Why aren't there offset differentials for offroading?

WinkOsmosis

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Sep 18, 2002
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I don't understand it. People have trucks jacked up 2 feet, but then not only is the axle the same height, but there is a differential bulging downward. Why not mount the differential higher and connect it to the half axles with gears? That way the lowest part of a vehicle would be the axle. Would that make too much sense and sell too many units?
 

snut

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Oct 9, 1999
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the center dif "pumpkin" gets lifted too when ppl when their trucks to fit bigger tires..the bigger tires will lift the pumpkin....they do have special axels were the pumpkins are lifted if you do a search for unimog axels youll see the pumkin is alot higher then normall axels...rockwell axesl as well.
 

WinkOsmosis

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Sep 18, 2002
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Originally posted by: snut
the center dif "pumpkin" gets lifted too when ppl when their trucks to fit bigger tires..the bigger tires will lift the pumpkin....they do have special axels were the pumpkins are lifted if you do a search for unimog axels youll see the pumkin is alot higher then normall axels...rockwell axesl as well.

I've never seen any of those in real life though. Why not?
 

iamwiz82

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Jan 10, 2001
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Originally posted by: snut
the center dif "pumpkin" gets lifted too when ppl when their trucks to fit bigger tires..the bigger tires will lift the pumpkin....they do have special axels were the pumpkins are lifted if you do a search for unimog axels youll see the pumkin is alot higher then normall axels...rockwell axesl as well.

as do Volvo axles. The reason most dont is because its expensive. how would you plan on turning an axle shaft with a gear that can withhold 8000lb ft of torque with a small gear that would be required in an offset diff. Thats why geared hubs is more common.
 

snut

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Oct 9, 1999
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they usally are hard to get and expensive I see them on the trail on many high dollar trail only rights
 

Antisocial Virge

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Dec 13, 1999
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A Humvee uses this setup. Not the fake ones.

EDIT: well not exactly like you explained it. They offset the axle at the wheels.
 

iamwiz82

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Jan 10, 2001
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something similar

you can notice that the axle is still centered in the diff, however look at the hubs, the axle is on the upper portion, rather going through the center, increaing ground clearance.

The main reason people lift vehicles is to fit bigger tires, bigger tires means more ground clearance. Thats why total height is not as important as ground clearance. A Suzuki Samauri with 31" tires is actually has higher ground clearnance than a wrangler on 34's
 

Evadman

Administrator Emeritus<br>Elite Member
Feb 18, 2001
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Unimog axles do that as was mentioned. Portal axles, and the ones ont he hummer are the same style. The rockwell is higher because the power input is at the top of the pumpkin, not roughly in the center.

Unimog, Portal, and Hummer axles all have an extra gear reduction at the hub that makes it so you can use smaller driveline pueces since the torque is not being multiplied as many times. For instance, your engine makes 200 ft/lbs. you have a 3.00:1 first gear, a 2:1 transfert case, and a 4.11:1 diff.

Your 200lb/ft turn into 4932 ft/lbs as soon as the power hits the axles. (200 x 3 x 2 x 4.11 =4932) Twist city. by moving that last 4.11:1 to end of the axle shaft, the axle shafts can be smaller. Since the last reduction is at the axles, the gear reduction takes up space, so the axle is offset. the designers decided to offset the axle upwards which means more space under the axle. Yay.

 

WinkOsmosis

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Sep 18, 2002
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Originally posted by: iamwiz82
something similar

you can notice that the axle is still centered in the diff, however look at the hubs, the axle is on the upper portion, rather going through the center, increaing ground clearance.

The main reason people lift vehicles is to fit bigger tires, bigger tires means more ground clearance. Thats why total height is not as important as ground clearance. A Suzuki Samauri with 31" tires is actually has higher ground clearnance than a wrangler on 34's

Yeah I thought about that too, but figured it would be difficult to have it be as strong as a standard axle. What if that axle also had an offset diff though?
 

snut

Golden Member
Oct 9, 1999
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Originally posted by: WinkOsmosis

Are you saying with these pics that there are no axles with a differental offset relative to the axle?


i was jst showing ur how the axels look in case you never seen a unimog or rockwell before