Originally posted by e30 gangsta
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as long as you have IE3's you will have body roll. The shocks are not going to fix that completely -
j stocks it is then.Comment
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update: yesterday i ran on track with j-stocks and have some feedback. The car is as follows for reference: 318is, e30 m3 sway bars, m3 5-lug swap, m3 brakes, s50 motor, toyo ra-1's, IE camber plates set to max neg. camber
The car had a very neutral balance to it, more neutral than the H&R sports I generally run on the street. There was still plenty of push but I think that could be dialed out with larger swaybars, I'm running baby stockers for now. The push was very predictable though and easy to handle, plenty of hook up with the tires so throttle oversteer was not a problem. Basically the car liked to slide through the corners. It was actually a lot of fun to drive that way although it had considerably less grip than the m3 I'm accustomed to driving at the same track. Overall I think it's a usable setup although if you track regularly larger sways would be ideal. Despite the push and sliding the car around the corners I was still able to go pretty quick and keep it well under control.
There's nothing better than pulling on e46 m3's and porsche's in your little e30!Comment
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how is it on the street? rough? what shocks are you using?Comment
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it's rough. I'm on revalved bili sports and stock m3 sway bars. The roads where I live are horrible though, it's been a month and I'm tired of it now, ready for softer springs on the street. on the track though it is very nice!Comment
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I suppose that I could have found this in the search but how much of a drop are those J-stocks and what's the rate?
You might just be noticing bottoming into the jounce bumpers, espically if your street driving consists of alot of broken asphalt. I've been in E30's with ride rates in the 2~2.2hz range (500fr, 650Rr springs) and the ride on the street is pretty acceptable except for the bottoming on large abbrupt inputs. The specific e30 that I'm thinking about actually would launch the rear since it was bottoming so baddly, this was with outa-the box koni SA's.
I'm a chassis engineer and I've had good luck on street cars with cranking up the compression valving to stay out of the jounce bumpers.
The other option could be just cutting the strut (or shock in the rear) down to gain more travel, this is a major issue with lowered cars. This could also be attributing to the understeer that your getting, assuming that its stead state.Comment
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Turner specs the drop at 1.5" fr, 1.25" r drop, and progressive spring rates from 200 - 900 lb/in. Also there's supposed to be "a large ratio of rear to front stiffness."
I believe the J-stock valved Bilsteins have the compression damping cranked up a notch too.
Originally posted by whysimonComment
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Hummm, 200~900lb/in I wonder what their curve looks like, alot of times a spring manufacturer will use a progressive spring just to maintain pre-load in the spring when the wheel goes in full droop.
I'd still put $$ on the crappy ride quality being talked about has alot to do with crashing the jounce bumpers.
Its very common, I worked on a program last year for a lowered 1/2 ton truck. I was lowering only with springs, the truck I was working on had a very hard non-progressive jounce bumper. We could really crank in the mid~high speed compression damping and improve the feel over broken/patched asphalt. The down side of the increased compression damping was increases acceleration feel over tar strips and smaller expansion joints.
Many after market damper tuners are fearful of the compression becasue they believe that it'll kill ride quality. In my opinion my Bil sports are soft on comp and so are the koni's that I've worked with . Nothing that a little developement can't solve just not so easy for the guy in his garage.
Koni and Bilstein are pretty good about doing re-valvings, I had pretty good luck with my freind's launching problem.
Actually on another project I'm working with Koni DA's and we've got bottoming on those as well, I'm asking koni to cut the shocks to gain travel. We'll see if that solves the crashing (joucne bumper), if not we'll start adding damping force.
Wow I don't know if this is helpful,
Sorry I just started rolling there.Comment
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from Doug at Turner Motorsports the j-stock spring rates are 650F and 1026R max. They are much stiffer than the Eibach comps I have and the H&R sports (obviously). Don't use these springs with off the shelf Koni's they will bottom out regularly. IMO the stock Koni SA's are not up to the task...I much prefer the feel of the bilsteinsComment
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[QUOTE=1990m3;803183]from Doug at Turner Motorsports the j-stock spring rates are 650F and 1026R max.
Assuming that those are the rates at ride height, your around 2.3~2.5 hz ride rates in a 2800lb car. TComment
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