Weight Placement
- Thread starter derbydadgeek
- Start date
I really think what the OP wants to know is what configuration would you START with before ever running it down a track? Start them straight up and even? Start with biased slightly to one side? If you don't have access to a track to see what the car "wants" what would you do. I know not all of you have your own tracks to test this on. For the ones that have had success without a track what did you do? Just keep tweaking after seeing results from league races?
V
Vitamin K
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ngyoung said:
I keep hearing there's a lot of value in watching the car during the "slow roll" phase, but I'm not exactly sure how this would apply to weight placement.
ngyoung said:
Thanks ngyoung - you pretty much nailed it.
TBO, I'm not even sure that 12 behind the rear is a good idea with a standard wheelbase. I remember a post, I think from Kinser, that said not to put more than 1.8oz behind the rear axel on a standard wheelbase. This equals 11 instead of 12 cubes. Hard not to listen to this advice!
A few days ago, I attempted to verify these results but came to a different conclusion.
My track setup - 42' single lane BestTrack set up to BestTrack specs of ~26 degrees.
The car setup - 5" wheelbase running front and rear fenders, rear axle placed 5/8" from the rear of the car. Drilled with silver bullet 3 degree rear camber, right DFW with 4" over 4' steer. Wheels - Dynasty BASX double step removed using 92X axles running krytox. cg - .672 measured using a micrometer and car balancer. Weight 5.030 oz
Weighed car using 3 MyWeigh Triton T2 at the same time. I had to take multiple weights since occasional the weights didn't total 5.030
I performed a similar test as Max-V moving weight to the right side, left side and then even weight across the rear wheels without making any steering adjustments. Here's my results...
Baseline setup - 12 - 1/4" tungsten cubes behind , 11 1/4 tungsten cubes centered in front of rear axles and topped up to 5.030 with tungsten putty (centered on car). Similar to this configuration...
P
XXXXX
XXXXXX
--axle--
XXXXXX
XXXXXX
Note: Weight is concentrated on the left rear or left side of car.
Right Rear (RR) - 1.755 oz
Left Rear (LR) - 2.605 oz
DFW - .670 oz
cg - .672
Result: 5 run average = 3.05766
-----------------------------------------------------------------------------------------
Setup - 12 - 1/4" Tungsten cubes behind axle with the same 11 - 1/4" Tungsten cubes and putty in front of the rear axle but moved to the left side of the car. Similar to this configuration...
P
XX
XX
XX
XX
XXX
--axle--
XXXXXX
XXXXXX
Note: Weight is positioned to place the weight as evenly across the rear wheels (or as close as I could).
RR - 2.090 oz
LR - 2.135 oz
DFW - .805 oz
cg - .800
Result: 5 run average = 3.08486
----------------------------------------------------------------------------------------
Setup - 12 - 1/4" Tungsten cubes behind axle with the same 11 - 1/4" Tungsten cubes and putty in front of the rear axle. Similar to this configuration...
P
XX XXX
XXXXXX
--axle--
XXXXXX
XXXXXX
Note: Weight is positioned so the weight on the left side of car is equal to the right side of the car (or as close as I could). LR = RR + DFW
RR - 1.840 oz
LR - 2.530 oz
DFW - .660 oz
cg - .650
Result: 5 run average = 3.03228
--------------------------------------------------------------------------------------------
I took this a little further and reduce the steer until the times stopped dropping. I assume since the car was better balanced it wouldn't need as much steer. Final steer was 2" over 4'.
Final Result 5 run average = 3.03006
My track setup - 42' single lane BestTrack set up to BestTrack specs of ~26 degrees.
The car setup - 5" wheelbase running front and rear fenders, rear axle placed 5/8" from the rear of the car. Drilled with silver bullet 3 degree rear camber, right DFW with 4" over 4' steer. Wheels - Dynasty BASX double step removed using 92X axles running krytox. cg - .672 measured using a micrometer and car balancer. Weight 5.030 oz
Weighed car using 3 MyWeigh Triton T2 at the same time. I had to take multiple weights since occasional the weights didn't total 5.030
I performed a similar test as Max-V moving weight to the right side, left side and then even weight across the rear wheels without making any steering adjustments. Here's my results...
Baseline setup - 12 - 1/4" tungsten cubes behind , 11 1/4 tungsten cubes centered in front of rear axles and topped up to 5.030 with tungsten putty (centered on car). Similar to this configuration...
P
XXXXX
XXXXXX
--axle--
XXXXXX
XXXXXX
Note: Weight is concentrated on the left rear or left side of car.
Right Rear (RR) - 1.755 oz
Left Rear (LR) - 2.605 oz
DFW - .670 oz
cg - .672
Result: 5 run average = 3.05766
-----------------------------------------------------------------------------------------
Setup - 12 - 1/4" Tungsten cubes behind axle with the same 11 - 1/4" Tungsten cubes and putty in front of the rear axle but moved to the left side of the car. Similar to this configuration...
P
XX
XX
XX
XX
XXX
--axle--
XXXXXX
XXXXXX
Note: Weight is positioned to place the weight as evenly across the rear wheels (or as close as I could).
RR - 2.090 oz
LR - 2.135 oz
DFW - .805 oz
cg - .800
Result: 5 run average = 3.08486
----------------------------------------------------------------------------------------
Setup - 12 - 1/4" Tungsten cubes behind axle with the same 11 - 1/4" Tungsten cubes and putty in front of the rear axle. Similar to this configuration...
P
XX XXX
XXXXXX
--axle--
XXXXXX
XXXXXX
Note: Weight is positioned so the weight on the left side of car is equal to the right side of the car (or as close as I could). LR = RR + DFW
RR - 1.840 oz
LR - 2.530 oz
DFW - .660 oz
cg - .650
Result: 5 run average = 3.03228
--------------------------------------------------------------------------------------------
I took this a little further and reduce the steer until the times stopped dropping. I assume since the car was better balanced it wouldn't need as much steer. Final steer was 2" over 4'.
Final Result 5 run average = 3.03006
What you were doing is finding out what the cars wants. You will build another car in the future where the final weight configuration from this past test will not be the most optimal. Just a note on the testing, the steer may very well likely be different for each different weight configuration.
Psssst. Lighten up that FDW and you will be faster on a Besttrack.
Psssst. Lighten up that FDW and you will be faster on a Besttrack.
Something not working very well in the car test.
You are getting way too much time change for such small adjustments . Imagine your time if you moved all cubes to the center of the car- time should still be under 3.055 sec.
Just a minor point but the max-v tests all kept the same cg.
two of your tests should have had the same cg if you were just moving around without changing distance from axle.
You are getting way too much time change for such small adjustments . Imagine your time if you moved all cubes to the center of the car- time should still be under 3.055 sec.
Just a minor point but the max-v tests all kept the same cg.
two of your tests should have had the same cg if you were just moving around without changing distance from axle.
W8NONU said:
Interesting - didn't think of adding both dominant side wheels and having them match NDRW. Wonder why your cog changed between 1 and 3? Makes sense that the shorter cog would be faster. Big difference with the steer change also. Thanks for testing this out.
- Nov 24, 2011
- 3,903
- 30
- 48
- 13
derbydadgeek said:
If it said ounces it wasn't me bud. Anything I have ever said would have been in grams.
- Nov 24, 2011
- 3,903
- 30
- 48
- 13
- Nov 24, 2011
- 3,903
- 30
- 48
- 13
Tuning tonight and we are hearing a weird sound....almost like something is rubbing. DFW doesn't seem to be touching, maybe it is just because it it going so slow. Have you guys heard this sound before? And please, don't be jealous of our high tech tuning setup!
[video]https://www.youtube.com/watch?v=-FRv84QiIXw&feature=youtu.be[/video]
[video]https://www.youtube.com/watch?v=-FRv84QiIXw&feature=youtu.be[/video]
Does this link work? If not, anyone know how I make it public?
[video]https://www.youtube.com/watch?v=-FRv84QiIXw&feature=youtu.be[/video]
[video]https://www.youtube.com/watch?v=-FRv84QiIXw&feature=youtu.be[/video]
Sounds like the bumps on the edge of the dfw running down a tuning table.... Sounds correct to me.
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