Long Pedal

[Peter Truman]

As reported previously I've converted my daughters Mk2 Spitfire from Type 12 Calipers to Type 14, the upgrade requiring a new larger Master cylinder with larger reservoir, but the same 5/8in piston, I used the type 12 master cylinder rod should it have been changed, is the type 14 rod different?.

I initially had bleeding issues ie getting fluid through to the calipers but loosening the fixed to flexible pipe joints got the fluid through, but there was a major air lock with a lot of air, normal bleeding got pedal pressure through, But I didn't bleed in the correct sequence I did the front first, then the rear then the front again but not at the same time, a day between the rear to front bleed. Hopefully another bleed tomorrow in the correct sequence will remove the last bit of sponginess?

My issue is with the original type 12 set up the pedal was rock hard with little pedal travel, now with the type 14 calipers the brake pedal appears to travel further which appears to give a softer pedal. The brake pedal travel is logical to some extent as the master cylinder piston is the same diameter but the caliper piston is say 50% greater in dia and hence volume so you have to push more fluid.  The new brake pads need bedding in too.

Can any one advise the normal Type 14 pedal travel & if a different master cylinder push rod was used.

[Pete Lewis]

i dont see any reason to have any different mcyl push rods 

have you checked the hub float is it causing pad push back ??

sequence is immaterial  but you have to start somewhere   

do make sure the Mcyl and pedal return fully not a stiff pedal pivot can stop the recouperation 

pete 

[Colin Lindsay]

On the original Herald setup, as with the early Spitfires as Peter says, only the size of the reservoir was changed by using an extension neck when switching from drums to discs so the master cylinder and push rod were the same.

I've swapped type 12s for type 14s many times and never changed the rod.