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Tandem brake master cylinders
http://forum.triumphdolomite.co.uk/viewtopic.php?f=4&t=35419
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Author:  Standardthread [ Tue Nov 19, 2019 3:07 pm ]
Post subject:  Tandem brake master cylinders

I intend to service and replace the seals in the tandem brake master cylinder on my 1300. This has come about because my clutch suddenly failed. On inspection the fluid was ‘boiling’ in the master cylinder when the pedal was pumped. The master wasn’t leaking but fluid was circulating between the two internal seals, something I have never experienced in 45+ years of driving and maintaining Triumphs.

There are different part numbers for set of seals for the 1300 and for the Sprint brake masters. Anyone know what the difference between the two masters is, is it that the bore and stroke of the Sprint are greater because of different braking requirements, if so, can a 1300 be fitted with a master from a Sprint, but not the other way round?

In terms of seals for the 1300 does anyone know if seals from, say a Spitfire will fit the 1300, reason for this question, a well know supplier lists the Spitfire parts at a third of those for the 1300?

Final question. Has anyone fitted a totally different tandem master cylinder to their cars? I’m thinking of, for example Sherpas. A brand new tandem for a Sherpa is half the price of a re-con 1300. I realise there could be differences in thread size for the unions but between different models/makes but are there any in terms of performance?

Anyone got a serviceable spare servo and tandem master for sale please email me.

Author:  Richard the old one [ Tue Nov 19, 2019 6:23 pm ]
Post subject:  Re: Tandem brake master cylinders

The Rimmers site and parts catalogue indicates that both the 1300 and 1500 use the same Tandem Brake master cylinder which is also the same as the later sprints / 1850s. The site indicates the repair kit is an AEU1284 which I believe is different from the Spitfire.

I believe if you do rebuild it or replace it with another you may have a problem bleeding the complete system if you do not bleed just the master first.

I hope you have read my article in the August - September edition of Dolly Mixture in which I go into some detail on the Brake Failure Warning Sensor (or PDWA ) as I believe this unit often gets blamed in error, for not being unable to bleed the system.

Author:  Carledo [ Tue Nov 19, 2019 11:51 pm ]
Post subject:  Re: Tandem brake master cylinders

As far as I know, there are only 2 Tandem master cylinders fitted to Dolomites, the one fitted to all models from late 78 onwards and an earlier, different one fitted to export Sprints (and possibly other models) from 1973. So there ARE 2 kits available. But the export cylinder is vanishingly rare, it's unlikely that you will have that one.

Several people have experimented with alternative cylinders from Saab, Volvo, Jaguar, Landrover and possibly Sherpa, but mainly to upgrade the performance, or because, until recently the original (GMC 1224?) was getting very difficult to obtain. The hard bit is not the pipe fittings but getting a body that matches the fitting at the servo. Lack of available originals has now been sorted by the club supplying recons that have been sleeved in stainless steel. And very good they are too, I have one on each of my cars, fit and forget! Contact Alun Nicholas (xvivalve on here) for details of the club cylinder.

Steve

Author:  Standardthread [ Wed Nov 20, 2019 9:52 am ]
Post subject:  Re: Tandem brake master cylinders

Thanks Richard & Steve for your posts. They answer my questions, and I suspect for many others.

I'm not a club member yet, owning Heralds and looking after my daughter's Standard Companion membership of clubs is getting expensive.

As to what I have fitted to my car going from my previous post on Trackerjack brakes/brakes I don't know. You will see what I thought of the car's previous owner (thanks for your help on that subject Steve, sorted). What he did with the car has probably caused issues with the brake master, it is weeping slightly between the reservoir and piston unit from being knocked doing other correction jobs. He also said he had issues with the fluid warning light so he disconnected it, I now know why. My problem occurred with the clutch master because I ordered the correct seal repair kit only to find the master was a 3/4" version, not 5/8" (previous owner or Mr Leyland altering the spec?).

Incidentally, I had previous issues with the cast iron clutch slave, that was sorted by re-sealing but when the master went I ordered new cylinders for both ends. I haven't fitted the slave (it wasn't leaking when I took the line out of the car) but the slave I got came from MGB Hive, it's identical in terms of fitting, bore etc to the Dolomite, the unions are also the same, just rotated by about 45' so thanks RobSun for the pointers. I also took the opportunity to do a permanent job on the pipe, making it all copper with an Omega loop in, as per Heralds.

I did wonder about there being multiple variations on the masters, it didn't make much sense, Mr Leyland doesn't help with the 1979 parts catalogue, nor do Rimmers because I would have ordered the 1300/1500 version, now it will be a wait and see until I get the old cylinder off, or more likely go down the club route of the S/S version. Either way, the cylinder fitted to the Dolomite is crap compared to the tandem version fitted to the Spitfire, the reservoir is pinned to the piston section, I have a new one I intend to fit on my Herald estate (possibly USA influenced for safety?)

Richard did highlight a potential problem of bleeding the system I hadn't thought of. Now it will be, fill the reservoir to the top, open both lines and a few good thumps on the pedal.

Thanks again to both of you.

Regards,

Steve

Author:  Carledo [ Wed Nov 20, 2019 10:09 am ]
Post subject:  Re: Tandem brake master cylinders

Quote:
Thanks Richard & Steve for your posts. They answer my questions, and I suspect for many others.

I'm not a club member yet, owning Heralds and looking after my daughter's Standard Companion membership of clubs is getting expensive.

As to what I have fitted to my car going from my previous post on Trackerjack brakes/brakes I don't know. You will see what I thought of the car's previous owner (thanks for your help on that subject Steve, sorted). What he did with the car has probably caused issues with the brake master, it is weeping slightly between the reservoir and piston unit from being knocked doing other correction jobs. He also said he had issues with the fluid warning light so he disconnected it, I now know why. My problem occurred with the clutch master because I ordered the correct seal repair kit only to find the master was a 3/4" version, not 5/8" (previous owner or Mr Leyland altering the spec?).

Incidentally, I had previous issues with the cast iron clutch slave, that was sorted by re-sealing but when the master went I ordered new cylinders for both ends. I haven't fitted the slave (it wasn't leaking when I took the line out of the car) but the slave I got came from MGB Hive, it's identical in terms of fitting, bore etc to the Dolomite, the unions are also the same, just rotated by about 45' so thanks RobSun for the pointers. I also took the opportunity to do a permanent job on the pipe, making it all copper with an Omega loop in, as per Heralds.

I did wonder about there being multiple variations on the masters, it didn't make much sense, Mr Leyland doesn't help with the 1979 parts catalogue, nor do Rimmers because I would have ordered the 1300/1500 version, now it will be a wait and see until I get the old cylinder off, or more likely go down the club route of the S/S version. Either way, the cylinder fitted to the Dolomite is crap compared to the tandem version fitted to the Spitfire, the reservoir is pinned to the piston section, I have a new one I intend to fit on my Herald estate (possibly USA influenced for safety?)

Richard did highlight a potential problem of bleeding the system I hadn't thought of. Now it will be, fill the reservoir to the top, open both lines and a few good thumps on the pedal.

Thanks again to both of you.

Regards,

Steve
Don't slam the pedal when bleeding against an empty system, you can damage the Bakelite bit in the servo which is NLA.

Its OK to just open the taps on the master to bleed it, gravity will do the rest! The PDWA really does cause a lot of problems bleeding the brakes on late cars. Lately I have a tendency to throw them away as they don't do anything useful and use the wiring to power a level sensor cap on the master which does! Not a 5 minute job to delete the PDWA though as you need 3 new metal pipes plus a 3 way and inline joiner.

Steve

Author:  Standardthread [ Wed Nov 20, 2019 3:30 pm ]
Post subject:  Re: Tandem brake master cylinders

Thanks Steve, noted.

Is there a surcharge on the cylinder from the club or is it on an exchange basis, I don't want to take the car off the road?

Author:  Standardthread [ Wed Nov 20, 2019 4:23 pm ]
Post subject:  Re: Tandem brake master cylinders

Quote:

Don't slam the pedal when bleeding against an empty system, you can damage the Bakelite bit in the servo which is NLA.
Quote:
Just a thought, off at a slight tangent, does anyone have the complete Bakelite part in pieces to put back together? Reason I ask, over the years I have done a lot of casting, white metal, pewter, resin (that can be filled/strengthened) and just wanted to look at the bits as a potential pattern! And had lost wax brass parts cast.

Author:  triumphdolomiteuk [ Wed Nov 20, 2019 7:43 pm ]
Post subject:  Re: Tandem brake master cylinders

Quote:
Thanks Steve, noted.

Is there a surcharge on the cylinder from the club or is it on an exchange basis, I don't want to take the car off the road?
You pay a surcharge which is refunded when the old unit is returned to us.

Author:  xvivalve [ Thu Nov 21, 2019 6:15 pm ]
Post subject:  Re: Tandem brake master cylinders

Err, is there an elephant in this room???

You say the fault with the master cylinder was highlighted with the loss of clutch...so why are you looking at the brake master cylinder??? It is not 'tandem' as it provides a fluid head to both brakes and clutch, it is 'tandem' because it operates two braking circuits.

The clutch master cylinder is the smaller solid aluminium reservoir slightly lower and to the right of the servo when looking direct at the bulkhead in the engine bay.

(It is only the Sprint bakelite servo disc which is NLA)

Author:  Standardthread [ Fri Nov 22, 2019 9:47 am ]
Post subject:  Re: Tandem brake master cylinders

No elephant in the room. Old car, cast iron clutch slave, hydroscopic brake fluid, or was, rust in the slave causing pressure loss and failure. When it happened the intention was to replace the seals on the slave and master, slave yes, the ones I ordered were the correct size, the master should have been correct, no, it had been replaced by a ¾” version so the seals didn’t get changed, I needed the car back on the road so put the master back in. The seals in the clutch master then failed about a year later, circulating fluid between them but not leaking. New master fitted, clutch now OK again.

In terms the brakes, because the seals are potentially old and the previous owner has ‘played’ with things, at times dangerously, I decided to follow the preventative maintenance course and change the master, or the seals. As part of my correcting previous tinkering I, and no doubt others, have occasionally knocked the reservoir on the brake master. This has caused one of the seals between reservoir and body to very slightly weep because of the crap design of the cylinder, the two units not being pinned together as per the Spitfire tandem cylinder.

In terms of brake servos, what’s the difference between them, is it related to braking/force ratios?

Author:  Carledo [ Fri Nov 22, 2019 10:29 am ]
Post subject:  Re: Tandem brake master cylinders

In the beginning there were 3 or maybe 4 servos for the Dolomite range, 1 or 2 for the OHV cars, 1 for 1850 and 1 for Sprint. As near as I can tell, this was rationalised down to 2 from around 79>, 1 for OHV and the 1850 got the Sprint servo. At this point the threads on both ends of the servo changed from imperial to metric.

They are all distinguishable by size so anyone with a bit of experience can tell, just by looking, which one it is. And yes the boost ratio varies too, but i've never seen any actual figures.

The main point of note though, is that ANY Dolomite servo can be fitted to ANY model of Dolomite, even imperial to metric swaps (or vice versa) are fine so long as the appropriate nuts are used. I can also state conclusively, having done it myself, that a Sprint servo WILL fit an OHV car with the cast reservoir clutch master, though topping up the clutch fluid becomes a bit of a fiddly chore. Obviously not much point in fitting an OHV servo to a Sprint, but a downgrade from Sprint to 1850 servo on my Vauxhall powered, TJ braked Toledo, a move forced on me by the failure of my Sprint servo and no available replacement, has become permanent as the brakes have a more progressive feel to them in my (highly subjective) opinion.

By the same token ANY Dolomite brake master, regardless of engine capacity or number of circuits, will bolt up to any Dolomite servo.

Steve

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