[E39] Floaty steering at hwy speeds

"Pete" wrote

Oh yeah, here's the printout from that last alignment:

e39 at highway

were

path.

pulled out

detracts from

stable at higher

Apparently, BMW's own recommendation is to tweak the alignment specs a

it help?

exactly

manual with sport pkg, 32K miles, OEM

tires. I had the alignment done when

now practically in the middle of

the suspension/steering

damage of any kind.

this car, but

used to

can be.

twitchy

replacing items 9, 10, 11 in this

behavior, I might end up replacing the

before I find the problem.

It may well be the same problem I had which was that a rear wheel control arm was worn out: One rear wheel had a lot of play in its alignment, requiring me to correct the car's path all the time. This was with my previous E39 528i. Replacing the control arm cured the problem.

I now have a similar problem where I need to correct the course of my newer E39 530i more often than expected, but I suspect this time it is due to excessive friction in the steering system (perhaps the steering column itself). The symptoms include weak self centering of the steering wheel and a dead steering feel, even though wheel alignment ought to be ok (BMW just examined the car throughly).

"pfloding"

Which part exactly are you refering to? Is it nr. 14 in this diagram?

Hmm... that also sounds familiar, i mean that dead steering feel. So, what are you planning to do about it? More inspections? Blindly replacing of the steering column (what if that's not it?). Just living with it?

Pete

My car follows the grooves they cut into the concrete. This is normal.

"Jeff Strickland" wrote

Sure. But in my case the floaty feeling exists even on smooth asphalt with no grooves.

Pete

which was that a rear wheel

lot of play in its

time. This

the

this diagram?

I'm pretty sure it was part 18. It was a very thick alum> "pfloding"

where I need to correct the course of

expected, but I suspect this time it

steering system (perhaps the

include weak self centering of the

what

of

No, I tried lubricating it today. Read up on similar problems with other BMWs. Not sure how to get access to all bearings though. I just lubed the U-joint for now, and some areas around it more or less in hope. Access was not good. Unfortunately you can't hire ramp-time here in the UK.

I suppose the power servo itself could be to blame. At the moment my mother's SAAB 9-5 has more steering feel, and that won't do!

Patrik

"pfloding" a écrit dans le message de news: snipped-for-privacy@no-mx.cardealerforums.com...

For some reasons, when my Z3 has been delivered, the rear wheels were inverted and the tire sculptures pointing backwards. The car was floating a lot. Where I was driving 130 kph with the old E30, the Z3 was badly handling. I realized the mistake some weeks later, looking at pictures I took of the car ! Large tires have a tendency to tramlining on the ruts, especially on the right lane :-)

The tramlining of my Z3 was reduced considerably when I replaced the OEM Michelin MXM tires with Conti SportContacts.

Tom K.

BTW, Pete,

If you can jack up the rear wheels (one at a time will do), you can feel the problem I described as the wheel being able to move in and out. Grab it at the bottom with both hands and pull and push.

I think I restored some feel by lubricating the steering column U-joint, but I could be dreaming. I just think I can now just about feel the point where both front wheels are planted straight ahead (or following the curve on a cambered road, as it were), and self centering is a bit more positive. It's still a bit of the case of having to "steer straight" though, so perhaps there is more friction in the system to take care of, or there is some other problem -such as toe-in, or worn joints. The car has only done 50k miles, but is from 2002, so excessive friction in the steering system seems the most likely explanation (especially as the steering seems kind of heavy).

Check all the steering geometry, tyre inflation, wheel alignment, bearings and shock absorbers (or just put it in for an MOT).

This should reveal the problem.

Also check the badge - you might really be driving a yank car...

car follows the grooves they cut into the concrete. This is

Sure. But in my case the floaty feeling exists even on smooth

with no grooves.

inflation, wheel alignment,

for an MOT).

you might really be driving a yank car...

I doubt an MOT would find any subtle problems. Not even BMW's own check-ups finds smaller problems that, when they add up, degrade the feel of the drive. I suspect they rather like older cars degrading so their new models seem better than they are. ;)

"R. Mark Clayton" wrote

No such thing as MOT here in Florida. As a matter of fact, the cars don't have to pass any kind of state inspection at all. But I had the car checked at both the dealer and a BMW indy shop, and neither one could find anything wrong. Well, the dealer found leaking thrust arm bushings, which I replaced. It reduced the floaty feeling a little bit, but it's still not perfect.

It sure feels like driving a Buick sometimes.

Pete

Often on the big heavy cars you can't spot that there's some play in the supension until you've got the parts off. If the car's just wallowy then it's either just because that's the way the bigger cars are, or you need new shocks. I can't see the alignment measurements you have but in general toe-in leads to better straight ahead driving than toe-out which is better for cornering. If there is wear in the system you'll often get dynamic toe-out at speed even if the static figures don't show it.

"adder1969" wrote

Here are my alignment specs:

The only thing that's noticeably out of spec is the right front caster value, but the shop claimed that it was impossible to adjust it. Next time I get new tires, I will probably take it to a BMW dealer for an alignment.

As for the shocks, when I first got the car and when I observed this issue, it had 30k miles on the odo. Everyone I talked to said that it could not be the shocks at such low mileage. The roads down here are pretty good (no potholes), so the suspension doesn't typically take a beating. Then again, I am not the first owner so I have no way of knowing how and where the first owner drove during those first 30k miles.

Pete

I'm disallowed access to the photo site from work :-( I was going to mention caster but thought nah it can't be off. It can be adjusted but not necessarily without modifying other parts of the car - it depends how far out it is. Simplest is to elongate the strut top mounting holes. ...or again, it's a sign that something somewhere is so worn that the strut is way out of line. Positive is toe-ing out. I'd suggest setting it to 0 or slightly toe- in and see if it helps. You can do it yourself and if you count the number of turns you can always set it back.

"adder1969" wrote

The specified range for the caster is from 6 to 7 degrees. Mine is at 5.5 degrees on the right and 5.9 degrees on the left.

in and see if it helps.

The specified range for front toe is from -0.04 deg to +0.13 deg. Mine is at +0.08 deg.

The specified range for rear toe is from +0.05 deg to +0.22 deg. Mine is at

Pete

"adder1969" wrote

in and see if it helps.

The funny thing is that BMW TIS actually recommends setting the toe-out (but still within the recommended range) on the front in order to counteract the floatiness at high speed. This BMW TIS recommendation is what started my original thread. Here's its content again:

I did have the shop realign it using these recommendations, however, it made no noticeable difference in handling/stability.

Pete

suggest setting it to 0 or slightly

funny thing is that BMW TIS actually recommends setting the toe-out

within the recommended range) on the front in order to

floatiness at high speed. This BMW TIS recommendation

original thread. Here's its content again:

realign it using these recommendations, however, it

difference in handling/stability.

Yeah, but for the other case (pulling to one side) they recommend a relatively (compared to the toe-out) large toe-in. BTW, I wonder if BMW loaded down the car as recommended before alignment, and if not using it with the same total load and distribution affects things. Especially if some suspension component is worn out.

I assume the rear axle was checked for wear as well?

Mine is going to my local independent on monday to see what causes the slightly dead, non-centering steering. If he can't find any worn out parts, I guess it's back to BMW for a 4 wheel alignment. BTW, my car is perfectly stable on the highway, it's just that I got spoiled by another car that did a lot more of the steering (following the road) by itself

-and then I started to question where the famous BMW feel was...

Toe in will help high speed stability but might make the car not feel very responsive. Toe-out will do the opposite. You can have different settings front and back and that'll give the car a different feel depending how you have it. ..but thaving said that, if the specs are close enough to straight on then it sounds like there's something else at play, the castor being out of spec won't help.