There are two accepted options on fixing this. The first is to fully replace
all of the subframe bushings with hard aluminum items. However, it's a very
painful process to remove the whole subframe, get the bushes pushed out, the
new ones pushed in, and get everything back together.
Instead, there are several manufactures offering lock bushing inserts. I ordered a set of the Japanese Kazama lock bushings from Aikmeng. (tell him you got his link from my site, and maybe one of these days he'll give me a discount!) They were reasonably priced compared to many others. I've been eyeing up other Kazama parts, and I thought these would be a good part to check quality and fitment. The lock bushes are aluminum inserts that take up the space between the rubber on the subframe itself, and the rubber on the mounting stud.
Subframe "front" bushing.|
Left side shown.
Subframe "rear" bushing.|
Left side shown.
"Front" bushing reinforcement|
bracket. With and without lock
bush. Cleaned too!
"Rear" bushing bolt and washer.|
With and without lock bush.
Yep, cleaned too.
- Jack up the car by the diff. This is all you need to hold up the subframe.
Jack up enough to get jack stands under the 2 rear positions on the frame
- Remove the rear wheels for easier access to the subframe bolts.
- The front bushing is right before the front of the rear fender. The bushing has a reinforcement bracket that must be removed when putting in the front subframe locks.
- The rear bushing is above and to the side of the diff, all the way to the rear of the subframe. It is held in with a nut and a large washer only.
- With the jack still supporting the diff/subframe, remove the 4 x 17mm subframe nuts. Then remove the 4 x 14mm (2 per side) that hold on the reinforcement brackets.
- I took the time to do my once a year "clean everything up" which I had things apart, so none of the pieces are new (other than the red parts). Lay out the brackets and large washers from the rear. The solid lock bush (one without a slot in it) goes on these pieces as shown in the pics.
Dropping the jack makes a good|
amount of space, easily.
Just slide the upper, slotted|
bushing in (flat side up).
- With all of the nuts pulled out, slowly drop the jack under the diff by only
about 2". This should give you plenty of space to insert the slotted bushing.
Don't drop the subframe past the studs, as you are just making more work for
yourself getting it lined back up.
- When inserting the upper locks, the flat part goes towards the car, and the other side goes into the bushing. The front bushings on my car had a tab, where I had to rotate the lock bushing so the slot lined up with this tab.
- That's it. Jack back up the diff a little, and make sure the upper lock bushes are in a good spot, and fitting within the rubber. Jack up the subframe the rest of the way and torque things down. If you don't have the FSM, the torque settings are 87 ft-lbs (max) for the 17mm bolts, and 41 ft-lbs (max) for the 14mm reinforcement brackets.
|Old front bush.||New front bush.||Old rear bush.||New rear bush.|
Here's matching before and after pics. When I was done, I took a test drive
and a little run around a skid-pad to see what things felt like, and to make
sure everything was settled into place.
First impressions are that the car feels a lot more solid under you. Enough to notice, and boost your confidence with the car in turns. NVH (noise, vibration, harshness) was increased a little bit, but almost not even noticeable. The biggest thing I noticed was I can now hear the rear diff clink just a hair as it takes up slack when letting out the clutch. My S13 racecar, with all the rubber still in it is MUCH louder just be removing the rear seat and plastics.