Robert K
07-09-2006, 03:52 PM
It always pays to research the forum before starting repairs. I was a bit apprehensive about doing the subframe bushings but read a couple of posts where guys pushed them out using a little heat and the weight of the car. So first, I made a block to push the old bushing out using a piece of 2" thick mahogany. You have to make the outer edges of the block just slightly less in diameter than the bushing. I then borrowed a heat gun (it's a high heat version of a hairdryer) and a bottle torch as backup. I jacked the car up and put a jackstand under the outer frame near the normal jacking point. Then I placed the jack under the subframe near the bushing and removed the large nut and two small bolts that attach the bracket to the subframe bushing and body. With the bracket removed, I put the nut back on the large pin and drove it up until I could remove it from inside the car under the rear seat. Then I slowly lowered the jack to allow the subframe to come down. I had to pry it down slightly to install my wood block. I then used the heat gun to thoroughly heat the area of the subframe that holds the bushing. When it was fairly hot, I began to jack the subframe up. It didn't take long before the bushing began to slide right out of the subframe. Then finally it was out. I cleaned the subframe bore. I replaced the wood block between the floorpan and the subframe. I then took the new bushing (frozen solid from a night in the freezer-figured it couldn't hurt), put a little water on the outer casing, and positioned it on a piece of softwood on the floor jack. I used the heat gun again to heat the subframe. I aligned the bushing in the hole properly and began jacking it up. The bushing pushed up into the hole pretty easily but stopped about 3/4" short. I then lowered the subframe enough to heat it again with the heat gun. I put a little more pressure on it with the jack and it pressed the rest of the way into the subframe. I put the pin back into the hole and drove it back down to seat the knurled area. You have to whack it pretty hard to make certain it's fully seated. Then I pushed the subframe back up and installed the bracket. Then, on to the other side.
While doing this work, I also replaced the short pitman arms that go between the subframe and trailing arm. I also replaced the control arms up front and put new 750i bushings in the thrust arms. Finally, I replaced the front sway bar end links.
All in all, this work really tightened up my 1991 535i. I believe putting new subframe bushings and pitman arms really helped the rear end a LOT! Mine used to always feel like the rear end was about a half step behind the front end. Now it feels much more connected. However, the steering response is still not as precise as I wish it was. I think the only cure would be to replace the steering box with a proper rack and pinion system with a little quicker ratio.
If you choose to do any of this work, do your homework on this and other BMW forums. If you have the tools and the patience, you can do quite a bit of your own work. Most importantly, always make certain that the car is safely and adequately supported if you're going to under it.
Grace and peace,
Robert K
1991 535i
While doing this work, I also replaced the short pitman arms that go between the subframe and trailing arm. I also replaced the control arms up front and put new 750i bushings in the thrust arms. Finally, I replaced the front sway bar end links.
All in all, this work really tightened up my 1991 535i. I believe putting new subframe bushings and pitman arms really helped the rear end a LOT! Mine used to always feel like the rear end was about a half step behind the front end. Now it feels much more connected. However, the steering response is still not as precise as I wish it was. I think the only cure would be to replace the steering box with a proper rack and pinion system with a little quicker ratio.
If you choose to do any of this work, do your homework on this and other BMW forums. If you have the tools and the patience, you can do quite a bit of your own work. Most importantly, always make certain that the car is safely and adequately supported if you're going to under it.
Grace and peace,
Robert K
1991 535i