Larger Bore Brake Master Cylinder?

[xvivalve]

I know the subject of the merits and demerits of having a larger bore brake master cylinder has been discussed at length, but opportunity has arisen if someone would like to test theory in practice!

In all the years I've been liaising with the reconditioners, they have been telling me they have a box of items they did for Ted on behalf of the Club somewhere, that came to light when they moved premises, but has since been misplaced again; I've always said that when found, we'd happily take ownership and pay them for the work done.

Well, last time I went in, they presented me with a single line brake master cylinder that they proudly stated was one they'd done for Ted; an experiment he'd asked them to do, boring and sleeving (in stainless) to a bore size of 13/16", an incremental increase over the standard 3/4" with new oversized piston to suit. They had replaced all the seals in recognition of how long it had been since the original work had been done, and given my earlier undertaking with them, I felt obliged to take it.

So, if anyone is feeling inquisitive, (maybe this will facilitate a smaller servo to be used on a Sprint?) we have a (currently) one off opportunity to experiment in practice....a write up of your experience and conclusion would make excellent copy for the magazine! So where are all you MoT testers with access to brake efficiency testing equipment?

Outwardly identical to the standard single line master cylinder, even the originality purists could consider this...

Available at cost, £70 inc postage to UK addresses (slightly more for overseas), it also represents a saving on the standard item.

First come, first served; a one off opportunity!

[soe8m]

I use Jag xj brake masters for over 15 years and these go fine. Slightly bigger bore than std so I guess the one you have is a Jag one. Physically exact the same.

Jeroen

[GlenM]

I use Jag xj brake masters for over 15 years and these go fine. Slightly bigger bore than std so I guess the one you have is a Jag one. Physically exact the same.

Jeroen

Jeroen,

Are these a tandem cylinder? Have you got a link, or a part number?

Glen.

[gmsclassics]

I used a Nissan BM-44 tandem master cyl (Nissan Skyline/ Sylvia) on my race Sprint for many years without any issues. 15/16" diameter. Did require mounting holes to be filed out a very small amount to match the std Sprint booster. Also new brake pipe ends as these are metric. Cheap from a wreckers.

[GlenM]

Thanks. Will take a look at the BM44 cylinder.

[sprint95m]

I use Jag xj brake masters for over 15 years and these go fine. Slightly bigger bore than std so I guess the one you have is a Jag one. Physically exact the same.

Jeroen

Jeroen,

Are these a tandem cylinder? Have you got a link, or a part number?

Glen.

Yes.
They are XJ6 series 1 and have a 22.2mm bore (7/8”)

Another 22.2mm bore option is from a Saab 99/900.
The pipes need redoing because metric unions are required.
These are dual circuit, fit a Dolomite servo
and their fluid reservoir also serves the clutch hydraulics.


Ian

[GlenM]

I use Jag xj brake masters for over 15 years and these go fine. Slightly bigger bore than std so I guess the one you have is a Jag one. Physically exact the same.

Jeroen

Jeroen,

Are these a tandem cylinder? Have you got a link, or a part number?

Glen.

Yes.
They are XJ6 series 1 and have a 22.2mm bore (7/8”)

Another 22.2mm bore option is from a Saab 99/900.
The pipes need redoing because metric unions are required.
These are dual circuit, fit a Dolomite servo
and their fluid reservoir also serves the clutch hydraulics.


Ian

Thanks Ian.

I have had a couple of Classic 900s and I remember the spigot for the clutch fluid outlet very well. I fitted a new master cylinder to one of them and a couple of years later had some issues with the clutch hydraulics. I hadn't realised that the end of the spigot was moulded shut for automatic cars and needed to be cut off for a manual. I might have to fit a Sprint clutch master cylinder when I change the engine, so the spigot could be useful.

No problem with the fittings being metric, I have a flaring tool and pipe bender.

With both the Saab and Jaguar master cylinders, you can get them new for a reasonable price but they don't come with the reservoir, so might have to get a used one.

Glen.