Brake Discs Off Road a bad idea?

20 replies [Last post]
mercfan
mercfan's picture
Offline
Joined: 31.07.2004
Location: Hertfordshire
GWOA Groups: Members

Are brake discs for serious off roading a bad idea?

Two reasons behind this question: Serious catastrophic brake problems on disc equipped Unimogs are not uncommon. And secondly, Mercedes presumably put all of their off road know-how into the Zetros and equipped it with DRUM BRAKES all round.

Any thoughts?

TvaiX
TvaiX's picture
Offline
Joined: 18.05.2009
Location: Latvia
Re: Brake Discs Off Road a bad idea?

"Off road" is very stretched word. Every country has own scenery. But in my experience in mud off roading brake disc pads tend to run twice longer then brake shoes, and every other G localy the same.

I have heard from wood workers that drums are more isolated so they work better. But when mud gots in drum, when harder to get in its harder to get out... It eats faster brake shoes. Also in pure theory disc brakes work better in wet then drum brakes.
 

mercfan
mercfan's picture
Offline
Joined: 31.07.2004
Location: Hertfordshire
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

"Off road" is very stretched word

You're right - it could mean so many things...

Suppose I should have explained better. Was thinking of keeping an eye out for another mog, apart from the 404 I have. 

Something bigger, more powerful, one of the 6-cylinder ones.

But lots of them have disc brakes.

And then heard a few stories of mud and rocks compacting in the wheel until it all jams up and the caliper being ripped apart and off the hub.

Add to that Mercedes' own know-how and going with drums all round for a vehicle which they clearly market as very off road capable

Hence why I wondered if the disc issues were isolated or more common.

gav.helme
gav.helme's picture
Offline
Joined: 29.04.2011
Location: North Lincolnshire
GWOA Groups: Committee, Members
Re: Brake Discs Off Road a bad idea?

Hi

The vast majority of MB commercials that are designed for site work all run Drum Brakes

I can remember in the late 90's when Discs became the norm and a few off road trucks had disc spec.

MB had to come up with a modified deflector system (read tin plate) to keep the mud and crap out of the disc and as stated more importantly the caliper

OK these things in the main were driven to do a job by people who also in the main didn't give a monkeys or pay the repair bills but all the same...

All these spec vehicles up to at least last year ran all drum set ups whether 4x2 4x4 6x2 6x4 8x2 or 8x4

Not sure on the latest generation  Actros / Antos / Arocs but assume still Drum...

mercfan
mercfan's picture
Offline
Joined: 31.07.2004
Location: Hertfordshire
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

This is where your experience counts, Gav. Thanks for sharing it.

Pistonhead
Pistonhead's picture
Offline
Joined: 17.12.2006
Location: Loughborough
GWOA Groups: Committee, Members
Re: Brake Discs Off Road a bad idea?

Having had a look at the Unimog axles and brake set up; no wonder the brakes get clogged up with rocks and muck causing your reported damage. The back plate if fitted is so far from the disc and caliper its self. The problem can be solved if the back plate were more closely mounted. 

My choice would be for disc brakes - reduces the unsprung axle weight.

mercfan
mercfan's picture
Offline
Joined: 31.07.2004
Location: Hertfordshire
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

My choice would be for disc brakes - reduces the unsprung axle weight.

We probably have to agree to a difference of opinion.

Following what Gav commented above and considering Mercedes probably know a thing or two by now about off road trucks and that they went with drums all round on their latest and best, I'll be looking for a Mog with drums all round. 

Pistonhead
Pistonhead's picture
Offline
Joined: 17.12.2006
Location: Loughborough
GWOA Groups: Committee, Members
Re: Brake Discs Off Road a bad idea?

mercfan wrote:

My choice would be for disc brakes - reduces the unsprung axle weight.

We probably have to agree to a difference of opinion.

.................................................................... I'll be looking for a Mog with drums all round. 

 

This a quote from the "Horses mouth", as it were;

"Hi Rakesh 

Thank you for your e-mail, all Unimogs have had disc brakes on all wheels since 
1976.

Unimog brakes are generally very reliable and we do not know of any catastrophic 
failures in an off road situation. 

If you have any further questions we would be happy to advise.

Many thanks"

So you would be looking for a pre 1976 model then.

 

 

 

mercfan
mercfan's picture
Offline
Joined: 31.07.2004
Location: Hertfordshire
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

Looks like it Rakesh.

Here is what Daimler themselves had to say:

As a result, for several good reasons the Zetros has opted for conventional drum brakes: for one, their maintenance requirements are extremely low. In addition, the system is simple and much less complex than the floating-calliper disc brakes normally found in trucks - so much so that the drum system is generally preferred throughout the world basically on account of it being simpler to maintain and repair.
In addition, unlike floating-calliper disc brakes, drum brakes are to a large extent immune to freezing, for example following a night of heavy frost. They are also barely affected by driving through copious amounts of mud and water, whereas floating-calliper disc brakes can suffer problems as a result of water ingress.

Seems like two horses from the same stable not quite saying the same smiley 

 

mercfan
mercfan's picture
Offline
Joined: 31.07.2004
Location: Hertfordshire
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

An aquintance and fellow mog owner looking in on our discusion just pointed me to this link:

https://www.youtube.com/watch?v=yBn-eBgUg2Y

mark
mark's picture
Offline
Joined: 06.11.2003
Location: England
GWOA Groups: Committee, Members
Re: Brake Discs Off Road a bad idea?

Wouldn't happen on a Sprinter. cheeky

TvaiX
TvaiX's picture
Offline
Joined: 18.05.2009
Location: Latvia
Re: Brake Discs Off Road a bad idea?

You did not say what is your off road, rally raid and trofy raid for example are so different. For both you can build G and will be different car.

What is true for trucks not always true for normal cars, what is Gwagen.

Drum brakes are cheaper in theory to make, but in real world I can say my G drum brake repair costs are bigger than disk brakes.

Also as I wrote, drum brakes shoes in muddy off road has twice shorter life then brake pads for disk brakes. And are better for stopping power. Drum brakes can offer better protection from dust and rocks.

But you must find your best way for your project, what ever it is.

mercfan
mercfan's picture
Offline
Joined: 31.07.2004
Location: Hertfordshire
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

TvaiX wrote:

You did not say what is your off road, rally raid and trofy raid for example are so different. For both you can build G and will be different car.

What is true for trucks not always true for normal cars, what is Gwagen.

Drum brakes are cheaper in theory to make, but in real world I can say my G drum brake repair costs are bigger than disk brakes.

Also as I wrote, drum brakes shoes in muddy off road has twice shorter life then brake pads for disk brakes. And are better for stopping power. Drum brakes can offer better protection from dust and rocks.

But you must find your best way for your project, what ever it is.

You are absolutely right. Take your pick and take your chances.

Whichever it is, probably the most important is to understand and know and properly maintain your vehicle.

Quietly wondering if the damage in the above video could have been avoided by perhaps a few inches reversing.

And the other important thing it shows is why not to venture out alone. Imagine if the people in that vehicle were on their own and it happened in the middle of that lake.

mark
mark's picture
Offline
Joined: 06.11.2003
Location: England
GWOA Groups: Committee, Members
Re: Brake Discs Off Road a bad idea?

Bit OT cause no Mercs, but yes, not good to be on your own. 

https://www.youtube.com/watch?v=f8trkgFX6wI

 

 

 

 

mercfan
mercfan's picture
Offline
Joined: 31.07.2004
Location: Hertfordshire
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

mark wrote:

Bit OT cause no Mercs, but yes, not good to be on your own. 

https://www.youtube.com/watch?v=f8trkgFX6wI

Great post, Mark, never mind OT.

Lots to be learnt from this - excess weight, cool head, know what you're getting into, etc, etc.

Not far from where I grew up in Namibia, a hunter, purely by chance, not so long ago found a dust covered VW Camper van. Weird was there was no-one. Closer inspection showed remnants of failed attempts at fixing a fuel hose. Keys still in ignition, foreign passports, documents, everything still there. Major search. Police trackers found them. Family of 4 under a tree. Deceased, estimated 6 weeks prior. Left the vehicle, disorientated, wrong direction, away from the main road, not enough water, searing heat, exhaustion, rest is self explanatory. Unprepared, no idea of basic survival skills, but crucially, no-one knew of them, where they were going when and the fact that whilst doing so they also went alone. No one even missed the vehicle, as they had bought it a few weeks before then, the day they got off the plane at the start of their holiday, presumably as it worked out cheaper than renting. Despite their unfortunate mistakes, may their souls be blessed.

This stuff is still astoundingly "common" in this day with modern comms. Invariably relying on a mobile phone is vitual suicide.

Constantly reports of people gone missing over on horizonsunlimited.

diesel_jim
diesel_jim's picture
Offline
Joined: 24.07.2013
Location:
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

FWIW, I've had Land rovers since I was 15 (41 now), started with a series 2, then several S3's, all of which were drum braked front & back.

 

Moved on to 90 & 110's, early ones were drum/disc, then from 300Tdi onwards LR fitted discs all round, and subsequent 90/110's that i've built or tinkered with, I've always fitted discs on the back.

 

I also do a lot of off roading, used to go laning up in Wales a helluva lot, and now around Wiltshire/salisbury plain area, where there's lots of flint & chalk stones. Have had no problems whatsoever with discs.

can probably count on one hand (bear in mind I'm Wiltshire born & bred, so have 6 fingers...laugh) the amount of stones that have got jammed between the caliper and disc. and these usually pop out with a bit of reversing, or just wear down.

 

LR do fit stone shields (tin plates, as mentioned above) which may/may not help things... the jury is still out on that one. Most people remove them and bin them, especially when they get rotten, But I'm a firm believer that LR developed them for a reason, so they must do /some/ good.

 

But I've had no accelerated pad wear when off roading in comparison to drums. The best thing though, is the fact that after every off road session, I don't have to fanny about removing the drums, cleaning the clag out, then readjusting the shoes again... maybe it was a LR thing (and maybe MB drums are uber good) but it was a royal PITA as they would be out of adjustment, or badly worn, when filled with watery mud.  Discs are just fit & forget; self adjusting, no hassles, clean off with one press of the brake pedal to get muck off of the surface.

 

As soon as someone comes up with a good disc conversion for the back of my 460 I'll be doing that!

 

anyone....?????

cox.adrian
cox.adrian's picture
Offline
Joined: 23.05.2010
Location: HAILSHAM E SUSSEX
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

 

 

 

As soon as someone comes up with a good disc conversion for the back of my 460 I'll be doing that!

 

anyone....?????

[/quote]

     there was a post on this a year or 2 ago can be done 

             

Pistonhead
Pistonhead's picture
Offline
Joined: 17.12.2006
Location: Loughborough
GWOA Groups: Committee, Members
Re: Brake Discs Off Road a bad idea?

Hello Adrian,

Question to ask is why do you feel the need of disc brakes; true, there are advantages in disc brakes but considering the cost for conversion and use of vehicle - is it worth it? Yes, the conversion is possible but considering your vehicle is now a turbocharged diesel or just inter-cooled diesel the power gain does not ask from your braking that your current set is not designed to cope with.

For the example of the chap who did do the conversion; I believe latter converted back to drum brakes as he was not happy with the disc set up either. 

Save your money for now and live with what you have. My suggestion to you.

cox.adrian
cox.adrian's picture
Offline
Joined: 23.05.2010
Location: HAILSHAM E SUSSEX
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

    rakesh not for me im happy with discs front drums on the back 25years of

     trouble free motoring 

    diesel Jim was asking and there was a post  some time ago

     about a conversion

     

Pistonhead
Pistonhead's picture
Offline
Joined: 17.12.2006
Location: Loughborough
GWOA Groups: Committee, Members
Re: Brake Discs Off Road a bad idea?

AH, I will try to find the thread for you. From memory, it was not detailed enough to instruct the actual work just generalised detail.

diesel_jim
diesel_jim's picture
Offline
Joined: 24.07.2013
Location:
GWOA Groups: Members
Re: Brake Discs Off Road a bad idea?

Great, thanks if you can find the link ^^^^

 

I'm sure drums are good.  as are crossply tyres and sealed beam headlights, but the world moves on.