Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) ARP4 rear brake calipers

Oh dear. Soft doesn't mean squishy and therefore more grippy; neither does hard infer cast iron properties.

It is highly unlikely, as good as impossible, that any difference might be detected in the effectiveness between different pad specs. It is entirely possible that the mere act of changing the pads eased the handbrake cable, compensator and caliper mechanism producing the improvement.

As someone who sprinted, raced and use my car on the road over many years, believe me, I have a lot of experience in this area. Changing pad specs will not have any affect on the effectiveness on the handbrake.

Definitely with david and SBM on this one.

Maybe a set of chocks is the way forward

When I was 17 I had a £15 Morris Minor van. I had to tie a knot in the handbrake cable to get it through the MOT.

Thank you for the apology..

Sorry to get technical Rog, but can you say whether the knot you used was a reef, bo'line or fishermans knot? Only asking!

PS This wasn't a dig, just a weak attempt at humour!

Oops! So sorry Sir



Can’t remember. So so long ago but I think there was more than one

Just noticed the discussion with interest as I am currently investigating this exact issue (ARP4). There are truths lurking in many of these posts however: -
1. Pad material selection for an OEM is always a balance of many criteria - often conflicting. Friction is only one (but the most important) of these criteria.
2. As expressed above, hard/soft refers to the range of temperatures over which effective/consistent operation is assured.
3. Friction materials have dynamic/kinetic friction properties and also static friction properties.
4. The relationship between these 2 properties is not linear - meaning you can have (relatively) high static but low dynamic and vice versa.
5. Assuming the car is stationary then the static friction properties are of course the key. And it is quite possible to find a pad material with higher static friction but which doesn't significantly affect braking balance dynamically.
6. Don't forget that front/rear brake balance changes in all cars over temperature (even if material is the same front and rear the spot temperatures will not be). In most road cars this balance change is not critical - especially when you have ABS (whats that Morgan ask?) - but its the reason race cars have adjustable front/rear brake balance.
7. So for an ARP4 the holy grail is rear pad material with higher static friction with broadly similar dynamic friction levels at typical operating temperatures.

All of the above is of a lower order of significance than cable routing/sticking, lever installation issues etc. So needless to say you need to be sure these are all addressed first.

Alternatively save time, ignore the problem, leave it in gear and/or take a chock with you :-).

The problem is that the majority of motors factors will give the customer a blank look if asked for a set of pads with a high static friction but a suitable dynamic friction for an ARP4.

I think you may be right :-). If we were very harsh we might even wonder why Morgan didn't cover this during development.

Ironic laugh!

Wow, your learn something new everyday, a very interesting discussion of pad materials, and thank you DaveW for your link to Mulfab, I do believe the calipers are from a Sierra Cosworth as I surmised.

It was hARPpy chappie who posted about KH changing his pads, but having spoken to them it appears that what they actually did was change out a set of faulty calipers, which I assume had new pads too, but they didn't go on to say what the fault was on new calipers, possibly more to this than meets the eye?

It's not that the handbrake really bugs me, as it is just about OK, and I leave it in gear too of course, but I like a challenge, so if I could do better than MMC it would give me some satisfaction.

Apart from pads, what I will probably try next is to increase the leverage under the handbrake lever itself and see if that helps. I just need the time and inclination to get out into a cold garage and play around for a bit.