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Thread: Which steering box is the best?

  1. #1
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    Which steering box is the best?

    I have an 88 735il which needs a new steering box. Should I order another 735il Servotronic box and keep running Pentosin? Or should I go for a 735i or e34 box and convert to ATF? I would need to change the reservoir, but thats no big deal because the self leveling rear suspension has already been deleted and changed to conventional springs/shocks.

    TIA!

  2. #2
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    Check the Signature
    Well if I were you I'd just go for the ATF box in the E34.

    Easier to come by those and since you already deleted the rear, there just isn't much reason to keep it.

    Good luck
    Present:
    '84 633 CSi (Restoring) DD
    '86 944 NA AT
    '91 750iL DD
    Past:
    '93 325is (R.I.P)
    '95 840Ci (Sold)
    '86 735i (R.I.P)
    '02 Z3 3.0i (Sold)
    '09 328i (Lease)

    BMW CCA Member since '08

  3. #3
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    E32 750iL+98 E36M3
    the steering box is the same on 735i and iL and 535 E34.
    The only difference is the power steering pump. In case of older 735 with H31 hydraulic brake booster unit and 735iL with LAD the power steering pump is a dual vane pump from ZF, one part for power steering and the other part for LAD. In case of no LAD the power steering pump of the 735 is a simgle vane pump from ZF.
    So if you have removed LAD, you can just recirculate the flow from the power steering pump to the Pentosin container and the rest remains the same.

    You can compare the part numbers on www.realoem.com
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  4. #4
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    Quote Originally Posted by shogun View Post
    the steering box is the same on 735i and iL and 535 E34.
    The only difference is the power steering pump. In case of older 735 with H31 hydraulic brake booster unit and 735iL with LAD the power steering pump is a dual vane pump from ZF, one part for power steering and the other part for LAD. In case of no LAD the power steering pump of the 735 is a simgle vane pump from ZF.
    So if you have removed LAD, you can just recirculate the flow from the power steering pump to the Pentosin container and the rest remains the same.

    You can compare the part numbers on www.realoem.com


    Realoem shows different part numbers for servotronic and non servotronic e32's, and e34's have different part numbers as well.

    6/88 735il
    32131134105 (servotronic up to 09/1989)
    32131466159 (up to 09/1989)

    6/88 735i
    32131134105 (servotronic up to 09/1989)
    32131466159 (up to 09/1989)

    6/89 535i
    32411134389 (servotronic up to 09/1989)
    32131135629 (up to 09/1989)

    Are they all the same box, just different part numbers?

    I had ordered an M5 box on ebay, but didn't notice there was a core charge and didn't pay it. I got a call asking about the core charge before they would send the box, and wanting to know that I had an M5 box to return. I didn't so I had to cancel that order

    Are there better options than Ebay to order a steering box from?

    Here's what I'm looking at:
    http://www.ebay.com/itm/1989-1994-BM...item43a42c1dd9

    Thanks for the help guys! This is for my dad's car btw!

  5. #5
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    yes, servotronic and non servotronic are different. Servotronic is speed dependent and has a torque converter at the bottom of the steering box and a control unit behind left speaker footwell.
    But this has no relation to LAD, Pentosin or ATF.Easiest is you buy the same steering box which was inside the car.
    M5 E34 steering box also fits in a E32 735, advantage for you but maybe not for your dad is that it is a bit more direct steering, disadvantage is the highe price.

    Just for example:

    Rmfd hydro steering gear Servotronic.
    Stock Code 32131134105
    Alternate Stock Code 32131132922; 32131133265; 32131134105;
    HYDRO STEERING-SERVOTRONIC (735i Automatic (M30) Sedan: Up To 09/1989
    735i Manual (M30) Sedan: Up To 09/1989
    735iL Automatic (M30) Sedan: Up To 09/1989
    750iL Automatic (M70) Sedan: Up To 09/1989

    http://parts.bmwofsouthatlanta.com/p...131134105.html

    the other number, product fitment, see here
    http://parts.bmwofsouthatlanta.com/p...411134389.html
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  6. #6
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    Quote Originally Posted by shogun View Post
    yes, servotronic and non servotronic are different. Servotronic is speed dependent and has a torque converter at the bottom of the steering box and a control unit behind left speaker footwell.
    But this has no relation to LAD, Pentosin or ATF.Easiest is you buy the same steering box which was inside the car.
    M5 E34 steering box also fits in a E32 735, advantage for you but maybe not for your dad is that it is a bit more direct steering, disadvantage is the highe price.

    Just for example:

    Rmfd hydro steering gear Servotronic.
    Stock Code 32131134105
    Alternate Stock Code 32131132922; 32131133265; 32131134105;
    HYDRO STEERING-SERVOTRONIC (735i Automatic (M30) Sedan: Up To 09/1989
    735i Manual (M30) Sedan: Up To 09/1989
    735iL Automatic (M30) Sedan: Up To 09/1989
    750iL Automatic (M70) Sedan: Up To 09/1989

    http://parts.bmwofsouthatlanta.com/p...131134105.html

    the other number, product fitment, see here
    http://parts.bmwofsouthatlanta.com/p...411134389.html
    Cool. Thanks for the info!

    Shogun, without your help there would undoubtedly be a few less e32's on the road today!

  7. #7
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    here is a 21 pages training manual for Servotronik, in section 4.4 there is a cross section drawing of the torque converter which controls the speed dependent servo support, German language, good drawings
    ftp://bmw-wiki.org/PDFs/SeminarArbei...ervotronic.pdf
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  8. #8
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    two 3's one 5 three 7's
    I have the ATF reservoir & PS pump from an "i" car in case you would like to convert it.

  9. #9
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    Just a thought - E32 steering boxes are much stronger than necessary. Are you certain that your steering box is toasted?

    Some here have reported good results through adjustments.

  10. #10
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    Quote Originally Posted by E32FAN View Post
    Just a thought - E32 steering boxes are much stronger than necessary. Are you certain that your steering box is toasted?

    Some here have reported good results through adjustments.
    Symptoms are when cold there is no power assist when trying to turn right, then when warmed up there is a difference between assist in turning right and left. It is not super noticable, but its there and when turning right the assist is not constant, causing an overall unstable feeling.

    I have adjusted the box, replaced the servotronic thing in the steering box, and finally as a way of troubleshooting I looped the servotronic control unit in the driver's kick panel.

    Looping the servotronic control unit in the kick panel should prove that the issue is not with the servotronic system. By looping it, the system defaults to full assist all the time. Even with this looped the symptoms are still present.

    It is my understanding that generally when there are differences in turning right and left it is a steering box issue. Tie rods and such are in good shape, no play.

    The e32 box itself is robust, when they are rebuilt the only parts replaced are internal seals. I believe the internal seals of my box are leaking and causing my issues.

    I really hope I'm right, $300-$400 on ebay for a reman is what I'm looking at for a replacement.

    Thanks for the help guys, I appreciate any ideas I can get because this thing has been an ongoing issue for a few years now.

    Shortly after we had bought the car, my dad was on the freeway and had to avoid something in his lane, he ended up fishtailing one direction and then the other, and slapped the center divide with the left rear corner. It pushed the bumper to the pass. side and left a small scrape on the corner, I replaced the bumper with a pnp unit but the scrape is still there as a reminder. Pops was confident that it was the uneven steering issue that made the car hard to control. :/

  11. #11
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    E32 750iL+98 E36M3
    no power assist wehn cold:
    first of all I would flush the system so that all small channels get clean again, the torque converter might be dirty or the filter between torque converter and steering gear. Yes, there is a filter and most do not know, see here
    http://twrite.org/shogunnew/fixes/steering.html
    then the servotronic module might be defective, see also link above.

    And last but not least, the old hydraulic hoses have to be replaced, the get over the years "swollen" inside
    Kinked, collapsed, dented or clogged hydraulic lnes, hoses or connections - repair or replace faulty part.A hydraulic shop can crimp new hoses on the metal pipes of the system, cheaper than new hoses with steel connections from the dealer. I have done all my hydraulic hoses that way.

    "The e32 box itself is robust, when they are rebuilt the only parts replaced are internal seals. I believe the internal seals of my box are leaking and causing my issues."

    I have repaired my one. See pics here
    http://www.7-forum.com/forum/24/uber...ebe-87034.html

    the set of gaskets/seals was 32 13 1 134 768
    My parts guy told me in 2008 that BMW would stop providing this set and worldwide at that time 400 sets were available. Last year I ordered 6 more sets and then were only 40 left.
    But I got plenty of sets from China now.These are bought by the professional steering box repair shops worldwide. The only problem is that the chinese suppliers usually have minimum qty limits, some 200 sets as one order. They usually supply to wholesale.
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  12. #12
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    I am haunted by a comment that I heard years ago from a used parts supplier:

    "No, I refuse to sell you a used XYZ part, because mine will be nearly as old and tired as yours, and you will afterwards be angry with me."

    Perhaps the lesson is to love your very own OE core part, and rebuild it as shogun so often advises. This is spending quality time with your E32 . . . IF the rebuild works, of course!

    The problem is that it takes time and experience to become confident that you can make the repair a success. shogun has invested countless hours to get to the skill level where (almost) every repair is a win.

    shogun is like the bowler in the next lane, who only bowls Strikes. Erich, how can we each become better bowlers?

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