Hello, 1950 Buick Special When driving 60 Mph or more & hitting even a small bump the whoile front end starts to shake violently. When putting the cars on jack stands I do not feel much of any play in the bearings, king pins or anything loose, wheels seems solidly there. Is this shakeing a sign of too much toe in or that I have toe out?! Something else? This has increased over time.
Ah, The infamous Death Wobble! Bane of Jeep owners since the beginning of time. Seriously though, what is happening is that when the tire is excited by the bump strike and because there is an imbalance, the tire begins resonating at it's natural frequency, which happens to correspond to whatever the rotational rpm is at 60 mph. The steering and suspension components are worn out enough that they no longer provide enough dampening to calm the system back down. Start by having the tires checked for balance and rebalanced if needed. Then start looking closer for loose or worn suspension / steering joints. Take the tire off and use a bar to pry on components and replace any that seem loose. How are the shock absorbers? Do they need to be replaced, or stiffened up? Tightening everything up should solve the problem as you need to get more dampening capability into the system.
A little more info as to exactly what kind of Front End you have would help. Also have you ever had a real alignment done to it? Caster angle is very important and something you can't measure with a Tape measure or a Feeling by hand.
The best way I have found to find lose front end parts is to have the car on the ground and get someone to steer it from side to side while you watch each suspension piece. They should all move at the same time with no wasted motion. Had a mechanic that worked for me tell me that the bad tie rod I wanted him to replace was good. He showed me by grabbing it with a big pair of channel lock and yanking it all around, also prying on it. I had him put it on the ground and watch it while I turned the steering from side to side. He couldn't believe how much play was in the tie rod.
Try grease up the whole front suspension,(or you grease up bit by bit and testdrive) then out and drive and try feel if it handles better. This is not solving the problem but finding the problem, some wornout suspensionparts are difficult too feel by hand
Buicks of that era have the front shocks as part of the upper A frames. These rarely get serviced or replaced. They run out of shock oil and then the bushings go bad. I would check them out if you can't find anything else.
Good point, also they are a nightmare too fix. They usually starts leaking out all the oil, ive solved this by using a 50/50 mix of grease and oil, no leaking and the shocks does their job
What exactly are you doing when determining there isn't anything going on? If it doesn't involve a pry bar you're not testing it properly. Chris
Most likely your death wobble is caused by nothing more than worn frontend parts. Tierod ends, pitman or idler arms, etc. Time to get it up in the air and check every tierod end, steering arm end, and even wheel bearings. And don't forget to look at your tires also! More than once it's been wide tires, or worn tread causing death wobble. Testing steering components with both tires in the air sometimes hides wear. Keep one tire on the ground then wiggle the other tire vigorously as you watch the steering arms and joints. Best to have a buddy wiggle the tire while you watch. Without one tire secure on the ground, or on blocks, there's not a good way to check for play in joints.
https://buick.oldcarmanualproject.c...Shop Manual/06-Chassis Suspension/image3.html Looks like you have a rugged but old fashioned independent front suspension. The only times I ever had a bump trigger an IFS car shimmy, some suspension component or another were very worn and loose. TRW use to suggest having a helper turn the steering wheel back and forth a little bit with the car sitting on the ground. Kind of hard to get good look while lying on the ground, but it does put a decent force on the various links and joints.
Thanks very good points here. The one that I have not thought about at all is tire wear. I have real bias -ply that start to get quite worn.
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