1LikesU.S. Vintage Trans-Am Racing
12-30-2010, 07:53 AM
#9916
but I know how much you "love" the t-shirt...lol...
VTA, is the only way I will travel to race....I will run TC/RCGT/USGT, but VTA is a must...
also we have our 3 Edition of Thunder Jam for our Birds Warm-up...and its a money and trophy race...
Thunder JAM 3
Jan 23rd 2011
open 9am racing at noon
50% payback for TC and VTA
TC 17.5 $25 roar stock spec jaco blues 1400g
Thunder TA $25 25.5 4.0 fdr 21.5 4.9 fdr 1550g
for tc and ta no second class discount
payout based on entries and may be to 5th in A and and first in B and C
main spread based on half the field or 1/3 field if odd count +1 to the main.
12th scale $20 40% payback 1s lipo and open 17.5 speedo
Open TC $20 40% payback open, no really open any tire motor run sorex 24s run foams if you want open.
JR vta trophy class $5 top 3
www.thunderRCraceway.com
12-30-2010, 08:51 AM
#9918
He absolutely needs smaller spur gears. 72/45 is what I would do, and you need to Dremel or relive the chassis area around the motor pinion to allow it to fit in that area. No experience with the Pro4 personally, but I know that you CAN get that gear ratio—it just requires the smallest spurs you can find. PRS comes to mind as having all of the spur gears you need for VTA cars.
81/50 gets you there, too, but you will need to relive more chassis to do it.
It can be done.
81/50 gets you there, too, but you will need to relive more chassis to do it.
It can be done.
12-30-2010, 09:02 AM
#9919
50/81 should be good on BOTH vehicles. I've owned/own both.
On the Pro 4 it will be tight, but it think i've done 53/81 on that car before. You might have to open up the bottom groove on the motor mount so the head of the screw can slide way back. Just extend the slot with the Dremel so the motor can rotate all the way out.
The TC3 will need way more Dremel work than that on the motor mount, motor cam, chassi webbing and probably the chassis brace on that side. There's some good pics early in this thread on how to do it.
On the Pro 4 it will be tight, but it think i've done 53/81 on that car before. You might have to open up the bottom groove on the motor mount so the head of the screw can slide way back. Just extend the slot with the Dremel so the motor can rotate all the way out.
The TC3 will need way more Dremel work than that on the motor mount, motor cam, chassi webbing and probably the chassis brace on that side. There's some good pics early in this thread on how to do it.
12-30-2010, 09:38 AM
#9920
Divide the desired FDR times the internal ratio to get 1.6...this means that you need a ratio with your gears that will provide a 1.6 ratio when the spur teeth are divided by the pinion teeth, so the pinion needs a fair bit more than half of the teeth the spur has.
THEORETICALLY the 100 ALMOST gets there as the 60t pinion yields 1.67 ratio. I say "theoretically" because I'm thinking you'd have to grind the webbing pretty much down to the chassis deck to clear that monster.
So let's look at the 96T...just off the top of your head you should think "4% fewer teeth, so the same pinon will yield 4% less ratio, and that's about what we need, since .07 is pretty darn close to 4% of 1.67. Sure enough, 96 divided by 60 is EXACTLY 1.6 and as we'd found before, 1.6 X 2.5 yields exactly the 4.0 desired FDR. Provided the 60t pinion can be made to fit. This is actually a comparatively rare circumstance wherein a certain pre-determined FDR number can be hit spot-on.
An alternate way to look at it...to find the correct pinion for the spur. We know we need a ratio of 1.6, so divide the remaining spur gear choices by 1.6 to see what pinion it calls out...he might accidentally have the right pinion.
85 divided by 1.6 yields 53.125...DARN close to his 53t...for all practical purposes creates a 4.0 FDR. Precisely it's a 4.0094. Yeah, that's pretty close.
81 is almost 6 percent less than 85, so we'd need a pinion almost 6 percent less than 53 for us to get a "happy" result. 53 is a bit more than half of 100, 6 is 6% of a hundred, half of 6 is three, but we needed a "bit more than half" so we'd want something between 2 (since we're dividing, 2 yields results "more than") and 3 teeth less. I'm thinking the 50 looks pretty good, but will probably yield an actual FDR a bit higher, a 51 will likely be closer but a FDR a touch under 4.0
Let's check... 81 / 50 = 1.62 ... 1.62 X 2.5 yields an FDR of 4.05 . Realistically, this is little more than 1% difference from the desired FDR. If your racer is Mike Blackstock or Paul Lemeiux he MIGHT find a difference on the clock between 4.0 and 4.05 but mere mortals will not be able to measure a difference.
Just for craps and grins let's check my 51 estimate and see if it really is closer. 81 / 51 = 1.5882 ... 1.5882 X 2.5 yields an FDR of 3.9706. Yup, closer, but a bit below the target and he doesn't have a 51t pinion anyway.
The advantage of the 81 / 50 is that the 50 will be easier to "massage" into place. That said, iir to get the gear centers THAT far apart I think some of that massaging will need to take place on the motor mount itself, not just the chassis webbing. Not tough to do, but some folks are hesitant to grind away.
12-30-2010, 09:53 AM
#9922
I'm not running a TC3 anymore, but every other car WE'VE been running we experimented with going to lower FDR's and have all pretty much returned to FDR's right around the old 4.2 mark. The gain in top speed on the 65' (50-ish feet inside to inside) straight is offset by the loss of punch in the infield on a few different layouts we've tried. Times didn't change much, we just got more motor heat.
fwiw
12-30-2010, 11:31 AM
#9925
My applogies then. The original post kinda makes it look like he's trying to figure out how to make a particular FDR.
I'm not running a TC3 anymore, but every other car WE'VE been running we experimented with going to lower FDR's and have all pretty much returned to FDR's right around the old 4.2 mark. The gain in top speed on the 65' (50-ish feet inside to inside) straight is offset by the loss of punch in the infield on a few different layouts we've tried. Times didn't change much, we just got more motor heat.
fwiw
I'm not running a TC3 anymore, but every other car WE'VE been running we experimented with going to lower FDR's and have all pretty much returned to FDR's right around the old 4.2 mark. The gain in top speed on the 65' (50-ish feet inside to inside) straight is offset by the loss of punch in the infield on a few different layouts we've tried. Times didn't change much, we just got more motor heat.
fwiw
12-30-2010, 07:11 PM
#9926
Tech Master
iTrader: (41)
We have a Very tight track and lots of 180 degree corners and I am running my FDR at 4.7 And I am quite a bit faster (lap time wise not top speed of course) than those running at 3.8 or 4.2
It seems that some think that faster is better but with limited traction that is not the case
It seems that some think that faster is better but with limited traction that is not the case
12-31-2010, 05:01 AM
#9927
http://www.rctech.net/forum/norcar-c...-schedule.html