The angle gear, sometimes called bevel gear, is the gearset at the back of the front differential that "turns" the east-west motion of the front components to north-south (front to back) motion to spin the driveshaft.

It is a purely mechanical device with no clutches. It is similar in principle to the rear-end gears of the R and all RWD only cars.

It is not part of the Haldex system in any way other than the driveshaft is the input to the Haldex AOC. It always turns whenever the front wheels turn. The on/off of the rear axle to acheive AWD is done by the Haldex AOC.

It turns at at an RPM that is equal to the transmission output speed. Assuming no losses, it must handle up to 1000 lb ft of Torque in 1st gear.

Currently, there are 3 known failure modes, I believe they have no relation to each other.

1 - weeping fluid. The breather was redesigned to solve this
2 - failure of the pair of gears themselves.
3 - there has been one report (amongst SS owners) of an input shaft failure

A simple test for 2 & 3 is to put the car in Neutral, turn the front wheels, and watch that the driveshaft turns. This should be diagnostic step #1 on any car with AWD failure.

KVB

I can only speak for myself on this one....

I have no real leaks. I get at worst a weep when tracking the car. I have almost 1000 miles of track time, no failures.

Nothing other to to check the fluid level I guess...

so if yours is leaking, or may go bad, I'd get it fixed BEFORE the warranty expires.

I will also have them check out my crappy AM reception and my leaking power steering reservoir.

Thanskf or you help.

You can find the angle gear box at the front of the driveshaft.... your leak sounds like the steering rack.

Quote, originally posted by JimLill »

It turns at at an RPM that is equal to the transmission output speed. Assuming no losses, it must handle up to 1000 lb ft of Torque in 1st gear.

If leak is at END of rack, it can be either side.......

My 2004 V 70 R GT has shown increasing gear howl. I believe this is another failure mode, due to case flex, allowing gears to mesh too near the toe. Now at ~45,000, been noisy for ~10,000. First, is bustup coming, and second, any input from factory on recall or adjuastment?

Senilesurfer

Quote, originally posted by JimLill »
It turns at at an RPM that is equal to the transmission output speed. Assuming no losses, it must handle up to 1000 lb ft of Torque in 1st gear.

Jim,

That did get my attention. From a dynamics point of view, the variable rotational force from the front differential is acting on the length of the drive shaft. So, in first gear we see the max torque on the angle gear. The gear ratio has to be much higher just to get the car moving according to spec (or close), therefore, the high torque value.

To put it in simple terms.

And how do awd systems differ from engines that are mounted east/west(transversly) as opposed to cars with a traditional north/south setup like the boxer engines of the subarus/porsches and TT V6's of the B5 Audi S4?

From what I understand, the Angle gear or bevel gear is what Volvo calls their transfer case.

In a 4X4, where you can select whether or not you want 2wd or 4wd, the transfer case is adjustable, but serves essentially the exact same function as our Angle gear, except, our 'transfer case' is always set to 4wd. Some folk refer to this as the centre differential also.

From what I understand, its basically a differential that converts the motion coming out of the transmission from East/West to North/South so that power can be delivered through the driveshaft to the rear diff, where its converted to East/West again.

So every car with awd should in theory have an "angle gear" of sorts. Most are called center differentials though, I think.

Experts please feel free to correct/add to my shoddy diagram if I'm wrong.

My guess, based on what I gather: You have the front and rear differentials, which are open diffs (In audi and subaru, these are electronically lockable, computer controlled open diffs), and the centre differential, or angle gear, which is always locked. The haldex unit on the rearward end of the driveshaft controls how much power is pushed through to the rear diff.

In the Audi system, the "Torsen" centre diff is computer controlled and sends the power either to the front or to the back depending on need, and is usually under normal conditions set to some figure such as 50:50 split. My guess is that this "Torsen" is like our Angle gear and Haldex AOC rolled into one unit.

I'm hoping the experts on here will shed some more light on this, because most of my ideas are just educated guesses.

Modified by YK-GTR at 3:18 AM 3-31-2008

http://en.wikipedia.org/wiki/Haldex

This also answers the question about the difference between haldex and Torsen

Modified by YK-GTR at 3:21 AM 3-31-2008

The angle gear failures in a Volvo are more related to the concentric input shaft arrangement than because it is a 90 degree turn.

Every 4WD or AWD car every made has some form of this gearset.