What height are recommended for an E21? I contacted GC and they gave me choices of 6", 7", and a weight of 350lb. What's the difference between the heights, the car gets lower? I want to lower the front maybe 1.5 to 2.5 inches to get even with the rear. I'm getting the camber plates too. I don't want the car too low, don't want to be bouncing around.....

What are you doing with your old pro-kit? Can I take them off your hands? :redspot :devillook

The spring length doesn't really dictate how low the car will sit. With coilovers you can make a 6" spring sit just as high or low as a 7" spring. It all depends on the position of the threaded collar. If you're not going to be trying to really lower the car, I'd suggest the 7 inch spring. Less chance of the spring binding up and having a harsh ride. 350lbs is heavy for daily driving. My car is pretty stiff.

a 6 inch spring will sit 1" lower than a 7 inch spring, when the collar is set to the lowest ride height. I just bought some GC coil overs awhile back with some bilsteins. Got 6" on front and rear with spring rates of 400 front and 300 rear. I have yet to drive it because it is still a work in progress, but I imagine it will be a stiff bugger! Most of the bounce is from the sidewalls of the tires. :)

i have 350lb 6" front.....250lb 7" rear. IMO, they're the perfect length springs to make the adjustment on the lower spring perches about equal......in other words: both my lower spring perches are at about the same distance from the bottom of adjustment on the collars, yet the car is just about evenly lowered.

bouncing is really only going to be controlled by the shocks you go w/.

btw, when were you looking to pickup a set of GC's? I may change my suspension (yet again), and if i do, i'll no longer be using my GC's & koni adjustable's

....I would like to put in dibs on those Jason...... :buttrock

i have 350lb 6" front.....250lb 7" rear. IMO, they're the perfect length springs to make the adjustment on the lower spring perches about equal......in other words: both my lower spring perches are at about the same distance from the bottom of adjustment on the collars, yet the car is just about evenly lowered.

Ok, which spring rate would you recommend for a 1979 323i with coil overs?

400 front 300 rear? Or what rate and length of springs?

I am building a set of front threaded coilovers that need to be welded on the front strut assembiles. These are not Ground control but another old motorsport New old Stock - from parts from europe.

thanks

Joe

The spring length doesn't really dictate how low the car will sit. With coilovers you can make a 6" spring sit just as high or low as a 7" spring. It all depends on the position of the threaded collar. If you're not going to be trying to really lower the car, I'd suggest the 7 inch spring. Less chance of the spring binding up and having a harsh ride. 350lbs is heavy for daily driving. My car is pretty stiff.

Nic, the Pro-kits I have I think are 250, they are soft.... I would like to stiffen the front. I'm thinking 300lb should be a good compromise. Later on I can get stiffer or softer springs depending on surface: hillclimb, autox, drifting, etc... As for the length, having measured everything 7inches should be alright.
In any case thanks for your help Nic. I keep checking your site for inspiration.
Jbob, I've ordered the stuff already, but was waiting for some measurements

btw, when were you looking to pickup a set of GC's? I may change my suspension (yet again), and if i do, i'll no longer be using my GC's & koni adjustable's

Why?

joe: if ur not changing the heights of the stock lower spring perches (and pretty much let the base of the threaded collar rest on what was the stock lower spring perch), a 6" front spring & 7" front spring would work fine. as for spring rates for your 323i....i'm not quite sure. i would imagine that the 323i is a little more nose heavy compared to the 320i....i would ask around on tricord's site (i believe there are a few 6-cyl e21 owners there who have adjustable coilovers)

the koni adjustables (adjusted to full rebound) get the job done w/ 350lb springs on the street, they could be a little stiffer when it comes to autox/track but then again, they're the only e21 drop-in replacements w/ the most rebound (more than the bilstein sports)

Can the Bistein sports handle 350 plus spring rates?

How much are the koni adjustable and what about tonyka illumanas (<- Spelling-?).

I have Racing Dynamic Springs right now with the bistein sports and the rears sit way to high.

Thanks

Joe

I know people running 450/600's with Koni SA's. Granted thats with an E30 rear suspension. I wouldnt go any higher though.

joe...yeah, the billy sports should also be able to handle 350lb springs on the street. i know someone who is running 350lb/250lb w/ bilstein sports all around. but i have no idea what the ride difference is between his setup & mine (since we have the same spring rates but different shocks)

The reason why there are a few different spring lengths are because every car is different, especially if you add coilovers. Depending on the spring that's used, depends on where you need to have the coilover spring perch on the housing. If you use a shorter spring, you need to have the perch higher. If you are using a longer spring you can have the perch lower and still obtain the same ride height. However, depending on the vehicle, you can run out of adjustment on the coilover which is why you would need either a shorter or a longer spring.

I'm using 500 lb springs in the front, and 400 lb springs in the rear in the 6 inch length. Originally I had started with 350 front 275 rear, which is what ground control said I should use for the street. I just found that for the track it was way too soft, so I had to bump up the spring rates to accomodate track speed and g-forces.

With those spring rates, I'm using Koni yellow front shocks from a Camaro, which I had to fab into the strut housings, which ground control supplied the hardware necessary to do it. For now I just have Bilstein HD's in the rear, but they aren't stiff enough for the 400 lb springs, unless they are just really worn out.

With the springs that I'm using, on GC coilovers, I use the lower end of the coilover housing to make my measurements for ride height. It works really good since the housings are machined. I set the ride height by what visually looks good, along with knowing how much suspension travel I will have at that height. With the springs that I'm using now, I have the front coilover set at 2 inches, right in the middle, and I have the rear set at 1 7/8th's and the car is fine on the street with the suspension travel that I have.

So this is a track car **with coilovers** and you are a driving instructor of all people yet you didn't have the car corner weighted? :nono

joe...yeah, the billy sports should also be able to handle 350lb springs on the street. i know someone who is running 350lb/250lb w/ bilstein sports all around. but i have no idea what the ride difference is between his setup & mine (since we have the same spring rates but different shocks)

You talkin about me?

I honestly don't know that much about suspension. My stock stuff was so blown out it's not even funny. I just know that I *LOVE* the way my car handles now with the H&R's and Billy Sports all around. VERY tight, but not too stiff to make driving on the street uncomforable for me. Got rid of most of the body roll. Add strut bars and sway bars from an iS or aftermarket improvements and it'd probably all be gone.

So this is a track car **with coilovers** and you are a driving instructor of all people yet you didn't have the car corner weighted? :nono


Corner Weighting is a good thing to do since its something that can be done with coilovers. However, It doesn't really make that much of a difference. On standard street vehicles, or any vehicle using a factory spring and using spring rubbers, the percentage of difference between the spring rates and the rubber is pretty drastic. Factory vehicles are corner weighted to some degree to get the handling close to where they want it, but with the way that spring manufacturing is their tolerances are fairly high. The Average driver wouldn't know the difference between a car that was corner weighted or not.

The manufacturing tolerances of 2.5 ID springs are so close, that when changing to coilovers and taking measurements for ride height off of a fixed item in the suspension, you can get the corner weight closer then when the car rolled off the assembly line.

I will eventually corner weight my car, however, I'm still in the middle of changing many things, especially with items that effect the weight, or balance of the vehicle.

I will eventually corner weight my car, however, I'm still in the middle of changing many things, especially with items that effect the weight, or balance of the vehicle.

OK, **phew** this reassures my confidence in BMW CCA instructors :D

Yes I agree corner weighting is not necesary for a street car, however, your 320i was specified as a "track car" hence the question.

I also agree that it is very smart to wait untill the wieght and proportioning is set in stone before doing the cornerwieght. Also don't forget to add wieghts in the drivers seat, and have the same amount of gas you use on track while doing the cornerwieght.

Good luck.

:redspot

Also don't forget to add wieghts in the drivers seat, and have the same amount of gas you use on track while doing the cornerwieght.


Or you could just sit in the thing like I did. I took weights with me out and in the car. Me out of the car is like a current gross weight. Me in the car is a net weight... used for a power to weight ratio, etc.

I run the bilstein sports and they don't come close to handling my spring rates which are over 300# front and rear. Although I have not run with the koni adjustables in an e21 every other vehicle I've been in with them equiped, including my e36 with FK konigsport coilovers, don't provide enough compression or rebound dampening, high speeds dampening rates are so so but the low speed stuff is horrible. I will address those after the e21 is done, the other thing is the remove to adjust rear shocks, most annoying. I have looked into a bunch of options and the double adjustable koni's are my best choice, they are not that expensive. Biggest issue will be the custom parts needed to mount them, but as with most everything else on my e21 that is the only way to go.

Sounds like you need a set of LEDA's :devillook