Is the suspension on the normal chasis and TI chasis the same? Are they interchangable? I heard you can use the TI trailing arms on the E30 as well.

The front suspension is the same across the entire E36 lineup except for some of the early M3s that had different pickup points for the front swaybar.

the rear is basically the same for the E30, Ti, and Z3 based cars. The Sedan and Coupe' got the "z axle" which was a better design and kept the wheels more in contact with the ground under all conditions. The Ti suspension used the older style semi-trailing arm suspension that dates back to the 2002.

Personally, I think that makes our cars more fun to drive. The older style suspension was a more "lively" design that could be easily kicked out when driven hard. The only real difference between the Ti/Z3 rear suspension and the earlier cars.. we have 5 lug hubs