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      01-08-2020, 09:36 AM   #23
roastbeef
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i'm a big fan of solid subframe bushings. it is noticeable on the street and on the track. as for what it equates to in lap times- its probably not easily measurable as it plays into overall dynamics of the car.
kinda like brakes- brakes don't make the car faster, but a great brake kit will produce better lap times through confidence, feel, and being able to be on the throttle for longer.
solid bushings are just that- you're not upgrading the suspension, you are taking slop out of the suspension and drivetrain. the entire subframe moves about 1/2" (maybe a little less/more depending on where you're looking at it) under different loads. same with the differential. removing that deflection isolates all of the movement and forces the suspension to control it.
the subframe/diff movement takes energy to move. power used that moves the subframe/diff is literally lost power that could have been used to move the car.
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      01-09-2020, 07:34 PM   #24
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I've felt the rear "shift" before laterally coming out of corners on track before the car itself actually responded with a little oversteer. There's a noticeable delay that rears itself in specific conditions.

For the data critics, steering angle plot of a spherical solid subframe car vs OEM bushes:


Less angle should always translate to higher corner speeds.

From here:
https://www.1addicts.com/forums/show...5#post25287505
It's a 135i, yet everything counts. For those that don't want to read post #1 in the above linked thread.
The data is from a 135i with OEM M3 front arms, rear upper guide & wishbone, 135i toe and lower camber arms to
- tension arm monoballs
- SPL toe links (M3 is already spherical on both joints)
- SPL rear upper guide and wishbone (M3 is only spherical on inboard)
- BW lower camber inner spherical joint (M3 is also rubber. No idea what 135i is on knuckle side)
- BW RTABs (crap, they bind) -> OEM sphericals (M3 is rubber inboard & outboard).
- solid subframe

M3 lower camber arm shock mount for most of us with aftermarket dampers tend to also be spherical.

Last edited by gmx; 01-10-2020 at 08:06 PM.. Reason: Forgot to mention, subframe mount...
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      01-09-2020, 10:11 PM   #25
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What's a normal labor cost for this job?
.
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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
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      01-10-2020, 02:41 AM   #26
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$1K +/- depending on cost of labor in your area. May or may not include an alignment and brake fluid, probably not things like diff bushings. With parts, it’s $2K pretty easily without getting carried away, but being thorough. Subframe bushings are $300ish, diff is $200ish, etc...
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      01-10-2020, 06:09 PM   #27
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get "out the door" costs. an alignment and brake fluid will be necessary.
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      01-10-2020, 08:06 PM   #28
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And don't be surprised at alignment cost since all aftermarket mounts are a pain to centre unless you're guy just calls it good.
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      01-11-2020, 03:16 PM   #29
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Quote:
Originally Posted by wyatth View Post
$1K +/- depending on cost of labor in your area. May or may not include an alignment and brake fluid, probably not things like diff bushings. With parts, it’s $2K pretty easily without getting carried away, but being thorough. Subframe bushings are $300ish, diff is $200ish, etc...
Previous owner of mine did solid subframe bushings and purple diff bushings. In ZCP stock suspension. You can drive my car if your want. I'm busy today Saturday, and probably tomorrow. Next weekend I'm going to Tahoe I think, but after that I can probably make it happen. If you can make it to Foster City during the week though you could drive it then.
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      01-11-2020, 04:05 PM   #30
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One of my favorite mods because the difference can be felt immediately and really transforms the way the car feels overall. Street or track, IMO this is a must do mod for this car.

My only suggestion is to get everything else done in the rear because the labor costs are pretty high for this. I personally upgraded all my rear bushings, arms, swaybar etc at the same time I did the subframe bushings to save time and money. Since they had to drop the subframe to install the subframe bushings anyways, I was able to get a good rate on the installation of the other parts.

IMG_4464 by dj_dub, on Flickr
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      01-17-2020, 01:28 PM   #31
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^ That's partly the issue, often times people replace so much more than just the subframe, so attributing changes to a single part becomes imprecise. I'm sure it's rock solid back there now!

I'm not too interested in changing much else. I'd do differential bushings and whatever else is due for servicing, but mostly sticking with OEM other than the subframe. Someday perhaps coilovers when my ZCP dampeners are fatigued.

Still trying to wrap my head around the different designs though. BW and Turner look the same, but AKG looks very different. Do these really all fit and work the exact same way? There must be a reason for the differences.
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      01-17-2020, 05:17 PM   #32
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^Let me rephrase my suggestion then to change anything else in the rear that you plan on doing later anyways that may require the subframe to come down.

I track my car so doing all the above for me was worth it since I planned on doing all those mods anyways...and yes, it feels solid in the rear now. But very streetable!

Before doing the solid subframe bushing mod myself, I've personally driven and taken a ride in many cars that have only done the solid subframe bushings. So the difference felt was definitely precise to that particular part.
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      01-17-2020, 11:31 PM   #33
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Good stuff, thanks for the feedback!
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      01-18-2020, 07:31 AM   #34
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Quote:
Originally Posted by dj_dub View Post
^Let me rephrase my suggestion then to change anything else in the rear that you plan on doing later anyways that may require the subframe to come down.

I track my car so doing all the above for me was worth it since I planned on doing all those mods anyways...and yes, it feels solid in the rear now. But very streetable!

Before doing the solid subframe bushing mod myself, I've personally driven and taken a ride in many cars that have only done the solid subframe bushings. So the difference felt was definitely precise to that particular part.
how much did it cost to replace the subframe bushings?
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      01-18-2020, 05:23 PM   #35
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Originally Posted by gerikivan View Post
how much did it cost to replace the subframe bushings?
Most places I contacted were around the $1-1.2k mark for labor costs.
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      02-17-2020, 07:41 AM   #36
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It is quite a big job. I'm not sure I'd recommend it for someone just using their car on the road.

I agree with some of the others in that you don't notice how big a difference it makes until you drive a car without the solid bushes. A standard car just doesn't feel right without them.

If you are tracking your car then it really is a must-have upgrade. It just gives you so much more precision and stability in high-speed corners. I'm not sure about others but I noticed that the feedback from the rear greatly improved as well, it telegraphed what it was going to do much more clearly than before.

Another benefit I found was that drive was much more direct. I wasn't having to wait for the rear to settle before getting on the gas, I could just nail it and it would just go. - No slop in drive response.
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      02-20-2020, 09:41 PM   #37
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Hey everyone, What bushings should i go with on the rear subframe and diff? Unfortunately, my diff bolt broke and i kept driving... causing it to kind of mush the diff bushing from its place making the rear subframe shit. I got a used one from another M3... so I want to upgrade to good bushings so this doesn't happen again..

Any advice towards good bushings will mean alot, thanks guys.
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      02-20-2020, 10:17 PM   #38
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Quote:
Originally Posted by jamesS65 View Post
Hey everyone, What bushings should i go with on the rear subframe and diff? Unfortunately, my diff bolt broke and i kept driving... causing it to kind of mush the diff bushing from its place making the rear subframe shit. I got a used one from another M3... so I want to upgrade to good bushings so this doesn't happen again..

Any advice towards good bushings will mean alot, thanks guys.
Aluminum subframe bushings, and either powerflex purple or oem diff bushings are the go-to options. I went with the powerflex purples for the diff, and this probably provides the lower chance of repeated bolt breakage. Some extra driveline sound and diff whine comes with the poly diff bushings, but it does not come with oem diff bushings.
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      02-20-2020, 10:37 PM   #39
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Quote:
Originally Posted by Bartledoo View Post
Quote:
Originally Posted by jamesS65 View Post
Hey everyone, What bushings should i go with on the rear subframe and diff? Unfortunately, my diff bolt broke and i kept driving... causing it to kind of mush the diff bushing from its place making the rear subframe shit. I got a used one from another M3... so I want to upgrade to good bushings so this doesn't happen again..

Any advice towards good bushings will mean alot, thanks guys.
Aluminum subframe bushings, and either powerflex purple or oem diff bushings are the go-to options. I went with the powerflex purples for the diff, and this probably provides the lower chance of repeated bolt breakage. Some extra driveline sound and diff whine comes with the poly diff bushings, but it does not come with oem diff bushings.
Thanks bro, really appreciate the advice. I'm going to PM you 🤙🏼
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      02-20-2020, 10:43 PM   #40
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Quote:
Originally Posted by jamesS65 View Post
Quote:
Originally Posted by Bartledoo View Post
Quote:
Originally Posted by jamesS65 View Post
Hey everyone, What bushings should i go with on the rear subframe and diff? Unfortunately, my diff bolt broke and i kept driving... causing it to kind of mush the diff bushing from its place making the rear subframe shit. I got a used one from another M3... so I want to upgrade to good bushings so this doesn't happen again..

Any advice towards good bushings will mean alot, thanks guys.
Aluminum subframe bushings, and either powerflex purple or oem diff bushings are the go-to options. I went with the powerflex purples for the diff, and this probably provides the lower chance of repeated bolt breakage. Some extra driveline sound and diff whine comes with the poly diff bushings, but it does not come with oem diff bushings.
Thanks bro, really appreciate the advice. I'm going to PM you 🤙🏼
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      02-20-2020, 10:44 PM   #41
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Quote:
Originally Posted by Bartledoo View Post
Quote:
Originally Posted by jamesS65 View Post
Quote:
Originally Posted by Bartledoo View Post
Quote:
Originally Posted by jamesS65 View Post
Hey everyone, What bushings should i go with on the rear subframe and diff? Unfortunately, my diff bolt broke and i kept driving... causing it to kind of mush the diff bushing from its place making the rear subframe shit. I got a used one from another M3... so I want to upgrade to good bushings so this doesn't happen again..

Any advice towards good bushings will mean alot, thanks guys.
Aluminum subframe bushings, and either powerflex purple or oem diff bushings are the go-to options. I went with the powerflex purples for the diff, and this probably provides the lower chance of repeated bolt breakage. Some extra driveline sound and diff whine comes with the poly diff bushings, but it does not come with oem diff bushings.
Thanks bro, really appreciate the advice. I'm going to PM you 🤙🏼
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      02-21-2020, 05:40 AM   #42
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I use black 95A diff bushings and there is audible whine in some rpm ranges. I also have a 1 piece driveshaft and that may make it worse. Still, it’s not nearly as bad as my E36 that has two red 75D diff bushings and 1 solid one, along with a 1 piece driveshaft. That car sings loudly in some rpm ranges.

Unfortunately the diff whine tends to occur around highway cruising speed, like 55-70 in 6th, so you do notice it. A loud exhaust masks it a little. If this sort of thing gets to you, I’d stay stock. It might bother some but not others. Or purple 80A might be a compromised.

Obviously when you suffered damage, you want to address the problem. I will guess you do hard launches and have experienced wheel hop. Still subframe bushings and stickier tires will reduce hop, but next to nothing will eliminate it under all circumstances. You need to train yourself to recognize hop and lift throttle. Hop can damage stuff.
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      02-21-2020, 09:39 PM   #43
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Getting back to the original question, I went with BW because 1) They have a larger footprint which rests against the chassis when bolted. Every other brand I saw had a smaller footprint and leaves a gap between the chassis and subframe beyond the diameter of the raised area that actually contacts the chassis. Because of this, the BW is more difficult to install as you only have the rim of the subframe for support when pressing the bushings to allow them to pass through fully and seat.

A larger footprint provides better load distribution at the mount points, just my thinking and I dont have technical knowledge to support this.

2) The BW are anodized which none of the other brands are that I saw.
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