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Old 02-22-2018 | 10:12 AM
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Default Shimming 1/12 front end

Hey everyone,

I'm new to 1/12 and RC in general. I have a CRC XTI-WC and I need to shim my front end ride height from about 7mm to closer to 3-4mm. I was wanting to see if anyone could point me in the right direction of some shims that would fit my car. I saw CRC has some shims however I need them sooner than having them shipped and my local RC shop doesn't carry CRC parts. Any other brands/teams that would fit or any universal style shims would be great.

Thanks for the help!
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Old 02-22-2018 | 10:45 AM
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7mm front ride height? How big are your tires?
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Old 02-22-2018 | 11:46 AM
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The 12R5 series used wide aluminum washers
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Old 02-22-2018 | 12:50 PM
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Originally Posted by biz77
7mm front ride height? How big are your tires?
I'm running a GT class so they are spec tires.
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Old 02-22-2018 | 12:58 PM
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Not the shore rating. How big around are they? Do the rules state you cannot true them? Unless you want an unsatisfying and frustrating experience in 1/12th scale you don’t run tires at full diameter. This is most of your ride height issue.
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Old 02-22-2018 | 01:02 PM
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You should be able to use standard m3 washers to shim it up to the appropriate height. However 3-4 mm of shims is a lot. Are you not able to true your tires down?

If you are able to true tires, I would ask around your local track to see what a common diameters is, I run 42.5 f/r. if you run on full size foam you will traction roll and chunk your tires very easily and will not be much fun.
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Old 02-22-2018 | 01:08 PM
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The class requires to run spec CRC tires CLN2230 and CLN2232. We aren't allowed to true the tires down at all. Everyone glues the sidewalls of their tires though and this helps prevent traction roll. One of the guys at our track measured my car the other night while I was working on some setup and my front was around 7mm and the class has a minimum height requirement of 3mm. I agree though 4mm seems like a lot to shim..
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Old 02-22-2018 | 01:17 PM
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Originally Posted by loganblankk
The class requires to run spec CRC tires CLN2230 and CLN2232. We aren't allowed to true the tires down at all. Everyone glues the sidewalls of their tires though and this helps prevent traction roll. One of the guys at our track measured my car the other night while I was working on some setup and my front was around 7mm and the class has a minimum height requirement of 3mm. I agree though 4mm seems like a lot to shim..
Wow, that is a unique way to run 1/12 scale... Anyway, you could also add shims to your kingpin under the steering knuckle in the front to lower your ride height, although this will adjust your roll center as well. I think the bigger issue will be the rear since you will need to shim the motor mounts up by 4 mm which will raise your motor and put more weight up higher.
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Old 02-22-2018 | 01:25 PM
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Wow is right. I would just not run the class personally. Sorry I have nothing else constructive.
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Old 02-22-2018 | 01:50 PM
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https://www.facebook.com/QueenCityRC...type=1&theater

So how do you police that? I could run hundreds of laps on my tires to wear them down, or I could true them on the truer and then run a few practice laps on them and they would look exactly the same. I guess with the spec gearing getting the correct rollout is down to having tires that have "worn" to the correct diameter?
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Old 02-22-2018 | 01:54 PM
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Originally Posted by Serzoni
https://www.facebook.com/QueenCityRC...type=1&theater

So how do you police that? I could run hundreds of laps on my tires to wear them down, or I could true them on the truer and then run a few practice laps on them and they would look exactly the same. I guess with the spec gearing getting the correct rollout is down to having tires that have "worn" to the correct diameter?
My guess would be with new tires you would have a higher rollout and more top end but you would possibly traction roll more often and have terrible handling. But with "proper" sized tires you would be too low on rollout but you would have a better handling car. Maybe in the end that would balance each other out???
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Old 02-22-2018 | 02:08 PM
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Front tire height won’t effect rollout. The way the crc front end is designed the lower arm should snap into the carbon. If you shim that much your front end is going to tweak and more than likely the screws will start to dig into the carbon. I’m not even sure you can lower the rear that much on a crc.
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Old 02-22-2018 | 02:10 PM
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You can just shim the arms some and then add droop in the knuckle by screwing out the king pin. But I would shim between the knuckle and lower arm to take the droop out
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Old 03-20-2018 | 01:30 AM
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Not cutting tires down is like nothing I’ve ever heard !!! If you can’t wait for CRC shims rummage through your washers and pop them in. I guess!!
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Old 03-20-2018 | 06:12 AM
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https://www.tqrcracing.com/shop/prod....asp?p_id=1013

This is what you want for larger drops. It bolts between the lower arm and the caster block.
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