R&P steering

R&P steering

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Discussion

dan101smith

Original Poster:

16,806 posts

212 months

Sunday 22nd February 2009
quotequote all
What's the easiest way to get rid of the steering box and replace with a power assisted rack on an E28 M535i?

MartinD

2,138 posts

228 months

Sunday 22nd February 2009
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dan101smith said:
What's the easiest way to get rid of the steering box and replace with a power assisted rack on an E28 M535i?
I dont know how much of the E28 front suspension is the same as an E34 , if very/same then use the E34 525iX (4 wheel drive) rack set up ?

dan101smith

Original Poster:

16,806 posts

212 months

Sunday 22nd February 2009
quotequote all
The 525iX uses an E36 rack, which doesn't line up particularly well. Almost all other 5ers use a box, so they're out. An E21 has a rack, but that's something like 4 turns lock-to-lock, so too slow.

I'm wondering if going custom is the way to do it.

MartinD

2,138 posts

228 months

Sunday 22nd February 2009
quotequote all
dan101smith said:
The 525iX uses an E36 rack, which doesn't line up particularly well. Almost all other 5ers use a box, so they're out. An E21 has a rack, but that's something like 4 turns lock-to-lock, so too slow.

I'm wondering if going custom is the way to do it.
Does it matter if it doesn't line up so long as it works ?
Maybe a why you need/want a rack would help replies

dan101smith

Original Poster:

16,806 posts

212 months

Monday 23rd February 2009
quotequote all
Looking into this with a friend who has an M535i.

The problem with the standard steering box is that it has a load of dead travel around the straight-ahead, that means you always end up loading the steering slightly one way or the other, and so end up making constant corrections and having extra travel when changing direction. Annoying, particularly on a B-road blat.

The ideal solution would be to find a rack that lines up, and allows the geometry to stay within tolerance. From looking at something like an E36 rack, it would introduce a significant amount of bump-steer.

It may be that there's nothing off-the-shelf that can be bolted in with minimal work, in which case custom-made might be the way to go.

But if there's something else out there that is a nuts and bolts job then that'd be preference, obviously.

welwynnick

107 posts

193 months

Monday 23rd February 2009
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Buy a better car instead. Seriously, I wouldn't even think about fitting a rack, and I'm not the person to dismiss that sort of idea.

What I would really suggest is putting the front end on axle stands and adjusting the backlash/pre-load on the steering box. Thats the big nut on top with a a locking nut.

Experiment a bit and set the backlash to zero with the wheels in the straight ahead position, and leave it with positive backlash on lock. Racks generally don't do that, they bind on lock, which is exactly what you don't want. Recirculating ball boxes can be good!

Then have a look at all the couplings, joints, bushes and ball joints in the steering mechanism, and replace anything thats slack or worn. Have a close look at universal joints and sliding splines.

Sort all that out, and you won't want a rack any more!

Nick