12-02-2021, 05:10 PM | #1 |
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Another LSD thread
OK, so I had to go to the tire place today to get the TPMS sensors switched out on the rims/tires I swapped over (prior BMW was 2013, wrong sensors). I picked this 2016 M235i 6MT up from the dealer used a little over a month ago and I continue to discover mods from the prior owner - they had no history on the car...
While the car was up in the air at the tire shop, I asked if I could go spin the rear tires to see if by some spot of fortune I have an LSD in there. Car was in neutral, e-brake off. Both wheels spun forward. Repeated multiple times, forward and reverse, always same direction. Tried to get some pics of the diff (will add a post from my phone with them) but couldn't grab one of the top where the label is supposed to be. Tried to look the numbers in the pictures up via realOEM and Google to no avail - generic to both LSD and non-LSD. I haven't driven a car with an LSD in a long time, the car feels good to me but haven't really had a chance to test it yet. Last test I know to try is to jack one wheel up and see how much force it takes to move the wheel that's in the air (should require a good amount of force with LSD). TLDR; I need to know what kind of diff I have so I can buy the correct fluid for upcoming fluid changes. Installing FBO and changing oil/trans/diff fluids here shortly and the LSD and non-LSD use different fluids. Thank you for any help you can provide, or tips you can add to what I've already found in searching. Not trying to rehash old ways of testing or anything like that. Last edited by tgmsocal; 12-02-2021 at 05:18 PM.. |
12-02-2021, 08:15 PM | #3 |
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The external casing of the LSD is identical to the standard diff. The only way to be sure is to get a view of the label on top of the diff. There are several threads on the forum debating about whether someone has an LSD or not, and viewing the label is the only sure way.
However, if you car was in neutral, and both wheels spun the same way, you probably got lucky. |
07-21-2022, 02:05 PM | #5 |
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FYI, as an update, I do have an LSD. Snapped a shot of the label when I did diff fluid change a few weeks ago. Not sure the photos I posted earlier are relevant at all.
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01-14-2023, 12:25 AM | #6 |
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Does the car need any coding if a LSD is added, to enable it to work properly? Or, must DSC need to be fully defeated?
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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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01-14-2023, 05:49 PM | #7 |
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Drives: '17 M240i 6MT
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My Wavetrac didn't need any coding as far as I know. I've driven it as-is about 3000 miles with no issues. The shortened gear ratio (3.08->3.46) does get the ECU confused sometimes, but I've learned how to work around that pretty quickly. Most people don't go for short gears anyways; as far as I can tell, I'm the only 6-speed B58 car with a 3.46:1 axle so far.
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01-15-2023, 11:48 AM | #8 | |
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Quote:
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01-15-2023, 12:03 PM | #9 |
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Thank you both!
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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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01-16-2023, 12:13 PM | #10 | |
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Quote:
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M235i rwd 6mt
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01-16-2023, 12:32 PM | #11 |
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The car starts in limp mode most of the time. You get power for a split second after every shift before it dies again. If you let it coast in-gear for a few seconds, that seems to convince the car that the clutch isn't slipping, and it drives completely fine until the next startup. I've talked to a couple people who have changed the ratio on their N55 cars and they don't get this issue. It seems that the B58 ECU is programmed to protect the clutch if it detects slip, and my car is interpreting the elevated RPM at a given speed as clutch slip.
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2017 BMW M240i 6MT Slicktop | Wavetrac 3.46:1 Limited-Slip Diff - DinanTRONICS Sport Boost Controller - H&R Sport Springs - Millway Street Camber Plates - Agency Power Intake w/ Paradigm Engineering Turbo Inlet
Last edited by SpencerC_6MT; 01-16-2023 at 05:16 PM.. |
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05-10-2023, 07:53 PM | #12 |
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Just for asking sake:
If the car was on a lift, in Park, no E-brake and the wheels turned together forward or backward. Would that make it not an LSD? What is the technical reason on why it would need to be in Neutral? Assuming RWD only, not Xdrive. Thank you! |
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05-11-2023, 12:38 AM | #13 |
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The output shaft from the transmission has to be able to rotate freely, as opposed to being locked in position if in park. If it can’t rotate freely, then the rear wheels can’t be rotated in the same direction, only in the opposite direction to each other.
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05-14-2023, 10:14 AM | #14 | |
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As soon as I put the transmission in Neutral, then the wheels DID turn in the same direction. This is complicated by the fact that it's hard to put the AT in neutral unless the car is running. (There is a mechanical way to do it by tightening a bypass bolt.) You can see this in a poor video I did: |
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05-15-2023, 01:12 PM | #15 |
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M235i LSD
Just posted one in the classifieds if anyone's looking.
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