FDR question
#1
FDR question
hi! i have a question about FDR for touring car. internal ratio is 2.0 and i have 96 spur and 48 pitch pinion final drive ratio is 4.0 and i have 98spur and 49pitch pinion final is 4.0. both has the same FDR whats the difference for both or is it the same? thanks!
#2
Although the FDR is the same the feeling is little different on low speed. You need to check it at the track.
Last edited by nikoskar; 06-03-2014 at 03:37 AM.
#3
Tech Rookie
edit: deleted my post to avoid confusion... I noticed I have misunderstood the question
Last edited by thomsva; 06-03-2014 at 04:14 AM.
#4
Tech Fanatic
+1 for Thomsva re mixing pitch and the number of teeth, but bornox in his question is changing both the spur and the pinion (98 sized spur gear and a 49 pinion) to keep the same FDR so that the only different is the size of the gears being used.
Last edited by John Wallace2; 06-03-2014 at 04:36 AM.
#5
Tech Master
iTrader: (1)
From a mechanical standpoint the ratio is the ratio. As stated it is easier to set the mesh. From a pure mechanical side the larger the gear the closer it comes to a straight line and this increases efficiency. The step we can take in our cars is small and the location of the motor is probably the biggest change.
#6
Tech Fanatic
From a mechanical standpoint the ratio is the ratio. As stated it is easier to set the mesh. From a pure mechanical side the larger the gear the closer it comes to a straight line and this increases efficiency. The step we can take in our cars is small and the location of the motor is probably the biggest change.
+1 on the motor and even that amount of change is limited by the design of the motor mount to just a few mms in most touring cars (or at least the ones I'm familiar with) and in some cases further restricted by the motor itself (and I'm thinking of my ORCA motor with that big flange around the motor shaft that protrudes into the motor mount).
#7
thanks guys! one last thing the temp of my motor is gonna be the same if i use 96/48 or 98/49?
#8
Tech Master
iTrader: (5)
Outside of a labratory any meaningful measurment in difference is motor temp is tough due to the number of variables that are bound to change such as ambient temp, grip level, gear mesh, etc. Assuming you are using the same FDR the temps should remain stable but if they are off a few degrees be careful attributing that to a change in gear sizes.
#9
Tech Fanatic
Outside of a labratory any meaningful measurment in difference is motor temp is tough due to the number of variables that are bound to change such as ambient temp, grip level, gear mesh, etc. Assuming you are using the same FDR the temps should remain stable but if they are off a few degrees be careful attributing that to a change in gear sizes.
#10
There is theoretical differences and practical differences, in this case there will be very little of the former and none of the latter!
If you were comparing a light weight 64p set of gears vs a heavy 32p set with the same ratio you *might* notice the difference! but not with what you are looking at.
The comments about motor positioning and balance are valid, but not in this case either - you motor would be moving by about a millimetre. Picking up tyre debris and dirt will make more of a difference.
Having the gears you do means you have a set of spares in case you strip them at the track essentially
If you were comparing a light weight 64p set of gears vs a heavy 32p set with the same ratio you *might* notice the difference! but not with what you are looking at.
The comments about motor positioning and balance are valid, but not in this case either - you motor would be moving by about a millimetre. Picking up tyre debris and dirt will make more of a difference.
Having the gears you do means you have a set of spares in case you strip them at the track essentially
#11
thanks guys! i appreciate ur opinions about FDR.
#12
Tech Fanatic