Best rooute to 4 pot calipers

[Graham Sewell]

Having played with green stuff pads, and found that after they are bedded in they don't live up to the initial promise of the first braking session. I am looking into further upgrades that are not too expensive :)

 

My target is to increase the perceived efficiency of the front brakes in terms of reduced pedal pressure.

 

These fall into:

 

Large master cylinder - not sure of the effect here???

Moving to 4 pot calipers - these increase contact area for the pads and the effective area that the brake fluid acts on. This should increase pedal movement but reduce pedal pressure for a given level of deceleration.

 

The Princess calipers are often quoted in this context. Do they work, do they fit. Otherwise, who else do caipers that work and at what prices?

 

Cheers,

 

Graham

 

[allen]

I am not sure if Princess callipers actually fit triumph uprights, though they are a straight swop onto escort uprights - however they are pretty difficult to come by, I got some recently but none of the specialist suppliers do them anymore - halfords came up trumps and got them in by special order, pay a surcharge if you cannot tale old ones back in. email me if you want price part numbers etc.

 

A smaller bore master cylinder will give more movement, less effort (i.e. more leverage), as you say, changing to bigger bore slaves has the same effect, but two smaller pistons will probably not give that much of an increase in overall bore. Real difference is pad area.

 

Caterham do 4 pot calipers, so does James Whiting these are a bit cheaper (a good £300 getting on £400 I believe)

 

Regards

 

allen

[I.Mupferit]

Wilwood also do reasonably priced billet 4 pot calipers to fit the 7. I was going to give these a try but decided to take the cheap option initially and just fit the Green stuff pads, but like Graham have found that although marginally better they haven't lived up to the earlier promise.

But if you guys would like to pioneer this area, I am happy to save my own dosh for a while until you have proven the efficacy of replacement 4 pots thumbsup.gif smile.gif

 

Brent

[oilyhands]

The Princess calipers weigh the same as the Queen Mary and have the same bolt pattern as Cortina and Escort hubs, they need a spacer kit to fit a ventilated disk but work well. Wilwood dynalite and superlite calipers are excellent quality, good value and being aluminium are very light, they can be bought from Rally Design or Hi-spec motorsport, when I fitted Dynalites to my car the all-up cost was less than £250 including disks and pads.

 

The main perceived difference between the old single piston fist calipers and the Wilwoods was pedal feel which was vastly improved, its possible to brake right to the limit without lockup.

 

Oily

 

Edited by - oilyhands on 23 May 2001 16:17:20

[Graham Perry]

I have just moved away from the Princess Caliper set-up and am not as yet sure that I did the right thing. Princess Calipers are made by AP and work incredibly well, but are very heavy. If you want solid discs with them then you need the Triumph GT6 OR Vitesse disc. The spacers needed are not that wide with this set up although you would need to convert the caliper to single fluid feed pipe operation. I used to run Mintex 1144 pads with these and was very happy.

 

I have just moved over to the lightweight Alcon calipers sold by James Whiting with Green stuff pads, which fit the standard non ventilated Caterham/Herald disc. I just cannot get these to work so far. The car has gone back to the original problem that many Caterham owners suffer of the rear brakes coming on first and harder than the fronts which means they lock and can provoke serious instability under braking. I have bled them three times to no effect. I will be trying some 1144 pads in them soon to see if that rectifies the problem and if not then a brake balancer.

Potentially though they look to be very good as they seem to retard at the same rate as the Princess ones and offer a massive weight advantage. One of the reasons I did so poorly timewise at Curborough last week was because I was having to brake at 70 yards down the straight to remain stable rather than the normal 40 yards, so I need a little more time to shake them down.

 

I have just found out that Bremsport have started to make an Aluminium equivalent of the Princess Caliper (listening to their customers no doubt) , which may be the way to go for the future as it will allow the larger GT6/Vitesse disk to be used in the 13" wheel set up. They also seem to be good value.

[jamesm]

just switched to the ap four pots up front - these have made what feels like a big difference to ultimate stopping power and feel. they have also stopped the rears from locking up first. when hot they do suffer from a slightly long pedal but this can be cured with the bigger master cylinder

 

if you still have this problem after switching to four pots it may be because you still have a soft rear pad which is working better than the fronts at low temp - switching to a harder pad at the rear should cure this.

 

James M

[Blatman]

although you would need to convert the caliper to single fluid feed pipe operation.

 

I thought that if you did that, only two pistons (out of four) would function, and they would be diagonally opposed. Not good...

 

[allen]

Blatman, I am sure you realise, he means with a T peice, one pipe feeding both inlets on the caliper, hence all 4 'pots'.

 

I have done the princess conversion onto an escort upright - they look big & feel heavy, but weight wise there is very little difference between them and the ford M16 calipers, and they did improve braking feel and efficiency - cost, fully refurbished by AP - 120 quid the pair. (Though Graham Perry may have a cheaper pair going?)

 

Regards,

 

allenthumbsup.gif

[Blatman]

Allen

That's not how I read it, but more clarification won't hurt smile.gif

[Graham Perry]

From what I recall (I didn't make the mod) there was a Cunifer fluid transfer pipe from one side of the caliper to the other that replaced one of the flexables. I know that it worked because if you pressed the Brake gently you could see all 4 pistons move inwards. The mod was apparently very simple and required no great feat of engineering.

 

I sold the brakes a few weeks ago, got about GBP 100 for them including a new set of pads.

[Mick Day]

I fitted the Alcon front brakes in 1999 with Mintex 1144 pads. I too had the impression that progression was improved but still the rears locked before the fronts. After discussion with James Whitting I fitted green stuff to the front & harder standard pads to the rear & much, much better.

 

If you want to stay with the standard front brakes then why not fit Hawk HP plus pads available from Cambridge Motorsport (01767-677969). You will find the front discs will wear quickly but at 14 UKP a throw can be considered a cheap consumable part.

 

Mick