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Old 09-09-2005, 12:27 AM   #22291
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Well i know that serpent are planning on releasing one and that they work well on slippery tracks. I also know that almost every car but the 710 uses one. I have my ball diff set as loose as possible without slipping and still fell its too tight. Remember you race at NP which is damn grippy compared to where I come from.

Mike
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Old 09-09-2005, 03:00 AM   #22292
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Quote:
Originally Posted by Greg M
Yuck, a gear diff Mike?? I couldn't think of anything worse!!

After having a gear diff car and continually stripping gears, I love the ball diff, so easy to adjust as well. I would also assume a gear diff would weigh abit more, so more rotating mass.
There is no problem with the ball diff design or function. A lot of electric cars use 'em. The problem is the number of yahoos who assemble it once, put it in their car, and expect it to work forever with little or no maintenance. In other words, the number of people who find it hard to set and maintain a ball diff is higher than the number who find it hard to set a gear diff. I see a lot of 710s with the ball diff slipping and owners cursing the car because it won't drive 'right'. A gear diff is more straight-forward to assemble.

Plus, if someone will buy it, why not make it?

Last edited by going4#1; 09-11-2005 at 05:53 AM.
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Old 09-09-2005, 03:20 AM   #22293
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Default Brake lock up

Hi there!


Could someone pls give me his thoughts on this:

I got a Futaba 9402 servo for throttle/brake.
When I brake from high speed to medium speed (after the straight into a fast sweeper) the cars slows down very well, with no lock up.
But if I brake from slower speeds, or even when I come in for refueling, it is almost impossible to haul the car down to standstill without locking the brakes.
Is the servo to powerfull in terms of torque, or is something wrong with my Tx or linkage setup?

Thanks for your interest in this!
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Old 09-09-2005, 03:50 AM   #22294
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Quote:
Originally Posted by fulcrum2
I got a Futaba 9402 servo for throttle/brake.
When I brake from high speed to medium speed (after the straight into a fast sweeper) the cars slows down very well, with no lock up.
But if I brake from slower speeds, or even when I come in for refueling, it is almost impossible to haul the car down to standstill without locking the brakes.
I think it's because of the rotating mass in your car. It takes a certain amount of energy to slow it down. This energy is created through friction between your brake disk and the brake pads and dissipated as heat. That's why the brakes heat up when you're braking.

When all rotating mass is rotating at high speed, it takes more energy to slow down than when running at a low speed. The amount of energy dissipated per second will be the same, no matter the speed you're running at. But if you're running at a high speed it takes a fair bit of energy to slow down you wheels to a full stop, so you see the car slowing down gradually. When you're running at a slow speed, it takes very little energy, so the wheels block almost instantly.

I think this is also why I need to adjust the brakes on the track, when driving. I find that when I adjust them so that they 'nearly lock' when I just push the car forward manually, they are severely lacking in power on the track.
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Old 09-09-2005, 04:52 AM   #22295
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Quote:
Originally Posted by going4#1
There is no problem with the ball diff design or function. A lot of electric cars use 'em. The problem is the number of yahoos who assemble it once, put it in their car, and expect it to work forever with little or no maintenance. In other words, the number of people who find it hard to set and maintain a ball is higher than the number who find it hard to set a gear diff. I see a lot of 710s with the ball diff slipping and owners cursing the car because it won't drive 'right'. A gear diff is more straight-forward to assemble.
Exactly!
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Old 09-09-2005, 05:22 AM   #22296
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Quote:
Originally Posted by Qlone
I think it's because of the rotating mass in your car. It takes a certain amount of energy to slow it down. This energy is created through friction between your brake disk and the brake pads and dissipated as heat. That's why the brakes heat up when you're braking.

When all rotating mass is rotating at high speed, it takes more energy to slow down than when running at a low speed. The amount of energy dissipated per second will be the same, no matter the speed you're running at. But if you're running at a high speed it takes a fair bit of energy to slow down you wheels to a full stop, so you see the car slowing down gradually. When you're running at a slow speed, it takes very little energy, so the wheels block almost instantly.

I think this is also why I need to adjust the brakes on the track, when driving. I find that when I adjust them so that they 'nearly lock' when I just push the car forward manually, they are severely lacking in power on the track.
and don't forget downforce.....
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Old 09-09-2005, 07:53 AM   #22297
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Quote:
Originally Posted by M7H
and don't forget downforce.....
And shocks and springs...... and well, basicly everything on the car :P


Qclone's explanation is perfect... just put brake slowly when running slow, and brake hard when braking hard....

You might want to try and run down the main strait, and brake full until the car i totally still, even then the wheels will lock up and probably spin the car (for sure if you use one-way diff)... just easy off the brakes when the car get's moving slower and it stays ok
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Old 09-09-2005, 07:59 PM   #22298
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Quote:
Originally Posted by going4#1
Very pleased. I only use them in the front. Any advantage to using them in the rear?

Rob
Since no one gave comment, allow me to share:

I already see numerous broken serpent CVD in front.
Here, the problem lies when they are using new ackerman lever. The steering is can be thrown so much untill the CVD bone hit the wheel axle (cone area).
Some racers did not notice this and they max out the steering EPA. While on the full lock, small tap with concrete barrier is enough to braking it.

Now, all of us only using it on rear. Its longer pin, so easier for diff axle and more important thing, we can narrow down the trackwidth to 198mm.
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Old 09-10-2005, 11:16 AM   #22299
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Hi there!


Im just wondering why there are different materials for engine head shims.
My O.S. came with a 0,1mm copper shim and a 0,2mm brass shim.
My Nova got an aluminium one.
Why different materials?
I assume the copper shim is meant to go directly on top of the liner because copper seals very well. But why aluminium and brass?

Many thanks in advance!
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Old 09-11-2005, 05:45 AM   #22300
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Quote:
Originally Posted by fulcrum2
Hi there!


Could someone pls give me his thoughts on this:

I got a Futaba 9402 servo for throttle/brake.
When I brake from high speed to medium speed (after the straight into a fast sweeper) the cars slows down very well, with no lock up.
But if I brake from slower speeds, or even when I come in for refueling, it is almost impossible to haul the car down to standstill without locking the brakes.
Fulcrum:

You can try the Futaba 9451 for max torque and speed. It definitely is stronger.

The other posts have the right idea. Test the car on a straight braking hard. If the car takes too long to stop, tighten the brake. Eventually the car will start to spin out. This is bad Loosen the brake a bit so it does not do this.

Assuming for a minute you are using an unlocked one-way, keep in mind that while this is the fastest configuration for a lot of tracks the driving style is different. So much so that you don't use the brake much. In other words, you're fast on fast off the throttle and you coast into turns. If you lock the one-way or use a front diff (Julius' favorite!), braking is a lot more effective so you can brake a lot later. So much, in fact, you have to change your driving style to take advantage of it.

Also, don't forget engine braking. The effect is very limited on an RC car but it still works. A lot of new racers hit the gas 100 percent, the 2-speed kicks in, the car barrels down the straight, now it's time to control and brake as a turn comes up, so they fumble, grunt, groan, and make weird body movements hoping their car will magically turn. And when it hits the barrier they blame the car, the brake, whatever.

Next time, hit the gas, let'er rip, get off the 100 percent throttle a little earlier, start turning, and then blip or ease into the throttle again (it depends on the curve). Suddenly the car is more controllable and you're making the turn. Coming into the pit? off throttle a little earlier, a little blip just as you enter, and brake hard.

Also, don't forget to check for tweak. You should always do this but it is pretty critical if you're going to use the unlocked one-way. If the car is tweaked it will spin out to one side but at much softer brake/lower speed than if not.

Good luck.
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Old 09-11-2005, 05:50 AM   #22301
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Quote:
Originally Posted by Qlone
I used to have a shark pipe on my 710. The pipes definitely are ultra strong, and after a lot of crashes it still looks merely 'slightly used' instead of 'completely destroyed'. It's best to buy a complete set (pipe + manifold) since the connection between them is the other way round than on most other pipes.
I don't use the shark pipe anymore because it was rubbing against my rear side belt pulley and would require too much modification (to my liking) to really fit. Other than that, it's a very nice and strong pipe, which also looks good.
I wonder, is the Shark too heavy compared to other pipes? Is the rc-mushroom shark inline or joint coupler?
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Old 09-11-2005, 08:30 AM   #22302
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Quote:
Originally Posted by InitialD
Yes it would. I suggest more open holes with 35wt or 40wt Serpent shock oil. I think that's about the best for the car. Makes the car react very fast and stable in the corners. If you have the older 1.0mm shock pistons (how old is your car?), try 4 or 5 holes open in front and rear.
Well I found out what 5 holes (1.2mm holes) does in the front... traction roll. I didn't really follow your advise but I was curious so I gave it a try. I was running 3 holes (.9mm holes) and I switched shocks (to a new set I built with 1.2mm holes) and I thought I would see what happens if I opened them all the way. I had soo much steering that the car would traction roll almost on command. Oddly enough when I was rebuilding my shocks I only found 2 pistons with the larger holes so I used them in the front.

So the question now is, should I leave the front shocks open and open the rears, rotate the front sway bar, tighten the front diff, etc... to loosen the front or close them down until it stops traction rolling? It's almost like driving a slot car... in the front.

I feel I am very close to having the perfect (for me) setup. The car is working really well.

Thanks,
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Old 09-11-2005, 08:49 AM   #22303
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Quote:
Originally Posted by going4#1
Assuming for a minute you are using an unlocked one-way, keep in mind that while this is the fastest configuration for a lot of tracks the driving style is different. So much so that you don't use the brake much. In other words, you're fast on fast off the throttle and you coast into turns. If you lock the one-way or use a front diff (Julius' favorite!), braking is a lot more effective so you can brake a lot later. So much, in fact, you have to change your driving style to take advantage of it.

Also, don't forget engine braking. The effect is very limited on an RC car but it still works. A lot of new racers hit the gas 100 percent, the 2-speed kicks in, the car barrels down the straight, now it's time to control and brake as a turn comes up, so they fumble, grunt, groan, and make weird body movements hoping their car will magically turn. And when it hits the barrier they blame the car, the brake, whatever.

Next time, hit the gas, let'er rip, get off the 100 percent throttle a little earlier, start turning, and then blip or ease into the throttle again (it depends on the curve). Suddenly the car is more controllable and you're making the turn. Coming into the pit? off throttle a little earlier, a little blip just as you enter, and brake hard.

Also, don't forget to check for tweak. You should always do this but it is pretty critical if you're going to use the unlocked one-way. If the car is tweaked it will spin out to one side but at much softer brake/lower speed than if not.

Good luck.
That is very good advise.
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Old 09-11-2005, 09:15 PM   #22304
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Default blipping

is that so that most of off roader blips the throttle to the point where it sounds like a sub-machine gun ?
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Old 09-13-2005, 09:25 AM   #22305
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Hi guys,

Can anyone tell me what size of balls for rear diff? Thanks!
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