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Ron Stygar Carl Buckland Dale Beuning Forums Help
From digest.v6.n594 Mon Apr 28 18:49:23 1997
Bob Stommel, an instructor for the BMWCCA Drivers Programs, asks...
> xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx "Coilovers" is tossed around as a general term more than it should be. Technically, it just means "the strut sits inside the coil spring." The McPherson struts that are stock on most BMW's are "coilovers," though not adjustable. The stock setup for the rear of our E36 cars is a seperate shock and an inboard spring. The H&R coilover system retains the stock approach, whereby the fronts utilize a strut with a spring around it, and the rear is still a seperate shock and inboard spring. The H&R system, by retaining the stock setup, is legal in SCCA Street Prepared competition, whereas a system that converts the rears to "coilovers" is not. I have also heard that the rear shock towers will NOT withstand the pounding that they will get if the spring is brought in to the shock. I would recommend staying with the stock type arrangement. The Bilstein Group N system, as I understand it, converts the rears to coilovers. I also know that the shock/strut valving is VERY heavy, and the only springs that are offered are VERY heavy. There are also patched together coilover sytems offered by Koni and maybe others, but I think that the H&R is the only one that was designed ground up for the E36 . The H&R coilover system can be purchased from BMP at 1-800- 648-7278. I believe that the cost is in the $2500 range, although that is not a current quote. The front ride height is adjustable, because the spring sits on top of an adjustable perch. Be sure to also order the tools that are needed to make this adjustment easy. There are many factors to consider when determining ride height, one of them being "corner balancing." Even with only the fronts adjustable, lowering or raising the fronts affects the weight on the backs. The best way to adjust them is to put the car on 4 corner scales. Generally, the lower the fronts, the more weight is transfered to the front corners. The system comes with valving and spring weights that make the car very streetable, yet give a much improved, firmer ride for the track or autocrossing. The BIGGEST advantage of getting the H&R system is that Roland Graef, director of H&R USA, can offer you a vast assortment of spring heights and weights. The system starts out with 340 lb front springs and 380 rears (the stock springs are about 115 front and 335 rear). The car drops .75 at the rear, and the front, which is adjustable, drops .75 to 2 inches (that is very low). I have gone from the 340's at the front to several levels stiffer, which also entailes using tender springs. Roland can advice you on this. I have also gotten several sets of rear springs, and have found that you almost can't get too stiff for the track, but you will turn the car into a monster for street and autocross. Even with the "stock" coilover springs, the understeer has nearly gone away, as stiffening the rear springs and going to a stiffer sway bar traditional does. The springs, especially the front springs, are very small in diameter, and will give you plenty of room for all the negative camber that you could want. The stock size springs will interfere with the wheel and tire when you go to the more radicall camber settings. I would assume that the H&R coilover springs give a weight savings in the unsprung weight department as well. I have now had the H&R coilover system for over a year, and have had no problems. It seems to work with respect to the clock, as well, because with the system, my M3 has now become quite competitive in CSP, where the Hondas once dominated. I won the Solo Trials Nationals last summer, and Bob and Patty Tunnell, co-driving our car with us at the San Bernardino National Tour, and then the Pro Solo, each came away with a win. Bob has since begun setting up his car for CSP, but he is using revalved adjustable Konis with the traditional H&R springs. It will be hard to compare the two systems, not only because I have also done a lot of other development that Bob will not have done for a while, but Bob could beat me (and most other Solo 2 drivers) in a STOCK M3! For negative camber, I have tried both the Ground Control Adjustable camber plates, and the Dinan fixed plates, which come in two variations: stock plus .5 degrees, and stock plus 2 degrees. Each of the approaches to negative camber has its advantages. The GC adjustables requires removal of the stock, rubber strut mounts, while the Dinans do not. Metal-to-metal suspension mounting gives quite a bit more feel, but will further remove the car from that stock BMW feel. On the other hand, the Dinan stage 4 plates (plus 2 ) will give AT LEAST 3 degrees of ALL TIME neg camber, which is great as long as the car is always being driven hard thru corners, but will lead to rapid tire wear (inside edge) on extended long distance straight driving. I have gone so far as to have springs in the front that are SEVERAL times stiffer than stock, and rears that are off-the-map. It is probably way too stiff for autocross, but for the track it is like a panther on the carpet. For the street, as long as I retain the stock rubber strut mounts, the ride is decidedly "firm," but STILL not harsh. That is not just my opinion--others who have ridden in the car are surprised at how mellow the ride still is, considering how much stiffer EVERYTHING is over stock. If stock sponge is your cup of tea, the "stock" coilover system will be firm, but still fine, but I would not go any stiffer or you might be dissappointed. I would describe the ride, with ANY stiffness of H&R springs, to be "firm," but not harsh. Harsh , to me, is where your wheels are bouncing off the ground every time you hit a bump. The dampening and rebound of the struts/shocks are so good that it seems that the wheels and tires just follow every nuiance of the road surface. I won't have time for any more details. Please call BMP or Roland for more information. I will publish Roland's new number when I have it (I think that he has recently moved). good luck, Carl
Carl Buckland |
