Joined: Fri Feb 24 2006, 12:18AM
Location: Pismo Beach, CA
Posts: 160
Howdy fellas... been a LOOOONG time. After trying to sell my Fury through the recession, almost losing my house, my youngest being diagnosed with Type I diabetes (who is also Autistic)... things are finally settling down. I'm looking to get my baby up and running strong again.
The car developed a wicked shimmy between 35 & 65 mph. It only really happens when accelerating normally (punching it & keeping the rear-end under load reduces it greatly), and always happens when slowing down (like coming off the freeway). The source definitely feels like it's coming from behind me (seat of my pants rather thatn through the steering wheel). I checked everything... tire & wheel balance, drive shaft balance, replaced the u-joints (twice). It wouldn't go away. I had it up on jacks & my buddy noticed my drive shaft is about level between the trans & 3rd member. Then we noticed the leaf springs settled... badly. They are just about dead flat & my pinion snubber actually rests against the floor pan.
SO... my question is, could that bad of a pinion angle cause what I'm experiencing? What is the recommended angle? I have driven it like this a few times, is there anything I should check for damage?
Joined: Sun Feb 26 2006, 08:46PM
Location: Kingston,Ontario
Posts: 5622
Welcome back!!
Fresh springs will put the angle back where it belongs. C body springs are available through alcan. http://www.alcanspring.com/
Obviously,bagged out rear springs can change the pinion angle. Weak springs will twist much easier and load up the snubber against the floor,hence transmitting any vibration through the car. Take a closer look at the bushings in the front eyelets and bushings in the rear shackles. Old worn out shocks will oscillate at speed.
Check the pinion bearing for any excessive wear.(drop driveshaft,move it up/down for any play/slop)
Did you check the transmission mount?? If it is fubar it can cause a drive line vibration especially when not "under load".
Transmission mounts are readily available and will be the cheapest fix as a process of elimination. Food for thought,hope this helps
Joined: Fri Feb 24 2006, 12:18AM
Location: Pismo Beach, CA
Posts: 160
Thanks 68Cbarge. For my own personal satisfaction, does it make sense that that is my issue (can a bad pinion angle cause what I'm experiencing), or should I be looking at something else?
I did check all my mounts. I'm running solids on the motor & I did lose the bolt that keeps the driver side pieces together.. but that happened after I started experiencing the bad vibration. The trans mount is rubber & is fine... in fact I replaced it just to be sure, but the one I pulled out didn't show any signs of failure.
Joined: Sun Feb 26 2006, 08:46PM
Location: Kingston,Ontario
Posts: 5622
Since you ruled out the trans mount and motor mounts ; Look at everything else. Think about it. The pinion angle is set. The leaf spring pads are welded to the axle tubes. The axle is mounted to the springs. If springs are very weak,that changes the pinion angle when they are under load and twist up against the pinion snubber quicker and easier compared to fresh springs. Hope this helps
Joined: Fri Feb 24 2006, 12:18AM
Location: Pismo Beach, CA
Posts: 160
That makes sense. I guess I just didn't expect it would cause thst bad if a vibration. I had the wheels & tires balanced like 4 times. Even put it up on jacks, removed the tires, and ran it through the gears before my buddy noticed how flat the springs were.
Joined: Thu May 01 2008, 11:15AM
Location: Chicago,IL
Posts: 2868
Fury440 wrote ...
Are the front and rear U-Joints phased? If not you will get vibration.
Wait. This is only going to apply when the drive shaft comes apart like a 4x4 slip joint or 2 piece with carrier bearing. Both ends are fixed on our car shafts so no opportunity to mess this up. Right?