Are all Princes 4 pots the same

[Dave Woodward]

I'm having trouble with very soft brakes to the point of a lack of confidence and certainly no ability to conduct an emergency stop.

The front brake lines have been replaced recently but I am confident there is no evidence of any leaking to the circuit there and on use the reservoirs levels remain constant.

I can see on depression of the brake pedal that there is significant travel through the Tilton to the front circuit whilst the rear is firm from the start. The consequence is that my foot feels significant travel in the pedal before any real bite point, and I am ending up using the full travel of the pedal. The latest is that I've replaced both masters (in for a penny ...) and this has improved the situation slightly but not significantly.

I have bled in excess of a litre of fluid through the system, bleeding one front and one rear at the same time to enable full travel when bleeding.

I am now wondering if the seals in one of the Princess calipers has gone though there are no signs of brake fluid on the disks or floor under the car

I'm pondering next steps and think LMC23 in the Cob is now off the cards but wondered about getting refurbed Princess callipers. Mine are '3247' callipers but there seem to be many that state 'Princess / Escort' etc with slightly different codes on them.

Any guidance welcome, or is this an opportunity to take a different route?

Thanks

Dave

[clive]

Hi Dave,

Off the top of my head...

Has this problem just started since you replaced the brake lines or has there always been a problem?

Have you reset the Tilton bar since you upgraded your rear axle? (If I remember you changed from MGB to Jag) as the brakes on the IRS are so powerful the balance bar should be set to max front pressure.

When bleeding the system why are you bleeding one front and one rear at the same time, as the front and rear systems are completely independent of each other. You should bleed both front and then both rear separately.

See this video explaining the set up of the balance bar.
https://www.youtube.com/watch?v=ISLqGf0sMX0

[Dave Woodward]

Thanks Clive. I didn’t change the tilton so will have a look at that. Re the bleeding approach, I was concerned that if just bleed the front, the rear master would offer resistance and so not allow full travel of the pedal so impeding bleeding of the front, and vice versa.

[StuBaker]

Hi David,
I had a similar problem early on in that the tilton unit was not allowing the master cylinder to return fully. I had to pull it back by hand when bleeding.

[phlip]

Clive,
When you say "You should bleed both front and then both rear separately." do you mean that both front brakes should be bled at the same time? or bleed each front brake separately then bleed each rear brake separately??
Sorry if this is a daft question but bleeding with a Tilton fitted is new to me.
Phil

[clive]

Hi Phil, yes bleed each wheel separately. The front and rears are completely separate circuits so if for example only the front brake system has been disturbed then there is no need to bleed the rear brakes.

There shouldn’t be any special procedure for bleeding a system with a Tilton balance bar, that said I have always used a Gunson brake bleeding kit on mine.

[peterc]

I would agree with what has been said so far.
You do bleed one wheel at a time. Having the balance bar should make no difference or least it didn’t affect my operations.
Changing from MGB to Jag would need the balance bar adjusted to suit. I have mine equal bias front to back. Not noticed any issues with incorrect braking and the SVa Guy was happy with my demonstration of braking.
Peter C

[Dave Woodward]

Hi Phil, yes bleed each wheel separately. The front and rears are completely separate circuits so if for example only the front brake system has been disturbed then there is no need to bleed the rear brakes.

There shouldn’t be any special procedure for bleeding a system with a Tilton balance bar, that said I have always used a Gunson brake bleeding kit on mine.

I've tried the Gunson pressure bleeders but can't get a good enough seal on the reservoirs so they just fill up and leak

[clive]

Back in the day, Gunson did an additional set of caps for reservoirs that were different from the standard ones. I’m not sure if they are still available but I have a set and one of them fitted nicely on the Hawk supplied reservoirs.

[Dave Woodward]

One thing I’ve considered is that my two brake masters are the same size. Always have been, at 0.625 with the clutch master at 0.75. Seeing a lot of commentary stating front master should be larger which could account for the extra tilton travel in my front master?

Has mine always been wrong