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03-29-2021, 10:50 AM | #1 |
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RSFBs and springs/shocks at the same time
Hi All,
I'm going to be installing M3 RSFBs, doing the job on jackstands and using the Komen Tools bushing tool. Also have new springs/shocks to install, as well as a rear sway install kit (originally a base car with no rear sway). Is there any opportunity to reduce the total number of steps required by doing these jobs at once? For example, does lowering the subframe allow for the spring to be removed without disconnecting the control arm? Does removing the shocks allow easier movement of the subframe while finagling the bushings? Thanks in advance for entertaining my quest for "efficiency" (aka shortcuts) |
03-29-2021, 11:14 AM | #2 |
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Yes, it's definitely more efficient to do both at the same time. You may want to consider diff bushings as well while you're in there. I swapped subframes and now I'll be dropping it again to do coilovers and bushings.
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2009 Widebody 135i ///Build Thread
Instagram: ///TheAxisGarage If you ride like lightning, you're gonna crash like thunder. Last edited by Dieselboy; 03-29-2021 at 11:21 AM.. |
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03-29-2021, 11:37 AM | #3 |
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Appreciate the insight!
I wasn't planning to do diff bushings right now, unless I get in there and notice visible wear. Being a 128i, those aren't under quite as much stress. |
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03-29-2021, 02:53 PM | #4 | |
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Quote:
Using the correct tool, as you are, is a really good start to the process. Do you have a copy of Bentley's E90 E91 92 E93 Service Manual? It is a great resource for methods and torques. Section 330 of that manual assumes you are removing the subframe entirely, but you only need to lower it. It is tempting to skip some items because of that, but they can come back and bite you. Here is my 2 cents: Remove your camber and spring. Mark the eccentric before you remove it so you can get it back close so you can drive to an alignment shop, but you will need an alignment. Disconnect the shock at the bottom only with the two bolts, not the centre nut. Don't forget to disconnect your headlight leveling sensor on the LH side first. Press your brake pedal half way with a "stick" to prevent leakage, then disconnect your intermediate brake lines. You will only loose a drop of fluid, but will need to bleed the rears after you connect things up again. You WILL damage the brake lines if you don't do this. You need to remove you axle-back exhaust. Disconnect the drive shaft at the diff, which means removing the mid pipe and heat shield too. If you can get some long M12 metric threaded rod you can use this to lower the subframe down, support it while you remove and install the bushings, and raise it back up. I have done the job on jack stands without threaded rods (M3 bushings) and on a lift with threaded rods (solid aluminum). Find a lift if at all possible. And if you accept that some disassembly is required, and don't skip steps, your life will actually be made much simpler. |
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03-29-2021, 07:46 PM | #5 |
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Also appreciate the input.
- I didn't think about the brake pedal half down thing. I knew the lines needed to be disconnected to prevent damage, so that may help. - I've heard conflicting things about removing the axle-back and driveshaft. I'll do what needs to be done but...would be ideal to avoid. Could there be a 128i vs. 135i difference here? Small vs. large pumpkin, larger diameter exhaust? - Don't have the service manual, but do have the torque specs. And replacement hardware where recommended. - Definitely understand the drawbacks of doing the job on jackstands. I am planning to budget multiple time blocks over the course of a few days to get it done, not rushing. |
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03-29-2021, 10:45 PM | #6 |
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I had my indy shop replace the brake hoses with braided s/s pieces while they were disconnected. Not sure what your mileage/age is, but mine is a 2013 that had less than 60k miles at the time (a little over a year ago).
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E9x M3 front & rear suspension arms; BMW Performance brakes upgraded to drilled rotors in rear; BMW performance shifter; BMW Performance Exhaust; Wave Trac LSD with modified 'nannies'; BMW Euro Intake box; BMW Aluminum Strut Tower bar; ECS front and rear sway bars; 3 stage intake with BPC software; BMW style 78, 17 x 8" wheels with Bridgestone RE 980AS 225/45-17 tires; Koni Special Active struts/shocks, E9x M3 RTABs.
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03-30-2021, 05:54 AM | #7 |
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09 with 125k.
I wasn't planning on replacing the lines right now, if for no other reason than I'm already doing a bunch of other work right now and didn't feel like more scope creep. I'll be due for a full brake fluid flush next year, so I could always tackle it then. |
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04-05-2021, 11:19 AM | #8 |
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I'll be starting this exact job this weekend. I am most likely going to completely drop the subframe again.
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04-05-2021, 01:12 PM | #9 |
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Finished mine, except the hard brake lines which were a casualty due to rust at the connection. Putting on new ones tonight.
Having the subframe lowered does make the spring removal marginally easier. But as mentioned, it does not seem to save any steps. Still needed to disconnect the control arm at the spindle. |
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