Having now fit my 4 pot calipers ( princess ) in place of my Spitfire ones, I am now trying to get a decent pedal, and yet seem unable to do so. All seems well, now I have eliminated the odd weeping joint ( all is metric. Odd!!! ) Having bled all three nipples of each caliper several times, there is no great improvement, with a very long travel to the pedal. Any thoughts would be appreciated.

You have an airlock somewhere else...

Possibly if you remove the caliper hold the nipples upwards, then try to force the airout that way. Obviously putting a spacer in!

Also, do you have a pressure brake sender in an upright position. If so check that... may also be the back lines... just check everything hten is basically what I'm getting at!

Had a similar problem on my F27,eccessive pedal travel, turned out I had to fit a bigger bore master cylinder which sorted it out!!!
You can also try using a gunsons easy bleed kit ,and have a mate to push the brake pedal up and down too,then theres raising the car up at the front so that its higher than the master cylinder,and finally try keeping the brake pedal depressed overnight to get out any stubborn air bubbles.any one might sort it-hope this helps
regards,
Greg

I suspect the calipers aren't mounted true to the disc as a result the caliper brackets are forced to bend like a spring every time you press the pedal. Because of the hydraulic ratio the pedal moves many times the ammount the caliper moves. The bigger the caliper is the worse the problem.

The official way to check is to use a dial gauge but you can get a pretty good idea by resting a hand against the caliper and disc and getting a mate to thump the pedal on an off. If you feel any movement at all you will need to do some carefull setting up.

Also what size master cylinder are you using -- if you are using a single Triumph cylinder be aware some Triumph Spifire/Herald mastecylinders are only 5/8" dia.

Yes I have the 5/8 m/c which is brand new. ( Bugger if I need another new one!!) The pedal still feels very spongy aswell as loads of travel, so I suppose I could give it a more vigorous bleeding and see how the pedal feels and then assess the travel. Could be a combination of m/c and air??

try a pressure bleeder that works from the tyre valve,also there is a sequence for bleeding the front nips

Any idea what this might be?

The springiness in the pedal confirns the calipers aren't true to the disc --- takes a bit of patience to get it right by bending the brackets by tiny ammounts also you may put thin shim washers under the caliper lugs.

The pad must present absolutely square to the disc probing between disc and pad with a feeler gauge should give you an indication what adjustment is required.

The 5/8" master cylinder won't help for some reason Triumph used a smaller master cylinder than anyother car company with disc brakes ---although the calipers on the original disc braked Herald were tiny P12s.
Just changing to a 3/4 (19.mm) master cylinder will take away about 1/3 of the excess travel but it isn't a cure the spongeyness will still be there.

With the 5/8 mastercylinder just 0.25 mm movement at each caliper will give 30mm movenent at the pedal pad.
--- oops got the maths wrong on that 0.25mm gives 60+mm extra travel at the pedal

Personally I would have a long hard think if you really need the big calipers they must do wonders for the unsprung weight.

[Edited on 15/4/04 by britishtrident]

[Edited on 15/4/04 by britishtrident]

[Edited on 15/4/04 by britishtrident]

sequence for metro with 3 nipstwo side ones first then the top one
you could try clamping a hose one at a time that will show where the prob lies

[Edited on 15/4/04 by theconrodkid]

Just to back up Conrodkid, basically the sequence with any brakes is very logical, go from the lowest bleed niple to the highest. Air trapped near the lower nips cannot then move up to the upper ones and mean you have to start again.

Having bled the brakes again as recommended the pedal travel is certainly less. As for the spacing this seems okay. I concur that a bigger m/c might be needed and so which and what affect? The 0.70 or 0.75.
Regarding weight I take your point, but compared to the pinto I was going to put, in the caliper weight is nought. Besides my engine is further back and so limiting the effect a tad.

BTW thanks for all the help so far!!!

Also had a problem bleeding my brakes, even using a pressurised eezybleed, the solution was to unbolt the calipers and turn them upside down while bleeding, suprising how much air came out, it must get trapped inside the calipers. Pedal is now rock hard.

Al.


i]Originally posted by Sean
Having bled the brakes again as recommended the pedal travel is certainly less. As for the spacing this seems okay. I concur that a bigger m/c might be needed and so which and what affect? The 0.70 or 0.75.
Regarding weight I take your point, but compared to the pinto I was going to put, in the caliper weight is nought. Besides my engine is further back and so limiting the effect a tad.

BTW thanks for all the help so far!!!

The point about caliper weight is that is unsprung weight, unsprung weight is the most vital to reduce and the hardest to shed.

A car with a low ratio of unsprung to sprung weight will keep the wheels in contact with the road surface over bumps, undulations and surface ripples giving more cornering grip better traction and braking.

You can tell I am new to this can't you. Still going to persist with 4 pots for the mo, but always have the triumph to put back on. I do seem to be getting a better pedal, although annoyingly the bleed niples seem to weep regardless of how tight I do them. I wonder if I should get some of the originals rather than the universal ones I have. Still surprised it's all metric. Here's a pic of what I had to do anyway fopr reference.
Rescued attachment DSCF0014.JPG