brake and clutch cylinder cap corrosion

[ChrisR-4A]

I have recently acquired a Plastic cap part no 64474602 from Competition Supplies for the TR4a brake master cyl and it does not fit, it is approx 2mm too large. I spoke to Competition Supplies and they stated that it's the only large cap they do but its meant to fit a Girling master cyl, my cyl is marked LUCAS.                 Checking the Moss London website they only do one master cyl for TR4 & 4A and it is marked LUCAS like mine. So unless you have a Girling master cyl on your 4 or 4A the above plastic cap will not fit. 

For ref the internal dimension of the thread on the steel cap is 61.7mm and on the plastic one its 63.6mm.

Chris

[ianc]

ChrisR-4A has PM'd me to say that he purchased a plastic master cylinder cap for his TR4A - and it does NOT fit!  Glad to say that Competition Supplies will refund him.

I think Chris has put his finger on a problem: Competition Supplies states that the plastic caps which it supplies are for the Girling master cylinders.

Chris tells me that the casting of his brake master cylinder states Lucas on both sides, whereas that on 4VC states Girling (because it's installed, I can see only one side).

I think anyone who has any master cylinder other than a genuine Girling may well find a problem if they attempt to fit a Girling plastic cap.

I has sent an e-mail to Peter Wigglesworth (PeterW) who, I feel sure, will be able to shed some light on this.  At the moment I am baffled as to what Lucas, Prince of Darkness, has/had to do with Girling brakes!

I see that Chris has posted whilst I was typing - it looks as if any replacement master cylinder supplied by Moss (since when, I wonder?) will have been manufactured by Lucas and so identified on the casting.  Therefore, check the casting if you are contemplating a plastic cap and order only if the casting is marked Girling.

Apologies for the confusion I may have caused.

Ian Cornish

[BlueTR3A-5EKT]

Probably Lucas TVS

Sourced and distributed by TRW

Peter W

Edited December 22, 2020 by BlueTR3A-5EKT

[ianc]

The ever-helpful and exceedingly knowledgeable Peter W has added some more information in an email to me:

To unravel this.

Girling is the original maker of the TR 4 brake master cylinder.

There are 2 bore sizes.  3/4 & 0.7”

The product with Lucas on it is probably made by Lucas TVS of India.   An original equipment supplier, but not for Triumph.  Probably the best of the bunch who are making cylinders that fit our cars today.  

The wrong sized item (i.e. the plastic cap from Competition Supplies) probably comes about because of this maker change.

[silverfox4]

This is interesting.  I recently ordered the subject plastic caps based on this post and had a similar problem - the threads just did not want take. I tried several times and then pushed down hard on the cap while turning it and it seemed to catch and screw on - maybe I cross threaded it.  The garage was freaking cold so I gave up in disgust as either I have forgotten how to screw on a simple cap or the cap is wrong.  I won't know until I feel like challenging the cold to see what is going on.

For context regarding Girling vs Lucas,  I purchased this Lucas TRW brake MC for the 4A last June from the TRShop and at the time of order I chose to add the ali cap in place of the plastic  thinking it was more in keeping.  I found the ali cap kept weeping because of poor integrity of the threads, so when I saw this post I ordered the 64474602 plastic cap from Demon Tweeks with the experience as above.  In hindsight I should have stuck with the plastic cap that came with the MC

Neither cap makes reference to Girling or Lucas.  I look forward to any further insight from this post.

 

Merry Christmas  all,

Alf

[ianc]

I note that Moss lists two brake master cylinders for TRs 1953-1967:

- 131661 @ £157.50, casting marked TRW

- GR64067671 @ £72.00, casting marked Lucas - Out of Stock

From what Chris has found, it seems that the plastic cap, supplied for the Girling master cylinder according to the description on website of Competition Supplies, won't fit the Lucas  casting.  Whether it would fit the TRW casting, who knows!

On the first page of this topic, Andy states that the caps on the brake and clutch master cylinders sit close together and that use of plastic caps on both might cause interference, and it's true that the plastic cap, with its nice grips, is slightly larger in diameter than the metal lid. 

On 4VC, the two plastic caps are close, but they don't touch - however, I note that my clutch master cylinder is tilted slightly (clockwise, viewed from the front of the car) which helps create a gap.  Whether this is the normal arrangement, I cannot say because 4VC has so many non-standard features and I have no "standard" TR4 with which to compare.

Ian Cornish

[silverfox4]

The part number for my TRShop TRW MC is 1332909, (normally comes with a plastic cap). 

I also find that if two plastic caps are used, they sit can interfere with one another and my two MC'a also sit at an angle to one another (not vertical). I find the metal cap on the clutch MC is sort of OK in terms of fit and seal, so it's the brake MC cap that is the problem - the metal cap does not seal properly. I might have to re-order the TRW brake MC cap that is normally supplied with the MC and see if it is different from the 64474603 plastic cap.

Cheers,

Alf

[Z320]

Why don't you look for a NOS 0.625" master and boost your 4/4A brake with the smaller master piston?

Yes, if you want to keep the original design their casting is too long and the one for the 4/4A is special,

but I purchased one stated it is from a Ford Cortina. It fits well.

I also did this with the clutch master, this is not a special design of the housing.

Ciao, Marco

Edited December 23, 2020 by Z320

[silverfox4]

Thanks that is an Interesting and doable thought Marco, but in my case it would become another project. 

I have just completed this project with new brake, clutch masters along with new clutch slave, and new rear wheel cylinders (using your excellent post on the dust seals),  flushed and refreshed  fluids etc. I would prefer not to start over for want of a stopping a slight weeping cap when driving.  Better to locate the good sealing cap, which of course I thought I had.....

I do appreciate the thought though.

Cheers,

Alf

[rcreweread]

21 minutes ago, silverfox4 said:

Thanks that is an Interesting and doable thought Marco, but in my case it would become another project. 

I have just completed this project with new brake, clutch masters along with new clutch slave, and new rear wheel cylinders (using your excellent post on the dust seals),  flushed and refreshed  fluids etc. I would prefer not to start over for want of a stopping a slight weeping cap when driving.  Better to locate the good sealing cap, which of course I thought I had.....

I do appreciate the thought though.

Cheers,

Alf

Alf - if you have your old master cylinders, assuming they are OE, send then to Past Parts in Bury St Edmunds in Sufflok for refurband they will come back better than new with new alloy caps - my tops never leaked after this

Cheers Rich

[silverfox4]

Rich - it's not really cost effective to ship the OE master cylinders to and from the UK unfortunately.  I did have the Elan MC's sleeved locally back in 1996, but they really botched the job with some adhesive getting stuck in the port at the end of the sleeve, and it took 10 removal/install operations before the problem was corrected so the brakes and clutch could get bled - they kept saying there was nothing wrong and bench bleeding did not suggest a problem, until it was in the car. 

To have the 4A's MC's done locally, I would have to start all over, if walking down that path.

Thanks anyway

Cheers

Alf 

[Z320]

Hi Alf,

you can do that anytime in the future, it is always nice to have a modification in mind.

My advice is for everyone how is going to buy new master cylinders: why not a 0.625"?

The smaller piston results a higher pressure!

I know it is told this doesn't work, but ignore this, it works LOVELY on my 4A.

Ciao, Marco

[ianc]

Marco is correct in stating that a change from 0.7" to 0.625" bore master cylinder results in greater pressure to the brakes for a given force at the foot pedal.

I calculate that such a reduction in bore boosts pressure to the brakes by 20%.

I'm puzzled that Alf, with his master cylinders inclined to each other, finds that plastic caps interfere.  On my TR4, there is quite a reasonable gap between the plastic caps on my Girling master cylinders.  Is it the fact that both my cylinders are original Girling, not made by Lucas, TRW or any other after-market supplier?

Ian Cornish

[Z320]

1 / 0.8 = 1.25

If you get a recommendation for reliable 25% better brake pads - what would you do?

Just an idea....

BTW:

to transform this units to a 0.50" master does not work because of the parts inside the unit,

otherwise I would already have reduced the bore and piston and use a 0.50" seal from a motorbike,

that would be + 96%,

not so bad?

Edited December 24, 2020 by Z320

[RobH]

13 minutes ago, Z320 said:

that would be + 96%,

not so bad?

But surely the brake-pedal stroke required increases by a similar amount Marco?  Is there room for that?

[Z320]

On the brake I feel no difference at all with the stroke by using a 0.625" master.

And on the clutch we all always make a full stroke, don't we?

Edited December 24, 2020 by Z320
my bad english

[Z320]

Oh, by the way:

you may know this brakes with two cylinders 0.625" next to each other, connected with a bar? I fund the english word ist "balance bar brake"?

You base the force with the bar on 2 cylinders, so it is about half on each!

In this case the fluid pressure compared with a single 0,70" master is 125% HALF = only 62,5%.

It is told the force on the cylinders (and so the pressure) is adjustable by the bar - in my opinion (sorry me) in a ULITMATIVE LIMITED range.

Ciao, Marco

Edited December 24, 2020 by Z320
bar, not beam?

[stuart]

4 hours ago, Z320 said:

Oh, by the way:

you may know this brakes with two cylinders 0.625" next to each other, connected with a beam? I fund the english word ist "balance bar brake"?

You base the force with the bar on 2 cylinders, so it is about half on each!

In this case the fluid pressure compared with a single 0,70" master is 125% HALF = only 62,5%.

It is told the force on the cylinders (and so the pressure) is adjustable by the beam - in my opionion (sorry me) in a ULITMATIVE LIMITED range.

Ciao, Marco

Like these http://www.racetorations.co.uk/triumph-c56/tr4-c6/tr4-brakes-c33/racetorations-dual-brake-master-cylinder-kit-tr4-4a-p362

Stuart.

[rcreweread]

14 hours ago, silverfox4 said:

Rich - it's not really cost effective to ship the OE master cylinders to and from the UK unfortunately.  I did have the Elan MC's sleeved locally back in 1996, but they really botched the job with some adhesive getting stuck in the port at the end of the sleeve, and it took 10 removal/install operations before the problem was corrected so the brakes and clutch could get bled - they kept saying there was nothing wrong and bench bleeding did not suggest a problem, until it was in the car. 

To have the 4A's MC's done locally, I would have to start all over, if walking down that path.

Thanks anyway

Cheers

Alf 

Alf - sorry - I didn't see you were on the other side of the pond - that's the second time in a few days I need to get my glasses - doh!

Cheers Rich

[silverfox4]

Rich, No problem - still a good thought though.  Just for my information, how would they restore the OE Girling plastic reservoir and cap which appear to possibly embrittled or unsafe?

This is the MC that I removed and assume that is an OE master cylinder. That being the case, the new metal cap (70.86 mm) is 3.5 mm smaller in Diameter than the OE Girling plastic cap (74.26 mm) which in turn is the same diameter as the new plastic cap 64474603, which the topic of this thread. I could be wrong, but this suggests that the two plastic caps (new and OE Girling) should be interchangeable 

I have not yet tried the OE plastic cap on the repro TRW MC, but will so as soon as it warm enough, since that might be a solution to the weeping metal cap

Ian - sorry I may have pre-judged the interference.  I had a closer look and I believe the two plastic caps (if fitted to both MC's) will just have clearance.  The metal cap being smaller in diameter has plenty room - my apologies

Cheers,

Alf

[ianc]

Alf - is this the brake master cylinder from your TR4A?

I see it has a plastic reservoir, whereas I thought that the TR4 & TR4A used the same Girling master cylinder, which is a casting incorporating reservoir and cylinder (similar to Peter W's shot of the offering from Moss, but with Girling on the casting, as on my TR4).

This topic seems to have a life of its own, and just keeps running!

Ian Cornish

[stuart]

Thats possibly a market specific master cylinder as some markets even back then required you to be able to visually check fluid level.Not a N American one and not a UK one but Pete W may know which.

Stuart.

[silverfox4]

Ian- yes the master cylinder is OE removed from the TR4A.  I hope I am not solely guilty for extending this thread as I was only complementing Chris' experience

Stuart - My TR4A  is a Malines assembled unit.  Is it possible that the plastic reservoir was a legal requirement for say France and Belgium? 

Unless the plastic reservoir can be replaced, I envisage difficulty in getting the master cylinder rebuilt to as new condition, although the cap does screw on very nicely and leak free. I have to try this OE plastic cap on the new TRW master cylinder 

Cheers,

Alf

[Andy303]

On 12/24/2020 at 10:08 AM, stuart said:

Like these http://www.racetorations.co.uk/triumph-c56/tr4-c6/tr4-brakes-c33/racetorations-dual-brake-master-cylinder-kit-tr4-4a-p362

Stuart.

Revington have a similar kit, but with 0.50" bore:  https://www.revingtontr.com/product/rtr4409lak/name/dual-circuit-brakes-tr4a-lhd

They say:

It should be noted that the brake master cylinders supplied in this kit are 12.7mm (0.50") diameter which when two are uses in a dual circuit system have a combined surface area of 254mm² (0.393 inch²). This is slightly less than the surface area of the 19.05mm (0.75") diameter original cylinder (of which of course there is only one)

at 284mm (0.442 inch²) used on Girling systems fitted to TR3-4A. The result of this is that the pedal pressure will feel slightly softer than a single standard cylinder, however if braking system has been modified and the current pedal pressure is harder than standard then this new arrangement will improve matters.

This assumes the surface area of the calliper cylinders and rear wheel cylinders is standard. Larger pistons diameter at the wheels will make the brake pedal feel soft if this is the case already then to special order we can build our duel circuit braking system with 15.875mm (0.625") diameter cylinders having a combined surface area of 396mm² (0.614 inch²) which will normalise the situation. We recommend using these cylinders if a duel circuit servo is to be used.

 

I will be interested in hearing peoples opinion of this and the Racetorations kit as this is a modification I have been considering.

Andy

[Z320]

Hi Andy,

what is your hope about this modification?

In my opionion this construction is mostly fitted because of the hope for a stronger brake - but by doing simple calculations you see this cannot be the case.

Same issue with 4 pistion callipers when they (all?) have a smaller piston surface than the original Girling with its huge pistons.

Revington tells you the truth: one master 0.50" is 196% pressure, two masters 0.50" next to each other are 196% HALF = 98%, "slightly less"

And Revington tells you about the calipers a puzzle:

"For instance if a 4 pot calliper kit is used the size of the pistons in the callipers will affect pedal pressure."

The only advance in my opionion is "some" more safety by a (then) 2 circut brake system, but a single circut is not a probem.

Allow me to tell you the trouth:

don't expext a realistic assessement from someone who had big hopes, spend lots of money and effort in something without benefit.

The issue: don't allow yourself to realize realistic what will disappoint you.

I'm shure you will do the right thing and safe a lot of money.

Ciao, Marco

Edited December 26, 2020 by Z320