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Team CRC Xti 1/12th Scale!!

Old 01-19-2019, 08:23 AM
  #2641  
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It's interesting to hear the CRC chassis (or chassis generally) characterized as good on carpet/not on asphalt or vice versa. The designs among almost all are remarkably similar today—with virtually all using a link rear/center shock/teak spring and friction damper set-up, and the front being a fixed lower/articulated upper arm with common adjustments and sliding kingpin arrangement. Wouldn't the surface suitability really just be in the manipulation (set-up) of common adjustments?

Not being argumentative, but trying to learn as a chassis designer.

Last edited by ptrhahn; 01-19-2019 at 10:42 AM.
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Old 01-20-2019, 01:08 PM
  #2642  
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Originally Posted by biz77 View Post
Going to larger gears for the same overall ratio will increase overall mass (albeit a very small increase) as well as increase rotational mass. Larger overall gears will however move the heaviest part of the pod (the motor) closer to the pivot point, which is generally a good thing.

I'm not a fan of the CRC 3/32" ball spur gears. They have never been nearly as smooth as a 12-ball 1/8" gear for me and I've had binding issues with the lip they use where the bearing fits into the spur. I currently use Axon spurs in stock class, but have had good luck in the past with PRS, Xenon (16-ball 1/8") and RW spur gears as well.
Thanks. I will try the Axon one in 74t 64p. I assume they are ready for 1/8 diff balls. I was considering the Protek brand 1/8 ceramic. Is that a capatible choice? Will the CRC lightened diff rings work with that? Will my same CRC bearing work with the Axon gear?
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Old 01-20-2019, 02:42 PM
  #2643  
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Originally Posted by ptrhahn View Post
Wouldn't the surface suitability really just be in the manipulation (set-up) of common adjustments?

Not being argumentative, but trying to learn as a chassis designer.
In general I'd answer your question no. Two reasons. 1) The window of effective settings varies significantly with different surfaces. Sometimes to the point designers need to make different versions of a car for different surfaces because the setups change so much you must replace significant parts to achieve the setup balance. 2) The non setup differences such as chassis flex may be better suited to a surface and is difficult or impossible to duplicate with setup adjustment.
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Old 01-21-2019, 10:33 AM
  #2644  
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Originally Posted by gubbs3 View Post
In general I'd answer your question no. Two reasons. 1) The window of effective settings varies significantly with different surfaces. Sometimes to the point designers need to make different versions of a car for different surfaces because the setups change so much you must replace significant parts to achieve the setup balance. 2) The non setup differences such as chassis flex may be better suited to a surface and is difficult or impossible to duplicate with setup adjustment.
Thank you!

I certainly get that the set-up window varies between surfaces, but I guess my thought was, that they don't seem to vary much between chassis. The designs are so similar, wouldn't they have similar adjustment windows, unless you're modifying them from stock.?

I understand the chassis stiffness difference, that makes sense, though from a design ethos perspective, you're allowing the chassis platform to become the "suspension" in an uncontrolled way, vs. the ideal being a perfectly stiff platform with the suspension controlling all movement in a controlled manner. But, these are very simple suspensions in pan cars.

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Old 01-21-2019, 12:01 PM
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Which screws and spacers go with the 15281 locker axle?
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Old 01-22-2019, 07:22 AM
  #2646  
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Originally Posted by biz77 View Post
Which screws and spacers go with the 15281 locker axle?
The axle uses 4x40 threaded screws to lock the gear. The axle is 1/4 inch diameter so all shims and spacers should be .250 inside diameter.
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Old 01-22-2019, 07:36 AM
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I had good results from this setup:




This was my first race with the carbon chassis Z-Flex car. This setup was unusual for me as I always ran a more reactive front end setup, but it ran well and was easy to drive. I don't have much to compare the performance against, but it was more than 2.5 seconds per lap faster than my stock 1/12. The bite of the track was very medium and a little inconsistent from section to section, the layout seriously favored horsepower with multiple on-power sections and long straights, so much so that I actually dumped my somewhat worn out battery pack with 15 seconds left in my best pace qualifier. With a fresh pack and a little practice and a body more suited to Modified the car had an easy 40 lap run in it, and low or even sub 11 second single laps.

The S30 rear tires were a little unusual, I tried Pinks and Blues but they didn't last the distance without glazing over. For fronts the JFT A32's were good enough, but if I had some Pink fronts or Ulti J or X Soft I would have tried them as well.

Not listed in the setup sheet: I used an Xray servo saver, Savox servo, Spool axle. Turning circle was about 1/2 lane width or 3.5-4 feet.

EDIT: I forgot to note that the car had a fuel tubing bump stop on the shock that hit 1mm before the car bottoms out. Without the bump stop the car had considerable chassis drag.
Attached Files
File Type: pdf
CK25_EditableSetupSheet.pdf (638.7 KB, 21 views)
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Last edited by DesertRat; 01-22-2019 at 09:08 AM.
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Old 01-22-2019, 10:26 AM
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Originally Posted by RussF View Post
Thanks. I will try the Axon one in 74t 64p. I assume they are ready for 1/8 diff balls. I was considering the Protek brand 1/8 ceramic. Is that a capatible choice? Will the CRC lightened diff rings work with that? Will my same CRC bearing work with the Axon gear?
I meant 76t spur. I will get a 57t pinion also. If someone knows the answers to the rest that would be most helpful. Thanks.
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Old 01-25-2019, 02:28 AM
  #2649  
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Originally Posted by DesertRat View Post
EDIT: I forgot to note that the car had a fuel tubing bump stop on the shock that hit 1mm before the car bottoms out. Without the bump stop the car had considerable chassis drag.
When do you feel the chassis is dragging? Off power or on power?
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Old 01-25-2019, 03:00 PM
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Originally Posted by RussF View Post
I meant 76t spur. I will get a 57t pinion also. If someone knows the answers to the rest that would be most helpful. Thanks.
Yes to all of your questions.
1/8" diff balls
I'm sure the Protek ceramic balls are just fine
Your stock bearing will work
The lightend D-rings work just fine with the Axon spur
I'm running the exact setup except steel diff balls and it's silky smooth.
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Old 01-26-2019, 05:18 PM
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Originally Posted by Flygio View Post
When do you feel the chassis is dragging? Off power or on power?
Off power. I found that in order to keep the chassis from dragging I needed too stiff a main shock spring, so I switched to a bump stop and kept the softer main spring.
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Old 01-26-2019, 08:22 PM
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Originally Posted by DesertRat View Post
Off power. I found that in order to keep the chassis from dragging I needed too stiff a main shock spring, so I switched to a bump stop and kept the softer main spring.
How are you fitting a long enough bump stop for 1mm. My chassis still bottoms out but if I make my spacer on the shock shaft any longer I can't get the lower spring retainer installed.

Surely in overlooking something simple...
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Old 01-26-2019, 08:55 PM
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Originally Posted by iTz Nicholas72 View Post


How are you fitting a long enough bump stop for 1mm. My chassis still bottoms out but if I make my spacer on the shock shaft any longer I can't get the lower spring retainer installed.

Surely in overlooking something simple...
Unthread the shock end and put the spring retainer on the shock end, and then thread it on.
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Last edited by DesertRat; 01-26-2019 at 09:18 PM.
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Old 01-28-2019, 03:54 AM
  #2654  
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Originally Posted by DesertRat View Post
Unthread the shock end and put the spring retainer on the shock end, and then thread it on.
Thank you. Set the bump stop to 1mm under compression and it made a huge difference!
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Old 01-29-2019, 09:52 AM
  #2655  
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So i've been trying mod as well just recently and i'm starting basically trying to deplete my old tire stock that i have which consisted of magenta, pink, yellow, grey low, black, blue (old blues, not the new compound that's supposedly out) and the car seemed great with magenta(r) black(f), granted it was with a 6.5. i tried purp stripe with 6.5 and started getting a wash out at the end of the straight with braking, it's a 180 in essence. so i went to a grey low(r) black(front) figuring the grey low was a softer compound. after about 3 laps the car does the same thing, now with a 3.5 in it. i went from a green spring to a red center spring thinking that would help but to no avail. any ideas?
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