I was wondering if anyone had an answer to this. I buy a spur and a pinion for my TC5 to get an FDR that I want, but when I put it in the car the motor can't slide far enough close to the spur for the pinion to even touch. Or the other hand the pinion is too big to get away from the spur to fit. Does anyone have a cool chart or formula to help me out or else I keep buyng tons of spurs and pinions until I find the right fit. Thanks in advance.

there is gearchart.com but i think if you give the motor and fdr you can get some answers

I use gearchart.com to find the FDR, but I didn't see where to just put in FDR and motor info.

in general:
for stock motors, you will need smaller spur + larger pinion in order to get a smaller FDR.
for mod motors, you will need larger spur + smaller pinion in order to get a larger FDR.

each car is different because the motor mount spacing is different.
for xray, if i use 48pitch, i find the upper limit of the total tooth (spur + pinion) is around 112 teeth.
eg: if i use 84 spur, the largest pinion i can fit is 28

So if I had and 87 spur & 30 pinion (117 total teeth) be the smallest to fit, then in theroy a 76 spur & 41 pinion would fit exactly the same?

Why not just state what motor you hav and what fdr you are chassing and perhaps someone can help you out as too what will an will not fit/work in your car

it seems Nobody can understand what your attempting too do

beats buying ten million spurs etc and experimenting

also list what size spurs u already hav and pinions too

good luck

Yes, as long as you stay within the same pitch.

I was fairly comfortable with my FDR where it was but I had a crash which loosened the motor and when I hit the gas I stripped a spur gear. So since I was going to get a new spur gear I was going to mix up the FDR and experiment with a different size. I am running a 17.5 express duo 2 in a TC5R and I run on carpet with 96 foot straightaway.

Thanks andrewdoherty for the good advice on the number of teeth. That is something that I did not know and it helps me out. Thanks for everyone's replies.

If you have a 17.5R, most likely your FDR is around 4.5 to 5.5 depending on your application and track size. In order to get to these ranges, you will need a smaller spur to start. For 48pitch, I suggest maybe 78 teeth or less.

As for 87/30 vs 76/41, the fitting is the same. However, the loading on the motor is completely different. In this case, the 76/41 requires more work to turn compared to 87/30, given they have the same FDR, so the motor is hotter for 76/41.

Would the higher the FDR give me more punch in the infield where as a lower FDR would give me a higher top speed?

Theoretically yes. Track conditions (grip, layout) as well as ESC setup might actually mean you don't get the best out of your motor.

Use this site for a good indication of what pinions and spurs will work for a TC5 with the stock bulkheads:
http://abram.eu.org/gear.php

The gear options are reduced a bit if you use the UK bulkheads that have the lowered layshafts.

That chart is what I was looking for, but when I looked at the 48pitch chart it says that you can have a 75 spur with a pinion from 24-41. When I put in a 29T pinion the gear couldn't get close enough to the spur to mesh. Am I missing something? Thanks again.

I've never tried this combo so not sure if it'll fit.

Is there any space left in the motor mount slots? If there is check the M3 bolt that holds the stock motor mount to the rear bulkhead. When I put my car together the first time this bolt head was sticking out quite a bit and my motor wouldnt slide up close to the spur. I had to countersink the motor mount countersink some more to get the bolt head to sit flush with the motor mount. My motor could then slide quite a bit closer to the spur.

Thats good advice. I'll take a look at that today at the track. Thanks again.