Refreshing your E30, Z3, Z3M, or 318ti rear suspension (subframe bushings)
Time to talk a little about how to refresh the rear suspension (subframe) on your E30, Z3, Z3M, or 318ti. The most often neglected part in these rear subframes is the rear subframe bushings. Delrin or poly bushings in the rear suspension of a BMW E30 3 Series chassis can make a world of a difference.
The first thing you should do is water pressure/clean the rear suspension while its still on the car. No one wants to work on a dirty bmw.
In this writeup we are going to talk about our rear subframe bushings, rear trailing arm bushings, raised rear subframe bushings, diff bushings, differential reinforcement and a few other things.
If your BMW is excessively lowered, you may want to consider our raised sub-frame bushings. These cars already have excess camber from lowering .
All the bushings you need for a rear subframe overhaul are available in our online website at store.garagistic.com
Looking at the outer end of the subframe there will be a bushing at both ends. This original bushing must be removed. This can be done using a bushing remover tool or other alternate means. Now, its easier to do this when the whole subframe is out of your e30 but this can be done in the vehicle as long as you got the original bushing out first (which can also be done in the vehicle).
Please note: You can only install an OEM subframe bushing while the subframe is still in the car. Any “two-piece” aftermarket units such as ours but be install with the subframe out of the car.
Once the bushing is out, we clean the inside where it came out. It doesn’t hurt to then we’ll lubricate lightly so it makes the new subframe bushing easier to install. Lithium grease, Liqui Moly copper anti-seize compound, Super lube are all good choices. Use gloves.
Once we have that, we’ll also put a coating on the subframe bushing.
We have found that the copper anti-seize works best with urethane bushings as far as preventing squeaks in the future. We’ve used all kinds of silicon lubricants as well as others. This is a little bit messy.
Please note: If you use our raised subframe bushings, you will want the thin side on the top and thick side on the bottom. If you use the standard geometry bushing, the thick side goes on the top and the thin side goes on the bottom.
On our subframe bushings there are alignment tabs that line up with the subframe. Line them up and then install the bushing (a press helps in this case but is not needed). Push the E30 rear subframe bushing all the way up until it meets the bottom of the carrier.
You can use a press of tap the bushing into place using a mallet .
Now, we repeat for the other side of the bushing. Again, we’ll lubricate the inside of this where it touches the carrier as well as the bushing.
Now, finally, we have the aluminum sleeve. This is where the bolt goes through. It only function is to keep the bolt from touching the bolt. Again, we’ll put some lubrication in the hole and a little from the other side as well. A little bit on the sleeve itself. We fit the sleeve down through the hole and this may take a little bit of work with the mallet as well (a press will make it alot easier). Even a 20 ton harbor freight press is a great help here.
You will then need to repeat it for the other side. You would now be able to install the subframe back into the car. You will want to reuse your stock washers that go above. You will also reuse the original through bolt and nut for fastening it to the vehicle. This is ready to go.
Now, its time to install the trailing arm bushings. Your subframe is not adjustable, but using our camber/toe kit it would be. This will not affect the rear trailing arm in any way, we just want to mention it while on the point of the trailing arm bushing area. If you dont already know about camber/toe kit, they can be found here.
They basically allow for camber adjustment as well as toe adjustment by moving the locating points of the two bushings within the trailing arm mount by turning the eccentric hardware.
Now, installation for the trailing arm bushing is easy. The bushings just fit into the arm and the sleeve goes in the center. You will need to remove the original bushings. The easiest way to remove them is cut off the mushroom rubberhead on one side of the bushing and press it through the other side and they’ll come out fairly easily.
This can be done on the vehicle, just like the subframe ones. (they are a little easier than the subframe ones).
As with the subframe, the first thing we’ll do is place some lubrication all the way around the trailing arm hole and on each bushing.
Please note: The trailing arm bushings are two different sizes. There is a thick and thin flange type. The thinner flange goes on the inside (of the car). The thicker flange is on the outside (furthest from the center of the car). Easy way to remember that is with our cheezy little rhyme “thinner on the inner”.
Just like the subframe bushings, these go in with a tap of the mallet. Now, we’re ready for the sleeve. Again, we’ll get plenty of lubrication through the bore. The bore on the trailing arms is serrated to hold extra lubricant. Get as much lubricant as you can in there.
Finally, we’ll lubricate the sleeve as well. Now, its easiest to goe in from the outside of the control arm. (goes in from the outside). Again, you may need to strike it gently with a mallet.
Once you get all the trailing arm bushings installed the trailing arm is then ready to go back up into the subframe. You can use the original through bolt and nut to secure it in place. We do offer replacement hardware that has a thicker shoulder to eliminate some more play.
Now, finally for the garagistic diff bushing install. Now, again, as with the rest of the things we have gone over, the original diff bushing will need to be pressed out using a press. You can also remove the cover from the differential with the differential still in the vehicle and do this at your bench if you prefer.
Similar to the rest of the bushings, lubricate the bore in the diff cover. If you dont already know, a great upgraded diff cover for the e30 or 318ti is the Z3M unit. It holds a little bit more fluid and has fins to keep the fluid cooler under track use. As for which diff bushing is best, we go over that in detail here.
The lip on the diff bushing is closest to the back of the car. (You cant actually place it in the other way) Now, that we have the diff bushing in, press in the sleeve where the diff bolt goes into.
This uses the original through bolt from the original bushing to install it into the chassis bracket.
With that, your rear suspension is all done. Remember, we have all of the bushings we mentioned here in our online store at www.store.garagistic.com