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Old 01-03-2002, 09:09 PM   #946
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Quote:
Originally posted by muugen
Ok just been reading all that V one RR stuff and it seems they have an overdrive ratio on the RR, GRP, and Kawahara kits.

The front centre belt pulley has been reduced from the stock 27tooth to either 25t ( RR ) or 24t ( Kawahara ). I think rear is about 18.

What does this overdrive do for you exactly?

Is there a pulley and belt set or just pulley for MTX-2 ?

I once put a 19t on the centre front belt pulley instead of the 18t and it seemed to be less taily, though the turning circle at very low speeed was not as tight.

Ok heres where my logic gets all confused-
When my rear foams wear smaller than the front ( efectively creating an overdrive ) the rear end gets very taily which is exactly opposite to the example above

I read that 1/8 run an overdrive ratio of about 100:1 when the size of tires is factored in.

With the V one RR it would be considerably more

Whats the go ?? can anyone shed any light on the subject? I have never even seen it discussed in relation to an MTX-2
Here is an article written by Art Carbonell, the legendary US driver.

This explains Overdrive :

http://www.rc-racing.com/cgi-bin/pw/...em=12&rsel=all
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Old 01-03-2002, 09:10 PM   #947
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Damm, that never works :

Here it is :

Quote:
The following information concerns gear ratios, particularly the
overdrive ratio. Although this is written for the Serpent, the general
principles apply to any four-wheel-drive R/C car. (With two-wheel drive
cars, you don't have to worry about this.)

Selecting the "best" overdrive ratio is something you have to try
yourself, to get the best overdrive ratio, tires sizes, and tire
compounds. The overdrive ratio has a big effect on the handling of the
car. That's why the tire size and the pulley ratios are so important.
Usually the more overdrive you have (the more front drive you have),
makes it a little easier to drive the car - but the car will not be as
fast as if you set the car up with less overdrive in the front (closer
to 1:1).

The reason the car is slower with more overdrive, is that even with the
one-ways, the car still is dragging a little with a lot of front drive.
If you want to see what kind of drag you have on the car, just roll it
on the ground with the brakes off. Roll it forward, and you can tell if
you have a lot of overdrive - if so, it will feel like you have the
brakes applied - the car won't want to roll freely. Reduce the overdrive
and try it again (roll the car again) and the car should roll for a
longer time. (This doesn't mean that it's better because it rolls
freely, it just means you have less drag on the car. )

A lot of tracks here in the states require a little more front drive
than on European tracks. With European tracks in particular, speed is
usually more important. Normally US tracks are a little tighter than in
Europe; you need a little more front drive to make the car easier to
drive.

More front drive gives you a little less steering going into the turn,
but where it helps you the most is in the middle of the turn. The
overdrive helps bring the nose of the car around, when you apply power.
Coming out of the turn, more overdrive will make the car tend to push a
little too, making the car a little more stable coming out of the turns.

Setting up the car the other way, using less overdrive, gives you more
steering coming into the turn, making the car turn in a little sharper,
but as soon as you apply power, the car wants to push a little, because
the front tires are not helping bring the car around. Coming out of the
turn (as soon as you come out) you have a little more steering, commonly
referred to as "throttle steering". This happens as you apply power, but
it also makes the car a little unstable. If you apply too much power,
the car will want to spin out. It's not really harder to drive the car
this way, but it does take more control. Some people like a car to
handle like that.

On most tracks here in the states, it's a little better to run a little
more front drive, either by changing pulleys, or by changing tire size.
You can set the desired overdrive ratio either way. Changing the pulleys
makes the biggest change in overdrive ratio. Changing tires makes a
smaller change.

Remember that during a race, the effect of gear ratios on overdrive
remains constant, but as your tires wear, this can effect the overdrive
ratio, which may constantly change as the tires wear. If you wear your
tires evenly (wear 2mm off the rear and 2mm off the front), then it's
probably pretty good.

If you have a Serpent, the standard Excel kit comes with 19:23 gearing
for the two side gears. To increase the overdrive (put more front drive
on), you can change the 23 tooth pulley to a 22, giving you a 19:22
ratio. You can also go 20:22, which gives you even more front drive. On
a Serpent Excel, one thing you want to keep in mind when you run more
front drive, is that you have to keep an eye on the belts and on the
pulley, especially the little 16 tooth pulley in the front. You have a
16:24 drive ratio on the front belt. When you have more front drive,
there is more drag, so more load on the pulleys, so you tend to strip
them out more often. If you have to change the belt because it's
stripped, make sure you also change the 16 tooth pulley, even if it
looks good. The pulley is a lot cheaper than the belt. Remember, it will
wear out faster with more front drive.

You can also change the overdrive by selecting the appropriate tire
diameters. This is important because you want to keep the overdrive
ratio constant through the race. If you change it by pulleys, and then
check your tire diameters, and find the front wears 4 and the rear wears
only 2, it's going to change the overdrive quite a bit. You either have
to run a harder compound in the front so it wears less, or use less
overdrive ratio, so it remains more constant for the duration of the
race. This is something you have to try out on different tracks.

I like to run with the least overdrive I can get away with. That way the
car is fastest. But, in some cases I have to run more overdrive because
of track conditions, (or the way you have to drive the track). With more
overdrive, you can be a little more aggressive on the track, which
sometimes helps if you're in traffic, because the car is more stable.
You might make a very quick lap with a neutral car (with the overdrive
set 1:1) but that might be the only real fast lap out of ten laps. With
a little more front drive, your car might be not quite as fast for that
one lap, but it will be probably be a little faster consistently for the
other laps.

Try out different amounts of overdrive on different tracks, and keep
notes on how your car responds. This will help you select a good
starting point when you show up at a new track that you haven't yet
driven at.
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Old 01-03-2002, 10:56 PM   #948
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Wow thanks for that Novarossi!!

Thats really well explained.

so I wonder where the MTX is at from standard ( any overdrive )

does anyone change the overdrive with pulleys on touring cars??

So why u want a slurpent Novarossi
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Old 01-03-2002, 11:12 PM   #949
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Quote:
Originally posted by muugen
Wow thanks for that Novarossi!!

Thats really well explained.

so I wonder where the MTX is at from standard ( any overdrive )

does anyone change the overdrive with pulleys on touring cars??

So why u want a slurpent Novarossi
The Drive pulley on the MTX is 19 tooth. The Diff pulley is 48 tooth. So drive train ratio becomes 48/19 = 2.52631578947368421052631578947368
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Old 01-03-2002, 11:15 PM   #950
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Default front one-way+rear solid axle for MTX2

Anybody tried this combination on foam tire?

Tried this combination on V1R and it is great.
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Old 01-03-2002, 11:17 PM   #951
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Quote:
Originally posted by Novarossi


The Drive pulley on the MTX is 19 tooth. The Diff pulley is 48 tooth. So drive train ratio becomes 48/19 = 2.52631578947368421052631578947368
I guess you have a fever Novarossi !
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Old 01-03-2002, 11:23 PM   #952
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Default Re: front one-way+rear solid axle for MTX2

Quote:
Originally posted by Manticore
Anybody tried this combination on foam tire?

Tried this combination on V1R and it is great.
I'm running 100k rear and front one way on FAST foams if that qualifies
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Old 01-03-2002, 11:25 PM   #953
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Very good info Novarossi!

I wonder though how overdrive effects a car with differentials or how differnetials effects the overdrive.

Hmmmm will have to do some Internet searches.
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Old 01-03-2002, 11:30 PM   #954
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Quote:
Originally posted by Manbik
I wonder though how overdrive effects a car with differentials or how differnetials effects the overdrive.
Good question
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Old 01-03-2002, 11:37 PM   #955
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Default Re: Re: front one-way+rear solid axle for MTX2

Quote:
Originally posted by Novarossi


I'm running 100k rear and front one way on FAST foams if that qualifies
you have higher rotation mass for the 100K diff in the rear then the simple and light weight solid diff !
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Old 01-03-2002, 11:48 PM   #956
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Default Re: Re: Re: front one-way+rear solid axle for MTX2

Quote:
Originally posted by Manticore


you have higher rotation mass for the 100K diff in the rear then the simple and light weight solid diff !
So you guys haven't got the lightweight diff fluid yet?
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Old 01-04-2002, 03:01 AM   #957
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Default Re: Re: Re: Re: front one-way+rear solid axle for MTX2

Quote:
Originally posted by Novarossi


So you guys haven't got the lightweight diff fluid yet?
i dont need any diff fluid
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Old 01-04-2002, 03:09 AM   #958
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Default Re: Re: Re: Re: Re: front one-way+rear solid axle for MTX2

Quote:
Originally posted by Manticore


i dont need any diff fluid
Its the new Diet fluid
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Old 01-04-2002, 03:18 AM   #959
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Default Re: Re: Re: Re: Re: Re: front one-way+rear solid axle for MTX2

Quote:
Originally posted by Novarossi


Its the new Diet fluid
that would be nice if the scientist is able to impegnated this technology into the fuel and shock oil !
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Old 01-04-2002, 03:22 AM   #960
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Quote:
Originally posted by Novarossi

I've Spent like $5000 (Aus) + in 5 Years of RC Racing to win - is the price of parts really going to bother me if it means winning/losing? So your saying that you'd spend hundreds on a top engine, and take short cuts elsewhere to save money?
Wow thats cheap!! I have spent about $4000 in about 1 year, I have had a HPI which I hopped up majorly of course Whats your secret
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