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Old 01-09-2008, 12:33 PM   #3226
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Quote:
Originally Posted by djgoku View Post
Hello!

Been racing in a technical racetrack with lots of turns, V-one’s and Mugenīs are eating me on the turns I have to compensate with the smaller gears possible.
I’ve calculated the drive ratio of the serpent and it’s:
Front 1.92, Rear 1.95 to my understanding great on mid to large tracks, also calculated Ratios in other cars and they are over 2.00

Just saw on Serpent USA the Overdrive conversion set 720 18T (#803202).
If I calculate the New ratios:

Front (35/18)*(22/21)=2.037
Rear (47/24)=1.9583

They are to far to obtain near 2.03
If I had a 23T I’ll had:
Rear (47/23)=2.043
Close enough

Can I convert any serpent 23T pulley to the Serpent 720 Brake pulley?
Like the one on the F180 Pulley 23T (#301053)
Anyone knows if other brands pulleys are compatible with 720?

Any of you guys have some ideas to increase Ratio similar to the V-one or Mugenīs (around 2.00)

Tankyou
Be carefull not to confuse two different things:
Final drive ratio (your two speed ratio * the internal ratio)
And the overdrive ratio.

When you use an 18t pulley in front the internal ratio to the front wheels gets larger than the rear. Actually in your example you mixed up the side pulleys. In your example you'd need larger front than rear tires to get a 1:1 overdrive.

The Serpent cars have longer internal ratios than most others. But you can achieve fairly short final ratios if you use the shortest combo of 2speed gears. 16/61 will give a very short first gear.

The reason the 720 has a long internal ratio is that all drivetrain parts rotate relatively slowly. This helps a lot in acceleration as all parts need to be accelerated less.

Often going very short in ratio will not give better acceleration. Think of it in terms of a 4*4 Jeep. If you put it in low gear it can climb a mountain but it is of no use at a dragstrip (except for the first 50cm! )

In my experience, most if not all acceleration is created by a good clutch. Short ratios help mask clutch problems but will not solve them.
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Old 01-09-2008, 01:07 PM   #3227
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Default Out drives

Does anyone have any view on the durability of the out drives (cups coming out of the differentials to meet the CVD's or dog bones) on Serpent. I have had some bad experience with these on some other car, changing "many" times per season, and wanted to know if this is the same case in all cars and then especially Serpent. How often do you need to replace them so that the suspension is not obstructed by the dogbone pins getting stuck in the cups.
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Old 01-09-2008, 01:21 PM   #3228
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Quote:
Originally Posted by karlsen View Post
Does anyone have any view on the durability of the out drives (cups coming out of the differentials to meet the CVD's or dog bones) on Serpent. I have had some bad experience with these on some other car, changing "many" times per season, and wanted to know if this is the same case in all cars and then especially Serpent. How often do you need to replace them so that the suspension is not obstructed by the dogbone pins getting stuck in the cups.
Although i havent driven my current sedan often, before with my 710, which uses the same dogbones, rear differential, and front one-way, i dont recall ever replacing any of the drivetrain parts.
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Old 01-09-2008, 01:33 PM   #3229
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Quote:
Originally Posted by karlsen View Post
Does anyone have any view on the durability of the out drives (cups coming out of the differentials to meet the CVD's or dog bones) on Serpent. I have had some bad experience with these on some other car, changing "many" times per season, and wanted to know if this is the same case in all cars and then especially Serpent. How often do you need to replace them so that the suspension is not obstructed by the dogbone pins getting stuck in the cups.
It's one of the first thing I look at when check fellow racers cars. The outdrives are often the ones not being replaced on rebuilds and I see most of them worn out. I've driven other cars also and I replace them to get the car back to drive consistently.

On my Serpent, on the other hand, the outdrives are by far the best. I still have the original ones and they don't need to be replaced just yet. I've flattened the pins on the dogbones and replaced them but not the outdrives. And yes, I got the car around the time when the 720 came out .
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Old 01-09-2008, 10:05 PM   #3230
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In the rear of my 720 I am using the lightweight axles that I pulled out of my 710. They are about 4 years old & still not worn. The car gets raced hard 48 weeks a year at club races plus big races. In short other than the CVDs Serpent drive train parts are very tough
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Old 01-11-2008, 07:09 AM   #3231
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has anyone has any idea y my 720 (07 with one way front-locked) keep sliding out it's tail when of trottle??? it doesn't matter if it's corner entry, mid or exit... big or small corner... n it doesn't need much speed when it occurs... i tried dismantle my car a few times n set it back to basic/default setup n retry...


beside the default setting, this r what i've tried or done:

rebuild all the shocks
tried yellow springs on rear only with front red
tried yellow springs on all 4 corners
tried blue springs on front only with rear red
tried blue springs on front only with rear yellow
1 way front
lock front 1 way
different shocks position
stiffer/softer front anti-roll bar setting
stiffer/softer rear anti-roll bar
front n rear with 5mm ride height
front n rear with 6mm ride height
front 5mm n rear 6mm ride height
rear roll center block at bottom (lowest hole)
front 198mm track width
rear 200mm track width

it's all on default setup now again, but still has the same tail out when off trottle... i've tried my frens car (all 720 with identical parts except engine n pipe) but their cars seems all pretty well... even i setup my car the excact same way as their but i still get the same tail out... is there any part that i need to pay xtra attention in order to solve my problem, or is ther any faulty parts that i need to replace??? any idea will be appreciated... i've ask not less than 5 good drivers for help at my local track but no one has any idea n most of them gave up to my weird problem after trying n trying to get it done... a club race is coming on soon... well, i won't be able to race for a good result n most probably will end up within the last few places as i'm just a begginer but i just wanna to play better...

last checked:

the rear gear diff is ok
no broken parts anywhere
all bearings r ok
tyres r ok
bodyshell ok
diff oil n shock oil is default thickness

Last edited by fly_wheel; 01-11-2008 at 07:19 AM.
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Old 01-11-2008, 07:51 AM   #3232
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I had similar problem with my G4S and the problem was tire split.. don't know much about 720 split but someone may help about it here..


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Old 01-11-2008, 07:51 AM   #3233
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try 20,000 diff fluid in the rear. this will help keep the rear planted through corner exit. blue springs fornt shocks 2nd hole from bottom, and yellow springs rear bottom hole position. what tires are you using? maybe try 38front 40 rears or 38 front and rear for more traction
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Old 01-11-2008, 08:58 AM   #3234
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Quote:
Originally Posted by fly_wheel View Post

last checked:

the rear gear diff is ok
no broken parts anywhere
all bearings r ok
tyres r ok
bodyshell ok
diff oil n shock oil is default thickness

Check if remote in neutral, brake disc on the car did not engage
Check on rear lower arm, it is reversible between L/R, but most likely you need to cut the shock mounting part (bottom side) to avoid rubbing the wheels.
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Old 01-11-2008, 09:03 AM   #3235
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Quote:
Originally Posted by fly_wheel View Post
has anyone has any idea y my 720 (07 with one way front-locked) keep sliding out it's tail when of trottle??? it doesn't matter if it's corner entry, mid or exit... big or small corner... n it doesn't need much speed when it occurs... i tried dismantle my car a few times n set it back to basic/default setup n retry...


beside the default setting, this r what i've tried or done:

rebuild all the shocks
tried yellow springs on rear only with front red
tried yellow springs on all 4 corners
tried blue springs on front only with rear red
tried blue springs on front only with rear yellow
1 way front
lock front 1 way
different shocks position
stiffer/softer front anti-roll bar setting
stiffer/softer rear anti-roll bar
front n rear with 5mm ride height
front n rear with 6mm ride height
front 5mm n rear 6mm ride height
rear roll center block at bottom (lowest hole)
front 198mm track width
rear 200mm track width

it's all on default setup now again, but still has the same tail out when off trottle... i've tried my frens car (all 720 with identical parts except engine n pipe) but their cars seems all pretty well... even i setup my car the excact same way as their but i still get the same tail out... is there any part that i need to pay xtra attention in order to solve my problem, or is ther any faulty parts that i need to replace??? any idea will be appreciated... i've ask not less than 5 good drivers for help at my local track but no one has any idea n most of them gave up to my weird problem after trying n trying to get it done... a club race is coming on soon... well, i won't be able to race for a good result n most probably will end up within the last few places as i'm just a begginer but i just wanna to play better...

last checked:

the rear gear diff is ok
no broken parts anywhere
all bearings r ok
tyres r ok
bodyshell ok
diff oil n shock oil is default thickness
-Double check the brake pulley set screw and make sure it's tight. Check all the pulley set screws while you're at it.
-What body are you using? Make sure it's not rubbing on anything (i.e. rear tires or ground due to very low mounting)
-Check if the car free rolls when you push it back and forth. If it doesn't check for drivetrain bind which could be caused by a bad bearing, bad belt, etc. It helps to take off the side belt and check for free roll to figure out if the bind is in the front or in the rear.
-If you are using the wide bumper, make sure the edges are not touching the asphalt. It's ok to bend the ends up to make sure.
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Old 01-11-2008, 09:07 AM   #3236
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Are you running CVD's in the front? I experienced a similar problem when running CVD's because my track width was a but too short in the front causing the front of my car to bind and the rear of my car would come out off throttle. I tried everything to fix it but didn't realize that it was the front that was binding in the corners.
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Old 01-11-2008, 09:12 AM   #3237
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Quote:
Originally Posted by fly_wheel View Post
has anyone has any idea y my 720 (07 with one way front-locked) keep sliding out it's tail when of trottle??? it doesn't matter if it's corner entry, mid or exit... big or small corner... n it doesn't need much speed when it occurs... i tried dismantle my car a few times n set it back to basic/default setup n retry...


beside the default setting, this r what i've tried or done:

rebuild all the shocks
tried yellow springs on rear only with front red
tried yellow springs on all 4 corners
tried blue springs on front only with rear red
tried blue springs on front only with rear yellow
1 way front
lock front 1 way
different shocks position
stiffer/softer front anti-roll bar setting
stiffer/softer rear anti-roll bar
front n rear with 5mm ride height
front n rear with 6mm ride height
front 5mm n rear 6mm ride height
rear roll center block at bottom (lowest hole)
front 198mm track width
rear 200mm track width

it's all on default setup now again, but still has the same tail out when off trottle... i've tried my frens car (all 720 with identical parts except engine n pipe) but their cars seems all pretty well... even i setup my car the excact same way as their but i still get the same tail out... is there any part that i need to pay xtra attention in order to solve my problem, or is ther any faulty parts that i need to replace??? any idea will be appreciated... i've ask not less than 5 good drivers for help at my local track but no one has any idea n most of them gave up to my weird problem after trying n trying to get it done... a club race is coming on soon... well, i won't be able to race for a good result n most probably will end up within the last few places as i'm just a begginer but i just wanna to play better...

last checked:

the rear gear diff is ok
no broken parts anywhere
all bearings r ok
tyres r ok
bodyshell ok
diff oil n shock oil is default thickness
Simple dude... Check ur rear main drive shaft where there are 2 pulleys with grub screws to lock ur side drive pulley and the brake pulley. They are probably loose causing the rear timing belt not properly align with the diff pulley.. I can imagine how frustrating it is if u can't remedy the problem. I really can't see it from here but if u would like to share my 720 settings, u are welcome to mail me at [email protected]

I understand from the above that u r running front solid axle. Me too. If i receive ur mail, I will send u some pics of my car in detail ok.

In addition, check ur brake lever linkage, u could be running the car with the brakes applied so when u off throttle the brakes will throw ur car to one side

Cheers,
Raymond Chan

Last edited by raychan; 01-11-2008 at 06:07 PM. Reason: Additional Information
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Old 01-11-2008, 10:26 AM   #3238
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Quote:
Originally Posted by fly_wheel View Post
any idea will be appreciated... i've ask not less than 5 good drivers for help at my local track but no one has any idea n most of them gave up to my weird problem after trying n trying to get it done... a club race is coming on soon... well, i won't be able to race for a good result n most probably will end up within the last few places as i'm just a begginer but i just wanna to play better...

last checked:

the rear gear diff is ok
no broken parts anywhere
all bearings r ok
tyres r ok
bodyshell ok
diff oil n shock oil is default thickness
Double check you have the side pulleys installed correctly. The 21t on the 2speed axle and the 22t on the mid shaft. Make sure you start out with 1mm smaller front tires.


If you are running the optional 18t pulley you'll put the 22t on the 2speed shaft and the 21t on the mid shaft. You'll also need to run 3mm smaller front tires.
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Old 01-11-2008, 01:04 PM   #3239
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here goes one more thing to check, make sure you not getting rubbing from the extra tabs on the lower rear arms and lower front arms the tabs on the bottom you can tell if its rubbing by looking at the inside of you rims on the outer part. If its rubbing just clip them off.
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Old 01-11-2008, 01:42 PM   #3240
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What diff oil are you running in the rear diff?

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