bmwbav
bmwbav New Reader
8/26/13 5:10 p.m.

Hi All, Contemplating replacing the steering box in my BMW with a rack, it's an E3. I appears I can custom order a rack with the correct width to match my suspension geometry and the rack travel appears sufficient. Is there anything else I need to consider, is it that simple? Has anyone retro-fitted a rack into and older car?

Thanks

ransom
ransom GRM+ Memberand UberDork
8/26/13 5:30 p.m.

Rate: It doesn't matter if it travels far enough to get good lock if it takes fifty three turns of the wheel to get there... Apart from geometric considerations (in lieu of a better idea, just making sure the tie rod's inner ends are right where they'd be with the old steering) and getting the steering column hooked up to it, that's about all I can think of...

Where are you finding a rack done to specifications? Very much pertinent to me and my plans for the 2002; I'd appreciate the info...

bmwbav
bmwbav New Reader
8/26/13 6:26 p.m.

In reply to ransom:

Yes, rate is a concern as well, I'll see what I can get.

This company makes the racks to your specs. http://www.unisteer.com/

I'll talk to them and see what rates are available.

Knurled
Knurled GRM+ Memberand UberDork
8/26/13 6:59 p.m.

What are the possibilities of just swapping an E30 subframe and struts under there? If the framerail widths are similar, that'd be the best way.

ransom
ransom GRM+ Memberand UberDork
8/26/13 7:09 p.m.

In reply to bmwbav:

Thanks!

bmwbav
bmwbav New Reader
8/27/13 11:04 a.m.

In reply to Knurled:

Yes, I tried that a while back, the suspension geometry doesn't work unfortunately, as that would be ideal. The frame width is close enough, but the struts are at a steeper angle that won't work with the E3 strut towers. In this period of BMW chassis, E3-E34, E21-E36, there are two main front suspension designs. The 3-series and the 5/6/7 series, the track width is also pretty close, but the struts on the 3-series are at a sharper angle. The strut towers would need to be a few inches closer together on the E3, and it wasn't worth my effort to remake those...

bmwbav
bmwbav New Reader
8/27/13 12:30 p.m.

In reply to ransom:

So, I called and they quoted 3.25 turns lock to lock on the rear-steer racks, that's with 5.25 inches of travel. The stock rack width was 24 inches, where the E3 needs 19.5 inches to align with the control arms. It seems like it will work, but it wasn't clear what effect shortening it would have on the amount of travel...

ransom
ransom GRM+ Memberand UberDork
8/27/13 2:24 p.m.

In reply to bmwbav:

Seems like something they should be able to answer definitively...

Pulling numbers out of thin air, but... 24" minus, say 3" for end joints, minus 4" more for bushings at the rack's ends, minus 5.25" for travel, leaves 11.75" of working area inside the rack. 5.25" of that must be toothed for travel, leaving 6.5" available for shortening without adverse effects? Hopefully you're good with 2" to spare... Reality may disagree...

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