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. I, additionally, found a way to make the bushing kit perform better (in my estimation) and this may be the cause of some of the extra noise I hear. At any rate, any questions or comments about this modification may be directed to me here.
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):
And there is one located on the driver side as well:
Working one side at a time, remove the 17mm bolt completely. This is going to go quickly from here. For Old Skool Impreza models (1993-2001) you will use all 6 bushings in the kit- 3 per side (the small thick bushing goes inside the big thick bushing to make one bushing, and you use this combined bushing plus the large thin one). 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). In either case, the large bushing (or bushings) 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:
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.
Okay, as promised, the way I made things different (and perhaps better). It occurred to me that there was not much holding that thin bushing in place. On my RS, the solution was provided however. At the top of the stock rubber bushings, up against the body of the car, there was a curious metal plate with three "nubs" on it. I pulled it out for fun, and made the decision that it was essentially useless in terms of the new bushing kit- I'm certain it had it's purposes when used with the stock fluid-filled bushing. The item in question:
I had intended on hucking them in the woods (there is one per side) when the thin bushing dilemma came upon me. If I whacked the hell out of the "nubs" with a BFH (big fricken hammer) I could make this quirkly plate into what I needed- a giant washer. And so I did:
I slipped this plate in underneath the thin bushing:
I then tightened everything down, and off I went. Try as I might, I cannot get the rear end to "thump" now, and I'm extraordinarily pleased that a $25 bushing kit made this possible.
Standard Disclaimer: Modification of your car involves risks and may void your warranty. I can not be held responsible for the modifications you consciously decide to undertake nor for the results of doing so.
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