My car ( 1959 Mark 1, 3.4) now has begun to make a very strange, ominous groaning type sound when I step on the brake pedal. Happens maybe 70 -80 % of the time. Brake pedal is firm, but braking performance is very poor to the point that I consider it unsafe and dangerous to drive - not sure it will stop quickly enough from 40 mph in normal driving conditions... This sound happens when the car is being driven or even is parked in my driveway if he engine is running. Groaning sound is coming from the front right side on the car ( a LHD car). Does anyone have any thoughts as to what is the issue ? I suspect this could be a problem with the servo ?

BACK STORY: this is a project vehicle that I acquire whe nthe former owner died while it was being "re-commissioned". I have driven it very little as the Master brake cylinder needed rebuiding and the steering was not properly functioning. I had the MC rebuilt, installed it and bled the brakes myself. While driving over to the shop where the mechanic knows how to work on older British cars to have him install the new track bars and align the car, it started making this groaning sound emanating from the right front of the car. I asked the mechanic to re-bleed the brakes ( in case I did something wrong) and see what he thought of the noise. He installed the track bars, got the car aligned, bled the brakes again but told me he had no idea what that noise was. He heard it, checked the hub and other likely mechanical parts that would possibly cause it , but found evrything to be fine. On the drive back home from his shop, the car continued to make the groaning sound most times I put on the brakes. the brake performance was very poor, while the pedal was not spongy,but pretty firm. ( took a lot of brake pedal effort to get the car slowed down). I noticed that the sound happens even when the car is at a dead stop if I pushed on the the brake pedal.
THANKS for your thoughts and opinions !
Schmitty

 

i'm going to assume the brake pads are in good working condition\.

 

Have you inspected the brakes at the front right wheel? The best I can suggest is a piston has been pushed back into its cylinder and is stuck. Are the surfaces of the disc clean or is there surface rust? If the latter, the piston isn't pushing the pad against the disc. Are the correct pads present? Things do get forgotten during a recommissioning. In the Dunlop system, pads should be replaced well before all the pad material is consumed.

 

The problem could well be with the servo/booster hence your hard pedal & lack of confidence in the brakes. If you put your foot on the brake pedal & then start the car the pedal should soften a little as the servo/booster & vacuum comes into play. They were well known by Jaguar to make sighing sounds. One mans sigh could be anothers groan. From the literature on changes made right into the early Mk2 era. "The brake servo gained a two-stage air valve to eliminate the sighing noises characteristic of the earlier type."

I would take a long hard look at the servo/booster which is on the RHS. It might be finished, inoperative & ineffective & require changing completely.

It would fit with your symptoms. You need the newer type servo/booster.

 

Reading the description again, I think Glyn's diagnosis is much better than mine. I always suggest pouring some brake fluid down the servo breather to lubricate the vacuum piston - it sometimes helps and requires little effort. If it helps, you're sure where the problem is. Even if it seems to resolve the problem, it's still best to take a look inside the servo. If it doesn't work, the problem is still likely to be in the servo though probably not the air/vacuum piston.

 

If it were a brake pad or stuck piston in the RHS caliper I would expect the car to pull to the LHS under braking.

 

I got a chance to start engine today with foot on brake pedal. no difference in pedal pressure once the car started. Also, opened the hood and had my wife step on brake pedal while engine was idling. Groaning is for sure coming from the servo area. Looking at the unit, I don't see where the air breather is located. this servo is freshly painted and I am wondering if the guy painted the air breather shut ? would this be the possible culprit ? Also looking for where to add some brake fluid to try and lubricate the insides. Where is that located on the servo ?
At this point I am assuming the worst - that the unit needs replacing. What option might I have ? I will try and contact the guys who rebuild such stuff, but probably they don't have parts to do this on this old servo. I see that Moss Motors here in the States, sells a "generic" after market servo/booster which they claim can be fitted on these early Saloons as well as a mix of other British cars. Anyone have any experience with this Moss aftermarket product ? Thanks for your help, gentlemen. I will do some more tinkering in a couple days when I get the chance.
Schmitty

 

You need a new Servo. No point in rebuilding the old type. You need the smaller type that was fitted to most Mk2's & early S Types. The larger booster that the S Type finally moved to ~ approx 5 3/4" to 8" fitted to later S Types is wrong for your car ~ likely to cause rear wheel locking. Sounds like your car does not have the remote breather.

Post the Moss link please.

Remote Breather with top filter. You remove the filter & pour a little brake fluid down the pipe, This is Peters suggestion. I have the 8" booster/servo that is more modern & has it's breather built in. No remote breather.

This is the servo/booster you need.

 

See edit.

 

That groaning is typical of the early power brake servos fitted to any MK1s. I have encountered it a number of times (I have had 6 MK1s)
I agree with Glyn's recommendation to get a new servo. The Moss replacement looks OK.
The original servos are difficult and expensive to repair. Unless you are doing concourse, they don't warrant the time and money.
The repair typically costs several times the price of a new servo.
Your MK1 with disc brakes should have exactly the same braking as a MK2.
(In Australia I recommend the PBR VH40 remote booster as a replacement.)

.

 

Thanks for the support Bill . Now we are getting somewhere. I found the Moss replacement.

I'm pleased that Moss provide a mounting kit. That booster does not have peripheral mounting.

Otherwise seems the right spec. Don't overboost the brakes. You will suffer rear wheel locking on a single line system.

The big 8" booster fitted to later S types with IRS is not correct for your car & would not fit without a deeper/larger S Type cover in the wheel arch.

 

The Moss booster looks like the one that's often used in the UK on kit builds. If it is, it should work well and give the right amount of assistance. Though the old one isn't economic to rebuild, if it's the original type, it is a rare beast. It may be worth hanging on to until an originality enthusiast wants it.

 

Schmitty, you have not indicated your location in your profile (I wish everyone would), but White Post in the States will most likely rebuild your servo for a price:

Brake Sleeving & Rebuilding Services – White Post Restorations

That said, I also believe that Glyn;s recommendation makes the most sense, if the car is not being restored to Concourse specs.

 

Thanks to Bill for confirming the groan vs sigh ~ I thought they might be the same thing ~ Jaguar use the term sigh. Bill is the Mk1 Guru. Cass & I know S Types backwards as Peter does Mk2s. We also have general car & mechanical knowledge. Bill's knowledge includes aircraft.

 

Gentlemean, especially Bill and Glyn, Have not had any time to get back on line for a couple of days so I want to say a big THANK YOU so much for your help and thoughts!! Great to have such experts to lean on when dealing with these grand old Jaguars. I had suspected the servo was at fault and am glad to hear your agreement. I will get the Moss assembly unit and get it installed ( somehow) and move forward.
Schmitty