Just adding a few observations following two fairly recent overlanding trips:
The 1st was 5 days driving up/down the Italian & Swiss Alps on rough & steep offroad trails in June (plus driving motorways to/from London) and the 2nd was spent covering about 1,000 miles overlanding through Morocco on everything from flat sandy/gravel plains to come steeper technical ascents/descents (plus c.4,500 miles motorway to/from London). On the first trip I estimate that the total vehicle weight + myself was around 3.3 tonnes, and across Morocco we found a weigh-bridge which confirmed that we were running at 3.65 tonnes incl. 2 people.
During the trip in the Alps I did a number of long steep descents that brought me down 1,000-1,500 meters in the course of 30-45 minutes, and the brakes were absolutely roasting. I was using a combination of the built in hill descent mode plus foot brake on the less steep sections. I didn't have any noticeable brake fade, but the stench of hot brake pads was impossible to ignore. From what I've read about the Powerbrake X-line kit, the larger discs and increased disc ventilation their should help reduce heat build-up and improve subsequent cooling of the system.
In Morocco, there were a few occasions when I had to brake firmly when wayward cars/pedestrians/animals stepped onto the road, or cars in front did something unexpected, and in most instances I felt that the vehicle's weight was overtaking the brakes. On these occasions the brakes were not running hot - it was simply a matter of mass vs resistance. I feel that the Powerbrakes larger disc diameter will give me greater leverage, and the 6-pot calipers will give be greater braking force.
Much of the analysis in this thread looks at trailer braking. Does anyone have lived examples similar to mine, where the change to a big brake kit brought benefits as I'm expecting above? Noting that the kit plus fitment will not leave much change from £5,000, I want to get this right (alongside general peace of mind!).
I'm sure everyone who has fitted either the Alcon/Agile or Powerbrake x-line kit will say how much better and stronger the brakes are. It's the seat-to-pants instrument that has a built-in J curve for higher spends.
Naturally if you increase the rotor diameter and the pad surface area in contact you should expect an improvement in the braking effect. Improve the heat dissipation to keep everything within spec and it should be a winner. Take my money.
But like Alcon/Agile, Powerbrake don't appear to quantify their improvements via actual performance data. For the asking price I would want to see at least a comparison of deceleration and stopping distance tests to prove their claims. For towing I would also want to see repeat hot stopping test data to see the reduction in brake fade. This is not unreasonable to expect and it's where your money matters, right?
If the vehicle brakes are being overwhelmed because of a coupled trailer (>750kg) the trailer brakes are not doing their job. I would be addressing that before throwing money at better vehicle brakes, especially if you're happy with the vehicle brakes when not towing. You may still end up doing a BBK upgrade but improving your trailer brakes is never a bad investment.
Or, forget all that. Get the upgrade and hope for the best. Go for the red calipers. Red stops faster
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I posted earlier about the need for effective trailer brakes. Again:
- Vehicle brakes are responsible for the vehicle up to the maximum loaded weight and have sufficient reserve capacity for an unbraked trailer up to an approved amount. I think it's 750kg trailer GVW in the UK.
- Trailer brakes are responsible for all additional braking effort at combination weights above vehicle + unbraked trailer at GVWs.
I tow a 2 tonne camper with 10" Dexter style electric drum brakes operated by a Bendix brake controller (same functions as the Redarc TowPro Elite at about 40% of the Redarc price). Two tonnes is not particularly heavy and well under the towing limit of the Grenadier.
I press the manual override button to test the trailer brakes after every set off so I know they're operating.
I increase the brake controller dial setting at higher speeds so the trailer brakes produce more stopping power. The inertia/proportional control mode reacts to how hard you brake not how heavy you are, but inertia increases with mass so there is some crossover at higher speeds and weights.
I decrease the controller setting when off-road so the trailer wheels are less likely to lock up (no ABS).
I use the manual override button to brake the trailer first on slippery downhill slopes to help keep the trailer behind me.
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