i recently bought a havok 17.5 spec brushless system for my tamiya tto1, but it goes way too slow
i have a 61t spur gear(stock) with a 21t pinion gear in it and im wondering if i gear it with a 55t spur gear with a 28 pinion gear, will it make a big difference in speed(something that i can notice) or will it just change it tad?

That's a huge change. Probably way to big of a change.

Gear it to motor temps if you're really unsure. Do another run and check the temp after you're done your normal length of run times. Aim for 140*.

What is the final drive ratio? With 17.5 I see people run from 3.8 to 5.0 depending on timing, track size, and speed control timing.

my fnal drive ratio is 5.11
is that ok?

What temp is the motor when you pull it off the track? Like Scottmisfits said, it should be around 140. Remember others gearing will be different depending on track size, and driving style.

i dont know the temp, just bought it and installed it today
im gonna go to track tommorrw and buy gears. my driving stlye is kinda aggressive, its a small parking lot race, but the motor is ridiculously slow.

Sound strange! What batteries are you useing? Go to www.gearchart.com see if that helps. Check your batteries first.

Where do you run in Monterey Park? I used to live in Alhambra. I ran at the hobby shop on Las Tunas & Temple city every other sunday. Massy's Hobby Shop.

yes, but on some sundays i go out to race at san gabriel(speedtechrc)
if your interested go to www.speedtechrc.com
hey and thanks you for all your help

Internal ratio of the tt01 is 2.60. If you have a 61t spur and a 21t pinion that gives you 7.55 Final ratio ( 61 divided by 21 =2.90 x 2.60=fdr) Thats geared to the moon for a 17.5 !!!! The problem with the TT01 is that you can only use certain size pinions. The motor mount has specific mounting points for each size pinion you use as the mount is not adjustable.
I don't know that you can get the gearing to an appropriate number with that car. In our club we run pretty small , very technical track layouts and a 5.0 fdr is good. For a larger track we had to gear in the low 3's.

The lowest possible FDR for the tt01 is 5.72.
This is when using spur 55 and pinion 25
(55 / 25 x 2.6 = 5.72)

Because of TT01's motor mount design, only a 55 / 58 / 61 spur can be used. and each spur size can only use certain pinion size as well. this is the limitation of the car.

Speedtech open after I moved from Alhambra.Rose Bowl I see. Used to play golf @ Brooksiide Golf Course, and Bruin Football on Saturdays.

oh really. thats cool. ya speedtechs races are pretty fun. lots of people and they are all very friendly. the track is in a parking lot and in my opinion is the perfect size trackim gonna try to go to their next race if i am not busy. its a lot of fun!!!