So I'm in the middle of installing my BC Racing coilovers. I wanted to check and see if everyone preloaded the springs about 1/4" according to the write up on BC Racing (which I got off the G37 site...)

http://www.bcracing-na.com/G37install.htm

Also, there are quite a few guys complaining about a clunk or knocking noise when going over bumps. Anyone having these problems?

Also, did your rear springs come with a gold perch piece which sits in the lower spring bucket? See the attached pic. Mine didn't and I'm wondering if it should have....

 

If you have the newer springs(:Progressive) that are kind of fat in the middle you don't need the lower bucket according to Pete@BcRacing.

No clunking sound here.
I adjust springs first and then adjust the shock body until it gets tight or vice versa.

Remember you don't want slack on your springs cause that means that you will be riding on more shock than spring and can blow out your shock body.

 

I guess I'll have to check the shape of the springs and hope that I have the newer ones. I JUST bought the kit so I'm going to assume it does, and therefore I don't need the lower spring pieces.

Anyone know what the rates are for these new progressive springs and why they went to them??

 

Ummmm, there is a rubber part for the bottom part of the spring holder (the gold part). You need to place the rubber bottom mount from the original springs onto the gold part. I screwed this up and heard the bumping noise that you are describing, so that is probably your problem.

 

I think this is where the discrepancy lies. Whether or not we NEED to have this gold piece or not. I'll try to check into whether or not there are new progressive springs that don't require this gold piece. Since you still use the stock lower spring buckets, I just left that rubber piece in there and put the shock directly on that, oriented to the shape in the bottom of the bucket. My main concern is just whether or not we need this gold piece!

 

FYI just got this Email from Adam over at z1 auto.. Thanks Adam!

"Keith - just spoke to BC, and they said all of the newer kits (recently) all are retaining the stock rubber piece now. The "older" setup used different diameter springs, so they had to include that large gold piece. But they said they are using newer diameter springs now, which retain the std. rubber piece. No changes to the spring rates"

So the newer kits with the fatter springs just have a different diameter so they don't need to use the gold piece. Apparently not progressive either.

 

 

I need to get the new springs then. I have the gold piece and there is some clunking every now and then.

 

Maybe I'm not getting it cause I'm running
the stiffer suspension setup.

Revalved Shock body
Spring Rate 14K front and 12K rear

Even when I had the standard setup i never had clunking.
Gilley check that your spring doesn't have too much play.
If anything try tightening up the shock body in the rear
so it creates more spring compression.

 

I do have the gold piece with the "narrow" springs and have not noticed any clunking from that area.

 

well if you installed them correctly then you shouldn't. If you have placed the bottom rubber part from the stock springs onto the gold piece, then you are lucky, but you should fix this immediately. The base of the gold part is NOT level and it WILL wiggle around.

 

I did not use the stock rubber part. The gold part is directly sitting on plate.

 

The "clunking" issue seems to be a pretty big deal in the G37 community. I'm not sure if the suspension was completely redesigned, if there are different rear spring buckets, etc. But there are quite a few complaints about the BC kit on the G37.

14K and 12K? That's a pretty stiff setup there!

 

well, I strongly suggest you add it to the bottom of the gold piece. It's not safe to run this setup without it. The springs will not sit properly snug without it (again the base of the gold piece is not flat and is designed to be placed on top of the rubber mount).

 

that is interesting.... because i have not noticed any kind of noise especially from the rear. I have had the whole suspension checked out by a guru and everything seemed fine. I wonder what the instructions say... do we have to use the stock rubber mount or not?