First Drive after building, Major shake

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I have a couple ideas I ran into with one of my darts. First, I know the tires are new but how much weight did they take? Could have thrown a small one when you got up to 50, you might not have noticed it, if it were right next to a big one or on the inside, also certain tires have heavy spots in them. I have had this problem with a brand that rhymes with SOOPER, if this is the case you will likely have a lot of weight in one certain area. I have seen tire techs grind the inside of the tire so it would take smaller weights likewise I have seen them grind heavy spots out of the wheels themselves, yes really, less likely to throw those weights then. Also consider the wheels. An old Mopar ralley could be bent, or warped a little bit, and I have seen wheel mounting machines bend wheels especially steel wheels. It would not take much of a bend or warp to cause exactly what you are saying, you can jack it up yourself and roll them and look for any side to side motion or a bad belt, remember COOP..... OOPS I meen SOOPER tires. You might want to unhook the e brakes, and change the other wheel cylinder. You said the drum brakes were new but did you turn the drums as well? I think I read you had new rotors on the front, were they trued up? A hot spot from certain pads could also cause this, again you can jack it up and roll it by hand and see if it scuffs or slowes down in a certain part of the revolution. Hope you find it, sounds like you got a nice ride. GOOD LUCK, JOHN.
 
My son pulled the brake booster yesterday and we found this. I'm not sure if this is our shake problem but it's definitely a problem. I'm sending it back to Parts Geek for a refund and having ours rebuilt by a local shop.
I will continue to update this thread and let everyone know what unfolds.
Thank you all again for the help and suggestions.

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Try swapping the tires from front to back & see if the vibration moves. If not, try turning the drive shaft 180* & see if you still have the vibration. But as RRR said, I've also experienced bad "brand new" tires.
 
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Just throwing this out there. Whatever is causing this, only does it after it gets hot. So it has to be in my opinion, tires, wheel bearings or brakes.
 
One more thought. Since it only seems to happen at the higher speed, could it possibly be what is called, death wobble. This is what happens when upper and lower ball joints are worn out. Had it happen on my 98 ram truck. At lower speeds under 50 or so it would be ok, above that it would about shake your teeth out. No signs of anything wrong that I remember. Just got in it one evening after work and it started shaking.
 
UPDATE:
So we sent the original brake booster out for rebuild (Karps in Upland Ca. great people) and returned the one we bought from Parts Geek. We also replaced the Master cylinder since it was the only thing we really haven't replaced.
We got the brake booster back yesterday and installed it and the master cylinder last night. I pulled it out of the driveway and did a couple of laps around the block just see how things were and everything seemed fine; the pedal was a little low but we will bleed the brakes again this weekend and I think it should fix that. So I chanced it and took it for a longer drive keeping it at low speeds. Again, everything seemed fine the brakes were working well and the car was driving well. I then decided to get her up to speed and see about the shake........and nothing; all was well. We drove her for about 20 min getting it up to 40-55 mph and NO SHAKE! So at this point I drove her to the freeway and jumped on. I cruised in the slow lane for about 4-5 miles at about 50-60 with no shake and then took her up to 75-80 for another 5-10 miles and it drove very nice. Alignment was nice, the braking was nice and NO SHAKE. We jumped off the freeway and took side streets home and everything was nice and as it should be. She pulls a little to the left when braking and I still want to bleed the brakes again but I think the shake situation was in the braking system. Could a faulty or bad booster apply the brakes enough to grab on its own? My thought is while driving at higher speeds could the engine be increasing vacuum in the booster which would apply the brakes???? Because in our shaking situations with the Parts Geek booster, every time we applied the brake it would go away thus bleeding off the vacuum??? Just a thought. I'm really just happy that the shake is gone and the brakes are almost (the pedal is a little low) where I think they should be.

Thanks to everyone for the support and help! There is no better site in my opinion than this one. The best information, knowledge and most of all understanding of what owners go through. I should add patience for a Chevy guy trying to build his first Mopar!

Thank you,
Matt
 
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