brake shaking question

Hi guys,

I did search but somehow I couldn't find.
Mostly posting were wrap rotors but my case is little different.

I have 525 sports and Rotor and brake pads are kind of new(less than 1 year)
However, I bought this car about 5 month ago and when I brake from 60, 50m/h, front wheel is shaking. when I drive down(down hill) it shake more than climb up. And some time, it doesn't shake at all.

I did wheel balance and wheel alignment and rotor and pads are kind new(I could tell by it's color and it looks still factory gray paint on)

What do you guys think?
Thank you.

You have loose bushings in the front suspension, esp tension strut.

Thank you.
By the way, which one is the tension strut bushing?
Is it DIY available?

Type /vibration F3 in the VERY best of E39 Links and you'll find, among others:

- The main causes of vibration while highway driving (0) (1) (2) (3) (4) (5) & while highway braking (1) (2) (3) & why it's not rotor "warp" (1) & severe ABS shuddering while slow speed braking on bumps (1) & how fluid-filled thrust arm bushings crack and tear causing the BMW to vibrate at speed (0) (1) (1) (2) (3) (4) (5) (6) (7) (8) & a comprehensive TireRack vehicle vibration diagnosis chart (1) (jpg) with wheel match mounting hints (1) & how a worn drive shaft, flex disc, center bearing, or "giunti Boschi", aka giubo (it's not spelled guibo although it sounds like it is to some) can cause the vehicle to vibrate (1) (2) (3) (4) & how to repair the rear driveshaft seal by the differential (1) & how to repair the inner constant velocity (CV) half-drive shaft (1).

EAC has taken OEM arms (Lemforder or TRW), removed the weak bushings, and installed HD bushings. If your car has the dreaded front end shimmy, replace your control arm (thrust arm, tension strut) with these. The OEM bushings are fluid filled that loose their fluid easily leading to premature failure and front end vibrations. These non-fluid filled bushings rid your car of the shimmy while lasting much longer.


http://www.eaceuroparts.com/catalog/product/453

Thank you so much guys.

I'll replace them as my next DIY.

Ok, people.
Here is an update.

I replace all brake disc to OEM new one.(and yes, I replaced pads as well)
And all control arms and bushing are tight and stiff.(I try to shake and move but they seems very tight)

However, I still have a front wheel shaking sometime when I brake. No shaking on low speed.
Like 50 ~ 60m/h and apply brake, it shake little bit.

Wheels? and tires? it has been balanced and did alignment.
ABS unit? it has been replaced by ABS unit fail.

Does anyone have an idea?

Thanks

Tires. Did you check that out? are they balanced?

Yes, Tires are very good and wheels are well balanced.
And while I drive, I don't have wheel shaking problem. Only when I apply brake on 60 mile to 30 mile down, it shake little bit.

Originally Posted by mikeson

And all control arms and bushing are tight and stiff.(I try to shake and move but they seems very tight)

if it shakes while braking it is either the discs(which you have replaced) or the thrust arm bushings.these bushings need to be visually checked.you can't see them in situ coz it is covered by the plastic protection cover.

when i i checked mine they were tight as well until i did a visual and later confirmed upon removal,they were torn....not to bits but they were torn.....

Originally Posted by mikeson

Ok, people.
Here is an update.

I replace all brake disc to OEM new one.(and yes, I replaced pads as well)
And all control arms and bushing are tight and stiff.(I try to shake and move but they seems very tight)

However, I still have a front wheel shaking sometime when I brake. No shaking on low speed.
Like 50 ~ 60m/h and apply brake, it shake little bit.

Wheels? and tires? it has been balanced and did alignment.
ABS unit? it has been replaced by ABS unit fail.

Does anyone have an idea?

Thanks

Edjack gave you the the best advice in the 2nd post. Renew the thrust arm bushings.

I know it seems counter to normal experience that suspension bushings would cause a shake under braking ... but that's the way it is with E39s. The E39 multilink front suspension is not a common configuration, so the common wisdoms don't work. This isn't to say that every brake shake is caused by the bushings. But for these specific symptoms the answer is virtually always the infamous thrust link bushing. This cause and effect has been confirmed time after time as described in the links that Bluebee gave you.

There is no test method to check the bushings, unless you get lucky and are able to see leaking fluid. Rather, one knows that the thrust link bushings are shot when the symptoms you described are present. BMW's TIS lists these bushings as a cause & also says that there is no check available.

FWIW, I am speaking with the voice of experience. I had the symptoms, checked my brakes again although they had less than 500 miles when I bought the car, checked the bushings visually and by push - pull, etc., etc. Everything was good ... except the driving results. I finally renewed the bushings and the shake disappeared.

Thank you for suggestion.
I'll replace them and will update here.

Thank you guys again.

I have one more question.

Sorry about to bug you guys.
Which one is thrust arm?

There is 2 arms and don't know which one is the thrust arm. Long one?
Because I removed plastic cover and visually check all bushing and shake but all of bushings were tight.

However, I'll take you guys advice and plaining to replace them but don't know which one is the thrust arm.

Thank you

OK, I find out which one is which.

I still have a question.
The thrust arm was right below end of strut. So do I have to lift strut up or I can take the arm out without touching the strut?

Originally Posted by cn90

[B]1998 BMW 528i




----------

Yes, the bottom of the strut must be removed to remove the thrust arm ball joint.

Hmmmm,

It sounds big job then. I may just replace bushing it self without removing whole arm.

Anyway, thank you.

You cant replace the bushing without removing the whole arm. Besides, new arms come with new ball joints too. Its not a hard job. I replaced both arms each side (4 total) in about 30-45mins on a lift. You just need to loosen the bolt that holds the strut in place and slide it up a little. It adds about 2 mins to the job.

Replacing the bushing is a HUGE PITA. Moving the strut is a minor PITA. Move the strut and replace the entire arm. And use the Lemforder arm with Meyle HD bushing.

As said dropping it down the strut isn't hard, one bolt to loosen and then slide it down. If you need a bit more clearance you can disconnect the anti-roll (sway-bar) links which allows the hub to drop further.

Ok, Thank you for you guys suggestion.
I'll drop it and will replace whole arms.

Thank you again and will report after replace. =)