Rear coilovers on e30

[matt]

does anyone else think that having wider rubber might outweigh the rear coilover idea? or is that just me??

What do you mean?

[Firestorm]

I Can't be the only one here who has long since ran my own rear coilover setup...

I'm doing one similar to yours (the upper mount its self) and i've thought up a nifty bar to reinfornce it aswell, yet to draw the bar up though.

What do you mean?

The coilover shock/spring will be a little wider than just the standard shock, so you might lose a tiny bit of choice when it comes to chosing a tyre. I dont think it'd really affect it too much though. I dont think the coilover shock would be any more than 15-20mm wider than a standard shock though.

Trent, what was the extended length on the bilsteins? I might run a QA1 DR5855B (17" ext length) shock on my setup, with a 400 or 450lb spring in it.

[Eric]

trent cool setup. did you sorce that from another car?


The above posting is just to keep this relevent to the thread.... all i wanted to say is bianca beuchamp is so facking hot!

[trent]

Trent, what dia. spring is that? Shock length? Any rubbing issues on the gas filler line?

The spring is 2 1/4. This shock is designed to work with a 2 1/2 spring, so the hardware had to be cut down in a lathe to work. The bilstein IIRC is 14 extended length, and I added the joint at the top to gain an extra inch. There is hardly any droop.

Yes, that metal covering thing isn't for the gas filler line. The only hoses that run through that piece are for the evap tank.

Eric, the idea came from the old DTM cars. The shock is just an off the shelf bilstein race shock that I found that had the correct extended and collapsed length.

[Bruce Colby]

I posted a link earlier but here are some images showing my rear coilover setup. When the car is on the ground, the gap between the spring top and the top mounting point is closed. The fronts are also adjustable coilovers. With this arrangement, it is relatively easy to adjust cross-corner weights. Mine are within 15 lb with my chubby body in the drivers seat.

[gobuffs]

I have a set of used Bilstein shocks for the rear that have threaded bodies so you can run them as true coilovers (but you don't have to). $300 for the pair (plus shipping).

[SA E30]

I'm planning on running something like Bruce Colby, in the rear I'm just going to use a Rose Jointed setup top and bottom ( kind of like the old DTM Cars) I plan on using a 1 7/8 Spring and Koni shocks.

This is what I'm doing roughly...

[SA E30]

While we at it what spring rates ?

I'm thinking 850lbs - 950lbs in the front, and 500-650lbs in the rear... as a rough starting point

[Bruce Colby]

I'm using 200 lb/in in the rear and 400 lb/in in the front. I know the rates are correct because I measured them myself. My front sway bar (Ireland Engineering 25 mm, hollow and attached to strut tower not the control arm) is set full stiff and the rear (Ireland Engineering 22 mm) is set full soft. Based on some pictures I've seen of hard right turns (turn 4 at Willow Springs), the inside front wheel is just barely touching the ground. If I changed anything, I'd go to 180's in the rear. Oh, my engine is a stock M20B25 and the car weighs 2200 lb (dry & wo/driver). If I had more power, I'm sure I'd go to a slightly stiffer front and/or slightly softer rear spring setup.

I've also taken a couple more pictures of the rear coilover setup the other day. They show tire clearance (205/50-15's on 7", ET 20 wheels) and the top of the shock with the spring in its normal position.

Finally, it's worth noting that there are springs available for this rear setup which range from 60 to 500 lb/in in 20 lb increments. Individual springs run around $50 to 60 and changing them is easy.

[trent]

I'm using 200 lb/in in the rear and 400 lb/in in the front. I know the rates are correct because I measured them myself. My front sway bar (Ireland Engineering 25 mm, hollow and attached to strut tower not the control arm) is set full stiff and the rear (Ireland Engineering 22 mm) is set full soft. Based on some pictures I've seen of hard right turns (turn 4 at Willow Springs), the inside front wheel is just barely touching the ground. If I changed anything, I'd go to 180's in the rear. Oh, my engine is a stock M20B25 and the car weighs 2200 lb (dry & wo/driver). If I had more power, I'm sure I'd go to a slightly stiffer front and/or slightly softer rear spring setup..

Interesting rates. I am running a 400 in the front, and 375 in the rear. However, I am running no swaybar in the rear, as I would rather compensate for roll with spring than sway bar. The car is a bit twitchy in the rear, and thus I have been tempted to try a lower rate.

[Erick]

By the way, I spoke with Brian @ Vorshlag. The reason why they separated the spring from the shocks in the ASTs is due to the regulations in the racing class they used the 318iS.

[Bruce Colby]

Interesting rates. I am running a 400 in the front, and 375 in the rear. However, I am running no swaybar in the rear, as I would rather compensate for roll with spring than sway bar. The car is a bit twitchy in the rear, and thus I have been tempted to try a lower rate.

Interesting indeed. Are the rears in the conventional/stock position or are they coilovers? I'm aware that some people run really stiff fronts to reduce dive on braking. What do you see as an advantage in stiff springs and no swaybar in the rear? On the odd day when we have a wet track, I think it's kind of nice to be able to disconnect the rear swaybar. But that doesn't happen very often so I'm curious.

BTW, is SD South Dakota or San Diego or ...?

[SA E30]

Ok, is it just me or is everyone here running very soft spring rates to what I'm thinking ?

Also wouldnt squat and dive be controlled by the shocks bound and rebound to an extent ?

[Bruce Colby]

Ok, is it just me or is everyone here running very soft spring rates to what I'm thinking ?

Different people have different ideas about what constitutes the best way to tune a suspension. Track surfaces, driving style, "conventional wisdom", etc. all get involved. I've tried really stiff springs on other cars and they don't work well for me on the tracks I drive. They seem to result in chatter in corners when the track surface is uneven and I don't like the instability they generate when I hit a curb a little too hard. Perhaps if I were a better driver I would feel differently.

Also wouldnt squat and dive be controlled by the shocks bound and rebound to an extent ?

Shocks affect transient response. Springs set the static limits for dive and squat. Springs plus swaybars set the static limits for body roll. What will work best for you, driving your car, will depend on many things. The best anyone can hope for is a decent compromise.

The nice thing about coilovers that use readily available springs is that it's possible to try different combinations without going broke. They're also nice because it's easy to set ride height and adjust cross corner balance.

[trent]

Interesting indeed. Are the rears in the conventional/stock position or are they coilovers? I'm aware that some people run really stiff fronts to reduce dive on braking. What do you see as an advantage in stiff springs and no swaybar in the rear? On the odd day when we have a wet track, I think it's kind of nice to be able to disconnect the rear swaybar. But that doesn't happen very often so I'm curious.

BTW, is SD South Dakota or San Diego or ...?

Yea, a real coilover, I posted pics on page 2. I guess you missed those.

I am not a fan of the huge rear swaybars on these cars, as I like keeping the trailing arms completely independent. I may be doing some experiementing with a stockish bar one of these days. I am in San Diego.