Series IIA 88 Brake Master Cylinder...?

**Johnno1969** · 2nd February 2013, 05:34 PM

A quick question, if I may:

My 1965 IIA 88 has for many years had a "CV" type brake master cylinder (originally, it had the earlier "CB" type).

I recently ordered a new master cylinder as part of work I am doing on the vehicle and mistakenly ordered the unit "LR 4cyl LWB+SWB (F>) (CV) (1.000") 90569128 (C)".

This unit has, I presume a one inch bore, as opposed to the 3/4" of the one previously in my vehicle.

The cylinder I meant to order, which is the same as the one for the clutch, is : "LR 4cyl SWB (>6/1980) (CV) + CLUTCH (3/4") 90569126 (C)"

I ended up correcting my order and the 3/4" version is on its way to me now as well... but my question is what benefits or problems might result if I was to stick with the 1" bore cylinder and use it instead?

Yours in anticipation,

John

**JDNSW** · 2nd February 2013, 07:02 PM

The 1" bore means you move a lot more fluid for the same stroke - in other words, less pedal movement. But pedal pressure needed for the same braking effort increases by the same proportion. And the proportion is the ratio of the piston areas - you would need 78% higher pedal pressure, almost certainly enough to make it unroadworthy (unless you have an independent booster such as a VH44).

Not practical, I'm afraid, unless you are also replacing the wheel cylinders, for example if fitting lwb brakes (a worthwhile improvement to 88 braking).

John

**Johnno1969** · 3rd February 2013, 08:40 AM

Thanks a lot, John. I ordered the correct master cylinder on Friday, but posed this question here just in case there was a good reason for me to keep the 1" bore version. Your reply pretty well answers that. Much appreciated.

Cheers,

John

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Series IIA 88 Brake Master Cylinder...?

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