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Discussion Starter · #1 ·
I have been told that the MSC Impreza, inline version (and I suppose all the other MSC cars using the same chassis) carries different size drive band axle pulleys front and rear. Can anyone verify this ? If this is so, what would the reason be, as the front and rear carry (I assume) the same diameter wheels/tyres so no difference in gearing should be necessary.
Steve
 

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There are several cars that are set up this way- All Avant Slot and some Ninco Prorace cars have the smaller front pulley
The theory is that the front wheels turning faster will pull the car through he corner quicker
Does it work- I don't know have not really done any testing- might be worth doing though
 

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Confirm Avant Slot 207 has 12mm rear and 9mm front (I quoted ID in my review) and MSC Metro has 14mm front and the same 14mm rear. Avant slot has bigger tires all around but both cars have the same sized tires front and rear. (The AS rear tires did disappear quite fast on scaley plastic track so now having swapped the front to the rear the front ones are now smaller!).
 

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Back in the 60s when a lot of scratch builders were experimenting with 4WD there were several theories.
Some reckoned the front wheels should run faster than the back to pull the car through he corner quicker.
Some reckoned the rear wheels should run faster than the front because the cars cornered with the tail out so the rear wheels had further to go.
Some reckoned they should be geared the same
Some used a separate motor at each end, which meant the front wheel could run faster or slower than the rears (and probably which was running faster changed at different points round the lap)

All these claimed some success. The twin motored ones were probably most successful, but who knows why - could be that with the motors available at the time, two light motors were better than one bigger one.
Eventually better tyres came along and rear wheel drive cars did all the winning.

Of course what matters is what works for real - if the lap timer says its faster, it is faster whatever the theory says.
It would be interesting to try different front rear ratios on the same car and see what differance it makes.
 

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Discussion Starter · #5 ·
Many theories out there. I'll have to experiment when I get my MSC Impreza soon. Now I'll add another dimension to the equation- tyres: If I'm running silicones on the rear (Scaley Sport track), should I run silicones on the front as well or should I mix the tyre types with silicones rear/ rubber front ?
 

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QUOTE (300SLR @ 17 Aug 2012, 15:45) <{POST_SNAPBACK}>....Some reckoned they should be geared the same...

Of course what matters is what works for real - if the lap timer says its faster, it is faster whatever the theory says.
It would be interesting to try different front rear ratios on the same car and see what differance it makes.

Geared cars , at least mine are the same. SCX pro has different ratios I assume because the front tyres/tires are smaller.

I think it work differently on belt drive cars because there is some slippage so the front wheel probably have some stored energy and thus spin faster. As you say lap times count, but I do know the 4x4 works at least the way I drive. I have had a 4x4 rear end hanging off the edge of the track
and the front pulled it back onto the track
 

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Discussion Starter · #7 ·
Abarth Mike, thanks for that. I know the normal SCX direct-driven cars are geared the same and work fine (my son's Citroen C4 is a formidable competitor at our club where we run rally cars in non-magnet format) and I understand why the SCX pro have different gearing front/rear ( to compensate for the different diameter wheels). I just wasn't sure about the belt drive cars.
Steve
 

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QUOTE (steveaca @ 18 Aug 2012, 01:06) <{POST_SNAPBACK}>Now I'll add another dimension to the equation- tyres: If I'm running silicones on the rear (Scaley Sport track), should I run silicones on the front as well or should I mix the tyre types with silicones rear/ rubber front ?
Good question
It raises questions like do you want more grip at one end than the other or the same both ends..........and how much grip - as much as you can get or what?
With so much else in tuning slot cars there is no "one size fits all" answer. You wouldn't necessarily expect the same combination of front/rear grip to be best for all types of 4WD car. The standard answer is try different things and see what actually works best on your chosen car.

Running a mixture of different types of tyre on a track sometimes causes problems. If all the cars are using a similar sort of tyre, the grip often improves. Some types of tyre don't mix, the most often quoted example is silicones and rubber (some but not all types of silicones cause the rubber tyres to loose grip). This sort of problem is probably due to tyres either depositing or removing material from the track surface. A good starting point might be using the same type of tyres both end and perhaps play around with more or less grippy compounds of the same basic sort of tyre material. And of course try different things and see what actually works best still applies.
 

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QUOTE (steveaca @ 18 Aug 2012, 20:22) <{POST_SNAPBACK}>Abarth Mike, thanks for that. I know the normal SCX direct-driven cars are geared the same and work fine (my son's Citroen C4 is a formidable competitor at our club where we run rally cars in non-magnet format) and I understand why the SCX pro have different gearing front/rear ( to compensate for the different diameter wheels). I just wasn't sure about the belt drive cars.
Steve

Steve,

Somewhere there is an article about how to calculate the "correct" belt length for a given car. I looked but so far I can't find it.
 
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