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vagman2 (Automotive)
28 Jun 13 17:20
Hello everybody,
Right now I'm in a big trouble with my rear axle differential. Short story is I need to turn the pinion(propshaft)in reverse direction to get forward move of the car. This is due to my gearbox which have opposite input to output shaft rotation. So if/when engine crank turns anticlockwise(watching forward), the propshaft turns clockwise which is obviously the opposite to almost 100% of all RWD car diff pinion rotation. My idea is to turn over my rear axle(and diff)so when propshaft turns the pinion clockwise car will have forward move.
So, what if I turn the diff's hypoid gear mesh in reverse direction? Also my pinion will be more on the top of the diff housing instead more to the bottom as been designed.
Thanks!
MikeHalloran (Mechanical)
28 Jun 13 19:04
The pinion bearings will die young.

Mike Halloran
Pembroke Pines, FL, USA

CoryPad (Materials)
28 Jun 13 20:23
Are these aftermarket systems on your personal vehicle? A custom designed system? Too little info to provide meaningful tips.
Tmoose (Mechanical)
28 Jun 13 21:42
In addition to aforementioned features inside designed to distribute oil, some say the tooth profile is unequal angles on the drive/coast sides for strength. The picture of the pinion on page 2 here would seem to confirm it.
http://www.moserengineering.com/moser/wp-content/u...

Despite the theoretical strength disadvantage Some jeep like vehicles allegedly to it anyway on the front axle.
tbuelna (Aerospace)
28 Jun 13 23:15
What Tmoose notes about there being differences between the drive/coast flanks of hypoid gears is often true. Besides the slight differences in profile geometry between the drive/coast flanks, there can also be differences in surface finish or accuracy. Designers of production gear sets are very clever at using all sorts of little tweaks like these to improve performance and reduce cost of the gears.

Also, as MikeHalloran noted, reversing the relative direction of rotation with your hypoid R&P will change the loading condition on the bearings and housing. The change in direction of thrust at the mesh contact will likely have an adverse effect on pinion bearing life, and the deflection changes produced in the housing may be enough to affect the load distribution at the mesh contact.
Fabrico (Automotive)
29 Jun 13 23:14
If you need something robust, you might look into flipping one of the many Dana high-pinion front 4WD axles. When placed at the rear, the pinion will be toward the bottom and turning the wheels the right direction. The gears and bearings will be fine, but the axle housing will likely need to be modified to fit the application.
vagman2 (Automotive)
1 Jul 13 1:39
Guys,
Endless thanks for your inputs. Seems I'll have to find another diff/rear axle solution.
@ Fabrico
Front 4wd axles usually have their diff assembled not in the middle of the axle which is a problem for rwd installation in a car.
For those who are interested my manual gearbox is from 2001 Audi A4 Quattro and rear axle is from Volvo 940 diesel.
Thanks again!
Tmoose (Mechanical)
1 Jul 13 15:21
Seems like a simple axle lube system with a pump and jets might allow operating at any orientation.

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