Personally I think that disc brakes and spring brakes are incompatible. When you drop off a trailer with hot brakes, the spring brakes will come on, six hours later the disc will have cooled down to ambient temperature except for the bit clamped in the calipers which will still be far too hot to touch. This warps discs in no time.
Well, I bought 7 new double deckers off Montracon about 5 years ago with drum breaks and every one of them failed the MOT after the first year and were a right pain to get through on a pass. Maybe they were poor drums or what I don’t know but let’s just say I’ll be trying discs if I ever buy new again. One year old trailers and them all failing MOT, nearly started crying…
repton:
chaversdad:
i,ve been running over the A171 between scarborough and middlesbrough at 44ton all weekRaflatac?
Paul
no mate, that waste paper recycling place near morrisons
if you cant look after drum brakes on 1 year old trailers you have no hope with discs!
what was the problem? were you testing them empty, or a result of poor servicing?
double deck montracons/stepframes on drums are ror as a rule and you dont get much simpler!
moose
I have had ejetor trailers on landfill work for 4 years with discs merc axles and no bother.
the mercs are about the best as far as discs go!
Harry Monk:
I’ve been told by people who have operated both to get one on drums, everybody seems to have more trouble with discs.
I would have said the same, up to about 5 years ago, Modern discs are massively better than the originals, and also more efficient (across the life of the pads) than drums, again IMO. This was one of the deciding factors to change to discs, as VOSA seem to be setting more roadside brake testing facilities up and I didn’t fancy getting ‘a pull’ fully freighted with my shoes starting to get down a bit.
My CF pulling a frehauff with Merc discs and axles, was probably the best stopping truck I’ve ever driven, loaded or empty. Trouble was it could make you lazy, as ‘it just stopped!’
I like the Knorr Bremse discs,there dead easy to service .
If you start getting a problem with the calipers,the service
kit for the sliders is only £80 
Harry Monk:
I’ve been told by people who have operated both to get one on drums, everybody seems to have more trouble with discs.
I think they’re probably OK when they’re new - all 3 of the calipers I’ve had to replace have been the original ones so 9 years old now. One of the others had been done before I got the trailer and the remaining two are still the originals.
Paul
I started speccing trailers with disks back in 2000, and not looked back since.
FOR:
Lower labour costs + shorter maintenance times + easier to work on. Much better stopping distances, even brake effort from day one until you change the pads, loaded brake tests no problem. Disks and pads last longer than drums + shoes.
AGAINST:
Slightly higher price when new, slightly higher parts prices. Don’t like long periods standing idle (ie months not weeks). Have heard they don’t like tipper work and getting full of cr#p. Must be inspected regular (i.e. proper visual inspection every 6/8 weeks). Braking system must be set up correctly with tractor units that are pulling them.
This last point is very important. Trailer rental companies have gone away from drums as they don’t know what or who is pulling their trailers. I badly set up trailer control valve on a tractor unit can wreck a set of pads and disks in under a week. When a trailer on drums is abused and tries to do more work than it should, the drum will expand away from the shoes, and is more forgiving. When a disk braked trailer is overworked the disk has to expand but cant as its sandwiched between brake pads and a calliper, hence something in the end has to let go, be it calliper or disk or pads.
I have the same size disk on my trailers that I have on my tractor units (Volvo FH/Meritor Elsa225), so the physical size is the same. The tractor units are set up from new with a 0.3bar predominance (so the trailer does slightly more work than the tractor unit). The disks on the tractor unit should run approx 20 degrees lower in temperature than the trailer, a visual check of the brake disk should make apparent any problems in the setup.
As for cost and wear, disk parts are more expensive than drum parts, but labour times are lower on disk. We run at 44T most of the time and do a lot of our work North West to East Yorkshire and Midlands, so they have a lot of work to do. I can get approx 18 months to 2 years out of a set of shoes, and 2/maybe 3 sets of shoes to a drum.
I can get approx 3 to 4 years out of a set of pads, and 2 sets of pads to a disk.
This is all with genuine OE parts. You can’t get anywhere near the life out of cheaper copy parts.
So my opinion is, if you’re using a trailer regularly, especially if it’s your only one, go for disks on the trailer. Get the trailer set up so it matches what your doing with it. (No good having a trailer with massive disks if your pulling half a tonne of cabbages around all the time). You’ll save money and have a safer more efficient braking system. But get it wrong and it can cost you dear.
Drums are better for fleets who may stand idle part of the year, if you’re not running with a lot of weight on, or your planned maintenance consists of a quick tick box exercise on the dining room table on a Saturday evening every six weeks.
Thats some post Coiler, thanks for the info.
Thanks for that Post Colier.
Not really what I wanted to hear though, we have 2000 Montrocon Box van with discs,
The whole set-up (unit, traielr and load) is around 21t and it has now sat for the best part of 3 months, It’s due for inspection when I go back to work, they’ve already commented about the discs last time it was inspected. I’ve been told it needs some weight and heavy use really.
I reckon they’ll be a big bill before the annual test in July. 
Moose:
if you cant look after drum brakes on 1 year old trailers you have no hope with discs!
what was the problem? were you testing them empty, or a result of poor servicing?
double deck montracons/stepframes on drums are ror as a rule and you dont get much simpler!
moose
At a year old, they shouldn’t need any “looking after” and should sail through the MOT test surely.
They were inspected every 6 weeks. They failed on low effort or air pressure or some such, the workshop looking after them wouldn’t have brake tested them on a rolling road every 6 weeks, just a visual inspection. They would have been tested empty at MOT, by VOSA order. I’m not mechanicaly minded, what difference would that have made? They were or 17.5" rims.
Still ■■■■ poor in my opinion even if Stevie Wonder was maintaining them, if they weren’t set up properly to pass an MOT brake test when they left the factory, they shouldn’t have left the factory i’d have thought. I wouldn’t have minded if it has just been the odd one but all of them…
muckles:
Thanks for that Post Colier.
Not really what I wanted to hear though, we have 2000 Montrocon Box van with discs,
The whole set-up (unit, traielr and load) is around 21t and it has now sat for the best part of 3 months, It’s due for inspection when I go back to work, they’ve already commented about the discs last time it was inspected. I’ve been told it needs some weight and heavy use really.
I reckon they’ll be a big bill before the annual test in July.
One thing about disks is that with some good hard use you can restore function back into them. The manufacturers recommend no mechanical cleaning with corrosion build up on the disk, just give it plenty of work to do and it should clean itself up.
If you can, get a heavier load on it a few times, turn off the engine brake or retarder and give it some work to do. if not you could try upping the pressures a bit to give it some more work to do, the only thing is if you alter the pressures this is strictly speaking a notafiable alteration.
It’s amazing how much they will clean up though with a bit of work.
Silver_Surfer:
Moose:
if you cant look after drum brakes on 1 year old trailers you have no hope with discs!
what was the problem? were you testing them empty, or a result of poor servicing?
double deck montracons/stepframes on drums are ror as a rule and you dont get much simpler!
mooseAt a year old, they shouldn’t need any “looking after” and should sail through the MOT test surely.
They were inspected every 6 weeks. They failed on low effort or air pressure or some such, the workshop looking after them wouldn’t have brake tested them on a rolling road every 6 weeks, just a visual inspection. They would have been tested empty at MOT, by VOSA order. I’m not mechanicaly minded, what difference would that have made? They were or 17.5" rims.
Still ■■■■ poor in my opinion even if Stevie Wonder was maintaining them, if they weren’t set up properly to pass an MOT brake test when they left the factory, they shouldn’t have left the factory i’d have thought. I wouldn’t have minded if it has just been the odd one but all of them…
I have found its a common misconception that brakes don’t need looking after in the first couple of years. Ideally as soon as you take delivery of a new trailer it should have a first use inspection and laden brake test. This will point out any problems and you can fire it straight back to the manufacturer if there’s a problem. After one year it’s difficult to argue your point that it was incorrectly set up leaving the factory.
If you’re having problems getting a triaxle through mot brake test un laden there’s something wrong big time. Do your drivers complain about the brakes when running unladen, or laden, come to that?
If you have a lot of the same trailers all with the same problem it sounds like the pressures haven,t been set up properly from the factory.
It was all very light stuff to be fair, you could have just driven it round on the unit brakes so probably never came to the fore before the MOT. Once bitten twice shy, i’d have any new trailer with drum brakes tested now before accepting delivery from the factory. You just assume everything is right when buying new from a reputable manufacturer.
just one thing to consider, the trailer manufacturer, will probley buy all the axle’s in as compleat unit’s, axle, bearing brakes, possabley wheel’s all ready bolted on, ready for them to bolt on and go.
as a car mechanic myself, after working on any part of the braking system, i all way’s drop the vehicle in the roller’s before it goes out on road test. a visual inspection is not good enough, it the same when torquing wheel up, you don’t buzz the wheel nut up with a 300nm buzz gun, and then check them with a torque wrench set at 120nm 
a mate proved a point, buzzing wheel’s nut’s up on one side of a transit (i’m doing the other), buzz buzz buzzzzzzzz twang one streched wheel stud, which we all knew about, is now in 2 parts .
Silver_Surfer:
Well, I bought 7 new double deckers off Montracon about 5 years ago with drum breaks and every one of them failed the MOT after the first year and were a right pain to get through on a pass. Maybe they were poor drums or what I don’t know but let’s just say I’ll be trying discs if I ever buy new again. One year old trailers and them all failing MOT, nearly started crying…
Turn the pressure up a little.
One of our customers has a few ‘Decker’ trailers with the same problem, easilly sorted.
Ross.
bigr250:
Silver_Surfer:
Well, I bought 7 new double deckers off Montracon about 5 years ago with drum breaks and every one of them failed the MOT after the first year and were a right pain to get through on a pass. Maybe they were poor drums or what I don’t know but let’s just say I’ll be trying discs if I ever buy new again. One year old trailers and them all failing MOT, nearly started crying…Turn the pressure up a little.
One of our customers has a few ‘Decker’ trailers with the same problem, easilly sorted.
Ross.
Oh, another factor when deciding on disc or drum is do you go to quaries regularly as the wheel wash will wreck your calipers in no time flat!!
Ross 
bigr250:
bigr250:
Silver_Surfer:
Well, I bought 7 new double deckers off Montracon about 5 years ago with drum breaks and every one of them failed the MOT after the first year and were a right pain to get through on a pass. Maybe they were poor drums or what I don’t know but let’s just say I’ll be trying discs if I ever buy new again. One year old trailers and them all failing MOT, nearly started crying…Turn the pressure up a little.
One of our customers has a few ‘Decker’ trailers with the same problem, easilly sorted.
Ross.
Oh, another factor when deciding on disc or drum is do you go to quaries regularly as the wheel wash will wreck your calipers in no time flat!!
Ross
I think Paul (Repton) Might tell you different, the lad who He mentioned changing his trailers every 3 years, does some of the horriblest work you can imagine. Corrosive, quuarries, serious hills all at 44t obviously, and as he says. 3 years without a penny spent.