Brake Master Cylinder

[DJT]

Just over 3 years ago I fitted a new (TRW) master cylinder sourced from a respected supplier in Herts. Filled from the start with Dot 5 (silicon) fluid it has been fine, until now. Yesterday, after a short run I felt the brakes were binding. Investigation revealed the front brakes were stuck on. After leaving the car for an hour or so the brakes were fine again, but today the same fault has appeared. I disconnected the front brake pipe from the master cylinder and they released. Pressing the brake pedal with the pipe disconnected released one shot of fluid, then nothing. I've never experienced this fault before. It seems to me that the master cylinder has failed, despite its relative newness (19,000 miles). I am reluctant to strip and overhaul the unit, but I am also annoyed at having to buy a new one - again!

I see that SOC Spares, Robsport and Paddocks all list the TRW (Lucas) unit which is the same as the one I have, but EJ Ward list a new Lockheed unit at twice the price. I don't mind paying for the expensive unit if it is going to remain reliable for many years.

Any thoughts?

PS. Don't send me a PM as I still cannot access them

[Andrew S]

Hi Dave,

I have had one of those TRW ones and has been fine for many years so you may just be unlucky. I may have bought it from Peter at LDPart or similar but i was under the impression that it had be relined wit stainless insert and I too run on DOT 5

[Goldstar]

Hi Dave,

I have had one of those TRW ones and has been fine for many years so you may just be unlucky. I may have bought it from Peter at LDPart or similar but i was under the impression that it had be relined wit stainless insert and I too run on DOT 5

The SS liner is an upgrade, rather than standard Andrew. If Peter has a lined one I would buy that otherwise I’d go Lockheed as the OE

[DJT]

An update:

I spoke to EJ Ward about m/cylinders. They used to offer a rebuild/re-sleeve service, but don't do it anymore due to lack of supply of new pistons. They also severed ties with Lucas/TRW a few years ago due to too many premature failures. The ones they now supply have been commissioned by RB under the Lockheed brand and are the ones they now fit.

I replaced the original (or at least the one fitted when I bought the car in 20028) Lockheed cylinder in 2016 at 101666 miles. This was a TRW unit bought from Robsport along with a reconditioned servo, after the servo failed. This cylinder lasted until it failed in 2022 at 119440 miles and was replaced with another TRW unit, which is the one that has now failed.

New Lockheed unit on order for delivery tomorrow. TRW unit removed ready.

If anyone wants any m/cylinders for rebuild, let me know. R-L Original Lockheed, TRW (2016), TRW (2022)

IMG_3829.jpg

[richardthestag]

Not heard of issues with TRW until now. just playing devils advocate here but why DOT5, wonder if DOT5 is a contributing factor? no reason why just thinking out loud.

I am finding more and more that the brand name means nothing any more, most of them have been bought up by ### (insert company name here) based in #### (insert Country of manufacture here). The production costs/quality are driven down to make for bigger profits for the moguls in #### (insert country of your choice here). In a few cases there is a shining light, those companies need to be rewarded with 100% of the UK business. The traders and suppliers who sell the cheese products should be held to account, but that won't happen because of T&C which you agree to before you hit the buy it now button - you do read the T&C don't you?

shoddy ****e

The personal experience that really gets my goat, a very famous Austin Martin specialist (you know, shiny website, deals with expensive motors) told me that no need to harden the crank journal surfaces on a stag v8, because and roughly in their words (it was 6 years ago) they do 1500 miles a year and get sold every 4 years. Not your problem is it?

Attitude stinks, **** em! **** em all

[Philip Wardle]

... no need to harden the crank journal surfaces on a stag v8, because and roughly in their words (it was 6 years ago) they do 1500 miles a year and get sold every 4 years. Not your problem is it?

Disgusting attitude, so snobbish ... remind me not to take my Aston there in future ...

[DJT]

Not heard of issues with TRW until now. just playing devils advocate here but why DOT5, wonder if DOT5 is a contributing factor? no reason why just thinking out loud.

First TRW unit that failed had been used with DOT4. When I bought the second one, along with the servo, I flushed the system and changed the fluid to DOT5 which was bought at the same time, from the same supplier.

[Philip Wardle]

I fitted a TRW unit during my restoration, it failed straight out of the box. But we purchased it a long time ago, and seem I to have a vague recollection of a faulty batch ... just can't remember more details.

[sujitroy]

I'd be happy to take the original one from you. the Reservoirs are worth holding on too. they crack with age.

[jbuckl]

Crumbs thumbs didn’t mean to delete!

trw…. Had failures

resleeves no failures

used this place for a few master cylinders.

its a one man band….turnaround sometimes 3 weeks.
hopefully still offering a good service though.

pressure tested and stamped.
must have reservoir on iirc

https://cbccarspares.co.uk/triumph-stag-original-lockheed-brake-master-cylinder---gmc218-6712-p.asp

[Seaking]

Dot 5 requires different types of seals.
chap was selling dot 5 approved master cyclinder rebuild kits. I purchased a couple .

[DJT]

Dot 5 requires different types of seals.
chap was selling dot 5 approved master cyclinder rebuild kits. I purchased a couple .

Interesting. Something I have not heard before.

Both Robsport, who sell TRW units, and EJW, who sell Lockheed, also sell DOT5. Robsport sold it to me alongside the TRW unit and EJW were prepared to sell it to me with the Lockheed unit, but they were out of stock. Neither said that it wasn't suitable.

[Philip Wardle]

Dot 5 requires different types of seals.
chap was selling dot 5 approved master cyclinder rebuild kits. I purchased a couple .

I was aware of advice to change the seals and rubber hoses when changing to / from DOT5 but hadn't known that different seals were needed, I haven't seen any suppliers for different parts or rationale - would be interested to learn more out of interest although not personally intending to make the change. Pretty happy with the standard set up when everything is working as designed, which I reckon was pretty good by the standards of the 1970s.

[mopoole]

I was aware of advice to change the seals and rubber hoses when changing to / from DOT5 but hadn't known that different seals were needed, I haven't seen any suppliers for different parts or rationale - would be interested to learn more out of interest although not personally intending to make the change. Pretty happy with the standard set up when everything is working as designed, which I reckon was pretty good by the standards of the 1970s.

Interesting.
I changed to Dot 5 a few years ago in the course of upgrading the front brakes and I replaced the rear cylinders and fitted a new TRW master. That has only lasted about 3 years and needed changing last year The only seals I didn't change were those in the PDWA switch which recently gave way on me. See my posts.

Food for thought perhaps?

[richardthestag]

ah ha, a customer of mine has a recently purchased stag with what I believe is exactly this issue.

I have suggest that next time it binds the front brakes up tight to loosen the fixings that hold the master to the servo and see how many mm of clearance between master and servo before the car rolls again.

The ****ty thing is that most of the time there is no issue, just every now and then both front brakes get locked on. pump the pedal a couple of times and sometimes they release, leave it an hour and they release.