Want to change rear diff gears

[aaron]

Hi got a 99 2.8 td want to change diff gears in rear diff as doing 100km the 2,8 is reving at around 2800 rpm doing 120km around 3100rpm bit hi for my likeing any one know what standard gearing is ? or what gear raito to drop rpm down to 2400rpm- 2500rpm at 100km. and how bad will it affect off road 4wding ? running 33in claws atm or shuld i run 35in will that lower my reves at 100 km

thanks for any help guys

[YNOT]

You have 4.6:1 gears at the moment, 4.3:1 may suit you better but will make the engine work harder so you will "seem" to loose power.
How will it affect off roading - it will be completely stuffed because your front and rear diffs will be constantly fighting each other due to having different ratio's, you MUST change both diffs if you change ratio's. After you've done both diffs it will be the same as on road, the engine will have to work harder.

Tony

[aaron]

hay thanks man

is the front diff raito same as the back i take it ?

[MudRunnerTD]

Hi Aaron, Everything Tony said is spot on mate, and yes your front and rear dif ratios go hand in hand mate, you must address both ends.

My understanding of the 2.8 is its a good torquey engine and will happily sit at those revs all day. It has for years. what kind of fuel economy are you getting?

Your 4.6 ratios are well sort after by guys looking to upgrade for running bigger tyres. I certainly have a set in my GQ. Your already running 33s so imagine how it came out of the factory running 30s!!! putting 35s on will drop it down but you will be getting further and further away from the engine sweet spot for power and that is basically where the factory sat it at 100km/h

On the up side, if you do want to change gears your diff ratios will bring a good penny mate and will likely fund most of the change you want to make......

I think you will be disappointed with the power loss though.

my 2c

[aaron]

Hay thank's guy's ill stick with the standard gear raito for now just about to put 4'' lift in is so going to put 35'' on as the 33'' will look wierd with the lift

thank you for your info