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Old 11-16-2010, 05:57 PM   #1
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Default CRC Gen X UNDRIVEABLE (Please Help!!)

The Gen X is totally undrivable ... Going in a straight line at slow roll the car will go straight for about 30ft then start to veer to one side (sometimes left, sometimes right)

If any speed is able to built up. the rear end rotates out of control like driving on ice as soon as you touch the wheel.

the front end is even, we set the car on 10mm blocks measured up with calipers to make the sure front axles are even. Using a setup board the axle is centered underneath the car. The car will balance on the pegs with all electronics on board. Tires are cut on lathe at 45mm. Diff has been gone thru a million times exactly like the instructions show. Tweak is set level using a tweak station. I've tried 2 different servos , hitec 225 and JR 3650.

The track is asphalt and other people with 12R5's hook up just fine

I have no idea what could possibly be driving this car nuts??

I can answer any questions please please help
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Old 11-16-2010, 06:57 PM   #2
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Default fixing the genX

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Originally Posted by easy e View Post
The Gen X is totally undrivable ... Going in a straight line at slow roll the car will go straight for about 30ft then start to veer to one side (sometimes left, sometimes right)

If any speed is able to built up. the rear end rotates out of control like driving on ice as soon as you touch the wheel.

the front end is even, we set the car on 10mm blocks measured up with calipers to make the sure front axles are even. Using a setup board the axle is centered underneath the car. The car will balance on the pegs with all electronics on board. Tires are cut on lathe at 45mm. Diff has been gone thru a million times exactly like the instructions show. Tweak is set level using a tweak station. I've tried 2 different servos , hitec 225 and JR 3650.

The track is asphalt and other people with 12R5's hook up just fine

I have no idea what could possibly be driving this car nuts??

I can answer any questions please please help
suggestions for a few things to check:

up front, remove the wheels and then the bottom kingpin eclips and the springs. Clean the kingpins and the bottom pivot balls. when you raise up on the steering blocks and let them go, both steering blocks should drop down fully and smoothly under just their own weight. If they do not, then something is bound up. you'll need to find the bind and eliminate it until the suspension on both sides will drop under its own weight.

In the back, remove the shock, both side dampers, and both side plates so that only the bottom plate, the center pivot, and both side links are still attached to the main chassis. In this condition, the bottom plate should pivot freely and smoothly in the front to back and also the side to side motions. There cannot be any binding and especially no notchyness in the motion of the bottom plate. This can't be felt with the car fully assembled. It needs to be taken down to just the bottom plate and the side links in order to verify that its free enough to work properly. if it's not totally free and completely smooth in both axises, there's a binding that must be purged. both side links must be free and the center pivot must be free and also adjusted to eliminate any notchyness in the side to side motion.

Once you've gotten both ends of the car totally freed up, then the rest is just setup stuff that can be adjusted to suit your preference and track conditions. But if there's any bind at all on either end of the car, it's not really possible to diagnose or to fix an ill handling car with setup adjustments. First, all of the suspension components need to be freed up so that they will go thru their motions without any binding whatsoever.

good luck.
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Old 11-16-2010, 07:20 PM   #3
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Also make sure your rear axle is not too tight. If it is the car will pull to one side.
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Old 11-16-2010, 10:41 PM   #4
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Originally Posted by InspGadgt View Post
Also make sure your rear axle is not too tight. If it is the car will pull to one side.
I fought this same problem acouple of years ago after a bad crash. Take apart the rear pod, and make sure the motor plates (both sides of the rear pod) are straight and true. I couldnt notice any bend until I took it apart and laid them flat on my work bench.

Once I got new plates the car has been amazing. Its a wicked car once you get it dialed.

Also, what type of body are you using, and what surface? You might find a bigger rear wing will help with directional stabiltiy at speed. (more drag at the rear of the car)

Shawn.
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Old 11-17-2010, 05:16 AM   #5
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I'll add...

Check the servo and servo saver, make sure they aren't broken or otherwise deformed.

Check each wheel to make sure it spins true and doesn't wobble. Had an erratic issue with a touring car once because one wheel was SERIOUSLY out of round. Easiest way to do this is slowly roll the throttle while the car is on a stand.
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Old 11-17-2010, 09:53 AM   #6
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Check theaxle bearings. Is the car new?
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Old 11-17-2010, 01:49 PM   #7
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I would also check the links and pivot ball to make sure the rear pod moves freely in all directions as it should. To do this, take the center shock and side springs off. I bent one of the balls the links attach to and it caused a similar issue, it felt as if the tweak was always way off. 1/12 cars are very finicky and require constant checking of everything to keep them driving well.
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Old 11-17-2010, 07:36 PM   #8
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I have to second for you to ck the motor bulkhead. I just went through this with my XL after a high speed sweeping wall hit. The behavior was similar to yours. Wondering left or right on straights and also behaving like the rear end was loose but for no apparent reason.

The bulkhead that support the axle and motor was bent. This was not noticeable until after taking it apart and ckng it with a straight edge. Mine bent just behind where it mates with the CF top plate.
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