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I started a new thread and copied the contents over to this new one. I fear that my original thread title was too specific and not drawing enough readers to get feedback. Thanks for reading guys...


Hi Guys,

The steering rack on my pre-facelift ML55 totally shit the bed. After topping it up over the last few years it suddenly started leaking very, very badly and so it was time to finally pull it out for a rebuild.

I pulled the unit out myself in my driveway and took the assembly to a respected local rebuilder who does a lot of ZF racks like ours.

Unfortunately there is 1 big problem. The steering shaft itself it not re-usable. It has surface corrosion on one end (the boot had some holes in it allowing moisture & road salt etc. to attack it) that once removed and polished, would result in a slightly smaller diameter due to the loss of a tiny amount of metal. The smaller diameter probably wouldn't seal properly with a new seal and there aren't any tighter seals that are available to compensate. Furthermore, the teeth on the shaft itself or the worm gear attached to the column are worn badly in the on center position so that there will always be play in the assembly and that play would lead to early failure of any new seals installed.

So the natural course of action would be to buy a rack from a dismantler and salvage the shaft and/or worm gear from it to rebuild mine. Even though a V6 and some V8 racks don't have the extra speed sensitive steering bits on my AMG, I imagine that the hard parts should interchange so long as the lock to lock ratio remains the same.

Easy right? Unfortunately not so easy when I look at the multiple part numbers. With so many variations of part number between the pre/post facelift, V6 vs V8, speed sensitive V8 (AMG vs. Ml500) vs. non-speed sensitive models, I just don't have the confidence to go buy a used rack until I hear from the experts on the forum. The 2000 ML55 has a specific part number that is supposedly not interchangeable with other W163s but I theorize it's because of the speed sensitive steering assembly. I would think that a speed sensitive ML500 rack from a 2002+ should be the same as the rack from my 2000 ML55 but it apparently has a different part #.

Can anybody provide some insight as to whether I can go buy any other W163 rack and salvage the shaft and worm gear from it?

Thanks!
 

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Just get any W163 second hand rack with the speed sensor(if your car has the sensor originally). I would suggest don't have your rack rebuild, fit the second hand one. All W163 racks are interchangeable, don't worry about part #'s.
My 500 has a rack from 270 from a junkyard. Never had a problem.
I have fitted many second hand racks on different W163's. As long as it's a W163 rack it will work.
 

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Just get any W163 second hand rack with the speed sensor(if your car has the sensor originally). I would suggest don't have your rack rebuild, fit the second hand one. All W163 racks are interchangeable, don't worry about part #'s.
My 500 has a rack from 270 from a junkyard. Never had a problem.
I have fitted many second hand racks on different W163's. As long as it's a W163 rack it will work.
I'm looking for a rack for my 01 ML55. So any rack with the speed sensitive steering option will work? Got a link to a Canadian supplier? I'm looking on a couple sites and they aren't showing the info for the speed sensitive steering option.
 

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Thanks. I'm finding some of those online, but they say they fit a few different ML's. I imagine that's not true?
Do not believe what you read. They are ignorant as to what fits what or they want to sell you anything.

It will only fit ML55s in different markets, but again, only ML55s.
 

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Just get any W163 second hand rack with the speed sensor(if your car has the sensor originally). I would suggest don't have your rack rebuild, fit the second hand one. All W163 racks are interchangeable, don't worry about part #'s.
My 500 has a rack from 270 from a junkyard. Never had a problem.
I have fitted many second hand racks on different W163's. As long as it's a W163 rack it will work.
Art, I need to replace the rack on my 01 ML320. I was at a junkyard today and tried to pull the rack off a 2000 ML430. I got everything loose and got the bolt out of the cowl but I could not get the steering column to detach. Any suggestions on what I should do to get that thing out? Or would I be better off getting a rebuilt one? Appreciate your feedback.
 

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Art, I need to replace the rack on my 01 ML320. I was at a junkyard today and tried to pull the rack off a 2000 ML430. I got everything loose and got the bolt out of the cowl but I could not get the steering column to detach. Any suggestions on what I should do to get that thing out? Or would I be better off getting a rebuilt one? Appreciate your feedback.
You won't be able to R&I the rack without a lift and even with that, it is a PITA.
 

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You won't be able to R&I the rack without a lift and even with that, it is a PITA.
I got the PITA part, for sure. What a pain. It literally is barely holding on. Both bolts through the steering column are off. I just can’t figure out how to get the column to release from the gear box. I didn’t want to try to force it and break something. Does it need some downward persuasion to uncouple?
 

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Did you remove the 14mm nut & bolt holding the shaft to the rack? If you did, push the shaft up & it will separate from the rack.
Leave the steering column alone. You have nothing to do with it. There is a square shaft that is attached to the rack. A 14mm nut & bolt are attaching the shaft to the rack. Remove the bolt & pull the shaft up & the rack will be free.
 

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Did you remove the 14mm nut & bolt holding the shaft to the rack? If you did, push the shaft up & it will separate from the rack.
Leave the steering column alone. You have nothing to do with it. There is a square shaft that is attached to the rack. A 14mm nut & bolt are attaching the shaft to the rack. Remove the bolt & pull the shaft up & the rack will be free.
Art, I removed one nut & bolt below the cowl and one above the cowl. Are those the ones you are referencing?
 

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Removing either one of those nuts and bolts is enough to separate the shaft from the rack. Push the shaft up. The shaft can be pulled/pushed.
Thanks, Art. Unfortunately, it will be next week before I can get back to the junkyard but I will let you know how it goes. The steering on my ML320 is slipping when I turn the wheel to the right and a mechanical problem is the only thing I have been able to narrow it down to. Want to try a used unit before I invest in a rebuilt one. Given what a hassle it is to remove, though, if the used one works that may be all she wrote.
 

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Thanks, Art. Unfortunately, it will be next week before I can get back to the junkyard but I will let you know how it goes. The steering on my ML320 is slipping when I turn the wheel to the right and a mechanical problem is the only thing I have been able to narrow it down to. Want to try a used unit before I invest in a rebuilt one. Given what a hassle it is to remove, though, if the used one works that may be all she wrote.
Art, finally got back to the junkyard and the rack was still there. I did a little jiggling and got it to come free from the steering column. Couldn’t get it out from the subframe, though. Do you have to take apart the torsion bar and lower control arm mount in order to remove it?
 

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no need to take apart anything. You have already separated the column from the rack. Remove the 2 screws holding the rack to the subframe and the rack will slide out from the wheel well. Take a friend with you. It is a 2 man job
 

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01 ML320 Rack Removal

no need to take apart anything. You have already separated the column from the rack. Remove the 2 screws holding the rack to the subframe and the rack will slide out from the wheel well. Take a friend with you. It is a 2 man job
Art, I am finally getting time to get after this and have run into a snag. The bolt holding the unit to the subframe is located directly below the front propeller shaft. What is the best way to get that bolt out of there? I am thinking that I might need to remove the bolt for the subframe bushing and lift the engine? Or loosen the lower control arm bracket to the torsion bar and get some room that way? Both? Here are some pics. Any guidance is appreciated.
 

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Unscrew the bolt and pull it out on both brackets. Steve I don't understand why are you having problems unscrewing those bolts
Art, the nut has been removed from the bottom of the bolt. There is not enough clearance between the front propeller shaft and the top of the bolt for it to be removed. Therefore, I cannot get the rack out. As you can see from the photo, the bolt is already loose as some thread is exposed. The front propeller shaft is directly above it. If you have seen this before, I am asking if you know the best way to tackle getting it out of there.
 

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I understand now. I have seen this before. The direction of the bolt is wrong. Someone has fitted the rack on the car with the bolt upside down. You have only 1 option , get a hacksaw & cut the bolt.
Well that may explain more things than it may appear at first glance. Do you happen to know the part number for those bolts? I will go ahead and replace both of them.
 
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