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Tire chatter


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#1 gatormark

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Posted 09 March 2017 - 08:32 PM

Running a Koford Group 12 and a Beauf chassis, body is a Parma Bill Pinch body (Bill's stuff is sweet), using a 9/38 gear combo.

 

I'm getting tire chatter in turn 6 big time on a 200 foot Engleman track. Tried different tires, moved body further back to get more spoiler over the rear axle, bent the spoiler up, and run a little glue on the tires to no avail. This thing is a rocket and I just cant get that tire chatter (loose rear end) out.

 

Any ideas?


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#2 Samiam

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Posted 09 March 2017 - 08:47 PM

Loose bearings or bent axle?


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#3 Dominator

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Posted 09 March 2017 - 09:13 PM

Make sure the pillow blocks and motor are soldered in properly to eliminate any flex.

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#4 Tim Neja

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Posted 09 March 2017 - 09:50 PM

Check the rear bearings and be sure to have a motor brace.  


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#5 Racer36

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Posted 09 March 2017 - 10:26 PM

If none of the above work, try narrowing the tires.


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#6 gatormark

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Posted 27 March 2017 - 05:32 PM

Added motor brace on the front of the can, problem pretty much gone, many thanks gents.


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#7 gotboostedvr6

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Posted 28 March 2017 - 01:12 PM

Post pics for us guys to see your mod.

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#8 LindsayB

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Posted 28 March 2017 - 05:59 PM

Never seen the need for a front motor brace on a Buef Box 12. I expect you have just masked some other problem.

 

Soldering the motor in three places makes motor changes hard. Is the chassis clean and are the normal solder joints for the motor solid? Are the axle bearings soldered/glued in properly - we have already checked axles and rims from being bent. Are the wings attached to the body properly, not starting to give way at the back?

 

If all else is good go to a softer tyre.


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#9 Robert BG

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Posted 28 March 2017 - 07:54 PM

I think you're going to find something loose in the rear like a pillow block or motor brace causing the chatter that you masked by adding the brace.

Depending on what Koford it is, that chassis might have more flex than you realize. It wouldn't be the first time I've seen a Koford chassis pop a pillow block loose, leaving the motor brace to hold it all together or vice versa with the brace loose and the pillow block holding it together.

 

If everything is right you shouldnt need that brace. If you can post a pic and we'll help you get it figured out.

 

You mentioned different tires but no specs or brands... What have you tried (it still could be tires. too)?

 

Also what lap times are you running?


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#10 gatormark

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Posted 03 April 2017 - 07:12 PM

I'm running 3.4 to 3.6 and the car is handling pretty dang good.

 

Now I don't know what a pillow block is gents so I don't know what to check.


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#11 Bill from NH

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Posted 03 April 2017 - 07:42 PM

Mark,

 

Pillow blocks are the uprights at the rear of a chassis that hold the rear axle bushings/bearings and the rear axle assembly. On a wing car chassis and some scale chassis, the uprights are separate parts that must be soldered or brazed to the chassis's center section,


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#12 old & gray

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Posted 03 April 2017 - 07:56 PM

Illustration:

 

box stock tripod.JPG

 

 

 


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#13 Robert BG

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Posted 04 April 2017 - 03:17 PM

To elaborate on what they've said, the solder joint where the uprights or pillow blocks go sometimes breaks loose inside the slot yet it will still be attached outside of the slot where it just butts up to the frame. It's tough to explain but there is a tab that goes into a slot and then a part that lays on the rail and is soldered with the motor brace. Chances are the joint on the "tab" that is inside the slot broke loose.

 

If you flip the car over and hold it by the mounts in the front and the axle in the rear while twisting it some, if its broken you'll most likely see some movement of the tab inside the slot from underneath.


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#14 gatormark

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Posted 11 April 2017 - 05:43 PM

I looked it up and the blocks are solid in place, I thank you all for your help, Yall have a Blessed Easter.


Mark Conner





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