Losi XXX-S

Old 11-19-2002, 04:52 PM
  #4381  
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Not to try and stifle people from trying to find speed but I think you guys are going over the edge with things that you will not see on the track. The things you are talking about are on a scale of diminishing returns. The XXX-S has a very lightweight drivetrain with very low rotating mass. The diffs are plastic based and very lightweight. They are also reliable and durable. Friction and suspension settings are a greater enemy to speed and accelleration than finding aluminum diff balls every will be. Larger bearing races will have less rotation than a smaller bearing. This has its benefits as well.

But what alot of people don't seem to think about is that you have to get a car that weighs between 50 and 56 ounces going. So you tell me what the bigger load on the motor is going to be.... .5 grams of narrow rotating mass or the 53 ounces of chassis that you have to put into motion. Or equate what a couple grams of rotating mass equals in terms of motor power or torque for that matter.

Spend your time making sure that your belt is aligned properly and that all of your bearings roll as freely as humanly possible. Find an effecient belt tension setting. As rotating mass takes up a larger radius from the center of rotation, its effect is multiplied. That is why you see a difference between running rubber tires and foam tires on the track. The Losi dogbones are bigger for a reason, because thinner bones like the TC3 bones twist like spagetti. Even Associated made their bones beefier for this reason.

Tenths of seconds in laptimes are gained in the corners by setup and driving. Better motors and batteries are important as well. You can always find a tenth or two by finding a better setup or tire combination. You won't find this much in modifying the Losi's drivetrain. Spend $70 on a full titanium screw kit, its a better investment of time and money.
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Old 11-19-2002, 05:08 PM
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Originally posted by Dave Kurschner
Not to try and stifle people from trying to find speed but I think you guys are going over the edge with things that you will not see on the track. The things you are talking about are on a scale of diminishing returns. The XXX-S has a very lightweight drivetrain with very low rotating mass. The diffs are plastic based and very lightweight. They are also reliable and durable. Friction and suspension settings are a greater enemy to speed and accelleration than finding aluminum diff balls every will be. Larger bearing races will have less rotation than a smaller bearing. This has its benefits as well.

But what alot of people don't seem to think about is that you have to get a car that weighs between 50 and 56 ounces going. So you tell me what the bigger load on the motor is going to be.... .5 grams of narrow rotating mass or the 53 ounces of chassis that you have to put into motion. Or equate what a couple grams of rotating mass equals in terms of motor power or torque for that matter.

Spend your time making sure that your belt is aligned properly and that all of your bearings roll as freely as humanly possible. Find an effecient belt tension setting. As rotating mass takes up a larger radius from the center of rotation, its effect is multiplied. That is why you see a difference between running rubber tires and foam tires on the track. The Losi dogbones are bigger for a reason, because thinner bones like the TC3 bones twist like spagetti. Even Associated made their bones beefier for this reason.

Tenths of seconds in laptimes are gained in the corners by setup and driving. Better motors and batteries are important as well. You can always find a tenth or two by finding a better setup or tire combination. You won't find this much in modifying the Losi's drivetrain. Spend $70 on a full titanium screw kit, its a better investment of time and money.
Well said.
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Old 11-19-2002, 08:06 PM
  #4383  
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Originally posted by Dave Kurschner
Spend $70 on a full titanium screw kit, its a better investment of time and money.
That's it, I'm buying a full titanium screw kit!

I have driven my Losi with pretty much the same carpet set up for the past year, without many changes, just a few subtle ones here and there. I really only run on two tracks (local one and Trackside in Milwaukee) and both are very similar. I have the car set up well and it's fast.

Tonight I was trying to find something to do to it, so I started trying to clean up some of the suspension slop. I found that there is a ton of play coming from the servo horn/saver assembly.

Is there any way of getting around this? I have some old purple aluminum servo arms I used to use to dress up cars, that fit tight and with very little slop. But I am wary running the servo without the saver; I run high torque servos, though, so it might not be the biggest of problems. What would you guys do?

And while we're on the topic, any more ideas for cleaning up suspension slop in the Losi car? I've found that my Losi has a lot more slop in it than some of my other cars (Yokomo, etc.).
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Old 11-19-2002, 08:09 PM
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geeeezz. Why paint the body? Paint adds weight as well.
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Old 11-19-2002, 08:12 PM
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And don't forget to mill out the case of your ESC and servo!
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Old 11-19-2002, 08:21 PM
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And I guess there is no need to buy those Aluminum Bones Either.

I agree that removing .5 grams from your driveline would be hard to notice. I think if you remove 23 grams (almost an ounce) from the driveline that then you might notice. If we run Roar rules then the car weight is fixed. We are just rearranging the placement of the weight. I think a titanium screw set is a waste of money as the car still needs to weigh the 54 ounces.

Full size cars use almost 40% of engine power just accelerating the driveline parts in a circle in the lower gears. I doubt it's much different on these electric cars. 1 ounce off of the driveline is probably worth several off the chassis.

Larger diff bearing races have the same rotation as smaller diff bearing races. The smaller ones have less rotational inertia.

Last edited by John Stranahan; 11-20-2002 at 05:32 AM.
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Old 11-19-2002, 08:25 PM
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I dont run any inserts in my tires think of all the rotational mass you save there........
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Old 11-20-2002, 12:29 AM
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Hi guys. Greetings from Malta.

A friend who is a very keen engineer once told me he reckoned it's 4 to 1. That means that every gram you remove that's rotating is equal to 4 grams on the chassis. It's probably about right.

But yes I agree I would put much more importance to a free running drive train.

At one of our recent meetings, as I put the car on the track I noticed straight away it was slower than usual. I raced it that way all day, and the results proved there was something wrong. Cars that are usually slower were holding me on the straights. My lap times were lousy too.

Next day at my shop I took it apart, and yes you've guessed - a very tight diff bearing, which whilst it may not have shown up so much in mod, made a hell of a difference in stock.

I ended up checking out all the bearings and binning most of them. Now it's back up to speed.

Just one of a dozen possible reasons for lack of speed.

However MARK (Senna) I wouldn't worry too much about speed with your XXXS. You have plenty of it. I reckon Noel's car, yours and mine are consistantly the fastest three in stock. Possibly in that order too!

Regards

Joe from sunny Malta.
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Old 11-20-2002, 06:58 AM
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Hey Kevin, you didn't tell them you were running foams.

When I switched from the stock steel bones to the alum. bones I thought I could feel a difference. Then again, I changed to a different radio as well so maybe that had something to do with it.
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Old 11-20-2002, 07:06 AM
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Originally posted by futureal
That's it, I'm buying a full titanium screw kit!

I have driven my Losi with pretty much the same carpet set up for the past year, without many changes, just a few subtle ones here and there. I really only run on two tracks (local one and Trackside in Milwaukee) and both are very similar. I have the car set up well and it's fast.

Tonight I was trying to find something to do to it, so I started trying to clean up some of the suspension slop. I found that there is a ton of play coming from the servo horn/saver assembly.

Is there any way of getting around this? I have some old purple aluminum servo arms I used to use to dress up cars, that fit tight and with very little slop. But I am wary running the servo without the saver; I run high torque servos, though, so it might not be the biggest of problems. What would you guys do?

And while we're on the topic, any more ideas for cleaning up suspension slop in the Losi car? I've found that my Losi has a lot more slop in it than some of my other cars (Yokomo, etc.).
Shane - I havent seen your car since the summer... but..

A - Do you have every one of the C springs in the servo saver?

B - I know you have the bearings, do you have the little plastic washers between the bearing and the screw?

I thought mine had a ton of slop, and I talked to Paul about a month or so ago. He took a look at my car, and said it was fine. His car probably had twice the steering slop that mine has, and yet he doesnt have a problem getting around the track.
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Old 11-20-2002, 08:32 AM
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just buy the graphite plus, align the belt and get a TIR ti screw kit 65.99 here. u get all the right parts, plus graphite LRC instead of aluminum. w/ the ti screws from TIR 5/64 ths wrench does them all! then u can add weight where ever u want to to achieve the best handeling possible. so sure a steel screw kit will keep ur weight close, but then u have no where to add weight if u need 1/2 oz somewhere.
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Old 11-20-2002, 10:38 AM
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How exactly are u aligning the belt???
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Old 11-20-2002, 01:39 PM
  #4393  
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Originally posted by TSR6
I thought mine had a ton of slop, and I talked to Paul about a month or so ago. He took a look at my car, and said it was fine. His car probably had twice the steering slop that mine has, and yet he doesnt have a problem getting around the track.
I am using an aftermarket servo saver, which already reduced some of the slop from the original Losi one (which I never liked).

I haven't ever seen a slop-free Losi car, which is why I asked the question. Of the Losi cars at our track, mine is far and away the best, but I'm always looking for that little edge...
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Old 11-20-2002, 02:49 PM
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Kraig.....darn I must have left out that little tid bit of info

What kind of set ups are you guys running with the T.O. 27 premount tires on carpet? I raced my car for the first time last weekend and it got better as the day went on but still not where I want it to be.
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Old 11-20-2002, 05:53 PM
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Default king pin screw from XXX-4

Hi,

Anyone seen the king pin screw from XXX-4 yet as "hing pin" ?

Wonder if works on XXX-S as hing pin replacement.
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