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Thread: I really want to reinforce my subframe. Mechanical-savvy, please help

  1. #1
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    I really want to reinforce my subframe. Mechanical-savvy, please help

    My car is a 99 M Coupe with about 25k miles. Subframe and diff mount have yet to crack, but reading cases makes me very disturbed. I have tried reading up as much as I could about ways to prevent these two things from breaking.

    I have a few questions however. I have no experience with reinforcing anything and have no idea what would help my case.

    1. Would a Butt-strut attached to the subframe help to prevent the subframe from tearing?
    2. Would subframe bushings (Ireland Engineering Subframe Bushings maybe) help to prevent the subframe from tearing?
    3. What are ways to reinforce the differential mount? Installing a "two-earred" differential cover? Replacing the differential completely with something more solid? Like what?

    God, this is the only thing keeping me from ever really pushing my car. It scares me.

  2. #2
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    contact mr. m

    you've prolly seen this subframe tech they had in nj.
    http://forums.bimmerforums.com/forum...d.php?t=242648
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  3. #3
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    I have explored this option and may take Don's approach. However, I want to know how well this proves to be a preventative measure.

    I got a price quote and I don't want to pay this kind of money unless I am guaranteed that it will help.

  4. #4
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    Quote Originally Posted by 6i9
    I have explored this option and may take Don's approach. However, I want to know how well this proves to be a preventative measure.

    I got a price quote and I don't want to pay this kind of money unless I am guaranteed that it will help.
    for those who are unsure...keep an eye on your diff mount/subframe...if there is no damage...wait...if you see that hairline crack start to develop..then think about doing something...otherwise...let me be the guinea pig...

    my car will be supercharged in the near future with the Eurosport TS kit...so i think i will definitely be testing how well this reinforcement holds up
    Boosted since '06

  5. #5
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    Another question...

    What are the differences between subframe mounts and subframe bushings?

  6. #6
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    Quote Originally Posted by 6i9
    Another question...

    What are the differences between subframe mounts and subframe bushings?
    This is a subframe mount




    This is a subframe bushing
    Attached Images Attached Images

  7. #7
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    And how are they related? Or are they? Sorry for the n00b questions.

  8. #8
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    Quote Originally Posted by 6i9
    1. Would a Butt-strut attached to the subframe help to prevent the subframe from tearing?
    2. Would subframe bushings (Ireland Engineering Subframe Bushings maybe) help to prevent the subframe from tearing?
    3. What are ways to reinforce the differential mount? Installing a "two-earred" differential cover? Replacing the differential completely with something more solid? Like what?
    1. No
    2. No, not by themselves, but they are a step in the right direction (limit travel)
    3. There's a few ideas floating around at present. Hmmm, what a concept
    Well, this is what I built for the Healey...
    Attached Images Attached Images

  9. #9
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    Quote Originally Posted by 6i9
    And how are they related? Or are they? Sorry for the n00b questions.
    The mount is for the bushing.

    The mount (stud) goes through the bushing (hole). That's what attaches the rear suspension and differential to the car (one each side & the infamous differential brkt-that fails).

    Incidently, those green things are the Ireland Urethane subframe bushings.

    Look under your car.

  10. #10
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    I get it now. Thanks Randy.

  11. #11
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    Are the rear subframe bushings the same on M coupe/roadster as the Z3? or more specifically are these the mounts to order from ireland engineering?

    https://secure9.nexternal.com/shared...D=545&All=True

  12. #12
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    Quote Originally Posted by kem
    Are the rear subframe bushings the same on M coupe/roadster as the Z3? or more specifically are these the mounts to order from ireland engineering?

    https://secure9.nexternal.com/shared...D=545&All=True
    Yes and yes.

  13. #13
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    Here's the picture from the ETK that might help folks visualize.

    <img src="http://www.rfdm.com/SubframeBushings/33_0998.gif">

    Part #1 is the rear subframe. Part #2 is the mounting stud Randy pictured, it threads into the chassis (one per side). Part #3 is the stock rear subframe bushing (which many of us have replaced with the Ireland Engineering bushings). Part #7 is the driver side trailing arm. Randy's Ireland bushing picture shows part of the subframe and the passenger side trailing arm.

    If you think of the subframe as a 'T', the differential hangs on the base of the 'T' and the trailing arms hang of the arms of the 'T'. The subframe is mounted to the chassis at the ends of the arms of the 'T'.

    If you think about this picture and look under your car, you'll realize there's really only three mounting points keeping the whole rear end pointing striaght ahead: the two where the subframe attaches to the chassis via the rear subframe bushings, and the differential cover mount. The stock subframe bushings permit a lot of movement (while you're under your car with the suspension unloaded, you can wiggle it with your hands). This permits a lot of stress on the differential cover mounting bracket (and the crossmember it's attached to, and hence the trunk floor...). Going to the Ireland Engineering bushings reduces the movement of the subframe at the subframe mounts, and hence the stress on the differential cover mounting bracket. It also reduces some of the handling anomalies like rear steer and the infamous wiggle.

    Incidentally, parts 8, 9 and 10 are the trailing arm bushings you'd replace with the KMACs to gain the ability to change rear end alignment. There's a pair of these per trailing arm.

    All three mounting points have rubber bushings to permit some movement and reduce vibration in the chassis from the drivetrain. However, NVH is only slightly increased by going to the Ireland green bushings. Even if our rear ends weren't falling apart, I'd recommend these. They made a significant desirable difference in my car on the handling front.
    Last edited by dwm; 03-08-2005 at 01:19 PM.

  14. #14
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    I just ordered the IE bushings does anyone have the tool required to remove them? I'm will to rent it and pay shipping both ways....
    2002 Alpine White w/ Black 368 (<OO \(||][||)/ OO>)
    Power: Custom Exhaust w/ High Flow cats, CSL headers, built, low-compression Supercharged and aftercooled S-54, ViPEC standalone ECU, Vortech V2 Si trim
    Driveline: Euro 6 speed, 3.64 diff w/ 40% Lockup, Rogue Octane SSK, UUC Red TME kit, UUC Stage 3 LTW Flywheel/M5 Clutch, SS Shift Knob
    Suspension & Brakes: TC Kline True Match Coilovers 500f/500r w/ adjustable camber plates, Racing Dynamics sways, Custom front sway endlinks, ATE fluid, UUC/Willwood BBK 6 piston f - 4 piston r , Slotted E46M3 Rotors, Stainless Lines, Strong Strut, IE Subframe & adjustable rear trailing arm bushings
    ICE & Misc: Projector Z's w/DDE & 5k HID, 19'' Gold HRE C20's, Custom Aux pwr outlet, footwell lighting, ACS Splitters, Areo Sideskirts, Custom gauge pods, Z8 Start, Pioneer AVIC Z3, Clarus Components, 10" RE Sub in a Mister-X Enclosure, Alpine PDX 4X150 + 1X600 Amps
    Coming soon: and a visit to Randy Forbes

  15. #15
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    Quote Originally Posted by clintjg
    I just ordered the IE bushings does anyone have the tool required to remove them? I'm will to rent it and pay shipping both ways....
    Did Jeff (or Jeremy) give you an idea when they would ship? I wound up with three (3) sets for my two (2) cars. I'm waiting on a UPS call tag to send one (1) set back.

    My black car (1999) that has the Ireland's feels great now that I have the "summer" wheels/tires back on it. Suspension is all stock pieces taken from the gray car (2001).

  16. #16
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    Quote Originally Posted by clintjg
    I just ordered the IE bushings does anyone have the tool required to remove them? I'm will to rent it and pay shipping both ways....
    I'd also like to rent one of these instead of purchasing them.

  17. #17
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    Quote Originally Posted by dwm
    Here's the picture from the ETK that might help folks visualize.

    Part #1 is the rear subframe. Part #2 is the mounting stud Randy pictured, it threads into the chassis (one per side). Part #3 is the stock rear subframe bushing (which many of us have replaced with the Ireland Engineering bushings). Part #7 is the driver side trailing arm. Randy's Ireland bushing picture shows part of the subframe and the passenger side trailing arm.

    If you think of the subframe as a 'T', the differential hangs on the base of the 'T' and the trailing arms hang of the arms of the 'T'. The subframe is mounted to the chassis at the ends of the arms of the 'T'.

    If you think about this picture and look under your car, you'll realize there's really only three mounting points keeping the whole rear end pointing striaght ahead: the two where the subframe attaches to the chassis via the rear subframe bushings, and the differential cover mount. The stock subframe bushings permit a lot of movement (while you're under your car with the suspension unloaded, you can wiggle it with your hands). This permits a lot of stress on the differential cover mounting bracket (and the crossmember it's attached to, and hence the trunk floor...). Going to the Ireland Engineering bushings reduces the movement of the subframe at the subframe mounts, and hence the stress on the differential cover mounting bracket. It also reduces some of the handling anomalies like rear steer and the infamous wiggle.

    Incidentally, parts 8, 9 and 10 are the trailing arm bushings you'd replace with the KMACs to gain the ability to change rear end alignment. There's a pair of these per trailing arm.

    All three mounting points have rubber bushings to permit some movement and reduce vibration in the chassis from the drivetrain. However, NVH is only slightly increased by going to the Ireland green bushings. Even if our rear ends weren't falling apart, I'd recommend these. They made a significant desirable difference in my car on the handling front.
    That was a very good visualization guide. Thanks.

  18. #18
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    Quote Originally Posted by Randy Forbes
    Did Jeff (or Jeremy) give you an idea when they would ship?
    I actually just got them yesterday.
    2002 Alpine White w/ Black 368 (<OO \(||][||)/ OO>)
    Power: Custom Exhaust w/ High Flow cats, CSL headers, built, low-compression Supercharged and aftercooled S-54, ViPEC standalone ECU, Vortech V2 Si trim
    Driveline: Euro 6 speed, 3.64 diff w/ 40% Lockup, Rogue Octane SSK, UUC Red TME kit, UUC Stage 3 LTW Flywheel/M5 Clutch, SS Shift Knob
    Suspension & Brakes: TC Kline True Match Coilovers 500f/500r w/ adjustable camber plates, Racing Dynamics sways, Custom front sway endlinks, ATE fluid, UUC/Willwood BBK 6 piston f - 4 piston r , Slotted E46M3 Rotors, Stainless Lines, Strong Strut, IE Subframe & adjustable rear trailing arm bushings
    ICE & Misc: Projector Z's w/DDE & 5k HID, 19'' Gold HRE C20's, Custom Aux pwr outlet, footwell lighting, ACS Splitters, Areo Sideskirts, Custom gauge pods, Z8 Start, Pioneer AVIC Z3, Clarus Components, 10" RE Sub in a Mister-X Enclosure, Alpine PDX 4X150 + 1X600 Amps
    Coming soon: and a visit to Randy Forbes

  19. #19
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    Quote Originally Posted by 6i9
    I'd also like to rent one of these instead of purchasing them.
    If someone has one we could do an install fest at my place and get them both done in the same weekend.
    2002 Alpine White w/ Black 368 (<OO \(||][||)/ OO>)
    Power: Custom Exhaust w/ High Flow cats, CSL headers, built, low-compression Supercharged and aftercooled S-54, ViPEC standalone ECU, Vortech V2 Si trim
    Driveline: Euro 6 speed, 3.64 diff w/ 40% Lockup, Rogue Octane SSK, UUC Red TME kit, UUC Stage 3 LTW Flywheel/M5 Clutch, SS Shift Knob
    Suspension & Brakes: TC Kline True Match Coilovers 500f/500r w/ adjustable camber plates, Racing Dynamics sways, Custom front sway endlinks, ATE fluid, UUC/Willwood BBK 6 piston f - 4 piston r , Slotted E46M3 Rotors, Stainless Lines, Strong Strut, IE Subframe & adjustable rear trailing arm bushings
    ICE & Misc: Projector Z's w/DDE & 5k HID, 19'' Gold HRE C20's, Custom Aux pwr outlet, footwell lighting, ACS Splitters, Areo Sideskirts, Custom gauge pods, Z8 Start, Pioneer AVIC Z3, Clarus Components, 10" RE Sub in a Mister-X Enclosure, Alpine PDX 4X150 + 1X600 Amps
    Coming soon: and a visit to Randy Forbes

  20. #20
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    Quote Originally Posted by clintjg
    If someone has one we could do an install fest at my place and get them both done in the same weekend.
    That sounds good. I just gotta order some bushings.

  21. #21
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    YOUR POST IS A KEEPER! Thanks!

    Quote Originally Posted by dwm
    Here's the picture from the ETK that might help folks visualize.

    Part #1 is the rear subframe. Part #2 is the mounting stud Randy pictured, it threads into the chassis (one per side). Part #3 is the stock rear subframe bushing (which many of us have replaced with the Ireland Engineering bushings). Part #7 is the driver side trailing arm. Randy's Ireland bushing picture shows part of the subframe and the passenger side trailing arm.

    If you think of the subframe as a 'T', the differential hangs on the base of the 'T' and the trailing arms hang of the arms of the 'T'. The subframe is mounted to the chassis at the ends of the arms of the 'T'.

    If you think about this picture and look under your car, you'll realize there's really only three mounting points keeping the whole rear end pointing striaght ahead: the two where the subframe attaches to the chassis via the rear subframe bushings, and the differential cover mount. The stock subframe bushings permit a lot of movement (while you're under your car with the suspension unloaded, you can wiggle it with your hands). This permits a lot of stress on the differential cover mounting bracket (and the crossmember it's attached to, and hence the trunk floor...). Going to the Ireland Engineering bushings reduces the movement of the subframe at the subframe mounts, and hence the stress on the differential cover mounting bracket. It also reduces some of the handling anomalies like rear steer and the infamous wiggle.

    Incidentally, parts 8, 9 and 10 are the trailing arm bushings you'd replace with the KMACs to gain the ability to change rear end alignment. There's a pair of these per trailing arm.

    All three mounting points have rubber bushings to permit some movement and reduce vibration in the chassis from the drivetrain. However, NVH is only slightly increased by going to the Ireland green bushings. Even if our rear ends weren't falling apart, I'd recommend these. They made a significant desirable difference in my car on the handling front.
    '00S52 RETIRED


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  22. #22
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    Quote Originally Posted by clintjg
    I just ordered the IE bushings does anyone have the tool required to remove them? I'm will to rent it and pay shipping both ways....
    Hey Clint where did you order these from & how much?
    Last edited by tripleM; 08-17-2004 at 12:11 PM.
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  23. #23
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    http://www.bmw2002.com

    $90 shipped for the pair

    You want in on the install fest? I got beer? If we can find someone to rent us the tool we can all cut our costs....
    2002 Alpine White w/ Black 368 (<OO \(||][||)/ OO>)
    Power: Custom Exhaust w/ High Flow cats, CSL headers, built, low-compression Supercharged and aftercooled S-54, ViPEC standalone ECU, Vortech V2 Si trim
    Driveline: Euro 6 speed, 3.64 diff w/ 40% Lockup, Rogue Octane SSK, UUC Red TME kit, UUC Stage 3 LTW Flywheel/M5 Clutch, SS Shift Knob
    Suspension & Brakes: TC Kline True Match Coilovers 500f/500r w/ adjustable camber plates, Racing Dynamics sways, Custom front sway endlinks, ATE fluid, UUC/Willwood BBK 6 piston f - 4 piston r , Slotted E46M3 Rotors, Stainless Lines, Strong Strut, IE Subframe & adjustable rear trailing arm bushings
    ICE & Misc: Projector Z's w/DDE & 5k HID, 19'' Gold HRE C20's, Custom Aux pwr outlet, footwell lighting, ACS Splitters, Areo Sideskirts, Custom gauge pods, Z8 Start, Pioneer AVIC Z3, Clarus Components, 10" RE Sub in a Mister-X Enclosure, Alpine PDX 4X150 + 1X600 Amps
    Coming soon: and a visit to Randy Forbes

  24. #24
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    Quote Originally Posted by clintjg
    http://www.bmw2002.com

    $90 shipped for the pair

    You want in on the install fest? I got beer? If we can find someone to rent us the tool we can all cut our costs....
    I'm game. If we can get 6i9 & dbsquirrel, Kurt, Khoi ,to go into it then the cost is 6 ways. Or maybe Kurt's got it already?
    & with the September drive (** ding ding Drive warning ** )through the twisties in MD, I can't wait to get these in!

    Lets see if we can start the ball rolling...
    '00S52 RETIRED


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  25. #25
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    I'd never seen it described so easily, that makes it see quite easy other that pressing bushings....
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