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Old 02-21-2007, 07:18 AM   #1
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Default Why use overdrive with split?

I wonder why many racers use overdrive with split on tires on sedan cars like mugens kyosho serpents etc...

for example if you use 24t side pulley on mtx4 with 64mm on rear tires and 61,5 on front tires(many racers makes these split or suggest) you will have zero overdrive, its same using same tire diameter on both using 25t side pulley
some people say that is for the rear tire not come to be smaller that the fronts on the middle or final of the race i disagree because i race for many years and its not a problem for sure,

In other words if you use overdrive with minimum split or equal diameter i can agree because you will have the handling diferent with more steering on power so resuming i really want to know why reason racers or chassis factories made the overdrive to more seering on power (of corse so stranger nobody use without split ?????? where is the advantage????) or to make the rear tires finish the race not too smaller

I like to make my cars have enough steering without use overdrive because you will have less drag on drive train so you will have better performance higher top speed improved fuel comsumption etc....

Please i want to know if someone can explaine me if i am wrong or what the advantages of overdrive????

sorry bad english

Thanks

Fabian Kaloustian
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Old 02-21-2007, 07:30 AM   #2
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Very good question that i to would like to know......but on a side note. I love it when someone that uses english as a second language apologizes for his bad english and i understood everything he had to say. i think they speak Portuguese in Brazil. I'd like to see a local try and get around in Brazil for five seconds. your english is fine my friend and no need to apologize.
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Old 02-21-2007, 07:47 AM   #3
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hey Fabian....are you Armenian?..
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Old 02-21-2007, 07:47 AM   #4
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Quote:
Originally Posted by Fabian K
I wonder why many racers use overdrive with split on tires on sedan cars like mugens kyosho serpents etc...

for example if you use 24t side pulley on mtx4 with 64mm on rear tires and 61,5 on front tires(many racers makes these split or suggest) you will have zero overdrive, its same using same tire diameter on both using 25t side pulley
some people say that is for the rear tire not come to be smaller that the fronts on the middle or final of the race i disagree because i race for many years and its not a problem for sure,

In other words if you use overdrive with minimum split or equal diameter i can agree because you will have the handling diferent with more steering on power so resuming i really want to know why reason racers or chassis factories made the overdrive to more seering on power (of corse so stranger nobody use without split ?????? where is the advantage????) or to make the rear tires finish the race not too smaller

I like to make my cars have enough steering without use overdrive because you will have less drag on drive train so you will have better performance higher top speed improved fuel comsumption etc....

Please i want to know if someone can explaine me if i am wrong or what the advantages of overdrive????

sorry bad english

Thanks

Fabian Kaloustian



Heres the explanation that I got when I asked the same question. In theory the car will handle differently even though there is no real overdrive when you run the recomended split because the arm position will be different in the front with smaller tires. The surprising thing to me was when I ran my mugen with the 25 tooth pulley and 0 split as recomended in the manual I actualy got less steering than the 24 tooth pulley with 2.5 split. It does change the feel of the car. I disagree with the notion that running a tire split will be better for rear tire wear. I think tire wear in general has more to do with overall setup and driving style.
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Old 02-21-2007, 07:59 AM   #5
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Quote:
Originally Posted by frankrehnelt
Very good question that i to would like to know......but on a side note. I love it when someone that uses english as a second language apologizes for his bad english and i understood everything he had to say. i think they speak Portuguese in Brazil. I'd like to see a local try and get around in Brazil for five seconds. your english is fine my friend and no need to apologize.

Yes ,we speak portuguese here in Brazil , Thanks a lot
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Old 02-21-2007, 08:01 AM   #6
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Quote:
Originally Posted by fastharry
hey Fabian....are you Armenian?..
Yes Fastharry i m Armenian so I was born in Brazil and live in Brazil
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Old 02-21-2007, 08:08 AM   #7
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Quote:
Originally Posted by Francis M.
Heres the explanation that I got when I asked the same question. In theory the car will handle differently even though there is no real overdrive when you run the recomended split because the arm position will be different in the front with smaller tires. The surprising thing to me was when I ran my mugen with the 25 tooth pulley and 0 split as recomended in the manual I actualy got less steering than the 24 tooth pulley with 2.5 split. It does change the feel of the car. I disagree with the notion that running a tire split will be better for rear tire wear. I think tire wear in general has more to do with overall setup and driving style.
Francis M,
i agree with you in everything, but when i told about the rear tire wear is just because rear tires starts bigger than the fronts, not about more or less wear than the fronts ones ,thanks
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Old 02-21-2007, 08:14 AM   #8
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Guys another think to say


when you use overdrive on initial of the race you will have zero or minimum overdrive on middle and final of the race you will have a lot of overdrive , a lot of drag on drive train etc... i think is better dont use overdrive for the reason you will have a natural overdrive during the race since the rear tires always wear out faster thah the fronts so you will have a natural overdrive with the fronts bigger that is the way that i like of my car handling better
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Old 02-21-2007, 08:29 AM   #9
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Quote:
Originally Posted by Fabian K
Yes Fastharry i m Armenian so I was born in Brazil and live in Brazil


makes it a little tough to get fresh Dolma,no?...Or does the neighborhood have a middle eastern grocery store?...

Don't forget to eat your Pilaf...(makes you a better driver..)
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Old 02-21-2007, 10:45 AM   #10
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Get MTX4 Overdrive Chart to find the best setup for your car and for your driving style.

If you look at the OD chart, anything more than 1.000 for ex. 1.035 means the front tires are rotating faster than rear by 0.35% ( Overdrive ).

1.000 means front and rear tires are rotating at the same rate ( full time 4WD )

Anything less than 1.000 for ex. 0.985 means front tires is rotating slower than rear tires by 0.15% ( slightly 2WD or underdrive).

Tire Split allows drivers to use smaller diameter at front than rear in order to minimize traction roll and/or increase responsiveness. Another reason for having less at front, rear tires usually will wear faster than front, so to get even wear at the end of 45min final, they start with less diameter at front tires. Try to measure your tires after the race and compare the result with OD chart to see what kind of overdrive or underdrive or 1:1 did you get at the end of race.

Always AIM to achieve the longest 4WD effect during the race to the finish lap. For this year racing strategy, I would like to start with 0.950 - 0.940, the car will be 2WD for the first 10-15 minutes, but after that period the car will be close and closer to 4WD all the way to the end of race. I can drive hard for longer period lets say from minutes 12 to minutes 35, and relax for the remaining 10 minutes.

Hope this helps.
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Old 02-21-2007, 06:06 PM   #11
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Quote:
Originally Posted by asw7576
Get MTX4 Overdrive Chart to find the best setup for your car and for your driving style.

If you look at the OD chart, anything more than 1.000 for ex. 1.035 means the front tires are rotating faster than rear by 0.35% ( Overdrive ).

1.000 means front and rear tires are rotating at the same rate ( full time 4WD )

Anything less than 1.000 for ex. 0.985 means front tires is rotating slower than rear tires by 0.15% ( slightly 2WD or underdrive).

Tire Split allows drivers to use smaller diameter at front than rear in order to minimize traction roll and/or increase responsiveness. Another reason for having less at front, rear tires usually will wear faster than front, so to get even wear at the end of 45min final, they start with less diameter at front tires. Try to measure your tires after the race and compare the result with OD chart to see what kind of overdrive or underdrive or 1:1 did you get at the end of race.

Always AIM to achieve the longest 4WD effect during the race to the finish lap. For this year racing strategy, I would like to start with 0.950 - 0.940, the car will be 2WD for the first 10-15 minutes, but after that period the car will be close and closer to 4WD all the way to the end of race. I can drive hard for longer period lets say from minutes 12 to minutes 35, and relax for the remaining 10 minutes.

Hope this helps.
That was a great answer, really helps clarifies this intersting field alot. What do you then recommentd? to adjust the fron tire size or pulley size or a balance of both.

Btw, where do you get OD chart from, any URL? Thanks.
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Old 02-21-2007, 07:00 PM   #12
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Quote:
Originally Posted by asw7576
Get MTX4 Overdrive Chart to find the best setup for your car and for your driving style.

If you look at the OD chart, anything more than 1.000 for ex. 1.035 means the front tires are rotating faster than rear by 0.35% ( Overdrive ).

1.000 means front and rear tires are rotating at the same rate ( full time 4WD )

Anything less than 1.000 for ex. 0.985 means front tires is rotating slower than rear tires by 0.15% ( slightly 2WD or underdrive).

Tire Split allows drivers to use smaller diameter at front than rear in order to minimize traction roll and/or increase responsiveness. Another reason for having less at front, rear tires usually will wear faster than front, so to get even wear at the end of 45min final, they start with less diameter at front tires. Try to measure your tires after the race and compare the result with OD chart to see what kind of overdrive or underdrive or 1:1 did you get at the end of race.

Always AIM to achieve the longest 4WD effect during the race to the finish lap. For this year racing strategy, I would like to start with 0.950 - 0.940, the car will be 2WD for the first 10-15 minutes, but after that period the car will be close and closer to 4WD all the way to the end of race. I can drive hard for longer period lets say from minutes 12 to minutes 35, and relax for the remaining 10 minutes.

Hope this helps.


Sorry not agree with you in some details;

I can race almost 90% of the race in 4wd effect(a little under and overdrive) without use overdrive pulley
simple start with rear tires 1mm to 2mm larger than the fronts, on the begining of the race you will have a little underdrive after few minutes you have 4wd effect so later(end of race) you will have a little overdrive
i can say for sure you will have more equal car balance instead using overdrive because using overdrive you will have overdrive after a few minutes and a lot overdrive after this

I can say it for sure because I race for 15years and the car that I won many nitro 1/10 nationals on my country do not use(has) optional overdrive



Thanks for the reply,

Fabian
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Old 02-21-2007, 09:08 PM   #13
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Quote:
Originally Posted by Fabian K
Sorry not agree with you in some details;

I can race almost 90% of the race in 4wd effect(a little under and overdrive) without use overdrive pulley
simple start with rear tires 1mm to 2mm larger than the fronts, on the begining of the race you will have a little underdrive after few minutes you have 4wd effect so later(end of race) you will have a little overdrive
i can say for sure you will have more equal car balance instead using overdrive because using overdrive you will have overdrive after a few minutes and a lot overdrive after this

I can say it for sure because I race for 15years and the car that I won many nitro 1/10 nationals on my country do not use(has) optional overdrive



Thanks for the reply,

Fabian
I gues you answered my question fabian, not to use overdrive but use difference in tyre width. Thanks.

I think you may have misunderstood asw7576, i don't think he said to use overdrive, just get a copy of overdrive chart to compare ratios. Correct me if i am wrong.

but where to get the chart?
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Old 02-21-2007, 11:09 PM   #14
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Quote:
Originally Posted by dr_catman
I gues you answered my question fabian, not to use overdrive but use difference in tyre width. Thanks.

I think you may have misunderstood asw7576, i don't think he said to use overdrive, just get a copy of overdrive chart to compare ratios. Correct me if i am wrong.

but where to get the chart?
Yeah, I can't suggest anything about overdrive or underdrive coz it's personal driving style, preference and strategy. And why Fabian raise the issue if he is already know the answer, 15 years experiences, and winning the race ?

BTW, Here you go Dr. Catman. I also made OD calculator base on Microsoft Excell. Please feel free to modify the formula if you think my formula is not correct.
Attached Files
File Type: pdf mtx4-overdriveratio.pdf (11.3 KB, 165 views)
File Type: zip OD Calc.zip (14.5 KB, 55 views)
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Old 02-21-2007, 11:23 PM   #15
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Hope these help.

http://www.gearchart.com/index.cfm?f...n=chart.create

http://www.gearmachine.net/

From my understanding the overdrive will effect the amount of split used when deciding on front and rear tire size.It would depend on tire wear characteristics of different tracks.
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