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View Full Version : D4 MY10 2.7 diesel compression braking - safe max revs?



jammers
31st December 2013, 07:04 PM
Driving from Braidwood to Batemans bay today - long downhill road - as usual I have been using the sports mode to control speed without cooking the brakes. Spending quite a bit of time in second gear to slow but revs often got close to 4k rpm (near redline).

So my question - what is a safe limit / what upper limit do you use when slowing on tarmac going down hill?

Tombie
31st December 2013, 07:07 PM
If you over run the vehicle will shift up regardless to protect itself...

However, brakes are there for a reason, 3rd gear and some occasional braking application will not hurt!!

phl
31st December 2013, 07:46 PM
The auto definitely upshifts as necessary, so you still have to hover over the brakes. It will also prevent you from downshifting if doing so will take the revs too high.

jon3950
31st December 2013, 09:46 PM
However, brakes are there for a reason, 3rd gear and some occasional braking application will not hurt!!

+1

I think 2nd is too low for that hill. You won't cook the brakes on a D4 or D3 going down there if you're driving sensibly. Stick to 3rd and use the brakes where necessary, maybe dropping to 2nd for the hairpins. I regularly tow up and down Clyde Mountain and have never had a problem with the brakes in either the D3 or D4.

Cheers,
Jon

PaulGOz
1st January 2014, 08:15 PM
I have found there is a fair gap between 2nd and 3rd and will often shift into low range on steep slow descents as the ratios end up much closer allowing more precise engine brake control. Max revs in 6th never been a problem either.

discotwinturbo
1st January 2014, 08:47 PM
I have found there is a fair gap between 2nd and 3rd and will often shift into low range on steep slow descents as the ratios end up much closer allowing more precise engine brake control. Max revs in 6th never been a problem either.

Ditto.
Brett...