Vague Steering

[donoman]

I just bought a new 2.5i and the car is great, love it! As a little background, I already have a 2.5i running RFTs, but this newer one has sport package and is running non-RFT's.

I feel like the car drives really well but there is definitely a vague feeling that is hard to describe:

-Feels like the dead zone is a lot wider than normal
-Feels like the car is harder to maintain in lane
-Feels like the steering ratio is not the same as the other car... I turn the wheel and expect it to turn but the car doesn't turn as much as I expect
-No shaking
-A slalom would definitely be more difficult in this car

I was pushing it a little the other night and when the car caught traction again, it bit harder and got wobbier than I expected and I had to correct. I was totally not expecting this. Front tires are balding but I don't expect this much loss of feel from that. Strange because I know RFT's are supposed to track worse than non-RFT's but this is not the case right now.

So what do you guys think? Where should I look first?

[keeton]

Originally Posted by donoman

So what do you guys think? Where should I look first?

Tires. This assumes you have checked for the obvious such as suspension wear (particularly the bushings) and have checked the tire pressure.

Just because RFT's have their issues (notably a rougher ride) doesn't mean that all non-RFT tires are better in every respect. The stiff sidewalls of RFT tires can actually provide for better turn-in.

You didn't say what your non-RFT tires were. If they were one of the softer tires (e.g. Continental DW), I could see where your observation was coming from.

[i2ichal2dZ4M]

whats the mileage on car? probably time for FCAB

[unluky]

FCAB is what I was thinking to. If you look through my posts I have been fighting this some as well since I bought the car. New non-RFT got 95% of it, but I still have some wandering with a neutral wheel. Mine drove and cornered great, just on straightaways while cruising with a neutral wheel, I would just some very slight back and forth play. I just changed out my FCAB to poly ones, and think that got it all fixed up. Been on a few hour long runs in it and I never experienced it anymore. Might not be yours, but you are probably due anyway if you have many miles on it.

[i2ichal2dZ4M]

Didn't older Z4's have steering rack/colluhm issues as well? I remember reading something of that sort

[donoman]

Thanks for the suggestions. The car has 80K miles on it.

The car actually feels more "normal" in turns than going straight.

I'll check the tires.

[donoman]

03-05 Z4 have electric power steering binding when the steering column mechanism overheats. The worm gear expands and binds in the mechanism... gives you notchy, binding steering.

[unluky]

That sounds like what I had - corners were fine and stuck like glue, I only noticed it in straight line driving. FCAB seemed to fix it for me so far. Easy change and if you have 80K on your OEM ones, you are probably due. I had 60K on mine.

[imz4n]

I would guess like others , the front control arm bushings. This being a new car to you, the cars when new have a strange alignment in the front, perhaps the previous owner had an alignment done and is different that your original car. Check that the tires have not been mismatched , all tires are the same brand and have the same contact patch. The non-M/// cars have electric steering and coding can be changed as to the amount of steering wheel feedback High, Medium, low. To check your fcab's jack up the front of the car or while on a hoist, hit the bottom of the tire while watching where the FCAB are and see what kind of movement you are getting at the bushing. IMHO any movement would suggest the need to replace.

[donoman]

imz4n,

that was an amazing post. I learned like 3 things from it! Thank you very much.

I will have the car on a lift very soon. Just found a cool DIY lift place 5 minutes from my house!

[donoman]

imz4n,

that was an amazing post. I learned like 3 things from it! Thank you very much.

I will have the car on a lift very soon. Just found a cool DIY lift place 5 minutes from my house!

[imz4n]

Happy to help, or at least try to help.

[donoman]

FCAB's are replaced and the front end feels tighter.

Now, I feel like the car tram lines or wanders more.

I'm going to do a rear control arm bushing refresh this weekend. What do you guys think?

[imz4n]

With tire pressures checked and the same tires other than size all around, tires balanced, I would have a look at the top shock mounts in front, the rubber top hat like to crack after time, this can be visually be inspected for the engine bay, looking at the shock tower mount, while you are there check where the firewall braces attach and make sure where they attach to the shock tower is not broken. I would then be looking at an alignment.

[donoman]

imz4n,

Pressures checked, but unfortunately running different tires up front vs. back. Why would this make a difference?

Popped out RTAB last night and it looked great. Installing new ones anyways with limiters.

My top mount bushings are starting to look worn so I have some front struts with new top hats going in soon. I'm starting to think this is an alignment problem so I'll get that done next week after I'm done going through the suspension.

What does a bad ball joint do? I hope it's not my ball joints... hate replacing those!!!

[donoman]

RTAB swap complete, both bushings looked great but car does drive a little tighter now. I also installed RTAB limiters so that may be what I'm feeling. Car does seek a bit on uneven surfaces compared to my other 2.5i. I'm going to run an experiment where I swap the wheels and see if it's the tires. If it's not the tires, then I'm guessing alignment because the top mounts are not really messed up that bad. Will report back.

[Shipkiller]

Originally Posted by donoman

Popped out RTAB last night and it looked great. Installing new ones anyways with limiters.

My top mount bushings are starting to look worn so I have some front struts with new top hats going in soon. I'm starting to think this is an alignment problem so I'll get that done next week after I'm done going through the suspension.

What does a bad ball joint do? I hope it's not my ball joints... hate replacing those!!!

As soon as you touched the RTABs, then your rear alignment is off.
The RTABs main function is to attempt to keep the rear wheels straight (minimal toe change) with relation to the thrust axis. The limiters help with this.

I do not think the ball joints on the ///M are replaceable. I think you have to replace the entire control arm. I could be wrong but I have not ever seen a way to replace just a ball joint.

[donoman]

Originally Posted by Shipkiller

As soon as you touched the RTABs, then your rear alignment is off.
The RTABs main function is to attempt to keep the rear wheels straight (minimal toe change) with relation to the thrust axis. The limiters help with this.

I do not think the ball joints on the ///M are replaceable. I think you have to replace the entire control arm. I could be wrong but I have not ever seen a way to replace just a ball joint.

I think you're right. This particular Z4 is my 2.5i (not my Z4MC) but the same holds true... ball joints are integrated into the control arm.

I know the alignment isn't perfect but I'm going to swap out suspension in the front and then probably get new wheels/tires. Then I'll be ready for an alignment!

[donoman]

Alignment is done and car is handling way better. Not perfect as it still tramlines a little but I will attribute that to the worn hankooks that I'm running up front in conjunction with the rear mismatched Cooper RS3s. I haven't had this car up on all fours yet so that might be next if I want to be picky.

[Vanne]

get some new matching tires , that would be my next move

[gas-can]

Originally Posted by imz4n

...The non-M/// cars have electric steering and coding can be changed as to the amount of steering wheel feedback High, Medium, low...

Sorry for the slight hijacking but...

Imz4n, do you know which programs allow access to this setting? It's the first time I've heard of this.

Thanks,
-gc

[imz4n]

Short answer is no ( head hanging in shame ). When we purchased the 2004 new, questions were asked re: steering wheel feedback. Sorry to say I was a newbe at that time and did not know to find out. questions about DRL's, softtop control and headlights ( how the inner and outer lights functioned ) were the questions asked at the same time before we took delivery.