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Old 04-29-2002, 12:42 AM   #1
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Default Oneway in back?

I've seen this discussed a bit here in the XXX-S thread, and on the old Tech Talk before it died.

Has anyone been running like this? Any reports on how it works? I noticed IFMAR just changed their rules to disallow the use of a oneway in the rear of a car... I guess that means it works...

I'm planning to try it in my XXX-S, but first I've got some mysterious handling issues to solve. I want to know the car is at least working before I try to make the change and see how I like it.

If anyone want's to share their experiences with the oneway in back, I'm very interested in hearing about it.

Thanks,

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Old 04-29-2002, 12:49 AM   #2
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You will like the one-way in the rear. The biggest benefit is it runs with a cooler motor if using the smaller pulley up front. The motor essentially has only the load of the front wheels down the straight and you have full use of your brakes.
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Last edited by RCCadet; 04-29-2002 at 12:51 AM.
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Old 04-29-2002, 03:34 AM   #3
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i dont understand how the oneway in the rear works. doesnt this make the car front wheel drive? can you explain it to me.
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Old 04-29-2002, 05:53 AM   #4
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Well a car with a one way replacing both diffs will be 4wd, but it will have no braking whatsoever.

I personally can't see how it would work, except in extreme circumstances - what if you overshot a corner?

EDIT - just realised the thread wasn't about double one-ways. A one way in the rear would give a car more FWD characteristics I suppose.

Last edited by sosidge; 04-29-2002 at 05:56 AM.
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Old 04-29-2002, 06:48 AM   #5
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It seams that this has been banned just recently.
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Old 04-29-2002, 06:58 AM   #6
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Yes it was banned recently, Trips mentioned it in the first post. It will act as a FWD car when the conditions are right. You will know when it's not! The back-end will swing around if the setup is not right or excessive throttle is applied out of a turn while it's still rolling through the turn.
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Old 04-29-2002, 07:29 AM   #7
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Default Rear one way

I`ve tried it once and the results were ok,nothing spectacular. The rules for its use are generally the same for a front one way, use it only on tracks with fast sweeping corners.
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Old 05-05-2002, 12:50 AM   #8
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What does this setup (one-way in the back with front overdrive) supposed to do? Make the car more planted while maintaining fast cornering?
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Old 05-05-2002, 12:55 AM   #9
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I tried it on a track where getting out of the throttle with a front one way sometimes caused the car to spin. With the one way in the rear it prevented the rear from "coming around" and still allowed the benifits of running a one way.
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Old 05-05-2002, 01:21 PM   #10
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In a corner unless the rear is totally sideways (which isn't a quick way round the track) the front wheels always travel further than the rear. With no one ways then one set of wheels will have to break traction. A front one way allows the front wheels to speed up without breaking traction so the car is more efficient through the corner. 1/8th off road cars use a centre diff to acheive this.

A rear one way won't add to the efficiency because the rear wheels are rotating slower than the front ones so one set of tyres must still scrub during the corner. It will probably be worse in fact as you have also got rid of the differential action in the rear.
What a rear one way will do though is kill all rear end braking. This means that the all the braking is done by the front so you will get understeer under braking and not be able to brake as hard.

I haven't tried a rear 1 way but theoretically it should only cause lap times to get worse unless your set up is wrong to start with.
The fact that you don't hear of any really fast guys doing this would tend to back my theory.
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Old 05-05-2002, 03:05 PM   #11
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I think the effecientcy stems from the fact with the 1-way in the rear, the motor is using one set of wheel to pull the car. There is no load in the rear. It is not straining to power the front and rear wheels. I can only think that it's more efficient by the lower temperature of the motor immediately after the race. I am willing to listen to other's comments about it.

As for braking in the turn, I have not experienced any ill effects. Powering out of it the back end can get loose.

I am pleased with it and my times have improved. It may just be the car(go LOSI!) or I have the right setup for my driving style and track. Any other comments?
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Old 05-05-2002, 05:26 PM   #12
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RcCadet
If you fit a one way at either end you are forcing yourself to brake less which will give a cooler motor.
The rear one way could be more efficient if you had overdrive on the rear wheels. Most cars don't use this though.

I am assuming you have the one way fitted so that it allows acceleration but not braking. If you had it fitted backwards that would also make the car more efficient.
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Old 05-05-2002, 05:31 PM   #13
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Backwards?

Please explain.

I use full brakes and I am using the smaller pulley provided with the kit up front and the standard pulley in the rear.
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Last edited by RCCadet; 05-05-2002 at 05:39 PM.
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Old 05-06-2002, 04:50 AM   #14
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I can't comment on xxxs drive ratios as I don't run one.

Assuming the ratios are the same at both ends of the gearbox both "diff" pulleys are forced to go at the same speed because of the belt / shaft connecting them.
The 1 way allows a speed differential between the pulley and the wheel but only for one direction of rotation.

The front wheels in a corner want to rotate faster than the rear ones. If they can't then one end of the car must break traction.
You have two options to increase eficiency . You can either allow the front wheels to speed up relative to the transmission (standard front one way set up) or you can allow the rear wheels to slow down. Because you want to slow the rear wheels down you have to fit the one way the opposite way round in the rear if you want to get increased efficiency. This means however that the car will be front wheel drive except for under braking. If you lift the front of the car off the ground and it doesn't try to go anywhere when you gun the throttle you are using this setup.

Hope this makes it clearer. It's quite tricky to visualise I know.
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Old 05-06-2002, 06:39 AM   #15
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That is what I thought you meant with backwards. No, I am not doing the backwards thing. Has anyone used it backwards? I know that I wouldn't, but let me know your take on it if you are.
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