Brakes & clutch rubber

[miked]

A few interesting points, whilst doing some winter maintenance/PPM's:
All refurbed 5 years ago, about 13K miles since. S4. Dot 5.1 being used.

Clutch cylinder was dribbling. Split and found seal rounded. Lot of heat in this area, so expected. Fitted new seals and started to bleed, found nasty black fuild comming through with bits in. Looked into rear of master cylinder in the car. Pulled boot back and it was all wet and red grease was brown. Changed rubbers, the other were well shot.

Also did the brake master while in there. Although this was mint. Moral is, it is worth a look under the dash and flip off the rubber boots to see what is happening or about to. I would never have thought after such a short time.

Having gone on some test drives, I decided the brakes were not as good as before in earlier years. Also seemed to stay on for part of a second when pedal released. Checked out servo, all fine. Last time I had this the servo was drinking fuild (fuel vapour had destroyed servo rubber). Not this time though.

I talked to David at Classicar and he says that by 3 years (with cars that are little used) that the caliper piston rubbers start to swell slightly tightening and stiffening.

I have pulled all four cailper off and cleaned and changed the rubbers. They were not marked but were quite stiff. The front did show signs of slightly swelled rubbers. The brakes are now back to being as good as they were. The nose is taking a dive now under heavy braking. Feels load better, was feeling a bit iffy'. David did say that cars that are in more often used do not tend to suffer this.


Thought I would share this and will be keping an eye on the master cylinders. Also did away with squeal shims at front. I think they actually help bind as they can be tight on the pins. I fitted some of that sticky back type stuff you get with modern pads. Also used some copper slip to rear and side of pads. All now quiet.

Mike

[mikealdren]

Mike,
5 years is too long between fluid changes - 3 years is recommended with non-silicone fluid because it is hygroscopic. It's easy to forget with low mileage classics but mileage is not really as much of a factor. The dirty fluid may well be due to corrosion as well as failed rubber seals.

Mike

[miked]

Mike,

Thanks for reply. I had changed the fluid probably 3 times in that 5 years.
2 year in and then when I went on a track day at 3 years. Then last summer.
The dirty one was the clutch and it was the rubber pieces from the master cylinder. You could literally rub the rubber and it came away on you fingers.
The clutch fluid had been changed twice.


Re brakes, thinking about it, 2 more times when the servo went.

Regards Mike

[billwill]

I've had that happen too.

I suspect petrol from the carbs getting onto the front rubber cap, corrupting that & then working its way past the piston to corrupt the rubber in the master cylinder.

[Frank Howard]

Dot 5.1 being used.

Mike,

You didn't mention the brand. Many brands harm the pure rubber parts (as opposed to Neoprene) in the Girling system. One brand that doesn't harm the rubber is Castrol LMA.

[miked]

Frank,

recently I had used the Halfords one. Previous to that I had the TTR racing one but can't recall the make.

Mike

[freddy22112211]

I also had brake rubbers ruined (went all soft and sticky) after less than 2 years, even using dot4, so I can only assume that not all dot4s are equal (??). Been alright since however.
Gordon

[patrics]

Hi all

Any standard non mineral type fluid is okay in any braking system except mixtures of silicon and standard glycol fluids.
If you have seal failures after such a short time then this will be down to contamination of some sort ? either from the carbs as already pointed out by Bill or from a cleaning fluid used during a rebuild.

Regards
Steve

[miked]

Everything done and now my 2 year old Lockeed servo is holding on.

After seeking advice, cleaned the little piston under the air filter arrangement. Also fitted a spring. Now back to superb and no holding upon braking.

Hope we now have some quiet years with the brakes. Everything has been re-done.

Mike

[triumphelan]

I`ve put plastic bottle bottoms over the brake & clutch caps to keep out any crap and ty-wraped them in place