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Post by yellowshark on Dec 6, 2010 20:31:41 GMT
Ok I have converted Craig's off roader to brushless and have stuck a 10.5 in. and need to get the gearing right. With a TC and non NG speedo we ran 5.2 FDR at Bashley and 4.6 at Aldershot.
I assume that as it is direct drive (?) ie no belts or other pulleys then the internal ratio is 1:1??
So should I gear for circa 5 or should I take into account the larger wheels and aim more for a similar roll-out?? Should I base that on the larger front wheels or the humungous rear wheels??
Blast just thought, the gearing in the diff could be different and no idea what that might be in either vehicle.
Anyway any ideas welcomed.
Will make a change from trying to remedy a perfectly good new diff that was pulled apart and put back together again ;D
Reubs, are you sure you put the thrust bearing back together properly?
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Post by yellowshark on Dec 6, 2010 20:37:16 GMT
Sorry typing without thinking. I guess you could say that the TC diff is geared because of the pulley but no idea if the off road diff, driven by the spur gear, has any gearing inside it.
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Post by mattsedgley on Dec 6, 2010 22:42:16 GMT
the ratio isn't 1:1 pete, theres a gearbox in the back almost certainly.. the manual should tell you - surely the answer is to stick a pinion on around 20 run it for a few minutes, if the top speed is good and temps are low then go up a tooth? trial and error the best way forwards..
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Post by yellowshark on Dec 7, 2010 0:06:56 GMT
Yup there is Matt although no indication in the manual as to the ratio though. I probably need to put some new grease on the diff planetary gears, so I can pull the the whole assembley apart and count the teeth. I'll have to go onto the Web or raid Craig's school books though to remind myself how to calculate it when you have a gear train with two gears on the same shaft. Mind you I can't work out in my mind how the size of the wheel would affect the load on the motor so maybe trial and error is the best way.  |
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Samspeed1
Hitting the Tyre
Cougar KF Cat K1
Posts: 37
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Post by Samspeed1 on Dec 7, 2010 2:07:43 GMT
Pete may i ask what car it is? I don't know of any 2wd off road cars that have 2 gears on one layshaft, or have direct drive from the diff to the spur gear. Thay all have diff gear idler gear and a layshaft gear which all give an overall ratio.
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Post by yellowshark on Dec 7, 2010 18:39:08 GMT
Hi Sam, thanks for asking,looking in the manual (will take the assembley apart tonight ) - correct it does not have a direct drive, that was just an opening question from me not knowing how it was constructed. It has the diff gear, an idler gear (ignored in the calculations) and a layshaft gear which is on the same shaft as the spur gear (so those two form a compound gear) and the pinion. So if my memory serves me right I calculate the ratio using the driving gear (the pinion), any compound gears (ie the one noted) and the driven gear (the diff gear). Happy to be told otherwise ;D It is a Duratrax Evader EXB,which I am sure was at the cheaper end of Terry's stock at the time; it is for fun in the garden, not racing. And it will be lot more fun with a 10.5 in it ;D Thinking about it some more I think I am going to gear it to a similar roll-out to the TC and then play around from there with the temperature guage |
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Samspeed1
Hitting the Tyre
Cougar KF Cat K1
Posts: 37
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Post by Samspeed1 on Dec 7, 2010 19:13:14 GMT
Some of them have it printed on the gear box casing, worth a look. I would think somewhere like 2.6.1 to 2.16.1 in that range. I would start somewhere in 9-10 overall ratio. Never used a 10.5 tho in off road only mod.
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Post by yellowshark on Dec 7, 2010 21:12:17 GMT
Is that with a non NG speedo Sam?
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