Mild steering wobble at speed

zcacogp · May 8, 2015

Chaps,

Quickie; my S2 has a slight steering wobble at speed. It feels like a wheel is a bit out of balance and it comes and goes a little. It's most noticeable at around 90-95mph but sometimes doesn't seem to be present at all. Gentle application of the brakes or steering in either direction makes no difference to it.

It's always been there, as long as I have had the car (10 years / 70,000 miles), which means it's outlasted several sets of front tyres and brakes, a change of wishbones and bushes and some new steering tie rods. The wheels are perfectly balanced at the moment (recent new tyres) and yet it's still there.

What else could cause this? What are the likely suspects? I know that some people have had great results from changing one of the steering column parts but I don't know which one or whether the symptoms I have are of this part wearing out.

Thanks,

Oli.

Monkeythree · May 8, 2015

Sounds like uniformity. Most often this down to tyres but if you've been through several sets with no discernible difference then I would look at the wheels. It may be that a wheel has taken a knock some time in the dim and distant past. It will still balance within limits on a workshop machine but uniformity and balance are not the same thing. I would find a tyre fitter who has a Hunter uniformity testing machine in their shop and get them to spin them up on that. Ask them to measure the radial run out too.

white944 · May 8, 2015

Luckily the speed limit in the UK is 70 mph, so it isn't an issue[

]

kdp · May 8, 2015

Do you have locking wheel nuts on the car?
I put a set of locking wheel nuts on mine and that caused a noticeable wobble at about 70 to 75 mph that wasn't there beforehand. They were heavier than the lightweight wheel bolts that they were replacing and as soon as I removed them all was back to normal.

Eldavo · May 8, 2015

Is your Porsche crest on the centre cap pointing to the valve or not?

(I always feel that someone needs to assume your role when you ask a question [

])

Waylander · May 8, 2015

top mounts have been know to cause this as well

BlackMagic · May 8, 2015

I had this problem for 180,000 miles before I found that one of the front wheels was slightly 'wavey'. It would balance out fine but the wobble always came back.
Try and borrow a pair of front wheels from your local indy, or a good friend, and see if it disappears.

William

944Scott · May 8, 2015

Is there anywhere that still balances wheels on the car ?

bmnelsc · May 8, 2015

My '91 S2 developed a vibration after several years on the same tires - I assumed the balance had gone off tho I had a strut/shock change on my to do list so I left it. After the struts and shocks were changed (Koni strut inserts and rear shocks) and a fresh alignment - vibration was gone!

My struts and shocks held up to the push down test and were not leaking - I replaced them at only 90K km due to age but turns out they were on the way out.

As for top mounts - mine were still in good shape. I suspect the S2/turbo top mounts are quite durable as they are the later design with lots more metal and less rubber.

Diver944 · May 8, 2015

Sounds like one of your front wheels has a slight buckle or the universal joints on your steering shaft have a bit of wear.

A new shaft with both UJ's used to be under £100 from Porsche but I think I read they've gone up now

zcacogp · May 8, 2015

Thanks for the ideas chaps. Sounds like the easiest thing to try would be some replaement front wheels. Snag is that I don't know anyone in the area who has a 944. JasonP would have been ideal, but he sold his.

Maybe it would be worth asking a local independant porsche place whether they have a set they could lend me for an hour or so? I'l try creating a thread on here too.

Oli.

Cater_Racer · May 9, 2015

Not something daft like after market locking wheel nuts? Most LWN are steel affairs much heavier than the light alloy OEM nuts.

George Elliott · May 9, 2015

Reading all that, it has to be a buckle.

I'd say balance can accomodate a buckle,so the tyre fitter will be happy at their fixed speed, but a balanced buckle will still cause a shimmy which will vary with speed.

Good luck

George
944t

944Scott · May 9, 2015

The closest I could find.

http://vibrationfree.co.uk/our-services/wheel-balancing/

zcacogp · May 9, 2015

Chaps,

Thanks for the answers. I'm going to be using the car this afternoon for a motorway journey so I'll try taking the locking wheel nuts on the front off and replace them with some spare alloy ones.

Failing that, I'll try the loan of some spare wheels - I have three offers on the other thread.

Oli.

zcacogp · May 9, 2015

ORIGINAL: 944Scott

The closest I could find.

http://vibrationfree.co.uk/our-services/wheel-balancing/

Thanks for the link. I'm sure it's a great service but at £80 for two wheels, I'll try other avenues before going down that route.

Oli.

zcacogp · May 9, 2015

ORIGINAL: Eldavo

Is your Porsche crest on the centre cap pointing to the valve or not?

Cheeky oik! [

]

Oli.

zcacogp · May 10, 2015

Chaps,

Update on this one; I changed the locking wheel nuts on the front for a pair of regular wheel nuts (I had a few left around from when I bought new ones) and took it on a brisk outing last night. And, to my significant surprise, it seems to have cured the problem. 140ish miles at speeds of not more than 70mph* and the steering was much, much more stable than before. It's not totally smooth - there is still slight vibration, but I'm happy to put that down to the other few bits of the steering system that are still original.

So, many thanks for the suggestions, it looks like I have got to the bottom of the problem. Always nice when it turns out to be something simple, eh?

The next question is what to do about the front wheels, which currently don't have locking wheel nuts on. But I think that's one for another thread.

Thanks again.

Oli.

* - This may not be quite true. That S2's easily outperform Turbo's is a well-known fact, and I'm told that a 951 can top 80mph with a good following wind ... [

]

jonnyporsche · May 10, 2015

This thread has answered the question of why my 951 has only got locking wheel nuts on the rear (since I bought it) I thought it was that any low life wanting to nick the wheels would have a go at the wider ones. [

]

944Scott · May 10, 2015

ORIGINAL: zcacogp

Chaps,

Update on this one; I changed the locking wheel nuts on the front for a pair of regular wheel nuts (I had a few left around from when I bought new ones) and took it on a brisk outing last night. And, to my significant surprise, it seems to have cured the problem. 140ish miles at speeds of not more than 70mph* and the steering was much, much more stable than before. It's not totally smooth - there is still slight vibration, but I'm happy to put that down to the other few bits of the steering system that are still original.

So, many thanks for the suggestions, it looks like I have got to the bottom of the problem. Always nice when it turns out to be something simple, eh?

The next question is what to do about the front wheels, which currently don't have locking wheel nuts on. But I think that's one for another thread.

Thanks again.

Oli.

* - This may not be quite true. That S2's easily outperform Turbo's is a well-known fact, and I'm told that a 951 can top 80mph with a good following wind ... []