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Thread: Steering rack issue's causing brake judder on track? S15

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    Guest S15_SAM's Avatar
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    Steering rack issue's causing brake judder on track? S15

    Ive had issues with my S15's steering for a while, when i turn sharply to the right the steering goes very tight when you initially turn the wheel then free's up. I've had a look so many times and can't see any UJ issues and have replaced most parts, new steering arms, rack bushes, tension rods, suspension, polly bushed Lower arm, new balljoints and wheel bearings And still the same. Could it be the rack? How many joints in the S14/15 steering system.

    So I had a track day today, was brilliant day but my S15 had really bad brake judder which i believe is related to my rack, as I was coming into quarry corner on the brakes and turning (tut tut I know) but I tried to turn in and the steering went tight and heavy, whilst judder was occurring. Any way the rack would cause judder when braking?

    I'm running stock caliper rebuilt a year ago, stop tech fast road pads, standard grooved discs only a week old. But even after two warm up laps I had judder.

    I'm thinking of replacing the rack and UJ's and then maybe uprights and caliper's to try and cure this, is really odd! Any simliar stories with successful cure?
    Last edited by S15_SAM; 29-09-2014 at 19:06.

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    Guest Si's Avatar
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    Checked the belt tension and belt and pump condition? Changed the fluid?

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    Guest richie s14a's Avatar
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    Brake judder would suggest something like worn track rod ends, as for tight steering could just be low power steering fluid level.

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    Guest S15_SAM's Avatar
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    The belts are a year old and tension seems ok, fluid is at max and is 3 years old so I would imagine its ok. When steering normally there is no tightness its only when you want to flick the car into a right hander and you really turn in fast it goes tight as then frees up.

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    Guest Si's Avatar
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    Does it do it when turning both ways, or just right? Are you talking track driving or drifting?
    It's just when you say 'flick' it puts me in mind of a very fast steering input, and if there's an issue in the hydraulic circuit somewhere, it's possible that it may not be supplying enough assistance. I run a Saxo PS pump on my car and I get a similar feeling with fast inputs, as if it's not keeping up with the requirements.
    Last edited by Si; 30-09-2014 at 11:33.

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    Guest S15_SAM's Avatar
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    Its when I turn right only, I can get it to do it when the car is static too. I'm really thinking its a rack/UJ now. I will change the fluid though and see if it changes, part from that I think I may buy a new/2nd hand rack, new hubs to eliminate and bent parts there and then see why happens. May upgrade the brakes too as I don't do drift days at the moment its track only for me, and big brakes would defo help!

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    Guest S15_SAM's Avatar
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    So to update my thread. I had two issue's.
    The tight steering I believe was my rack, I replaced it with a 2nd hand unit and also replaced my UJ with a brand new item and now the steering is brilliant. (Old UJ felt ok, also used new fluid)

    My brake judder issue I finally resolved today. I bought some wildwood calipers and 345 discs. And I still had the brake judder....
    So today I got the dial/DTI gauge out to measure my disc and hub runout, my RH disc moved from -0.3mm to +0.4mm (not right). So I removed the disc and measured the hub directly and all ok. Then I spotted the back of the disc mounting face, it had indents around the wheel stud holes. Basically the splined knurl section of my extended wheel studs, which I fitted 4 years ago, Protruded through the hub too far and the disc could not sit 100% flat. So if you've had the same issue as me then please check this.

    I ground out 2mm of the back of the disc hole so the disc could sit flat. Runout was reduced to +0.04mm only and have driven it hard and no judder! Only took 4 years, and 4 sets of discs to find this! Pillock!

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    Bet its such a relief to finally find out the problems tho mate!

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    Guest S15_SAM's Avatar
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    Yeah big time! Can finally get back on track and not have to worry about the brakes!

    Photos for future reference:

    Marks on disc

    Marks on knurl of stud:

    The runout video:

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    Guest jon200's Avatar
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    Bit of a thread bump, Sam did you have a look at the old Rack to find any faults with it?


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    Im having the same problem with my 14 for the last year. Same symptoms you describe only my cart also has a lovely habit or running the PS pump loose every other month, no amount of lock nuts, threadlock etc can keep the dam thing tensioned!!

    Nothing seems to fix it so my next step is replace the rack. Did you recon the new rack or just fire in a second hand unit?

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    He had a brake disc stud issue that caused the judder under braking. The rack caused "tight steering". Im assuming you didn't read the thread or som how managed to miss posts 7 and 9 that tell you this?

    Regarding your steering belt loosening have you tried a new belt and double checked you're tightening all relevant tensioner bolts? Have you checked that you're running the right fluid and it's not airating? FYI S bodies use ATF, NOT power steering fluid. Give the system a good bleed too. Try it with the front jacked up and slowly go from light lock to lock, engine off probably 20times+ for a full bleed.

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    He also had a steering rack/UI issue that caused his tight steering, his response to this is what I'm asking about since iv tried everything but the rack so far to fix my car.

    And yep tried all the above, including new bolt and adjuster, even tried another pump and still the same thing happens. The very last thing I can think is a knackered rack is causing feedback in the hydraulic system and "knocking" the pump causing it to vibrate itself loose. It's a long shot but as iv tried literally every other component in the steering system the only thing left I haven't changed is the rack itself.

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    Guest jon200's Avatar
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    Jordan, do you have judder when turning slightly or?


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    Occasionally yes but it's far more severe when I'm pushing on a bit, say going hard into a tight corner, it happens with or without applying the brakes but it's defiantly worse if I'm hard on the brakes at the same time as steering aggressively. To completely hijack the OPs thread, I'd love to hear any other suggestions for possible causes.

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    Guest jon200's Avatar
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    Same as mine, hopefully i am getting the rack rebuilt in the next few weeks.


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    Guest jon200's Avatar
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    Did anyone sort their issues?


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    I have Sam's old rack, haven't been out on track with it yet but pushing on on the road it has been fine so far, I didn't reuse his UJ though and have new basically everything around it. Agree with him that UJ seemed fine off the car, sorry I know that isn't terribly helpful but means it may not be the rack itself.

  19. #19
    Guest jon200's Avatar
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    Let me know if anything changes. I am finally replacing the inner lower arm bushes in the hope is sorts my problems but i am not convinced


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