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CK25AR 1/12th car kit from Team CRC

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CK25AR 1/12th car kit from Team CRC

Old 11-24-2021, 05:51 PM
  #76  
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Higher roll center is lowering the pivot, sort of backwards of what it sounds like
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Old 11-24-2021, 08:35 PM
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Originally Posted by Racermac73
Higher roll center is lowering the pivot, sort of backwards of what it sounds like
I thought it was obvious that the rear roll center is the pivot point on the rear pod. Do you have a diagram that shows that it is not? Just very curious about something I thought I've known over the years. It would certainly not be the first time or the last time I've been wrong!
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Old 11-25-2021, 05:41 AM
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Just re reading the CRC post. -I was the last drivers for Leisure and Delta. Leisure also had the best charger at the time. Delta was an awesome company- some of the best guys in the industry (Especially Art Carbonel). Known Frank since the Class Charger days (still have onr but broken). CRC is the last American manufacturer and they make the best stuff for me to race. They always made quality and affordable stuff that wins races. Looking forward to racing the newest version CK25AR this weekend.I will be converting my F1 as soon as the parts can arrive. This is the best company- with the best Equipment for everyone to race pan car classes!
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Old 11-25-2021, 07:15 AM
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What are the must have Imperial Tools you need for this car?
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Old 11-25-2021, 09:02 AM
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Originally Posted by VanBee
What are the must have Imperial Tools you need for this car?
From Post #23: "The metric hardware thing... well someday we will probably convert. It is tough being the last American company in the market. For the CK25AR, we almost included a SAE hex wrench /nut driver set in the kit. The reality is, you need maybe 4 extra wrenches; .050, 1/16, 3/32 and a 3/16 nut driver. But we do understand and we will work on it in the future."
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Last edited by glennhl; 11-25-2021 at 09:44 AM.
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Old 11-25-2021, 10:42 AM
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DOH!
Missed that one.

Thanks!
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Old 11-25-2021, 03:46 PM
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Originally Posted by glennhl
I thought it was obvious that the rear roll center is the pivot point on the rear pod. Do you have a diagram that shows that it is not? Just very curious about something I thought I've known over the years. It would certainly not be the first time or the last time I've been wrong!
I don't make the discriptions bud, I'm just telling you what higher roll center on this car means 🤷🏻‍♂️
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Old 11-25-2021, 04:43 PM
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Originally Posted by Racermac73
I don't make the discriptions bud, I'm just telling you what higher roll center on this car means 🤷🏻‍♂️
OK, are we talking about the rear? If we are, pretty sure the pivot point is the roll center. And if you raise the pivot, you raise the roll center. If you lower the pivot, you lower the roll center. Since it's a pod that has a single pivot point at the pivot, makes it pretty simple.
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Old 11-25-2021, 05:28 PM
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Call Frank and tell him he moved it the wrong way then.. pretty simple.
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Old 11-25-2021, 07:59 PM
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Originally Posted by Racermac73

Call Frank and tell him he moved it the wrong way then.. pretty simple.
Looks to me that Frank lowered the pivot point and thus lowered the roll center which will give the rear tires more traction. If you want to raise the roll center, just put shims under the pivot assembly and that will give you less rear traction. Frank knows exactly what he's doing.

EDIT: Even though this photo does have two shims under the Pivot Mechanism, the design of the horizontal versus the old vertical pivot ball lowers the ball down so that your adjustment range includes a much lower roll center than before. And the main point was that the statement "Higher roll center is lowering the pivot, sort of backwards of what it sounds like" is not correct when it comes to a pod design with a pivot point. Lower the pivot to lower the roll center. Now if you were talking about the standard suspension design that uses two A arms, you would be correct. On that design if you raise the inside pivot of the top arm you actually lower the roll center.

Final thing is I've attached a video from Alexander Hagberg on the X12. The X12 has a very similar pivot design as the new CK25AR. Go to the 5 minute mark and he says, we have a new rear pivot design which mounts a lot lower which lowers the roll center.
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Last edited by glennhl; 11-26-2021 at 09:50 AM.
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Old 11-25-2021, 08:05 PM
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Directly from the Manual:
"Rear Roll Center: The rear roll center greatly affects the handling of the car. By raising the center pivot point, your decrease the amount of chassis roll making the car steer more. This keeps the inside tires planted, resulting in a more aggressive chassis. Conversely, when you lower the rear center pivot point, the chassis is more affected by weight transfer and exhibits greater chassis roll. This weight transfer, or roll, takes weight off the inside front which takes steering response away from the car. The AR center pivot makes adjusting the rear roll center very easy."

I am in full agreement with the description above regarding the rear roll center adjustment. It doesn't matter where the rear roll center actually is, tuning the car by adjusting this pivot will have the affect described. It is easy to see that in this case, the roll center is lower than the center of gravity (CG) of the rear. If the rear roll center was higher than the CG of the rear of the car, the affects would be opposite. My experience with all the 1/12 cars I have owned and raced supports my comments as I have made these adjustments in the past and those changes follow the description in the manual. Comment number 76 above is sort of confusing to me.
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Old 11-27-2021, 05:32 AM
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I've read several times in this thread that this is the last "American" made car but isn't Speedmerchant still producing cars?
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Old 11-27-2021, 09:56 AM
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Originally Posted by DavidNERODease
I've read several times in this thread that this is the last "American" made car but isn't Speedmerchant still producing cars?
Yes. The REV 8.5 is a very nice chassis.
Reflex Racing is still producing the RSD RR12 T2 as well.
Now we just need Jason to bring BMI back into the game.

Congrats to Frank and the Team. It looks like the new car is having a good showing at the USIC.
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Old 11-29-2021, 04:49 AM
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Just so everyone understands the roll center affects side bite. With this mount it could affect forward traction but on carpet that isn't a problem, even on rubber tires.
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Old 11-30-2021, 11:02 AM
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Originally Posted by glennhl
Looks to me that Frank lowered the pivot point and thus lowered the roll center which will give the rear tires more traction. If you want to raise the roll center, just put shims under the pivot assembly and that will give you less rear traction. Frank knows exactly what he's doing.

EDIT: Even though this photo does have two shims under the Pivot Mechanism, the design of the horizontal versus the old vertical pivot ball lowers the ball down so that your adjustment range includes a much lower roll center than before. And the main point was that the statement "Higher roll center is lowering the pivot, sort of backwards of what it sounds like" is not correct when it comes to a pod design with a pivot point. Lower the pivot to lower the roll center. Now if you were talking about the standard suspension design that uses two A arms, you would be correct. On that design if you raise the inside pivot of the top arm you actually lower the roll center.

Final thing is I've attached a video from Alexander Hagberg on the X12. The X12 has a very similar pivot design as the new CK25AR. Go to the 5 minute mark and he says, we have a new rear pivot design which mounts a lot lower which lowers the roll center. https://www.youtube.com/watch?v=_jC8UWJKgYk

I was told by CRC that the new pivot is 2mm lower roll center than the previous car when the kit setup three .5mm shims are installed. So with no shims it would be 3.5mm lower.
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