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Old 03-05-2011, 09:31 AM   #1
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Default Gear diff benefits

Can anyone tell me the benefits in using a gear diff over a ball diff in the rear. Also, when should a gear diff be used over a ball diff in the rear.

In the front, why would you use a gear diff in place of a spool, onecway etc?
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Old 03-05-2011, 10:04 AM   #2
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ok, well a gear diff needs a lot less maintenance, it can also be loser without slipping, there for giving you more grip, 99% of the time you use a spool so you dont understeer, if you put a diff in the front and turn left it could give the left wheel more grip so your pushed into a straight line there fore giving understeer, i would only reccomend using it on an open flowing track
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Old 03-05-2011, 01:12 PM   #3
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A gear diff does not slip in any way. All of the torque transfer is done by gears, not by friction of rings on balls like a ball diff. As a result, none of the motor's torque goes into slipping the diff pulley/drive gear relative to the outdrives. If you setup the car properly, and do not let the inside tire become too lightly loaded in a corner, you will be able to put more power to the ground than with a ball diff. As far as the handling difference, with a rear gear diff only, you will notice that the car will rotate/oversteer on-power more than a ball-diff. This can be controlled with thicker or thinner differential oil. The car will accelerate off the corner much harder than with a ball diff, so if you can make the car work with it, it will be faster.
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Old 03-05-2011, 01:57 PM   #4
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Originally Posted by Schumacher MI4 View Post
i would only reccomend using it on an open flowing track
Weird - my experience is the other way around. In tight tracks with a lot of 180's, I feel that geardiff can be an advantage, as it can go through the 180's a lot faster. But this weekend I am racing on a more open track with almost no 180's, and I have swapped my geardiff for a spool.

I almost always use geardiff up front - but at the bigger tracks (like DHI Cup and this weekend's danish nats) I am using a spool.
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Old 03-05-2011, 05:04 PM   #5
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I think the ultimate adjustable set-up is front spool/rear ball diff , as long as the ball diff is set right (ceramic balls, gooped bolt etc...) before race day!!! When traction changes you want a ball diff; messing with oil thickness is a pain.....Also how much rear power do you really need on the ground while turning? Most rear gear diffs cause oversteer even with a front spool! What about rotational mass??? I'll keep running rear ball diffs anyday.......
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Old 03-05-2011, 10:35 PM   #6
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Originally Posted by bertrandsv87 View Post
Most rear gear diffs cause oversteer even with a front spool! What about rotational mass??? I'll keep running rear ball diffs anyday.......
I believe that may be more towards setup and driving style. I run gear diffs in my T3 as I get sick of all the maintenance required for rebuilding the ball diffs. Not only am I faster, but its literally been worry free for me. I've also run f/r gear diffs in mod, as I got sick of the front drive cups breaking on the spool. With 200k weight oil in the front diff, it feels like a spool, but has been way more forgiving on the drive cups in the even of a bump. The acceleration is outstanding.

I have not experienced oversteer with my setup, rather it's been easier to apply power...sooner.
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Old 03-06-2011, 06:11 AM   #7
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Default my setup

I run a rear ball diff with a front gear diff in my 416 and have found this to be a pretty reliable setup. When I first got the car it had real thick goop in the front gears, I washed that out and put in 1500 wt oil and found that freeing it up a bit up front really worked well for me, its stiffer than a ball diff but gives in a bump unlike a spool. I've run on 4 different tracks through the winter and havent found the need to change anything.
The rear ball diff needed rebuilding once and still works well after about 6 weeks, so pretty low maintenance and unless I wreck the front end whacking the wall. I havent needed any drive cups like the spools are prone to breaking.
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Old 03-06-2011, 06:46 AM   #8
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I run gear diffs front and rear in my 416X, and it works better for me. I run 1K in the rear, and 300K in the front which is almost like a spool, but is forgiving enough not to break spool cups. Front spools also tend to push off power, so if I need a little more turn in I prefer a gear diff. I race on carpet and asphalt with the same diff set up with no probs. Maintenance is minimal, and acceleration is great. I think every racer should at least have all three (gear,ball,& spool) on hand as tuning aids to figure out what works best for his/her driving style.
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