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vibration
Apr 2, 2014 6:53:53 GMT -6
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Post by rebel1mcelroy on Apr 2, 2014 6:53:53 GMT -6
After 5 or 6 laps under green I pickup a vibration,caution comes out we ride around a couple of laps. Take the green and no vibration for a handful of laps.seems like whatever it is cools and stoo then starts back after a few laps.any ideas? Thanks
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Post by street16 on Apr 2, 2014 7:38:36 GMT -6
My first guess would be brakes because of the amount of heat they generate racing Vs caution - depending on how hard you use them. Maybe a cracked rotor or drum.
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vibration
Apr 2, 2014 8:02:00 GMT -6
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Post by rebel1mcelroy on Apr 2, 2014 8:02:00 GMT -6
Thanks ill check the rear brake rotors this evening.
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vibration
Apr 2, 2014 8:07:49 GMT -6
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Post by rebel1mcelroy on Apr 2, 2014 8:07:49 GMT -6
Anyone else run across this? If so what did you find?
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Post by flipflopoo1oo on Apr 2, 2014 8:47:46 GMT -6
Not a miss caused by in-ballance of compression, a lifter over-coming a valve spring! A drive line angle changing when up to speed if it is not torqueing so hard or a tight u-joint! Check for torque marks in your joints! Jack the pinion and car to test angles! Is it constant in and out of the throttle or just on high end? More info please. Shocks warming up may allow more roll and lift to change angles! A right rear tire may have a knot and be out of balance when hot and more aired and flexible!
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vibration
Apr 2, 2014 11:01:39 GMT -6
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Post by rebel1mcelroy on Apr 2, 2014 11:01:39 GMT -6
Looked at the gear and u joints last week im thinking a hub. Tire or shock just got to keep looking. I did manage to win 2 features this past weekend . When it started vibrating I would slow down and hope for a caution!! Lol
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Post by flipflopoo1oo on Apr 2, 2014 15:10:37 GMT -6
Mud in a rotor or wheel with light shocks really shows up with a lack of weight! I have seen a left front quiver if being unloaded and not enough toe out 1/2- 3/4 is good unless angles are changing it when raised!
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Post by Toywagon on Apr 2, 2014 20:45:26 GMT -6
That is strange. Gonna be interesting to see what this is. Do you feel it in the steering wheel, or seat of the pants, or brake pedal?
When the vibration starts, does it change with the speed of the engine? Does it seem stronger on the throttle?
If you can think of it, and its vibrating and you get a caution, try kicking it into neutral and letting the engine drop to idle while the car is still at speed. ( Don't get ran over!) That might help separate a suspension rotating vibration from an engine vibration.
Flipflop already covered the stuff I was thinking.... Hope it doesnt show up in broken parts and a DNF.
Jim
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Post by Toywagon on Apr 2, 2014 20:46:53 GMT -6
Forgot...
Congrats on the wins!! Always good to get the first ones real quick at the start of the season. Hope you have more to come!!
Jim
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vibration
Apr 2, 2014 21:22:17 GMT -6
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Post by rebel1mcelroy on Apr 2, 2014 21:22:17 GMT -6
Thanks toy Wagon!! I did some checking and found that the u joint cap was spinning in the driveshaft also the rear bushing in the trans. Is alittle loose but not excessive. gonna try to get a new end put on the driveshaft tomm. The vibration feels like its in the rear and I found a upper trailing arm bolt broke on the rr chassis.still not sure if thats it!
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Post by Toywagon on Apr 2, 2014 23:30:08 GMT -6
Grab you an O ring that will go over your drive shaft yoke. After you sit the car down on the ground at the track, make sure that rubber o ring ( or Zip Tie) is pushed up against the tail shaft of the tranny.
After your race, check and see if the O Ring is bottomed out against the yoke of the drive shaft. If it is or if its missing completely, you are bottoming the drive shaft out into the tail shaft of the tranny.
On modified's we get so much suspension travel that we have to watch driveshaft travel to make sure we don't pull it out too much, but also to not bottom it out in the tranny. Depending on your suspension, you could have something in your suspension allowing unwanted movement that could bottom it out in the tranny.
Hope you get it figured out.
Jim
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Post by street16 on Apr 3, 2014 12:02:05 GMT -6
I'm still seeing it from a heat perspective. If it were something out of balance or suspension binding it would vibrate all the time at race speed. Exhaust and brakes generate the most heat, but with it coming from the rear of the car, exhaust is pretty much eliminated. Would a wheel bearing or third member bearing cool down enough under caution to stop vibrating for a few laps? I don't know. I've had U-joints going bad only vibrate at,or above, a certain speed, so it could be the U-joint problem you found. The broken bolt was something I'm glad you found before it became a problem during a race.
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vibration
Apr 3, 2014 12:17:55 GMT -6
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Post by rebel1mcelroy on Apr 3, 2014 12:17:55 GMT -6
At first I was thinking the gear but dont think it would cool down that fas
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Post by street16 on Apr 3, 2014 13:59:09 GMT -6
I like Toywagon's O-ring trick. I'll have to remember it if I ever go back to modifieds.
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Post by flipflopoo1oo on Apr 3, 2014 20:06:43 GMT -6
I have yet to hear any details of when and where!!! Sometimes or constant after it starts happening? Don't leave us out of the fix! In or out of the throttle!
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