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Old 09-17-2016, 12:23 AM   #991
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Default One way pulley

Will the TA06 one way pulley fit in place of the current belt pulleys? Tamiya #54302 or #54399

With the one way pulley installed, I read that (in the ta06) the brakes would be applied to the rear wheels.

But in the xv01 I believe the brakes would be applied to the front, because of the direct transmission. 70%+ of braking actually happens in the front of vehicles. So this theoretically should be better, braking wise, than then a real wheel braking car.

Coasting, will happen with the front wheels resisting. Acceleration will have 4 wheel power.

Will it fit? I feel like fyrstormer might have some experience with this? Observations in handling?

If the pulley is reversible, then I could also experiment with fwd and 4 wheel braking similar to fyrstormer's rwd car.

Last edited by 4roller; 09-17-2016 at 08:28 AM.
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Old 09-17-2016, 01:12 AM   #992
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Will the TA06 one way pulley fit in place of the current belt pulleys? Tamiya #54302.

With the one way pulley installed, I read that (in the ta06) the brakes would be applied to the rear wheels.

But in the xv01 I believe the brakes would be applied to the front, because of the direct transmission. 70%+ of braking actually happens in the front of vehicles. So this theoretically should be better, braking wise, than then a real wheel braking car.

Coasting, will happen with the front wheels resisting. Acceleration will have 4 wheel power.

Will it fit? I feel like fyrstormer might have some experience with this? Observations in handling?

If the pulley is reversible, then I could also experiment with fwd and 4 wheel braking similar to fyrstormer's rwd car.
You'll get a lot of understeer if you brake while turning with front only brakes.
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Old 09-17-2016, 08:26 AM   #993
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You'll get a lot of understeer if you brake while turning with front only brakes.
Before the increase in Ackerman, my car slighty oversteered on power. Now with the change my car oversteers like an angry bull. Especially with slicks.

Also, the reason for me wanting to try the one way pulley is because it will sort of act like a center differential, allowing for the varying of speed between front and rear wheels. This is something these belt drive cars are missing.
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Old 09-17-2016, 12:35 PM   #994
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Wowow! That thing looks fierce with those tractor tires and body lifted so high. Custom carbon fibre chassis? Or available only in euro market?

How do you like those Pirelli like tires? Good for asphalt?
That chassis is sort of custom. There's a guy who is doing them in very small batches, but you can buy them (and customize them if you want). Look at cirus[dot]cz/index.php?route=product/category&path=64_78. Nice thing on it is, that it allows you to position electronics as you wish, and more importantly, it allows you to greatly increase steering range (right now I'm on 120%, which requires cutting C and D parts). For more information, look at my build thread here: rccrawler[dot]com/forum/rally/570063-haplms-xv-01-carbon-mod.html

Those blue tires are not genuine HPI Pirelli, but some chinese knock off (Austar). They don't really work, even on tarmac. They are more or less drift tires. However, I don't believe that it tells anything about the HPI Pirelli tires, which I plan to buy (both compounds), and compare against V Groove super radials.
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Old 09-17-2016, 01:02 PM   #995
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I had a set of the actual HPI Pirelli D compounds on my TA02 rally car, and they were great tires on asphalt and dirt. They lasted a good while too, wearing slowly. Definitely worth the price over the cheap knockoffs, which initially have more tread, but don't grip and wear quickly.
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Old 09-17-2016, 07:36 PM   #996
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That chassis is sort of custom. There's a guy who is doing them in very small batches, but you can buy them (and customize them if you want). Look at cirus[dot]cz/index.php?route=product/category&path=64_78. Nice thing on it is, that it allows you to position electronics as you wish, and more importantly, it allows you to greatly increase steering range (right now I'm on 120%, which requires cutting C and D parts). For more information, look at my build thread here: rccrawler[dot]com/forum/rally/570063-haplms-xv-01-carbon-mod.html
Nice build thread. I wish rally was as popular as it is here in the US as it is over in the Czech Republic (?) All those rc rally cars at one event!

The cost of the carbon fiber chassis seems to be pretty good value.

I see in Your build thread, you are going for massive steering angle. It looks like it would make a good counter steer drifter with that much angle.
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Old 09-17-2016, 07:41 PM   #997
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As it stands, I think the xv-01 has plenty of steering. I have to tone mine down, by reducing my radio EPA values to 70%. And then also reducing the left right to about 90%. This is because with so much steering, the suspension actually starts compressing.

I went back to the original Tamiya plastic servo saver. It has the right height, but is really sloppy. So I ended shimming the servo and horn spline interface with some tape. I also CA glued the thing together. Now the car is very responsive. Also, when I brake really hard (slowing down from 40mph) the front wheels don't "quibble" anymore. They used to do it with the servo saver.
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Old 09-17-2016, 09:03 PM   #998
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Originally Posted by 4roller View Post
Before the increase in Ackerman, my car slighty oversteered on power. Now with the change my car oversteers like an angry bull. Especially with slicks.

Also, the reason for me wanting to try the one way pulley is because it will sort of act like a center differential, allowing for the varying of speed between front and rear wheels. This is something these belt drive cars are missing.
You could try disconnecting the belt temporarily just to get a feel for how it might handle off power before trying to source a one way.
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Old 09-17-2016, 09:10 PM   #999
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You could try disconnecting the belt temporarily just to get a feel for how it might handle off power before trying to source a one way.
Yeah you are probably right. It looks like the pulleys might not fit, since they need a pin to cross the back of the pulley, the ones I am seeing don't have such things.

1 way diffs and spools are the other option, but nah...
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Old 09-17-2016, 09:46 PM   #1000
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The TA06 one-way pulley does fit. I use it on the rear of my XV-01 SH-AWD, in combination with a smaller front pulley, so the car is effectively FWD except when accelerating hard. The difference in pulley size on that setup causes the rear axle to engage when the front wheels start to spin a little. The TA06 one-way pulley simply grabs the surface of the top shaft with the one-way bearing installed in it, it doesn't need a cross-pin to hold onto. It does understeer like crazy when braking hard (it would be better to say "it skids in a straight line"), but that just means you have to be more judicious about braking, that's all.

Build Complete: Tamiya XV-01 SH-AWD


I also tried something similar with my rear-motor XV-01, where I had it set up as RWD with 4-wheel braking, but RWD just couldn't put enough power to the ground to handle the power from even a 2-pole 380-size brushless motor. I converted that one it back to full-time 4WD.

If you wanted a front-motor/RWD setup with 4-wheel braking, the only way to make it work would be to use a one-way diff in the front, installed backwards. But that would have even less traction than the rear-motor/RWD setup I tried, since there's so little weight in the rear.

- - -

Regarding the steering turnbuckle being too long when the bellcranks are in the rear position: Tamiya has several lengths of turnbuckles available, and I used the next shorter one. I think it was 38mm instead of 42mm, but I don't remember for sure anymore. If you decide to try it, measure the length of the stock turnbuckle first, so you don't accidentally order more of the same length.
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Old 09-18-2016, 12:15 AM   #1001
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Ah ha. It's a one way bearing! I had to look up how they actually work. The rollers grip the drive shaft, so I should be okay with just ordering Tamiya
#54302.
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Old 09-18-2016, 02:51 AM   #1002
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Nice build thread. I wish rally was as popular as it is here in the US as it is over in the Czech Republic (?) All those rc rally cars at one event!

The cost of the carbon fiber chassis seems to be pretty good value.

I see in Your build thread, you are going for massive steering angle. It looks like it would make a good counter steer drifter with that much angle.
That massive steering angle is required because of how the tracks are designed. You rarely have a long straight, most of the time you find yourself either accelerating or braking into a 180˚ turn ;-). In fact, I wasn't able to steer into those turns with "just" 110% of steering range, I've really had to go up to 120%. At this angle, you also start hitting dampers with wheels, so all sorts of mounting fun begins...

And no, this is not a drifter :-). Exactly opposite - it needs all the traction it can get. Thus my search for really good tires....

Plus you need to be fit, as you run behind your car. So your motor only needs to be as fast as fast you can run ;-)).
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Old 09-18-2016, 08:25 AM   #1003
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My XV parts came, back in business!

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Old 09-18-2016, 09:11 AM   #1004
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That massive steering angle is required because of how the tracks are designed. You rarely have a long straight, most of the time you find yourself either accelerating or braking into a 180˚ turn ;-). In fact, I wasn't able to steer into those turns with "just" 110% of steering range, I've really had to go up to 120%. At this angle, you also start hitting dampers with wheels, so all sorts of mounting fun begins...

And no, this is not a drifter :-). Exactly opposite - it needs all the traction it can get. Thus my search for really good tires....

Plus you need to be fit, as you run behind your car. So your motor only needs to be as fast as fast you can run ;-)).
You could try putting less aggressive tires at the rear, and then when you find yourself at a hairpin 180 degree turn, turn the wheel and hammer the throttle, so that the rear end will swing around. This often works for me on the street.

I think the idea of this kind of rally you describe suits me better, because I love fitness and rc at the same time! If I am ever in in the Czech Republic, I am going to sign up for one of these events. Lol then I'll have to decide wether I want to represent Canada (where I am from) or the US where I live.

So jealous. I can't even find an rc track near me that is less than 1hour drive time (with traffic) and I live in California!!!
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Old 09-18-2016, 09:18 AM   #1005
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I think it was 38mm instead of 42mm, but I don't remember for sure anymore.
You have a good memory, the stock is a 42mm tie rod. I'll look for a shorter one, maybe with some bling.
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