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Restoration Lexicon (187): The lost game - recirculating ball steering

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The testers were enthusiastic at the time. It was 1953 when Mercedes-Benz took a big step into the future with the 180 model. The pontoon body already proved this at first glance. But the car also impressed when driving. In a uto motor und sport , Werner Oswald praised the 'ease of use, handiness and driving safety' of the new mid-range model: 'Primarily the excellent steering. '

Ladies choice: parking becomes child's play

It was the first time that Mercedes installed the smooth-running recirculating ball steering. The 190 SL was to follow. Other manufacturers - for example BMW, Opel or Land Rover - equipped various models with this steering system. Initially, however, there was no lack of criticism. The pontoon was seen by some as a 'lady's car' because it could be parked with an unexpectedly light hand.

Three and a half turns of the steering wheel were also enough to crank from lock to lock. However, according to the widespread opinion, cars for men have to implement steering commands more precisely. In the central position, i.e. the area in which one is usually when driving, not a few considered the Mercedes steering to be a little too indifferent. This was particularly noticeable when wear caused play in the steering gear.

'On the steering wheel,' says Mercedes-190 SL expert Fritz Wallner from Munich, 'the play may not exceed 25 millimeters.' If this is the case, the complete steering system with its tie rods and their linkages should first be checked. The faults often lie here and not in the interior of the steering gear, which is in principle robust. However, this is suspected if slight grinding noises can be heard when the steering wheel is turned.

The steering systems all die the same

This is what Fritz Wallner says from experience: 'First runs their oil on the hardened lower sealing ring. Then the friction causes severe damage inside. ' It would be a miracle if resourceful tricksters had not discovered a solution decades ago that can conceal this damage. Instead of the correct lubricant, the heavy-duty hypoid oil 85 W-90, they fill the steering housing with tough grease. The result is not very convincing: the grease remains in the steering gear, but wear still progresses quickly.

In addition, there is a popular mistake about the recirculating ball steering. Attempts are made again and again to minimize play in the steering wheel by adjusting it. Yet if for this game the wear and tearthe balls and their raceways are responsible, a correction is impossible. It can still be eliminated. For this, balls must be used in the appropriate oversize. Mercedes steering systems have between 60 and 64 units. Its diameter is correct if the nut runs tough but round. It must never get stuck.

However, this repair requires that the surface of the ball raceways is consistently undamaged. Breaks usually occur in the middle area (see photo show). This is not surprising because the steering engages when the steering wheel is in the middle position - it is the standard driving situation. In the event of such damage, a steering gear can only be repaired if a suitable steering worm and nut are available.

Nevertheless, the recirculating ball steering systems offer two options for setting. In this way the axial play of the steering worm can be corrected; the correct dimension is a maximum of 0.01 millimeters. In addition, a pressure screw (see photo show) minimizes the axial play of the steering shaft. In this way, the pan in the arm of the steering shaft and the ball of the steering worm nut can interlock without air. It is important that the steering shaft must not jam under any circumstances when it passes through the middle position. The bottom line is that defective steering remains a job for professionals. Even small mistakes can be dangerous - or at least expensive. A wrong setting is sufficient.

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