What wrong with my car- steering judder and loose vague feeling

[jon200]

I could do with some help. So I've done a few track days and they have ended rather quickly due to what feels like brake judder but i don't think it is. It gets progressively worse as things warm up. I can feel judder when all is cold when moving at slow speeds too when turning slightly on a smooth road. Apparently the wheels could be seen wobbling when braking on track which i could feel on the steering wheel too.

Brakes are Aston martin Brembo's mated to 370z discs with custom brackets. Discs have been replaced but made no difference. Brackets have been beefed up incase they were flexing and made no difference. Fluid is DOT5 and calipers were brand new.

Chasing the vague loose wobbly feeling i have also replaced all outer ball joints, tension arm bushes, rack bushes, coilovers!, swapped wheels from front to back. All tyres are good and recently balanced too. I replaced the power steering fluid as it was very dirty and replaced the belt too. Fluid is clear of air when running and sounds fine.

I have inner arm bushes to change but i don't think it will be this.

My thoughts are either
1, bad pas pump
2, bad rack although it feels solid with no play but maybe a little spongy
3, loose subframe?
4, wheel bearing getting play when warm(they feel fine normally and quiet) car has done 60k

I am tempted to swap brakes to try it but its strange why i can feel some judder when not braking when its cold still. Plus i don't have any

Any advise very much appreciated! If anyone has a pump i can have that would be good too.


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[Chriscooke]

Crap on the hub where the disk mounts?

[jon200]

Nope all clean and disc runout is fine. Forgot i had checked runout too. Good shout though.


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[CrazySx]

Are you running spacers?

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[Chriscooke]

Wheelbearing, brackets the tc arms mount too loose?

[jon200]

Are you running spacers?

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No spacers.


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[jon200]

Wheelbearing, brackets the tc arms mount too loose?

Wheel bearings could be another possibility will add it to the list the TC brackets have been removed and refitted when the bushes were done. They were bloody tight too!!


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[jon200]

Is someone can screen shot the page on the FSM that shows the power steering operating pressure that would be great. I cant get to the page on my phone without scrolling one by one!


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[Chriscooke]

I meant the big buggers at the front (nismo power brace style) parts. Sure they're bolted in

[CrazySx]

Have you jacked the car up and checked for play side to side and 12-6?

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[CrazySx]

I would be VERY worried if your wheel bearing was that shot.

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[jon200]

Yeah thats the ones I've had off chris. Will double check though.

I don't think its bearing but im open to any possibility to allow me to sort this out! No play anywhere. Did new coilovers as there was a little play 12/6. No play in inner rod joints


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[CMR]

Did you buy it with the Aston brakes on it?

[jon200]

No mate, i sourced and fitted them.


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[green_rs13]

vague front steering is usually bottom ball joints

[jon200]

They have been done, maybe vague isnt the right word. Just don't have confidence


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[ant1]

What are rear discs like? Had similar in mine could swear it was front related. Change rear discs and solved the problem or it randomly disappeared

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[jon200]

Rear im not sure about bit they look pretty good. One caliper was replaced with new a few years back and the other was in good condition anyway. The front wheels could be seen wobbling too which was why im looking front end.


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[ant1]

If it happens only when braking then it's brake related for sure. In some big brake conversions with bracket spacers that can sometimes cause issues. I think it would be obvious if it was wheel bearing. I would jack the car up get a long bar and lever every joint to see if any bushes have gone

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[jon200]

Surely with new discs i wouldn't have any issues and would see runout with a DTI? I have got two spacers/washers to get the caliper in the centre of the disk but would this cause wobble with good disks?


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