Hello guys,
I have been having this weird shaking problem up front. It does not sound like it is the suspension or anything is hitting it. But when I drive the car, it seems smooth at start, then roughly a mile, it progressively gets rougher in the front end. after I get the speed up to 60-80 it will eventually smooth itself out after a mile or 2. Then after I slow back down to a stop, and slowly come back up to speed or not the shake comes back under 50 mph.

What do you guys think this might be? I disconnected the ABS relay, the car does have 225k miles and some have had problems with the ABS module acting crazy. Does not seem to be the problem because it is doing the same thing.

BTW, it feels like something rotating that is out of round and unbalanced but it does not sound or feel like the suspension, which i think is odd but i do feel it in my steering.

 

Could be a bad wheel bearing. I was having more or less the same symptoms and it ended up being the bearing.
if you jack the car up, do you have any play in the wheel?

 

Do you have after market wheels? Make sure you have hubcentric rings, if so. Are you lowered? Make sure your car is aligned properly, either way.

Check;

- wheel/tire balance
- steering rack bushing
- lower control arm bushing
- wheel play for wheel bearing

 

this one is all stock. i have yet to check the wheel play from being lazy and no time. that is what i thought it was, but i have never noticed one that just randomly gets that bad that quick nor does it smooth out. but will check the bearing plays. hopefully it is something that simple.

this will make me finally finish my spare set and actually swap frames and all my ikeya arms over if it isnt the bearings i guess. haha

 

Put your front wheels on the rear if they're not staggered. The vibration will be much less. Two of my stock wheels were pretty bent and I couldn't balance them completely. When I rotated them to the rear it was much better. Just a quick way to find out if it's the wheels or not.

 

I think it's a wheel and/or tire. Suspension parts don't vibrate in motion. It's mostly a clunk or loose feel during stop and go and/or turns, not at traveling. I never heard of a bad wheel bearing that vibrates but doesn't make some sort of nuisance noise. This is all from personal experiences and work... If anything suspension vibrates at travel speeds, it's damn near falling off.

 

Did you figure out what it was?

 

I did not figure it out. I checked everything underneath and it all was fine for suspension, steering, brakes, wheels, and fluids. But the shake went away randomly. It doesnt come back any more, so i suspect it may be my abs module.
Thanks for the help though guys, even though i didnt figure out the exact problem, the suspension will get a complete over haul anyway. This still bugs the crap out of me with all the years ive been a tech and never have i come to this problem nor a problem i couldnt figure out.

 

My car does this exact same thing, it gets rough around 60mph, smooths out by 70, and the vibration gets bad when taking banking turns on the freeway, only for it to smooth out again after a banking turn.

I have zero vibration under 60, and i know my lower control arm bushings are shot.

 

your problem seems a little different from mine. mine can happen at any speed, and usually doesnt happen when the car is cold. once it warms up a little, it starts to do it. but then when it is about 10-15 minutes after of total driving it goes away. and if i am at highway speeds, after stoping, about 2 or 3 miles later it comes back and randomly goes away.

it is not doing it any more, but still bugs me i dont know what is wrong and couldnt single it out.

if i were you, i would go ahead and change the arms if you could. and only at 60 mph, how old are your tires?

 

The tires have decent tread, and i plan on buying a set of supra arms real soon, the bushings are pretty much gone on the lowers, and i get a clunk when hitting the brakes while reversing.

237k miles ftw.


About your problem, jack the car up and start inspecting the front suspension if you have time.

 

I would think its the wheels and tires. or perhaps the bearing

 

My SC has developed a similar issue as well, at about 60 - 70 mph the steering wheel starts to shake pretty bad. I had the wheels balanced earlier today, and the issue is still there. After driving the car again after the balance I noticed the shaking subsides a bit when I step on the brakes at those speeds (60 - 70 mph). From reading some of the other threads I'm going to check for bad/locked brake calipers next..

 

Here's some good info on the 300 ZX Twin Turbo site:

"This one takes a while to go through, because there are many causes for vibrations. Let's do the little stuff first.

Tires and wheels: common to have tires out of balance because of flat spots, etc. Symptoms are a vibration that comes on at a constant speed, increases, decreases and goes away. Your steering wheel will shake in unison with this kind of vibe if it comes from the front tires. The empty seat next to you will do the same if it's the rear tires. You need to have them spun balanced. Watch if possible so you can judge whether the wheels may be out of round, or the tires 'hop' or 'wobble' on the balancer. Could be a tire with a bad spot in it, or it could be that they aren't mounted properly. One thing to try if the tires 'hop' or 'wobble' and the rim is OK: it's called 'match mounting', and aligns the heavy spot of the tire with the light spot on the wheel. Can be done with a certain kind of Coates balancer at a shop that specializes in sports cars, etc. Not at Wal-Mart or Mr. Tire.

Next, brakes dragging or rotors that are warped. Swishing sound that starts just after you begin moving and increases to a kind of pinging sound with speed. Steering wheel will pull a bit in unison with the noise if it's the front brakes. Can be cured in a couple of ways: loosening and retorquing the wheels *may* be all that's needed. Or, having the rotors turned and new pads, then applying proper torque.

Next, driveline. This one is a bit tougher. The wheels feel fine, the car drives well, but at a certain speed, you start to feel a pounding through the seat of your pants. There's a sound also like something hitting something else, but not a pinging - more like a moan. You might think that the problem is in the rear of the car, but if you put your hand on the driveshaft tunnel, you can feel the vibrations. Steering wheel is not affected either. This is pretty common, starting around 65-70 mph, and going up from there, in cars that have about 60k on them. This vibration generally comes from the driveshaft: it indicates that the U-joints have started to fail or that the center support bearing has started to wear out or both. You can replace the center support bearing, but Nissan says the U-joints aren't replaceable. They are, but it takes a certain level of shop to do this. Because of its design, some folks replace their two piece unit with a one piece one that's made up custom.... Nissan's price on a replacement driveshaft is over $600, while custom one-piece units can be had for less than $300 from an outfit in Texas....

Other sources that are even less likely relate to the driveline also. If the driveshaft has been a problem for quite a while, it may have damaged the rear bearings in the transmission.... NOT a good sign! Also, the power halfshafts out of the differential have a CV joint at the inner and outer ends. These can wear out, but do so much later in a car's life than the driveshaft U-joints and the center support bearing.

Tom B(WI)

Drive the car at the speed at which it is vibrating and shift the trans into neutral. This eliminates the driveshaft and/or center support bearing as a possible vibration source. If the car is still vibrating, then the source is the wheels and/or tires being out of balance. I believe that since the engine will not be putting force on the driveshaft when in neutral, a bad center support bearing will be more noticeable...the contrast of no twisting force with the application of twisting force right after should be pretty noticeable... "

 

^^^ great info, thanks for posting that..

After driving the car this morning I'm fairly certain that either a rotor is warped or I have a sticky caliper. Hopefully I'll have time tomorrow to get under the car and get this sorted out.