Can you run a PWR steer rack unassisted
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  1. #1
    Fellow Frogger! jarrods's Avatar
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    Default Can you run a PWR steer rack unassisted

    Does anyone know how the power steering racks in a 604/505 work. It is my understanding that the steering input shaft is not directly connected to the pinion but somehow twists slightly and in doing so tells the pump how much assistance to apply to the ram.

    I had an unassisted pwr steer rack in a 504 many years ago and while it performed ok at first after a while it appeared to get sloppy. ie where you could turn the input shaft slightly and the pinion would not move. It appeared that the power steering head had been damaged.

    I have heard of many people doing this but have not heard of any similar complaints.

    My reason for asking is that my 1/2 share 505 turbo V6 racecar is nearing completion and we look like having to run the rack unassisted. We want to retain the rack because it is a quicker ratio. We are running a PRV V6 with a left had bell housing and even by turning the pwr head upside down we cant get it to fit with the starter, clutch slave and turbo crossover pipe. We tried moving the rack across but this didn't seem to work either. I am going to investigate whether right angle fitting out of the pwr head will work. I am worried that the higher loads place on the rack (wider race tyres, higher speed etc) will create a bigger problem than I had in the 504. And I'd hate to think of the conscequences if it let go.

    Hope someone can be of some help

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    Jarrod

  2. #2
    Fellow Frogger! jarrods's Avatar
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    Or is it possible to transplant the rack and pinion into a manual rack housing?

    Jarrod

  3. #3
    Budding Architect ???? pugrambo's Avatar
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    well as far as i know 2pugs is running the power rack in his 604 without hoses and it seems to be working fine which tells me that the valve on the rack only powers the cylinder to assist in turning and there is a direct link through the valve to the rack

    the thing to remember is the orbital valves are a bit like a pump in that they move fluid as well and direct fluid

    all 2pugs did was turn the valve around to clear everything but left it in place

    the other thing you could do is modify the bell housing and mount the starter on the other side to give you a bit more room
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  4. #4
    Guru davemcbean's Avatar
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    I drove my 505 STI for about 6 months with the power steering pump removed. It was vague on centre, but that was due to previous wear on the rack itself. The play never seemed to get any worse in the 6 months that I drove it like that, and it wasn't all that heavy to steer either. The only reason I changed it to a (slow) manual rack was because it was sloppy and because I had plenty of normal racks.

    I plan to run a lightened 504 in future with a 604 rack without the pump. I believe these racks are more likely to be in better condition, because it's easier for owners to maintain them properly (easier to replace the rack nylon bush) and because the rubber bushes on each end protect them from shock more than the ball joints on the 505 racks. There's also the fact that 604s have usually done less kms.

    Dave
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  5. #5
    Guru davemcbean's Avatar
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    Quote Originally Posted by jarrods
    It is my understanding that the steering input shaft is not directly connected to the pinion but somehow twists slightly
    The shaft is directly connected to the pinion via a torsion bar. The torsion bar allows a small amount of twist which inturn allows the direction control valving to function.

    Dave
    NZ Fleet
    1976 504 Ti
    1984 205 GT twin carb
    1991 205 SI 1.6GTI motor
    1994 106 Xsi
    1996 Mondeo V6
    Aus Fleet
    1955 203C
    1997 Civic Cxi (great allrounder- revy, flexible, nimble, comfortable , economical, simple and durable )

  6. #6
    Fellow Frogger! jarrods's Avatar
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    Quote Originally Posted by davemcbean
    The shaft is directly connected to the pinion via a torsion bar. The torsion bar allows a small amount of twist which inturn allows the direction control valving to function.

    Dave
    This is what I thought, I just couldn't put it into words like Dave did (thanks). I believe the tortion bar on my rack was stretched (for want of a better word) by being forced to turn the wheels without the assistance of the ram, resulting in excessive play not just in the center but everywhere. This occured in a everyday road car driven over a period of 2 - 3 years and gradually got worse.

    Any other thoughts

    Jarrod

  7. #7
    Fellow Frogger! MR604's Avatar
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    Im running the 6 with out pwr steer. I dumped the pwr and turned the valve around 180 degrees so I could fit the LHD bellhousing for the manual box.

    The steering is heavier , but it's not unbearable. It's even better now that i'm used to it .

    If you're going to do it just make sure you keep the valve lubricated.

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  8. #8
    Fellow Frogger! OddFireV6's Avatar
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    Jarrod

    Its unlikely that the vagueness you felt in your 504 was caused by the lack of the pump, there is a physical limit to how far the twist on the tortion bar can go, it is limited after a small amount as Dave said.
    Last edited by OddFireV6; 9th July 2004 at 10:55 AM.
    OddfireV6
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  9. #9
    Fellow Frogger! WAUTY205's Avatar
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    Quote Originally Posted by davemcbean
    The shaft is directly connected to the pinion via a torsion bar. The torsion bar allows a small amount of twist which inturn allows the direction control valving to function.

    Dave
    In my rally 504 I have fitted a 604 unassisted pwr steer rack but I ran a weld arround the top of the input shaft joining the torsion bar to the outer pinion shaft. I must say though that the "tee" flange must be included in the weld also as there is the posibility of the torsion bar breaking on the weld, (not good). This modification stopped all vagueness due to the torsion bar twisting.
    Last edited by WAUTY205; 9th July 2004 at 10:32 AM.

  10. #10
    Fellow Frogger! jarrods's Avatar
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    Thanks guys.

    We might leave it as it is and see how it goes.

    Jarrod

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