Vibe in footwell/steering whenever above 100km/hr

[enjefriy]

Hi All,

My 86 e28 will shake in the footwell, as well as on the steering whenever i am at 100km/hr.
It will continue and somewhat worsen to a higher vibe when exceeding 100km/hr.
The shaking on the steering however is not a radial vibe, but rather a shaking felt through the steering column.

My actions have included replacement of the rotors and pads (due to a previous problem of the shake also occurring during braking), replaced the Thrust arms, control arms, steering center link, Front roll bar drop links, Engine mounts, and Auto Gearbox Mounts.
The Prop shaft center bearing was inspected but not replaced.

My replacements have severely reduced the vibrations from shaking whenever i lightly applied brakes, to the current consistent shakes when at or above 100km/hr.

My thoughts now are rear pitman arms (doesn't seem likely from what i see), and the drive shaft.

Since the alignment and wheels were balanced repeatedly to no avail, and at different workshops, i would now start to look at the other rotating assemblies.

With this all, i have several questions below;

Any thoughts or things i may be missing?
I also wanna know what sort of procedures are avail with respect to checking the prop shaft. So far i've only check for excess play which i cannot detect?
Any tools needed to ensure that the prop shaft is mounted straight whenever adjusting the center bearing?

Cheers all

[JhwShark]

Did this shake start out of the blue or after car work? It seems front located due to speed 100km or 60mph is a common speed for wheel vibrations due to tire imbalance and/or wheel bearings

I did not see you list the front wheel bearings or spindle.

For the Pro-shaft & CB you need square's and levels but it doesn't seem that...it would be prevelant under load, accel, decel...
Jon

[enjefriy]

I had this problem for near enough two years.
Been attacking it gradually with avail time.
It started with a severe shaking which was apparent when approaching 100km/hr and above.
It was also there when the brakes were applied ever so gently.

A slight temporary vibe also appears when initially accelerating from stand still. This happens very suttlely and for a short time only. In fact if acceleration was carried out more agressivley,
this shake would easily go un-noticed.

So engine mounts, Auto gearbox mounts, Guibo were all replaced. Found all shot. However all this did not erradicated the shakes found during acceleration from stand still.

Being at lost, I brought it down to the mechanics. He suspected the Brakes were warped. No warping was found on all fours. So pads were replaced thinking that these were causing the braking shakes. Nil joy.

Bearings were checked by grabbing hold of the wheel and looking for play whilst loading the wheel vertically and horizontally.
It was not suspected thereafter as the tyre wear was normal even thru 2 years of this, and becos there was no whinning or rumbling noises normally associated with a shot bearing. Even whilst driving thru curves or turns, no noise was evident. Further at any other speeds, the problem does not appears.

Next was the Steering center link replaced due found with a shot joint.
Shakes reduced, but still there.

Next the Control arms (lower control arms) were replaced. No joy.

Then the Thrust arms (UCA) were replaced. The shakes during light braking dissappeared.

The suttle Shakes during accelration from stand still remains, as that whenever above 100km/hr.

The mechanic said he could not detect any probs with the prop shaft. Says that the uni joints were not worn and that the center bearing looked good. At this point i was not too keen to replace them straight. (Have a 911sc to worry bout too at the time).

So what i thought was maybe the prop shaft was not mounted straight enough. Well aware of the procedures associated with parts replacement as i sat down with the guy to discuss the Haynes manuals.

My thoughts now is i read somewhere that for Thrust arm replacements, the cars must be loaded, and with 150Kilos located in the driver seat, front Pax seat, and another in the middle of the rear seats. We did not do this. I never thought twise of this as other e28 here never bother and all seems fine.

[enjefriy]

Update.

Checked the rear pitman arms.
They wiggle easy by hand.

Will update once i've replaced these. I doubt any improvements thou, as i have no swaying probs with this car. In fact this car handles nice in the curves.

(BTW Jhwshark, your 72 CSI is one of the reasons why i love this e28. In Brunei, these noses are called the Shark nosed Beamers. When i needed the cash to get married, i parted with the E30 and kept the e28. I miss the e30 still thou)

[JhwShark]

fyi...Both the e9 and the Porsche 928 are known as Sharks.

CV joints???

[enjefriy]

What checks would i need to c/out on the CV joints.
I cant find any radial play, however i can move the shafts laterally, i.e. in and out.
Could this be the issue.

[mda185]

You don't mention what kind of wheels you are using. Are you using the stock wheels? If not, do you know if the wheels you are using have the proper hub centric bore? This could be a contributor to the problem. You have done everything else logical to track down a vibration. Tires being out of round or wheels slightly off center are the only thing I can suggest.

[enjefriy]

Am using stock 14" wheels.
Raised car on jacks and selected Drive.
All rotating assy were smooth.
Replaced pitman arms, sorted.
I can now exceed 120km/hr before the most subtle vibe is felt thru the steering wheel.
New tires will sort this as 2 years of driving like this will undoubtedly wear em unevenly.
Cheers JhwShark & mda. I learn now that the rears have such a big influence on the shakes. For two years I only looked at the front joints, bushes and prop shafts and mounts.

Thks again for ur advise