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Old 01-13-2003, 10:31 AM   #16
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Quote:
Originally posted by Boomer
Same with your prices. Here in Southern California you don't get ANY foams for less than $13 a pair. Jacos are almost always $14.95 a pair and up, TRC's are comparable as are the Italian foams. . .

MOST guys that I have talked to run about a millimeter overdrive. It makes the car significantly easier to drive around corners since the front will pull the car around. I haven't found anyone who drives an underdrive - that leads normally to a bad oversteer situation with the rear trying to push the back end around the front.

And last time I looked, 235 ran the same diameter tires, just different WIDTHS. Same with 1/8th scale. {walks out to garage}



{walks back in from garage} Yep, pretty much the same size (within a mill or so)
overdrive, if you are running it, is a huge tuning factor, not minor at all, especially on longer races.

Boomer I'm not sure about the accuracy of saying 1/8 scales don't use different diameter tires as I believe overdrive is even more important in 1/8 scale and racers use significant splits (7mm) from front to rear.

As with anything else the amount of overdrive/underdrive has to factor in with your other suspension settings to predict how your car will handle through the course of a race.

a lot of the foams are very good but like some have mentioned a durometer is a good idea for serious racing as the foam shores are different from brand to brand and sometimes from same brand's box to box.

I love the zac projects and yokomo multi-rings as the grippiest and the CRC trackmagnets for hands down stiffest/toughest wheel with decent grip.
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Old 01-13-2003, 03:54 PM   #17
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True, Patella - shoot, I run a small split in my NTC3 too. But they COME the same diameter and then you get to pick the split you want to run. . .

I should have said "come" instead of "ran" - oops.

Also, there is more to the tire than shore - I can run Jaco's at 45 and Zak's at 45 and I definitely like the Zak's better than that Jacos...

But to check consistency, yeah, that's good.
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Old 01-13-2003, 07:55 PM   #18
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Anybody had any problems with the new Jacos pulling away from the rim at the edges?
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Old 01-13-2003, 10:50 PM   #19
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I've had a few of the softer ones do that - 1/10th pan car Greens. . .
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Old 01-14-2003, 07:48 PM   #20
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tires for the price posted
http://shopping.rcmodel.com.hk/eshopping/default.htm


check around you can get close in this country also if you order quanitity...

now as far as overdrive..... lets see i did not see it as a tool at nats last year this year or at worlds all of which i raced at(200mm), so i am only talking from expierience and first hand info from your top drivers.. that goes for salvin, collins, burch, cyrul, etc etc... i may only run in the top 30 but i can tell you this.. overdriving the front of the car greatly improves how easy the car is to drive, BUT and i mean but, if you over or under drive a car that has the same diameter tire you now have a front or rear wheel drive car and the other end of the car does not do anything until the overdriven end slipps, that equalls less accelaration.. it is basic physics...... so try to tune your suspension for the handling with the car balanced for accelaration....

now if you lose more rear tire than front in a qual you may end up with more overdrive at the end of the race and should consider were in the main you would like to have the car balance optimum......

andrew mowery
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Old 01-14-2003, 08:01 PM   #21
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Well I cannot talk on that level of competition, but at recent state and club events I have seen many of the fastest guys truing their fronts around 1mm lower than the rears to improve handling. I have tried it myself and I have got better laptimes. Mayby an easier to drive car is faster for me, or mayby I just had a good day.
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Old 01-14-2003, 08:20 PM   #22
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The easy way to explain the quicker lap times is, that the overdrive removes the punch the rear wheels have, so it helps reduce understeer to a massive degree, and prevents the back end from steeping out, because the front end drags the ack around, over drive is more useful on tight and twisty tracks, but on long straight aways, Equal drive, or underdrive, is quicker because steering is more delayed, and with it being equal it removes drag from the rear wheels.
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Old 01-14-2003, 09:54 PM   #23
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so a smaller diameter tyres in the front make the car overdrive or underdrive? or do I need to change the side pulley infront to a smaller or bigger one?
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Old 01-14-2003, 10:13 PM   #24
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if u use a smaller diameter front wheel it will under drive, but only untill they wear the same


but if u make the car have a a different gear drive ratio so that the one on the front is bigger, it will overdrive.
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Old 01-14-2003, 10:14 PM   #25
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to play with over or under drive the car with the tires.
smaller front with give you under drive more steering.
ive. never considered this as a tool to dial in my car for optimum
performance on sedans. i try to run even diameter for qualifiers
and 20 min mains but i do start with 1mm under drive for
mains 30 min. and over so that i could have a car that will
stay close to optimum with my set up.
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Old 01-14-2003, 10:21 PM   #26
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An overdriven car gives better handling because its more like a Front wheel drive

an underdriven car handles like a rear wheel drive as the rear wheels spin before the front starts to do anything, thefore when in a straight line its pushing the front wheels into understeer


and overdriven car handles better.
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Old 01-14-2003, 10:41 PM   #27
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Quote:
Originally posted by jwf_frani
to play with over or under drive the car with the tires.
smaller front with give you under drive more steering.
ive. never considered this as a tool to dial in my car for optimum
performance on sedans. i try to run even diameter for qualifiers
and 20 min mains but i do start with 1mm under drive for
mains 30 min. and over so that i could have a car that will
stay close to optimum with my set up.
I hear ya, I think it is one of those last 1% types of adjustments. If you have a look at the latest kyosho v1rr it comes with an overdriven front end out of the box and the tuning instructions has a matrix showing overdrive %ages and the effect that they have on handling so somebody in Kyosho must like the idea Actually the whole purpose of the V1RR setup is that the front tires can be run 4.5mm lower than the rears and still maintain 1:1 drive ratio. This is so you can run a low profile front tire for good handling and leave the rear tires bigger for longer life.

I would never use underdrive, and i would never use overdrive without a front oneway.

Last edited by AMGRacer; 01-14-2003 at 10:48 PM.
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Old 01-14-2003, 11:04 PM   #28
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Quote:
Originally posted by AMGRacer
IActually the whole purpose of the V1RR setup is that the front tires can be run 4.5mm lower than the rears and still maintain 1:1 drive ratio. This is so you can run a low profile front tire for good handling and leave the rear tires bigger for longer life.

I would never use underdrive, and i would never use overdrive without a front oneway.
AMGRacer, you have the same thoughts and answers as I have
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Old 01-15-2003, 12:41 AM   #29
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Quote:
Originally posted by AMGRacer
Well I cannot talk on that level of competition, but at recent state and club events I have seen many of the fastest guys truing their fronts around 1mm lower than the rears to improve handling. I have tried it myself and I have got better laptimes. Mayby an easier to drive car is faster for me, or mayby I just had a good day.
This is simply good tire wear management.. Basically, if you start with 1mm smaller and end with 1mm smaller in the rear, you would have the least amount of deviation from the optimum ratio which may or may not be 1 to 1.

I personally don't consider this type of tuning to be true overdrive. Severe overdive by means of a huge split or pulley maybe easier to drive in some instances, but always carry the penalty of severe drag.
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Old 01-15-2003, 12:52 AM   #30
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Quote:
Originally posted by AMGRacer

Actually the whole purpose of the V1RR setup is that the front tires can be run 4.5mm lower than the rears and still maintain 1:1 drive ratio. This is so you can run a low profile front tire for good handling and leave the rear tires bigger for longer life.
I could be wrong, but I was under the impression that running the front lower was to allow better fitment of the lola type bodies. This allows the front to be slammed and the air dam to be trimmed completely, thus yeilding the least amount of drag. (aerodynamically).
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