Gear Ratios....
11-13-2003, 03:37 PM
#1
Gear Ratios....
Hey guys :)
I am currently running a Trinity Revenge of the Monster in my XXX-S. Running a 118 spur with a (currently) 37 tooth pinion. I chose these gears due to a spec sheet on the Losi website. Seems to me that it was overgeared though, so I figured I would take it down a few teeth on the pinion.
If I go down to a 31 tooth pinion for example, will I have to change the spur gear too? Or rather, would it be advisable for me to change the spur gear?
In addition to this I see gear ratios being touted around, and final drive ratios too. Whats the difference? And how do I work it out?
Its all very confusing. I wish I had kept my Optima Mid now, that was easy, I just crashed it a lot and carried the bits home at the end of the day!
Cheers
Rain
I am currently running a Trinity Revenge of the Monster in my XXX-S. Running a 118 spur with a (currently) 37 tooth pinion. I chose these gears due to a spec sheet on the Losi website. Seems to me that it was overgeared though, so I figured I would take it down a few teeth on the pinion.
If I go down to a 31 tooth pinion for example, will I have to change the spur gear too? Or rather, would it be advisable for me to change the spur gear?
In addition to this I see gear ratios being touted around, and final drive ratios too. Whats the difference? And how do I work it out?
Its all very confusing. I wish I had kept my Optima Mid now, that was easy, I just crashed it a lot and carried the bits home at the end of the day!
Cheers
Rain
11-13-2003, 03:53 PM
#2
5.8 
That is way overgeared(unless your on a hugh track).
External gear ratio = Spur/pinion 118/31 = 3.80
Internal ratio = ratio of pulleys (1.83 on stock xxx-s)
Final drive ratio = External x Internal (3.80 x 1.83) = 6.96 FDR
With a monster you'd usually gear around 7.0-7.2 to start with(on mid sized track) and then gear from there. Try out the 6.96 and I'm sure you'll have alot more pep then before. If the pinion can reach the spur then you don't have to change the spur unless your fine tuning gearing(or want to).
Hope this helps.
That is way overgeared(unless your on a hugh track).External gear ratio = Spur/pinion 118/31 = 3.80
Internal ratio = ratio of pulleys (1.83 on stock xxx-s)
Final drive ratio = External x Internal (3.80 x 1.83) = 6.96 FDR
With a monster you'd usually gear around 7.0-7.2 to start with(on mid sized track) and then gear from there. Try out the 6.96 and I'm sure you'll have alot more pep then before. If the pinion can reach the spur then you don't have to change the spur unless your fine tuning gearing(or want to).
Hope this helps.
11-14-2003, 05:47 AM
#3
Thanks, that helps a lot 
One thing that is confusing me is...
How is the ratio of pulleys (internal ratio) worked out? Both the standard pulleys in the XXX-S are 42 tooth I think, and I was thinking of changing the rear one to a 41 tooth, as the back end at the moment is very twitchy.
Very confusing
Rain
One thing that is confusing me is...How is the ratio of pulleys (internal ratio) worked out? Both the standard pulleys in the XXX-S are 42 tooth I think, and I was thinking of changing the rear one to a 41 tooth, as the back end at the moment is very twitchy.
Very confusing
Rain
11-14-2003, 11:16 AM
#4
On the xxx-s there is a pulley on the spur gear. Large pulley(42 tooth) / Small pulley(teeth on spur gear pulley) should equal 1.83 with the standard 42 teeth diff pulleys.
Mess around with the pulleys and see what they do, but your best bet would be to do some suspension tuning to gain rear grip(lighter springs at the rear may help).
Cheers,
fatdoggy.
Mess around with the pulleys and see what they do, but your best bet would be to do some suspension tuning to gain rear grip(lighter springs at the rear may help).
Cheers,
fatdoggy.
Last edited by fatdoggy; 11-14-2003 at 11:30 AM.
11-14-2003, 06:23 PM
#5
Ahhhh I see now! Thanks again. Race day on sunday (weather permitting) so hopefully I will be able to try all this out!
Cheers,
Rain
Cheers,
Rain
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