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HOW TO Rear SF mounts


wegweiser

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Decided I'd finally install the rear subframe mounts I've had for a few months, tonight. My reason for replacing them had to do with an occasional tendency for the F Bomb to take a second "set" in the middle of wide, high speed highway curves. Thinking the rear subframe might be squiriming a bit, I thought I'd try this fix. I haven't taken it on the highway to test the results, but here's a basic "how to". The old bushings were tired and starting to split, but didn't look *that* bad. On the road home, the car felt better. I can't wait for a dry day to really see how it does at high speed.

I'll start by saying that each and every fastener cooperated fully. The bolts weren't frozen/rusted solidly in the tubes of the subframe. The vertical floor studs yielded and re-seated perfectly...and I had a lift. Even without a lift, this would have been an easy task on this car.

Total time elapsed: under an hour for both.

1. Support car on jackstands on the pinch weld of the rocker panels just outboard / forward of the stabilizing straps that overlap the subframe mounts.

2. Do one side at a time. Support rear subframe with floor jack - support the beam - not the differential, for more stability.

3. Loosen and remove 17mm bolt holding forward end of the strap.

4. Loosen but do NOT remove the 22mm nut holding the mount to the floor of the car. Test that the mount isn't seized to the vertical stud by lowering the jack slightly. The subframe should drop a bit. If it doesn't, you'll need heat and hammers, and probably new vertical mounting studs.

5. Remove 22mm nut. Lower subframe slightly to gain access to the 17mm bolts / nuts that hold the mount to the subframe. Loosen nuts and tap lightly on the bolt ends to ensure they're not seized inside the tubes present inside the subframe. If they're stuck....get a torch and a dose of patience, while you order new hardware.

6. loosely install 22mm nut and tap stud upward. I used a large punch to avoid thread damage. Once it's free of the floor splines and moveable, lower the subframe further so that the mount can be slid toward the back of the car while one hand pushes the stud up lightly and out of the way.

7. Install bolts in new mount. Offer up mount to subframe, then drop vertical stud through mount.

8. Jack up subframe a few inches. Install 22mm nut and if you have air tools - Zip that baby on, so the stud re-seats into the floor securely. If you have only hand tools, you may want to get inside the car, under the back seat and tap the stud securely back down before tightening the large nut**.

Torque all fasteners - remembering (if you haven't already) to remove the 22mm nut and re-install the stabilizing strap!

**Since this is a splined fastener, I choose to re-torque and check after a brief drive.

Some additional tips:

Coat the length of the horizontal mount bolts and vertical floor studs with anti-seize. Use all new locknuts or at least coat old ones with BLUE loctite before tightening.

Now Drive!

Paul Wegweiser

Wegweiser Classic BMW Services

Nationwide vehicle transport available

NEW WEBSITE! www.zenwrench.com

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