Steering!

[Kevin Bird]

I've just joined here https://www.mye28.com/viewtopic.php?f=2&t=161385

Tonight was my first drive after checking over the car, which is surprisingly good.

The power steering is very heavy (which I don't remember from my 528i SE I had 30 years ago) and it has some slack straight ahead. Is this normally a symptom of a tired pump and rack?

[vinceg101]

Starting with an examination of the front suspension and steering components is in order. A bad/worn/tired center link and/or Pitman (or Idler) Arm may be one cause. After check the Tie Rods.
Otherwise, it may be the Steering Pump (or Steering Box) itself that needs replacing. You can buy these remanufactured.

If you don't know the repair history of the car with documented replacement dates & miles, then an overhaul of the whole suspension & steering systems might not be a bad idea. Depending on the driving conditions, if you're over 100K miles and being 35+ years old, it's likely time for this to happen (likely overdue).

[Kevin Bird]

Thank you!

[Randomg]

Do some more searching before you rebuild the box. On center slack is designed into the box. You can tighten the nut underneath the driver's thigh panel (but not so tight that you can't adjust the telescope or you hear/feel clunks), you can replace the u-joint between the box and the column (mine I could feel a bit of play, but didn't notice a difference when the new one was installed), you can replace that rubber piece between the lower and upper steering column (but I've read people here say they couldn't feel a difference), or you can rebuild or get a supposedly less mileage box (but I've read people here do both of those and say it felt worse than before). I'd focus on the steering linkage between the box and the tires first. Once everything else is perfect, you can look into adjusting the top screw on the box carefully with a really low tq wrench. Unfortunately, it's never going to feel as tight as a rack and pinion. Weakest part of the car imo, the on center feel. Still prefer it to super direct with no feedback like I've felt in newer M5s.

[Kevin Bird]

Do some more searching before you rebuild the box. On center slack is designed into the box. You can tighten the nut underneath the driver's thigh panel (but not so tight that you can't adjust the telescope or you hear/feel clunks), you can replace the u-joint between the box and the column (mine I could feel a bit of play, but didn't notice a difference when the new one was installed), you can replace that rubber piece between the lower and upper steering column (but I've read people here say they couldn't feel a difference), or you can rebuild or get a supposedly less mileage box (but I've read people here do both of those and say it felt worse than before). I'd focus on the steering linkage between the box and the tires first. Once everything else is perfect, you can look into adjusting the top screw on the box carefully with a really low tq wrench. Unfortunately, it's never going to feel as tight as a rack and pinion. Weakest part of the car imo, the on center feel. Still prefer it to super direct with no feedback like I've felt in newer M5s.

All the arms from the steering box have recently been replaced so I’ll try adjusting the box

[Kevin Bird]

I've adjusted out the slack, OK, and all the joints are good. But it's still heavy, but also the brakes don't have much assistance. I see the brake booster is from the power steering system. Could a weak power steering pump be causing both issues?

[Preyupy]

The steering effort on a M5 is different than all of the other E28 models. They used a different steering box with a faster ratio. I have also found that the brake pedal effort seems higher on the M5 as well compared to the other E28's I have driven. I used to be a BMW master technician and was still at the dealerships when the M5 showed up. I did pre-delivery inspections and noticed the heavy steering and brakes back then when I was driving 5 or more different E28s a day.

[Kevin Bird]

The steering effort on a M5 is different than all of the other E28 models. They used a different steering box with a faster ratio. I have also found that the brake pedal effort seems higher on the M5 as well compared to the other E28's I have driven. I used to be a BMW master technician and was still at the dealerships when the M5 showed up. I did pre-delivery inspections and noticed the heavy steering and brakes back then when I was driving 5 or more different E28s a day.

Thanks!

[Kevin Bird]

Update - New pads have bedded in, so the braking has improved, and I'm using M5 tyre pressures, which has also improved the steering