Steering feel at higher speeds

[Nmbrsix]

Since purchase, my '02 Box has had an odd sense of on-center slop at speeds above 75mph. I've had a suspension refresh including new front track arms, at least one rear control arm (bad ball joint) and track arm, new Bilsteins/strut bearings, new tires (Conti ExtremeSport Contact), and 4 wheel alignment all done by the best shop in the region. I've also had one of the front wheels straightened that was causing some vibration above about 70mph, but the steering feel issue has remained throughout. At any lower speeds the steering feels nicely weighted without this on-center slop.

Any thoughts on this? Is the rack bad? Control arm bushings? I've been trying to ensure the car is ready to do DE days, but I don't think I'd feel confident in it as it is currently.

[NewArt]

29 psi cold in front?
Recent alignment?

[Flavor 987S]

How many miles on the new tires? All 4 tires new? Need at least 200 miles to scrub off the mold release agents.

Probably bushings.

[thstone]

Inspect the inner and outer tie rods.

[jakeru]

Seeing as we're both in greater Seattle, I can offer to meet up and let you drive my 2001 box 'base, for comparison purposes, if you think might be helpful? I feel the steering and handling are decent, although it does have > 100k miles on it, and the suspension isn't completely noise-free. I've Done some suspension work, (the suspension was in very sad shape when I first go the car, to be honest...), although not sure if to the same extent as all that you've done. I've got M030 springs, and Koni sports (so far, in the front, installation of rear Konis will be happening eventually...) Michelin all-season tires. Live on the Eastside, commute to downtown Seattle. Seems stable at high speeds, but also am a bit curious how it compares to other 'boxes!

[RandallNeighbour]

One thing you can try that's free is to put some weight in the front trunk and drive the car to see if it changes the feel.

I had a very squirrely front end at speed and realized I had a box of parts in the back that were heavy enough to make the front end too light. Now I carry all trunk related stuff up front instead of in the back when I need stowage.

[Gilles]

Also worn front struts could cause vibration and the feeling of having 'loose steering'

.

[heymanwatchthis]

I have been working through the same issue. Over 75mpp feels squirrely, on DE's I did not feel comfortable at high speeds because front end of car felt light. On the other hand, the back of the car felt absolutely glued to the ground.

I have changed my rake - ie the height of the front relative to the back. Have PSS9's so this is possible for me. I raised the back of my car by about 3/8 inch, based on wheel well height.

Did it last week, I can feel a difference on the highway at higher speeds and still trying to figure it all out - but it does seem to help.

After playing around with it to get an idea of how it works, am going to take it to the pros for corner balance and alignment.

You may want to take a look at your rake - I understand the back should be a little higher than the rear - too high and you get oversteer, so be prudent.

Good luck!

[Nmbrsix]

The car has 73k miles on it currently; I bought it in June 2015 with 69k.

When I took it to Tru-Line, I instructed them to look for any suspension components that looked worn and replace them ahead of doing an alignment. I also replaced/upgraded the struts at that time as one was leaking.

This is what they replaced:

-Both front track arms
-LF wheel straightened (removed slight vibration at 70+mph)
-LF wheel bearing (suspect the bent wheel killed it)
-LR control arm (bad ball joint)
-LR track rod
-All 4 struts replaced with new Bilstein HD's; all related hardware replaced with OEM components (strut bearings, etc)
-New Contis have around 1000mi on them now
-4 wheel alignment was performed by the best shop in Seattle (who also did all of the suspension work ahead of the alignment)

All of this work has been done in the past 2400mi, or two Summers of driving. The car is primarily a Summer time highway commuter for me; it hasn't seen any DE/autocross days or anything that would have worn the new tires in an irregular way. This behavior was also present with the old tires and alignment.

I'm suspicious of the tie rods and front control arms, too...is there a standard way to check for wear on them?

[Nmbrsix]

Originally Posted by jakeru

Seeing as we're both in greater Seattle, I can offer to meet up and let you drive my 2001 box 'base, for comparison purposes, if you think might be helpful? I feel the steering and handling are decent, although it does have > 100k miles on it, and the suspension isn't completely noise-free. I've Done some suspension work, (the suspension was in very sad shape when I first go the car, to be honest...), although not sure if to the same extent as all that you've done. I've got M030 springs, and Koni sports (so far, in the front, installation of rear Konis will be happening eventually...) Michelin all-season tires. Live on the Eastside, commute to downtown Seattle. Seems stable at high speeds, but also am a bit curious how it compares to other 'boxes!

Hey Jake--I live in NE Seattle and would be happy to take you up on your offer. Maybe one evening after work in the next few weeks?

Jon

[Nmbrsix]

Originally Posted by heymanwatchthis

You may want to take a look at your rake - I understand the back should be a little higher than the rear - too high and you get oversteer, so be prudent.

Good luck!

Thanks for the suggestion. The car sits a bit higher in the rear at rest, so I'm not sure that's my issue here...that seemed to change after the suspension install, actually.

[heymanwatchthis]

I found raising the back of my car helped with high speed stability and cornering, however there is still some play on-center at higher speeds.

I am going to refresh some front suspension components - a question for you guys who have done this - to tighten up the on-center slop, what should I replace first? The tie rods or control arms? Which generally has most impact upon replacement?

Thanks!

[Racer Boy]

Originally Posted by Nmbrsix

The car has 73k miles on it currently; I bought it in June 2015 with 69k.

When I took it to Tru-Line, I instructed them to look for any suspension components that looked worn and replace them ahead of doing an alignment. I also replaced/upgraded the struts at that time as one was leaking.

This is what they replaced:

-Both front track arms
-LF wheel straightened (removed slight vibration at 70+mph)
-LF wheel bearing (suspect the bent wheel killed it)
-LR control arm (bad ball joint)
-LR track rod
-All 4 struts replaced with new Bilstein HD's; all related hardware replaced with OEM components (strut bearings, etc)
-New Contis have around 1000mi on them now
-4 wheel alignment was performed by the best shop in Seattle (who also did all of the suspension work ahead of the alignment)

I agree that you took your car to the best alignment shop in Seattle, That is where I had mine done, and I was greatly impressed with their work; they really know their stuff.

It's strange that the symptom you are getting only occurs over 75 mph. If the problem is a normal mechanical one, it seems like it would show up at all speeds. Is your front bumper cover undamaged? Are all the under-body covers in the front intact? I'm wondering if maybe something with your bodywork is amiss, and causing some lift at higher speeds.

[jakeru]

Originally Posted by Nmbrsix

Hey Jake--I live in NE Seattle and would be happy to take you up on your offer. Maybe one evening after work in the next few weeks?

Jon

Yes, this sounds fun! Let's connect via IM sometimes in the next few days, and we can make a Boxster get together happen, or perhaps just plan to get something on the calendar. If we pick the right weekend day, that could work well for me also. I sometimes travel to the view ridge neighborhood to visit family.

[Anker]

Bad toe-in alignment on either front or rear will give you exactly this feeling. As weight shifts from one side to another the car will have a tendency to drift towards the high load side. The reason why it feels worse at high speed is because the drift will be more severe as the speed increases.

Another possible cause, which I am sure you don't have is severe loss of tire pressure in the rear. The first indication of a punctured rear wheel is loss of steering stability. I was once a passenger in a Mercedes running at very high speed on a highway when one of the rear wheels had a puncture. The driver was barely able to control the car. After we changed the tire he then proceeded to fall asleep at the wheel. Scary trip.

[Nmbrsix]

Originally Posted by Racer Boy

It's strange that the symptom you are getting only occurs over 75 mph. If the problem is a normal mechanical one, it seems like it would show up at all speeds. Is your front bumper cover undamaged? Are all the under-body covers in the front intact? I'm wondering if maybe something with your bodywork is amiss, and causing some lift at higher speeds.

New front belly pan installed this spring; bumper cover undamaged.

The car had this issue with both prior sets of front tires, too, so I can't place the blame on the Contis (although they do tramline more than the others did).

Funny enough--I opened the frunk a couple of days ago to discover that I still had the box containing the OEM suspension for my Mk7 GTI in there. So there is some weight over the front wheels--with no change.

The steering is nice and heavy at lower speeds, only getting light around center at higher speeds.

[Nmbrsix]

Something just occurred to me...

My car came with a non-OEM (likely eBay) rear spoiler. Not the OEM unit.

It does extend, but I have no idea as to whether it has any real effect.

I wonder if that could be causing the higher-speed instability?

[Flavor 987S]

Originally Posted by Nmbrsix

Something just occurred to me...

My car came with a non-OEM (likely eBay) rear spoiler. Not the OEM unit.

It does extend, but I have no idea as to whether it has any real effect.

I wonder if that could be causing the higher-speed instability?

Yes. Aero is off. Too much rear downforce is making the front light, and changing the rake with the front lift.

[Racer Boy]

I doubt that any rear spoiler is making downforce. Most spoilers are only capable of reducing lift, not creating downforce. You need a wing to create downforce.

Nmbrsix, can you easily remove the aftermarket spoiler, and see what happens? Although I am skeptical that is the cause of your issue, it's worth a try.

[stephen wilson]

Originally Posted by Racer Boy

I doubt that any rear spoiler is making downforce. Most spoilers are only capable of reducing lift, not creating downforce. You need a wing to create downforce.

Nmbrsix, can you easily remove the aftermarket spoiler, and see what happens? Although I am skeptical that is the cause of your issue, it's worth a try.

Semantics, anything that reduces lift IS creating downforce. There are plenty of aerodynamic devices that create downforce besides a wing.