e36 steering rack swap sluggish & vague

[Rich Dixon 91is]

I did the e36 swap on my 1991 318is to a 3.2 lock to lock rack. I expected to have crisp, responsive steering in place of the 4.0 lock to lock nascar steering of the stock e30. Instead, I have to turn the wheel around 100 degrees just to swerve in my lane. After around 100 degrees, it feels more progressive, but there is a big, slow range for 90 degrees both directions off center. My column is tight and it engages without play, but the input is very low ratio.

The rack looked great on inspection and worked fine out of the car, without being able to test the ratio of course. I left the e36 tie rod ends on the rack because they looked and felt great. My tires are new. I can't think of any other variables but I can't believe this is what an e36 325is steering feels like.

Any advice or thoughts?

[tjts1]

Did you put the rack yourself from an E36 or did you confirm that you have an E36 rack with the part number on the rack? Did you do an alignment after the swap?

[Rich Dixon 91is]

Did you put the rack yourself from an E36 or did you confirm that you have an E36 rack with the part number on the rack? Did you do an alignment after the swap?

I did not check the number because I know what they look like, but obviously I should always check the part number. It's also exactly 3.2 lock to lock, which matches the 325is that the seller said it came out of. If there is another rack that looks identical to an e36 rack, then maybe there was a part mistake that I missed.

[tjts1]

hmmm, maybe you just have a bad alignment.

[DesktopDave]

I'm thinking (hoping) it's an alignment issue.  The steering should be progressive.

[Romrog318is]

shud have got an e30 M3 rack

[tjts1]

If the alignment was never re adjusted on the E36 tie rods, your wheels will be extremely far toe out. They need to be brought back in for the narrower E30.

[Rich Dixon 91is]

Thanks for the responses. I hadn't mentioned that I had an alignment.

It was user error. I had tried to reuse the rubber boot at the firewall which fit fine when everything was loose, but after I had tightened it up the clearance was too tight for the 3mm rubber section on the boot. It was binding at the boot causing it to be very heavy and stiff. I cut the boot off and the steering sprang to life. The dead zone was my imagination.

I usually don't solve stuff until I open my mouth and complain about it. What's the lesson here?

[Rich Dixon 91is]

If the alignment was never re adjusted on the E36 tie rods, your wheels will be extremely far toe out. They need to be brought back in for the narrower E30.

bump to bring it up again because this is definitely not right. My steering is much too vague for this to be correct. The response is immediate, but the input from the rack is minimal. It's like I'm driving a 1980 300D. When I make a u-turn with the wheel turned to lock it still has the incredibly small turn radius of an e30 which seems to indicate that the ratio is correct. So I'm baffled why large steering wheel input has little steering input.

My setup: e36 rack 3.2 lock to lock with e36 tie rod ends; vert front sway bar/H&R rear 18mm; bilstein sports; H&R Sport springs; AKG poly control arm, subframe, rear swing arm and diff bushings. I bought a new u-joint coupler that joins the column shaft to the rack but didn't use it because the original seemed to be perfect with no play when I had it out.

tjts1 or anyone, can you tell me what would be the effect if my toe was too wide? Could it cause vague steering? I had it aligned at a good shop and it tracks perfectly but I wonder if they were thrown off by the model of the rack or if they just made a mistake. One thing that surprised me is that they didn't center the rods up on the rack. I had to eyeball it just to drive it to the shop and that caused the tie rods to be offset to one side. I guess I can test the toe myself by making equal turns on both sides, but if anyone can tell me if improper toe could deaden my steering, I'll listen.

[Voluted]

Do you have a late model e36 rack? It has really large metal pipes on it compared to the e30 rack. I was reading that those racks have a variable ratio based on engine speed (or pump speed). Maybe the rack feels like crap because the pump on the M42 isn't moving as much fluid as it should to move the rack properly? Something to think about at least..good solid information seems hard to find.

[bmwman91]

Do you know what the donor car was that the rack came from?

Just FYI, the desirable rack is the Z3 1.9L unit...2.7 turns L2L.  It took me almost 2 weeks to get used to the ratio...a flick of the wrist was enough to change multiple lanes at once.  Even still, a 3.2 rack should feel faster, or at the very least about the same.  If it feels slower than you didn't put in the rack you think you did!

Anyway, the solution for the firewall is to take a round file & remove a little material so that the rubber boot fits in.  You should also seal the bare metal edge with PVC paint to prevent rust.

If the toe is incorrectly adjusted, it can wreak all sorts of havoc on your steering capabilities. The shop shouldn't care which rack is in there.  The laser alignment equipment (assuming that is what they used) just makes sure that all 4 wheels are good relative to one another.  The toe is the ONLY thing you can adjust on an E30 anyway (you can usually get them to cut the service fee in half if you argue this point, FYI).

Did you get a print-out of the alignment numbers?  Post it up if you did!

[nickmpower]

some of the e36 racks have variable ratio. The steering is slower just off center and then quickens up

[Ryann]

What you're describing is kind of how the steering felt in my '83 VW GTI after the large round of firewood I ran over ripped my steering rack from its mounting points. There was this huge dead spot until the body of the rack would jam into the subframe allowing the steering column to move the tie rods instead of the entire rack.

[PumpItUp]

i'm guessing its not the coupler ._. http://m42club.com/forums/showthread.php?t=11391

[Rich Dixon 91is]

This is the rack I have. The part number raised into the metal of the body is 7852 501 174 042. The riveted metal plate has another number printed on it: 7852 955 227, another number stamped on it: 068296, and what I presume to be a date of manu stamped on it: 0495. I am using the short coupler off my airbag 91 318is.