Darren
Hitting the Tyre
It's better to crash and burn than to fade away
Posts: 88
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Post by Darren on Aug 2, 2009 19:23:25 GMT
 Would any one be able explain why using 38 tooth diff and Spool with 20 tooth centre Drive improve on/off throttle. 009 standard kit is 34 tooth diff and spool with 20 tooth centre drive Full info as..... "38T conversion set for the T2'009EU and T2R Pro changes the internal transmission ratio from 1.7 to 1.9. Set includes top-quality 38T composite solid axle and 38T diff pulley, plus new front & rear belts to fit the new pulleys. Improves on/off throttle response, increases stability and makes the car easier to drive. Recommended for all surfaces and traction conditions". Any one know how and why, plus does it make sence or is it another sale pitch....
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Post by Simon Crabb on Aug 2, 2009 20:11:34 GMT
Think of it like a push bike, a larger diff pulley is easier to pedal - hence acceleration is sharper.
Stability might be due to a great 'flywheel' type effect?
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Post by Reuben on Aug 2, 2009 20:12:14 GMT
interestingly the Cyclone moved the other way from WCE to TC:
From 2.437 to 2.166.
Quote from Site:
"The larger pulleys allow the drive belts to wrap around the larger pulleys for extra acceleration and braking power. The drive ratio is now 2.167 (previously 2.4375), making the drivetrain more suitable for brushless motors, which have plenty of torque for low-end power. Improved drivetrain efficiency is another bonus, so you get more runtime and extra power from your existing electronics!"
Maybe its a case of the larger 38t pulleys allow the belts to wrap even further arround??
Maybe another sales pitch?
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Post by mattsedgley on Aug 2, 2009 20:13:06 GMT
can you adjust diff height on the Xray?
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Post by yellowshark on Aug 2, 2009 20:18:53 GMT
Doh you can adjust anything on an Xray Matt. You woould, I think, only want to do it for carpet so haven't done it myself. I would guess about 20 mins to do front and back
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Post by yellowshark on Aug 2, 2009 20:43:36 GMT
OK
When the 008 can out for the EU version, ie asphalt, it had an internal ration of 2.375, comprising 38T pulley and 16T layshaft. Now there were two problems on release.
1. due to the small 16T centre pulley some people were having problems with the belt grinding on the pinion screw and wearing prematurely.
2. People moving to Brushless were finding it difficult to get down to the higher gearing levels required – try getting a 3.0 FDR for 17.5 with an IR of 2.375!
Xray issued a free upgrade to all customers within a month of release to fix the pinion problem and probably a month later issued another free upgrade to all customers to change the IR to 1.7 comprising 34T pulley and 20T layshaft
I had a fairly lengthy conversation with one of the team drivers on the XRAY forum and the considered opinion was that for 27T the 2.375 ratio was better as it allowed you to carry more corner speed with 27T as against 19T which is more brake then accelerate.
When the 009 came out it came with the1.7 ratio and the 2.375 ratio – your choice on how to build it. Now some time this year this new 1.9 ratio has come out but with the pain that unlike 1.7 and 2.375 that use the same belts, you need different belts.
That’s the history lesson; what it all means and is one better than the other I have no idea nor any intent to change ;D
PS the 009 has an upgrade to move the motor forward. To do this you need new belts – maybe these belts are the same as those needed for the 1.9 ratio?
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Post by lesbaldry on Aug 3, 2009 22:14:20 GMT
IMHO....the lower internal ratio theory to suit brushless motors has just gone out the window latley,some new gen speedos allow 10,5 brushless motors to gear near and above any 19t that we used to use....some drivers use ratios over 8:1 on some of the smaller tracks and in the 6's on our larger tracks(Cotswolds)
A small pinion meshed to a large spur will give better acceleration,as for belts if its too slack the car will loose out on top end speed (belt slap causes drag)
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Post by yellowshark on Aug 4, 2009 11:13:35 GMT
IMHO....the lower internal ratio theory to suit brushless motors has just gone out the window latley,some new gen speedos allow 10,5 brushless motors to gear near and above any 19t that we used to use....some drivers use ratios over 8:1 on some of the smaller tracks and in the 6's on our larger tracks(Cotswolds) ) Glad I kept all my 2.375 pulleys ;D |
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Post by mattsedgley on Aug 4, 2009 11:38:09 GMT
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Post by yellowshark on Aug 4, 2009 17:21:32 GMT
Yeah I know. Only beating Glen once and coming in 1. ? secs after Jay was disappointing. Time to junk it and get a decent speedo  |
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Post by gwesty on Aug 4, 2009 17:52:39 GMT
love it ! i wouldnt look 2 far into that theory ! lmao  |
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Post by mattsedgley on Aug 4, 2009 17:59:19 GMT
Yeah I know. Only beating Glen once and coming in 1. ? secs after Jay was disappointing. Time to junk it and get a decent speedo Ha ha! that's good! - careful tho, they'll think your serious about making the A at SLCC!? are you guys coming along?? on a serious note tho, i didn't know that you could raise or lower the height of the diff's i wish i could play with that on the cyclone..  |
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Post by yellowshark on Aug 4, 2009 20:17:39 GMT
love it ! i wouldnt look 2 far into that theory ! lmao ;D |
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Post by yellowshark on Aug 4, 2009 20:23:59 GMT
Yeah I know. Only beating Glen once and coming in 1. ? secs after Jay was disappointing. Time to junk it and get a decent speedo Ha ha! that's good! - careful tho, they'll think your serious about making the A at SLCC!? are you guys coming along?? on a serious note tho, i didn't know that you could raise or lower the height of the diff's i wish i could play with that on the cyclone.. That's what great about the XRAY Matt, you can spend all night playing with anything you want to  Oh yes we will be there. Ross will be making his debut so if you seed the heats carefully he can take out some of the opposition for you, "oops sorry"  |
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Post by lesbaldry on Aug 4, 2009 23:11:39 GMT
Yeah I know. Only beating Glen once and coming in 1. ? secs after Jay was disappointing. Time to junk it and get a decent speedo Nah I dont think so Pete...the guy was practice/testing..when his Mi4's working I would expect him to be close to lapping me at our track during a heat....his fastest lap was 14.2 mine 14.4 does that make me nearly as quick...no way!!!..nice thought though |
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Post by yellowshark on Aug 5, 2009 11:39:32 GMT
Don't worry Les, the Pearl does the job for us (it aint the reason why Glen is faster  )and is perfectly matched to our Gen 1 tyres, so it it is not going anywhere (Craig was practising too ;D - pretty much nailed a new line through the chicane) |
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)and is perfectly matched to our Gen 1 tyres, so it it is not going anywhere