Talk Morgan Forums Morgan Sports Cars Morgan Plus Four, Supersport & Plus Six (CX & CXV Generation Vehicles) My23 brakes

Can anyone explain the advantage of single piston brake calipers when used on the front of a vehicle? The assymetric operation requiring provision and maintenance of a floating caliper body would surely offset any manufacturing savings.

I can see the advantage of using them on the rear as it aids mechanical handbrake linkage as on our F54 Mini, but that also has them on the front so there appears to be some modern thinking I'm missing

Absolutely no hydraulic advantage, (in fact negative as you have to conteract the friction of the slider & they don't retract well when corroded) the only real 'advantage' is significant reduced cost to vehicle manufacturer, I'm sorry but they look very underspec for a 200hp + car. Even the basic later trads got the Caparo 4 pot calipers

Sorry ... the picture is from yesterday. Wheel is back on and car again in another garage.
For me, that was clearly a one piston brake. Since I had the last ten years only with motorcycles to do I can also be wrong.

Thanks Jon entirely my thinking. The assymetric operation is always going to mean one pad contacts the disc before the other and the slightest friction and spring action in the floating linkage will reflect on some degree of uneven pad wear. Even my hybrid push bike has twin pot hydraulic calipers front and rear though.

For a moment I considered single pot calipers benefitted ABS but as that appears to work by electronically modulating brake pressure I cannot see the connection. Unless of course the ABS module used on CX is matched only to these single pot calipers

Maybe production costs are that much lower with only one body casting, no cross fluid feeds, either internal or external, and only one bleed nipple to worry about. At least our Mini has dust covers over the sliding pins though. Lack of these if that's the case on latest CX models seems a further negative long term.

Looking at the brand markings on the top of the callipers it looks like the manufacturer is 920Engineering.
See: https://shiftec.com/about/

Looks to be a bit of a messy history/status of brand names and ownership, but on the face of it 920E appear to have a good pedigree in motorsport.

Ignoring specs for a second, what I would say is the hire Plus Four I drive in 2021 had much worse brake performance and feel than both my Plus Four and that of the one I drove on the Driving Academy day (which was absolutely fine after 2 x 1 hour sessions on “track” at Bicester Heritage). The owners manual makes it clear that they are single piston callipers on the Four, front and rear, albeit with different size discs. The Six has four pot front callipers. Whilst I have no issues today it would be something I might look to upgrade in the future; if only to maintain braking performance over repeated descents in the Alps. If anyone is interested it looks like the dampers are made by SPAX, at least from what I could see on my front dampers with the wheel still on.

I also have no problems at all with my brake. However, I have only driven a few kilometers with my PlusFour.
Matt where do you find in an owner manual a specification of the brake ? The manual I have only has very superficial statements on how the vehicle should be operated. Can you take a picture of the manual and the brake specification page and post it here? That would be great

Clemens your pic was a good effort, how were you to know what might be the most interesting angle for those of us who ever want more...? (-:

I thought there was mention of using a caliper upside down ( swapping left to right..?) to counteract brake squeal...???? Were that the case I hope they did not leave the bleed nipple in it`s original position on the caliper, mounting the swapped over callipers effectively upside down with the bleed nipple now at the lowest point in the callipers cylinder, as it would then be bound to cause a soft pedal, given the likelihood of air to ever be left trapped in the upper reaches of the callipers cylinder...??

Single piston calipers would seem to be no more than a cost cutting design, but I too have been wrong more than once before..

Just thinking in type, claiming zero expertise.

Of course Clemens, here’s a link to the PDF:
https://www.morgan-motor.com/wp-content/uploads/2022/09/Plus-Four-Owners-Handbook-Digital.pdf

Page 8 in the file / marked as page 5 in the print.

I suspect the choice is down to cost and weight (unsprung mass), but I also wonder if size plays a part with the wire wheel option and strange offsets. One thing I found strange when I ordered mine is I was told that Morgan had stopped offering the colour callipers earlier in the year. I was wondering why that was, but thought it may have been due to the MY23 change coming but then the recall happened. One thing I haven’t seen mentioned (apologies if I missed it) is that the ESC stability control will use the brakes in order to work - that may be the most significant factor in any change to specification or supplier, assuming all else was equal (which we now know it isn’t).

Thanks Matt for the link. This is of course exactly the manual I have.
I must confess I have not paid any attention to the general technical specification. That was as I must now realize very stupid of me.
In any case, it is now definitely clear that a PlusFour front and rear one piston brake is installed.

I look next time in the books before I dismantle tires

If I had these calipers fitted to my car I don't think I would want to advertise the fact with fancy colour options

Looking at historical and current facts. All the trad range until their demise had four piston calipers at the front. The Plus Six still does apparently. The Plus Four has many complaints of brake performance. I don't subscribe to the excuses of cost or unsprung weight which would be minimal. If I'm missing something in the bigger picture I would love to know what it is