E36 M3 Front Suspension Overhaul Part III: Rebuilt Z3 Steering Rack, New Tie Rods and Universal Joint

So with the subframe all reinforced and installed I turned my attention to my freshly rebuilt Z3 Steering Rack. I picked mine up from the rackdoctor. Make sure you call him about the Z3 rack. He knows what they looks like and they take a couple weeks to procure. They come with a lifetime warranty for $375. He will not accept any other rack as a core.

Removing the rack includes the removal of two bolts through the subframe, tie rods on the end, universal joint on the shaft and the power steering lines. The bentley should have all this information on torques and what not. It's pretty straight forward. Here is my 95 M3 rack next to a 96 1.9L Z3 (TRW) rack. Most BMW racks are made by ZF but the Z3 is a TRW rack.

There is a TON of speculation on the forums about how fast racks actually turn. The only person that knows really what they're talking about is Itsablur on BFc. I can quickly summarize. There are 3 things to measure.

A) The distance in mm the tie rods extend per revolution of the steering gear from the direct center of the rack. This is important for track as you never really go much past 180º revolution from center. The 95 M3 rack for example is progressive and gets more aggressive after 180º degree revolution off center. (This is measured in mm/rev)
B) The overall 360º revolutions of the steering gear between locks. (Turns lock to lock or LTL)
C) The overall distance the tie rods actually travel between locks. (Rack distance LTL)

The information is scattered on BFc but I've measured 3 racks. A lot of info is in this thread. The 1995 M3 rack, a standard e46 rack and the TRW Z3 rack.

95 M3 Rack is progressive and different from 96-99 E36 Rack.

A= 40mm/rev on center. After one 360º revolution on center the rack moves about 50mm/rev on the outside. Which helps for parking.
B= 3.0 Turns LTL
C= 140mm total steering angle

e46 rack is linear (Part # 32 13 6 753 438) Almost the same as 96-99 e36 rack.

A= 46mm/rev anywhere measure on rack.
B= 3.26 Turns LTL
C= 150mm total steering angle

Z3 TRM rack is linear

A= 51-53mm/rev anywhere measured on rack. I couldn't really get a solid 53mm/rev. It was closer to 51-52mm.
B= 2.7 Turns LTL
C= 136mm total steering angle. I believe this is what I got. I remember is was slightly less than the 95 M3 rack.

Alright so that's the school lesson. The numbers are close enough. Within 98% accuracy. The idea is that the Z3 rack has the fastest response on center. The e46 rack looks like a nice rack too with decent on center ratio and a lot of angle for parking if you're on the street a lot. I would say the 95 rack is probably the strangest rack out there, but it is still a huge upgrade over the 4.0 turns LTL e30 rack.

When I installed my new rack I decided to change out the rubber guibo/universal joint on the steering shaft. The old one wasn't torn but it looked kind of beat.

My goal was to refresh any rubber on the front suspension or replace it with a solid mount if available. I tried to keep the steering wheel straight upon removing the old rack and putting in the new one. I calculated about where the z3 rack's center was and measured the distance the tie rods were at from the old rack just to get me in the ball park before I went to get an alignment.

Tie rods were new Lemfoerder e36 m3. I ordered the lock nuts from TheBMWPartStore. Great service, great prices and free shipping over a certain amount.

The Z3 rack is a rolled/stamped steel rack and not cast. The 95 M3 rack as well as others are cast with a threaded boss to secure the power steering cooling line. The Z3 does not have this threaded hole. To secure the "trombone" power steering cooling line that is used on the 95 M3 to the Z3 rack I borrowed another forum member's idea and created a small bracket out of stock aluminum bought from the hardware store.

I used an OE BMW hose clamp which is absolutely necessary. ;)

Torque down the subframe mounts, tie rods and power steering hoses. Remember to use new crush washers for the power steering hoses. I forgot and had to run to the dealer for $2.05 a piece!!

Here's an image of the rack installed. Yay.

After installing the Z3 rack in my car I can say it is much more responsive, but it is not like an F1 car where I can't go past 180 degrees or I'm at full lock. The 95 rack I had in there needed new tie rods so I went for a rebuilt rack. If my rack was fine I'm not sure I would go for the swap. I think the most steering effort is felt from the delrin control arm bushings.

We'll wrap this up with a strut mount swap and x-brace installation.