Originally posted by Turbonut
As driveshaft seems to surface, unbolt it from the rear and turn it 90 degrees to see if any change.

Originally posted by bob13bt
check the tranny mounts, and rear diff mounts

Originally posted by Amur_ a long time ago in a galaxy far away...

Here are some posts from the rec.autos.rotary newsgroup that I've saved that may be helpful (don't know who the original posters were, but I'm sure they wouldn't mind...)



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You can check yerself for wobbly wheels, preferably with a dial gauge, but the following is almost as accurate. Get the wheels off the ground (preferably the whole car up on jackstands). Clamp a pencil in line with a vise-grip. Using something solid, like 4x4s, a stack of Bibles,
whatever, make a stand up to the level of the rim on which you can lay the vise-grips. Put the pencil point agianst the rim inside the lip (which may be dinged) and gently rotate the wheel. The wheel should touch all the way around. If it does not (and assuming the bearings are good) you have a buggered wheel. Throw it away.

Do the same thing on the tread at about the midpoint, half way up the wheel. If the tire is out of round or flat spotted, you need to have it shaved, then balanced. (Do this after a run to heat the tires, they will flat spot sitting over night.)

If a front end shop does not shave tires, they are NOT into high performance and you need to find another shop, although it is rare that a new high performance tire needs to be shaved. Find a GOOD shop and pay
them whatever they ask, bow and scrape, kiss their ***, whatever it takes to get on their right side and stay there.

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> Anyone, here's a problem I'm dealing with for the last few months.
>
> Problem:
> Steering wheel shakes when I brake at speeds above 50-60 km/h. On some days the shaking is worse than on other days. Steering wheel is fine when driving normally or braking at low speeds.
>
> Things I've tried or noticed:
> -replaced brake pads and rotors with new ones. Did not have any effect on problem.

> -rotated the tires, made sure tire pressure is ok. Did not have any effect on problem. My tires are about 1.5 years old with about 20000km wear so they are still relatively new tires. I inspected the tire treads, they look good with no unusual wear on any of them.

> -the steering rods(tie rods?) do not appear to be loose or worn.
>
> Any ideas what could be the issue? My car is 9 years old about 100000km driven so I'm thinking it might be a worn wheel bearing or other worn part in my steering assembly.
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I had the exact same problem as you do, and tried the same 'fixes' you have, including all new wheels and tires, all six new balljoints in front end (2 control arm, 4 tierod), solid rear-steer eliminator bushings, polyurethane bushings in the front, replace driveshaft, replaced all 4 shock absorbers, and swore a helluva lot. Nothing helped!!

I finally fixed the problem after seriously considering selling the car--not that anyone would have wanted it!

The problem was traced to improperly tightened wheel lug nuts. The procedure used to tighten lug nuts is critical if you wish to be able to drive at all speeds with no steering shake. This is especially critical for aluminum wheels which do not have steel inserts around the lug nut holes. These inserts are for reinforcing the metal around the nut, to prevent stretching.


If you wish to know the proper technique for tightening lug nuts, ask me (on the newsgroup) and I will tell you. It's a little lengthy, but if you're interested in how it's really done I'll tell you. Hint: It's not nearly as simple as you thought! (Or as simple as you figured while watching your friendly neighbourhood "certified" auto mechanic do it.)


I have yet to meet ANY certified auto mechanic who has the foggiest idea of how to tighten lug nuts properly.


It's pretty easy, but you have to do it right.

First jack car up to height where the wheel will go on without touching the ground. Then install all lug nuts and tighten by hand, using only the socket--no wrench.

Knowing what the final torque is, tighten the nuts using a torque wrench in the proper sequence, but in 5 foot-pound increments. You know that for 5-nut wheels, you tighten #1, then #3, then #5, then #2 and finally #4. But the real trick is to only tighten them in 5 ft-lb. Increments so that the retaining pressure is applied evenly to the wheel hub. Keep working around the wheel so they have all been tightened to the required torque--and do it without lowering the wheel onto the ground, or using the brakes. Have someone hold the wheel if you have to.

Suppose the spec says "50 foot-pounds".

So, with a torque wrench (I like the bending-beam type, I have no idea how repeatable the snap-action ones are) first install wheel, then run on lug nuts by hand using only the socket. When all nuts are on, tighten by hand using socket. Make sure the wheel is seated properly before continuing

Now get torque wrench and tighten in 1-3-5-2-4 pattern (for 5 nut wheels) or 1-3-2-4 for 4 nut wheels. Tighten all nuts first to 5 foot pounds. Next, starting again at #1, tighten all nuts to 10 foot pounds. Then start at #1 again and tighten all nuts to 15.

Keep going until you reach required torque--then go around AGAIN, reapplying the final torque to all lug nuts.

I find that this method allows the wheels to run at all highway speeds without the steering wheel shaking back and forth. However, you must start with round wheels and round tires, and the combination has to be properly balanced.


Reason is that just slapping the wheel on and reefing up the nuts applies pressure unevenly to the wheel hub, even if all nuts are torqued evenly. The metal squeezes out slightly from around the first few lug nuts, and the stud hole circle enlarges. This causes warping. Now heat the hub up nicely with a scalding hot brake disc, and the unevenness in wheel spoke length will become really obvious to the guy with his hands on the steering wheel.

Some aluminum wheels, like my Eagle 5-spokes, do not have steel inserts around the lug nut holes. This makes the tightening procedure all the more critical, and the final tightening torque must be lower, regardless of what the manual says. I believe my Mazda shop manual specifies lug nut torque at 70 to 80 ft-lb., but in reality, the 16" Eagle 5-spokes must be tightened, sequentially, to only 50 ft-lbs--otherise the steering shakes really badly, to the point where my hands get right bloody numb after 20 minutes. If I do it properly, the wheel is dead smooth at all speeds.

BTW, sometimes I have to do it twice to get it right! You don't have to be quite as **** with the rear wheels, but I'm absolutely picky about the way I tighten the fronts. Lean down so you can really read the torque wrench scale bang-on when doing the fronts. Get someone else to hold the wheel if you have to while tightening.

Apparently engineers have known about this method for tightening high pressure caps and end plates for something like 100 years
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Originally posted by Thaniel
The drive shaft is a new unit from mazdatrix so I would expect it is balanced (there is a balance washer welded to the side of it). I can try reinstalling it 90 degrees. Didn't think of that. I can feel the vibration at low speeds as well so I doubt it is a balance problem but can never be too sure.

Tires, rims are good. I swapped the fronts with the rear and no change to the vibration. Vibration is always in the back.

Some times when driving real slow, when I let off and let it engine brake and the vibration became more pronounced. Which made me think the Axle shafts but I would have thought I could have felt something when rotating them and checking for play by hand. Then I started thinking maybe wheel bearings because it doesn't do it when there is no weight on the wheels. I've checked the wheel bearings but I can't find any problems with them (no end play, no roughness when spun with out a load on them). I'd just replace them to be sure but it looks like a pain so I'd like to be more sure.

If I can't find a definate problem I will probably do the axle shafts as they look easier to eliminate one possiblilty.

Keep the ideas and tips comming. This has got to be fixed and I'd like to not have to replace everything

Originally posted by MrFuzzy
My car has kinda a rattle on the passangers rear side would that be the wheel bearings?