Tired of the "bang" from your rear differential on those aggressive shifts? I have (finally) found the cure, in the form of 6 pieces of hard yellow polyurethane, courtesy of Whiteline and it is called the Subframe Bushing Kit. These bushings effectively eliminate the soft rubber bushings on the front of the rear differential carrier in favor of the harder poly bushing. The effect is less movement and "bang" from the rear of the car on aggressive shifts. The downside, as you can probably guess, is noise. In my case, a great deal more. Not more than is bearable, but definitely more than I was expecting. I do have Whiteline's Subframe Lock Kit installed as well, so it is perhaps just a combination of the two contributing to the extra noise.


This mod is very simple to accomplish, and won't take long to accomplish for the shadetree mechanic. To start off, let's locate the bolts that need to be removed to install this bushing kit. You will find the areas in question by looking just in front of the rear differential carrier/crossmember and out by the sides of the vehicle. You are looking for a single large (17mm) bolt- there is one on the passenger side (pay no attention to the 'cow' street sign nor the obligatory poster of a scantily clad female- stuff you find in any good garage):

http://www.ravensblade-impreza.com/modifications/drivetrain/lockbushing/1.jpg


And there is one located on the driver side as well:
http://www.ravensblade-impreza.com/modifications/drivetrain/lockbushing/2.jpg


Working one side at a time, remove the 17mm bolt completely. This is going to go quickly from here. For New Age Imprezas, you will use only two (the large thick bushing and the large thin bushing- the small thick bushing will not be used and makes a nifty conversation piece or desktop curio for work). The large bushing will be going on top of the differential carrier arm (between the arm and the body) and the thin bushing will go between the arm and the plate below it. Photos are much better at describing what is going on, so without delay:

http://www.ravensblade-impreza.com/modifications/drivetrain/lockbushing/3.jpg


Once everything is stacked in place (and your are probably going to have to do some wiggling/shifting to get things in place) you simply replace the large 17mm bolt, and repeat the proceedure for the other side.

Adding information from this mod.
http://www.scoobymods.com/forums/showthread.php?s=&threadid=1654


I figured I'd add a few bits of info and a different approach for those that don't have the luxury of a lift, or scanitly clad women posters nearby. ;)

At first, it looked like it was going to be a major pain to install these on my back in the driveway. There is little room under there with the car just on the the ground and I figured you'd have to support the crossmember as the instructions indicated with some creative jacking. But in the end, I realized that this mod can be done in 15 minutes with the wheels on the ground, and no jack.

Tools needed:

3/8" drive
17mm socket
12mm socket
jack (optional)
The packet of grease that came with the bushes (or some lithium grease will most likely do.)

If you're like me, you live in tight quarters with the neighbors. My driveway is too narrow to open both doors all the way, so that should give you an idea of how little room i have.

Make sure the car is on level ground on it's own wheels. Get under there and remove the main 17mm bolt all the way out.

Now remove the two 12mm bolts so the whole plate comes off. You might have to support the crossmember with your hand a little to prevent binding, but the crossmember will not fall farther than a few degrees.

Once the plate comes off, grab the thin bush and slather it with that grease and rest in on the plate.

There's a plate on the top of the bushing cylinder bar, pull it off and slather the thick bush with grease and place inside the plate

Here's where I know a lot of people get confused. The bushings in there already do not come out. These go on top to prevent the metal to metal contact that the stock super wimpy bushings cannot prevent.

Put the top (thick) bushing and plate back in and grab the plate with the bottom (thin) bushing and try to line them up. The top practically clicks in, the bottom needs to just be close. If you notice, the inner diameter of the new bottom bushing is exactly the outer diameter of the stock bushing. If you get it close, it will self align itself.

Here's the finished assembly

If you're paranoid or just a real do-it-right type of person, here's my suggested jacking procedure.

Place a small 2 ton type jack here.

The under side looks like this. Please note you do NOT jack up the car by the cross member, just get the jack to about 1/2 inch or so below the member, then after you remove the 17mm bolt, the cross member will rest on the jack. Be careful not to pinch the hose down there! You need a little play up top to get the top bushing plate off so make sure you're at least 1/2" below the arm before unbolting.

Again i've found this is not mandatory at all, but the instructions from whiteline suggest you do. Just a little CYA here ;)

The other side I did in about 7 minutes without the jack. I could do this mod again in less time than it takes to install a kartboy! This mod is that easy.

So how was the test drive? There is no more hard clunk on a 1-2 shift or an aggressive downshift. The top gears are silky smooth. I also have the subframe lock bolts to put in, but I'll do them another day. The NVH is, IMO, better since there's no clunck and I can't hear any more noise otherwise. To be honest, I would have paid $100 for something that would eliminate that clunck. :bang: Thank god whiteline didn't know that! :)

Happy modding!

-
Tom

http://www.scoobymods.com/forums/showthread.php?t=5034

Just my version of the install w/ KB bushings.