresh page for edits

 

This is what I sent them.

 

I have a 1967 Mark 2 (not a 340) and I replaced the booster with an LR18230 from SNG Barratt.
In 2016 I had to change the original one fitted to my car and bought an LR18230 from an unnamed vendor. This lasted about 3 years and it then developed a fault where it would not release the brakes cleanly.
I took it apart and it was clearly built to a poor standard with self tapping screws in place of the correct screws.
I bought a new one (LR18230) from Barratt's and it was clearly of superior quality to the last replacement unit.
It has worked flawlessly ever since.
So my takeaways are
1) not all LR18230's are created equal but SNGB does have good ones.
2) I needed to reorient the vacuum valve housing to get it to fit properly but this is pretty straightforward as I remember.
3) the braking performance and balance is fine even though the ratio is not as original

Bruce

 

I changed my servo for the upgraded one from SNG a couple of years ago. I cannot remember the ratio now but I recall the price was cheaper to buy the upgraded version than to buy the original spec version plus you had to send your original spec one to them as an exchange. No need to do that with the upgraded version. When it arrived I had no problems fitting it straight into the space the original sat. All the bolt patterns were the same and the brake lines, though difficult to connect just because of the position of the servo on the inner wing all went together with no alterations at all.

 

I contacted SNG Barrett here in the states and they no longer offer a rebuild service for the brake boosters. I'm in the middle of restoring my brake vacuum reservoir system - original reservoir had rusted through - found a good used one and I'm currently waiting for the temperature to get back above 60 degrees to finish painting parts. Big storm out here in California as well as just about everywhere else in the States!

I talked to the guys at White Post about their service in case my booster needs to be rebuilt. I would recommend them.

 

just called White Post and they will rebuild for $595. Now the big decision: Rebuild and pay more but it will be a correct fit .... or.... save some cash and get upgrade but have to tweak the installation.

...Why do people buy Jags?

 

The large Servo I show above was already an upgrade (approx March 1965) to 8in diameter instead of the earlier 6.875in diameter & maintained balance in the system. Going to greater ratio boosters/servos on the S Type is known to cause rear wheel locking.

 

Might be a UK build vs SA. Our brake lines were locally produced. I replaced my lines with a UK Automec kit in Copper/Nickel so no issues but I had the correct 8" Booster as shown above because I was going for concours which was achieved. Best in Country & 100 points plus. There are also multiple aftermarket boosters available, some might well fit better than others.

 

I could not find the one I purchased as it was from XK's Unlimited, now purchased by Moss Motors and they do not have it anymore; it was a direct replacement that had better performance. I think the one at S & G, https://www.sngbarratt.com/English/#...3.8%20&%20340=
is decent and only $369 and if you want to upgrade brake performance I recommend Fosseyway Performance as their brake it works with the stock booster. For me I went to the extreme with the large vented 6 piston front brake, used a proportioning valve and upgraded the rear to larger early E-type rear brake calipers. https://www.fossewayperformance.co.u...grades-dunlop/
they offer three levels of brake upgrades that work with stock booster.

 

Primaz is correct ~ numerous replacements have been available over time. Some more easily fitted than others and of varying quality. He has direct experience with Fosseway.

Slight boost ratio improvements depend entirely on how hard you want to push the pedal. As said above. Going to greater ratio boosters/servos on the S Type is known to cause rear wheel locking with some combos.

Stick to DOT 4+ max brake fluid a put up with a fluid replacement every 2 to 3 years. Bleeding these systems is dead easy being single circuit. The minute you move to silicone brake fluid you put yourself in danger of incompatibility with elastomers. Servos/boosters are a known area of incompatibility. On Alan Wiedie's car silicone fluid ate up all his seals including Master cylinder.