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Old 03-27-2009, 10:00 PM   #31
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A lot of it is really just driving style/ track layout, because if your on a track that would not require any braking/ very little braking in straight lines(except the drag brake which is a very effective tool with one-ways) then a spool is scrubbing more speed than is needed, and a one way will always be faster in this situation with the right driving style. The advantage of a spool over a diff is the pure exit corner acceleration, which a one-way still has, but does not have the disadvantage of the off power push (actually the opposite). Seems perfect, but its typically less consistent (no brakes in the corners) I'm not saying that it should always be used, but with with an extremely consistent driver/perfectly balanced car it should always give faster lap times than a spool. As far as racing goes, it can be really annoying to people your trying to pass (no brakes in the turn), Comin through!
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Old 03-27-2009, 10:02 PM   #32
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Originally Posted by lynell90 View Post
double diffs?
Front diff and rear diff
as a rule of thumb Diff's with foam tires
oneway,spool oneway, spool, with rubber tires, carpet or asphalt

thats what I have always been told anyways
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Old 03-27-2009, 10:08 PM   #33
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Originally Posted by RielTime Racing View Post
I'm confused Can someone explain or compare front direct coupling vs front one way? The two look the same from Tamiya.

"Direct coupling" is what the centre pulley is refferred to when it is solidly attached to the centre shaft. This is opposed to "centre one way". Both reffer to the pulley that drives the front belt.

"Front one way" is shorthand for the front one way diff.
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Old 03-27-2009, 10:33 PM   #34
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Front diff and rear diff
as a rule of thumb Diff's with foam tires
oneway,spool oneway, spool, with rubber tires, carpet or asphalt

thats what I have always been told anyways
Ok I have been out of on road for a long time,but isn't a spool and spool oneway the same thing? I mean a spool is just a solid diff right? It only rotates the way that the power is given to it.
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Old 03-27-2009, 10:55 PM   #35
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You can use a spool with a center one way, which allows the wheels to free spin forward, but together rather than independently. I believe XRay's old multi-diff had this option as well. It doesn't appear to be a popular choice.
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Old 03-27-2009, 11:20 PM   #36
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You can use a spool with a center one way, which allows the wheels to free spin forward, but together rather than independently. I believe XRay's old multi-diff had this option as well. It doesn't appear to be a popular choice.
Ahh, got ya.
Makes sense, I don't think I would do that either, I just dont see the point to it. I mean the center is gonna be where the spur is so why would you put a one way there if you have a spool up front? Maybe to control the rear diff but I don't think I would like the way that would make the car rotate and accel.

Josh
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Old 03-27-2009, 11:38 PM   #37
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Ok I have been out of on road for a long time,but isn't a spool and spool oneway the same thing? I mean a spool is just a solid diff right? It only rotates the way that the power is given to it.
nope they are different
I'm using the xray multi-diff
the spool is completly locked
spool oneway both wheels locked but freewheel like a oneway
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Old 03-27-2009, 11:45 PM   #38
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nope they are different
I'm using the xray multi-diff
the spool is completly locked
spool oneway both wheels locked but freewheel like a oneway
How could a spool "freewheel" like a one way? I mean there is no extra rotation from it? I think I am just getting lost. How can a diff that is built to go the same direction freewheel?

Josh

P.S. Don't mean to sound like a dick I am just curious, very interesting to me.
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Old 03-28-2009, 12:01 AM   #39
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If you have a spool up front, and a one-way in your center pulley, you will get the front wheels to "freewheel" like a one-way, but they'll spin together, rather than independently. Not sure how XRay's multi-diff achieved this, however. I can't say I've ever heard of someone using it.
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Old 03-28-2009, 12:55 AM   #40
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Originally Posted by Casey Belarde View Post
nope they are different
I'm using the xray multi-diff
the spool is completly locked
spool oneway both wheels locked but freewheel like a oneway
I think what is meant here is that both front wheels are locked to each other but not to the pulley that spins them (the "diff" pulley). This allows them to spin only together but drive is transmitted from the center pulley only as long as the front wheels don't want to spin faster than the centre pulley would dictate (i.e. when going around the corner off power). This means that as long as the front is going around the corner along a longer circle than the rear and no power is applied, the front wheels will freewheel but at the same speed left to right as opposed to each at its own speed.

The fron Xray multidiff achieves this effect by interlocking the front outdrives with a hex drive that connects the outdrives left to right inside the diff housing. This hex drive is not connected in anyway to the diff housing (the part diff the pulley attaches to) therefore drive is now applied from the housing to the outdrives only via the one way bearings, one for each side. The outdrives being locked to each other, they can only spin at the same speed.

There is however a diametral hole in this hex drive that can be lined up with a hole in the diff housing and a pin can be inserted through both to lock it to the diff housing effectively turning the front into a spool because now the housing is locked to the hexdrive and this in turn is locked to both left and right outdrives.

I think the benefit of having a oneway spool is that some drive is transferred left to right on power in tight corners where a normal oneway would only allow the inside wheel to drive the car (which can be less efficient). This probably means the front wheels will fight one another some, having to find a middle ground and creating a bit of understeer whilst still providing enough drive to pull the car hard out of corners. I would imagine on a high grip surface this would be less efficient than a simple oneway, but I admit I did not experiment with it personally. I think this system is just an engineering exercise to provide as much adjustability as possible to really fine tune the car to suit track conditions. I would be really curious to learn about the experiments carried out in developing this ingenious multidiff. I am convinced this would help a lot of us in understanding how to use it. At the moment i think this is a bit overengineered even for the needs of top racers and its lacklustre success is resemblant of giant leaps of technology of the past which surprised an unprepared public so much they just shunned it. I think it has a huge potential, but am not sure anyone will actually have the patience and the time to really understand what its benefits are and how to use it properly.

Hope this helps.

Last edited by niznai; 03-28-2009 at 09:13 AM.
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Old 03-28-2009, 12:35 PM   #41
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Originally Posted by JoshM20 View Post
How could a spool "freewheel" like a one way? I mean there is no extra rotation from it? I think I am just getting lost. How can a diff that is built to go the same direction freewheel?

Josh

P.S. Don't mean to sound like a dick I am just curious, very interesting to me.
no your not a dick
I will take some pictures when I get off work
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Old 03-28-2009, 12:38 PM   #42
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Originally Posted by niznai View Post
I think what is meant here is that both front wheels are locked to each other but not to the pulley that spins them (the "diff" pulley). This allows them to spin only together but drive is transmitted from the center pulley only as long as the front wheels don't want to spin faster than the centre pulley would dictate (i.e. when going around the corner off power). This means that as long as the front is going around the corner along a longer circle than the rear and no power is applied, the front wheels will freewheel but at the same speed left to right as opposed to each at its own speed.

The fron Xray multidiff achieves this effect by interlocking the front outdrives with a hex drive that connects the outdrives left to right inside the diff housing. This hex drive is not connected in anyway to the diff housing (the part diff the pulley attaches to) therefore drive is now applied from the housing to the outdrives only via the one way bearings, one for each side. The outdrives being locked to each other, they can only spin at the same speed.

There is however a diametral hole in this hex drive that can be lined up with a hole in the diff housing and a pin can be inserted through both to lock it to the diff housing effectively turning the front into a spool because now the housing is locked to the hexdrive and this in turn is locked to both left and right outdrives.

I think the benefit of having a oneway spool is that some drive is transferred left to right on power in tight corners where a normal oneway would only allow the inside wheel to drive the car (which can be less efficient). This probably means the front wheels will fight one another some, having to find a middle ground and creating a bit of understeer whilst still providing enough drive to pull the car hard out of corners. I would imagine on a high grip surface this would be less efficient than a simple oneway, but I admit I did not experiment with it personally. I think this system is just an engineering exercise to provide as much adjustability as possible to really fine tune the car to suit track conditions. I would be really curious to learn about the experiments carried out in developing this ingenious multidiff. I am convinced this would help a lot of us in understanding how to use it. At the moment i think this is a bit overengineered even for the needs of top racers and its lacklustre success is resemblant of giant leaps of technology of the past which surprised an unprepared public so much they just shunned it. I think it has a huge potential, but am not sure anyone will actually have the patience and the time to really understand what its benefits are and how to use it properly.

Hope this helps.
thanks for explaining I couldn't get it out of my brain LOL
but thats what I was thinking
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Old 03-28-2009, 09:30 PM   #43
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Originally Posted by Casey Belarde View Post
I will take some pictures when I get off work
I am pretty confident you can find pictures ont eh xray site (I have the manual, so I didn't try).

PS. Here you go:

http://www.teamxray.com/teamxray/pro...ca8dfd0881e8f0

You can see the hex drive I was talking about and the pin. The rest is just a normal one way assembly.
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Old 03-28-2009, 10:19 PM   #44
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I think you have to also take into consideration that American tracks are not like Over seas. At least all the ones around here, seems here is always tight tracks, and over there they have many more sweeping turns. Most people are to lazy to truly work and learn about that kind of tuning option. I know I would be but I think it [could] be an amazing ajustment with proper knowlege and understanding of it.
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Old 03-29-2009, 04:09 AM   #45
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Originally Posted by JoshM20 View Post
but I think it [could] be an amazing ajustment with proper knowlege and understanding of it.

That is my feeling too, but as I said, to truly do it right, you'd have to give up your day job.
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