JRZ RS1 from Bimmerworld
The great thing about the forum is the ability to exchange information and help with decisions on aftermarket parts or accessories. I have been riding on a stock E90 EDC suspension for the past 3 years and while the suspension is a pretty good dual purpose suspension, i.e. street and track itís a bit soft for the track. Iíve put several thousand track miles on this suspension and itís held up well with no sense of wear or loss of performance. So, starting approximately one year ago the search was on for an upgraded suspension system. The goals of the system for me were to preserve street manners with a reasonably compliant set up as well as adjustability. I didnít want to go with a race-type set up due to cost and complexity and I wanted something a bit higher performance than Koni or Bilstein.
The other item for me was to be careful about not getting a set up that is too stiff. My last dual-purpose street and track car was brilliant on the track, but it was so stiff on the street that I hated it, and most of my driving was on the street, didnít want to repeat that mistake again. Iíve done the same thing with camshafts. Install a long duration, high overlap cam and on the track itís so fun and tractable at high rpm but then on the street you say to yourself, ďwhy did I ever choose this cam?Ē
So over time I narrowed the choices down and was thinking about a Moton set-up, AST or JRZ. After talking to a few people including James Clay at Bimmerworld as well as Brian at JRZ I decided on the RS1 system. It was designed to be a truly dual purpose street and track shock with an emphasis on good street-ability and the ability to convert it to a reasonable track set up in less than 2 minutes. I had several conversations with James at Bimmerworld and decided to go with the JRZ RS1 as well as Hyperco springs which evidently come in matched pairs by poundage.
My goal for the new set up was to be 20-30% better on the track with minimal loss of daily driving street comfort/quality. James recommended 425 lb front springs with 700 lb rears. I drove up on Wednesday morning to Bimmerworld in Dubin, VA (very pretty little town with lots of trees now changing color) and by 4:30PM that same day I was on the road on the way home.
Impressions so far, which does not include any real cornering or handling impressions as the drive was all freeway and moderate traffic. Firstly, road feel through the steering wheel and your seat is improved. This is only a consequence of stiffer springs and more vibration and road noise transmission through the chassis. I like it, though, as the steering feel in the M3 is pretty good, itís not as good as my gold standard which is an early 1970s 911 T, E or S. Those cars you can drive blindfolded and be able to tell the passenger what type of pavement, asphalt or concrete, grate or manhole cover and just about any other surface irregularity. Road feel is better, i.e. more feedback to the driver which I like. Nothing is free so the downside is that there is a bit more noise in the cabin especially over rough surfaces, but it still doesnít stop you from enjoying the radio or talking with your passenger.
The overall ride quality is really just about the same as stock. The change is so small as to be almost trivial. Little bumps are just like stock and for larger bumps I think the compliance of the RS1 is better than stock. I have the shocks set at 4 clicks from full soft which is great for the street. The only thing perhaps and I just noticed this once is that over a series of bumps there might be a bit more ďbounceĒ in the front end that is not present in the stock system. Iím sure this could be fixed with one or two more clicks of firmness to the shock.
Iíve included a couple of pictures of car and shocks below. The overall ride height of the car is approximately ĹĒ lower than stock. I actually thought that the car was at stock height when I picked it up, but when I put the car up on my hoist it was evident the clearance between the jack pad and the jack point was about a half inch less. Iím looking forward to testing this out at the track but donít have anything scheduled as of now. Only other point is to say how good the customer service is at Bimmerworld with knowledgeable people, they kept me up-to-date as to progress on the car and James was great at explaining how to set up the car for the track, what to expect and how to adjust for different handling characteristics that are amenable to shock valving adjustment.