Help! Pelvis turned into dust with BC Racing Coilovers

[varg]

BC is a fairly reputable company. Why are they supplying such rates that dont seem to make any sense.

BC is a company that makes coilovers for people who want maximum stance, not maximum performance, as is evident by the availability of puzzling spring rates and "extreme low" being the first option listed on their website for the product.

It's disappointing to see companies half-ass stuff like that, it wouldn't have been hard for them to run a quick google search and just copy someone else's E30 spring rates as their default offering, but instead they chose to make 8k/8k the default even though it doesn't make any sense for an E30.

[e30davie]

My only experience with BC coilvoers was a mate put them in a Gen 1 honda civic. the first bubble one, 1970 or so. For the price I was pleasantly surprised with apparent quality of the shocks themselves, the ride quality and what seemed like a fairly controlled setup for the car. It handled quite nicely and didnt destroy the back vertibre. I've had many off the shelf "coilover" setups over the years in various cars, and id say it was one of the better street orientated setups. Sporty enough, but comfortable for daily use. Most of my other setups have been Japanese brands in Japanese imports and they are all just bone shatteringly stiff.

I was actually considering BC for my e30 as unfortunately its really hard to argue wit the price, but the more i look into it the more it seems they just havent been well thought out and i woudlnt be happy with them.

I heard a rumour BC use the same shock absorber in all the BC coilovers and just have 4000 adjustment clicks to make them work across the range. But no way to verify that i suppose.

[Jb325is]

They are cheap mass produced coilovers, just like all of the other versions that look curiously similar but are different colors. I've been saying this for years but people always get super butthurt about it. The adjustments make a clicking sound 30-something times, but there are varying amount of adjusrment. Usually the first 4-5 clicks make a large adjustment and the next 20-something don't do much.

[ForcedFirebird]

These companies treat the e30 as most other generic cars where all 4 corners are coil over damper - true strut assembly. Not many IRS cars have (or had) divorced springs.

[LorenzeTorres]

UPDATE: ISSUE RESOLVED

Problem has been solved! I blame my ignorance on this one. I've never worked on a divorced setup like this before. I ran KW V3's on my Focus ST, and the shock body in the rear did not have height adjustment.

So this was a first for me. The issue was the shock was doing all the work because the pre-load was not set properly.

What I needed to do is thread the body of the shock up to match the height of the spring at 0 preload, and go about 5mm up more to properly set preload.

The car actually rides better than my previous H&R sport + Koni KA setup.

Comfort is great aside from when I hit really deep craters on the road. The handling is super nice for $1000 suspension. Car feels more planted and steering response has increased.

I'll be posting pics later tonight in my build thread to better explain.

https://www.r3vlimited.com/board/showthread.php?t=417280&page=6

My only feedback is that the spring rates are meh. I think 6K might have been better for the rear at least.

[LorenzeTorres]

NEW UPDATE:

I suspect the car is bottoming out.

Situation:
When the car hits a bump or goes into a pot hole, it feels like the shock is going to blow through the rear tower. The rebound is really harsh and jarring.

What we think it is:
Bounced on the rear of car and discovered that the springs might be too short. Under load, the springs would fully compress. We suspect two things 1) the spring is too soft 2) the spring is too short.

I don't think there's enough suspension travel.

How it's currently set up:
The lower collar on the spring is 15mm higher from the perch. The dampening is two clicks back from softest. We added just a hair of extra pre-load on the shock body.

Any recommendations?
I'm thinking of going 10K rear and possible a longer spring for travel.

[e30davie]

Everything you describe is unfortunately what i have experienced on suspension setups that are really designed to be driven on billiard tables, not roads.

Edit, you arent hitting the bump stop are you? I dunno on the e30s but on other cars ive cut bump stops in half to allow more travel.

[LorenzeTorres]

Everything you describe is unfortunately what i have experienced on suspension setups that are really designed to be driven on billiard tables, not roads.

Edit, you arent hitting the bump stop are you? I dunno on the e30s but on other cars ive cut bump stops in half to allow more travel.

I'll have to take a look. I'm starting to believe that 8K rears do not have enough force to keep the back end up thus causing spring bind on my ride height.

I'll be placing an order for some swift springs today

[LorenzeTorres]

Fellas thanks for all your replies! This is all starting to make sense now.

I'm happy that you guys are able to pinpoint the cause of my frustration and I hope that this thread becomes a resource to others.

I've done some crosse referencing as well and discovered Fortune Auto from factory come with 8K/ 10K spring rates.

Maybe I can provide some feedback to the company and maybe they can implement this for future products for our cars. Or me being the cynical business college student I am, maybe their choice of spring rates are intentional so that you're forced to upgrade springs?

Any who, I've gone ahead and ordered 10K Swift Springs at 127MM in length. I will report back to you when I have them installed.

Also something else to note, according to their reps the shocks can take a deviation of +/- 4K spring rate. Which means that if order the factory setup with 8k springs, you can go to a max of 12K without revalving (but you should).

[varg]

My only feedback is that the spring rates are meh. I think 6K might have been better for the rear at least.

Other way. The rear needs to be substantially stiffer than the front. For example, my split of 450lb/in front and 650lb/in rear, and this split is smaller than some recommend but I didn't go stiffer in the rear because I didn't want to be oversprung with stock koni SA valving. 8kg/mm is close to 450lb/in, and 11.6kg/mm is roughly 650lb/in.