| |||||||||
|
This article the installation of a 1995 E36 M3 steering rack into an E30 M3. The E36 M3 rack, with modified steering coupler and instructions were obtained from ( www.zionsvilleautosport.com ) The goal of this conversion is to reduce the steering ratio. The E36 rack has a faster rack ratio - the rack moves a greater distance for a given angular rotation of the input pinion shaft. Since the "installation ratio" is the same (same subframe and steering arms) then the net result is a faster overall steering ratio - 24% quicker, in fact, with the E36 M3 rack. Note that using "number of turns lock-to-lock" is not a very useful way to compare steering ratios, as the length of the rack, as well as its installation, can and do change the # of turns lock-to-lock (from car to car) - with no change whatsoever to the actual steering ratio. The results of using a 1995 E36 M3 steering rack in an E30 M3 are summarized in the following table: | |||||||||
| |||||||||
| |||||||||
|
The E36 M3 rack housing is aluminum, whereas my E30 M3 rack housing was steel. The aluminum housing might offer better cooling - it is tough to know for sure. (Don Fields from Mr M-Car notes that many E30 M3's came from the factory with aluminum rack housings, perhaps mine was an early version). The two racks were not weighed for this article, but any difference in mass is not likely to be large (a qualitative assessment). One can see a difference in the angle at which the pinion enters the two different rack housings. This difference causes greater angularity in the joints in the steering coupler when using the E36 M3 rack in an E30 chassis. The coupler joints hence require modification to prevent them from binding up. Zionsville provides a modified coupler as part of their E36 M3 rack conversion kit. | |||||||||
| |||||||||
|
The steering rack swap gave me the excuse to do something I've wanted to do for some time. I made an aluminum spacer ring to replace the rubber steering Guibo that all BMW's seem to have. My old 1976 Rabbit did not have any rubber in the steering system, and I had always enjoyed the direct steering feel such a setup offered. The steering Guibo is intended to absorb kickback through the steering wheel - a job it does quite well. Unfortunately it comes at a price of reduced feel and communication. The aluminum replacement is quite easy to make and install at this point, since the coupler is out of the car. The difference is not huge, it's just one of the many little things that go into making a car feel great, instead of just good. | |||||||||
|
Note: Don Fields from Mr M-Car points out that the modifications to the steering coupler shown above, namely the solid Guibo and the bolts used to lengthen the coupler, both reduce the ability of the steering column to telescopically collapse in an accident. I drive with a roll bar and a 6-point harness, and I make a conscious decision to accept this change to the steering column. Make sure you think about it too, should you decide to follow suit. |