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      10-09-2017, 10:04 PM   #23
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Quote:
Originally Posted by buddalun View Post
Thanks roastbeef

Some more questions for ya:

-Do you recommend solid rear subframe bushings as a logical addition to the CF propshaft? I am considering these as they add no NVH. I will likely stick to OE diff bushings.

-Do you hear any sort of a "whine" especially as speed increases? Any other sounds or abnormalities as compared to the OE propshaft?

-I found that the clunkiness from the DCT was largely removed with the GTS tune. Is this what you're referring to?

TIA
this carbon shaft and solid bushings go together like peanut butter and jelly- i love pb&j, but you might not. if you are contemplating bushings anyways, definitely wait and do it all at once. the driveshaft install would take about ten minutes in addition to the subframe bushings install.
subframe bushings alone should be good, just know that it isn't a common route. the subframe and diff bushings work together to buffer NVH and soften the ride a bit. if you just do sub bushings and leave the diff bushings oem, you're going to transfer 100% of the shared load that was previously distributed among all of the bushings back there. understand what i mean? you might get more differential deflection since it is the only thing that can flex. i personally would go all the way with the bushings (solid sub, derlin diff) or don't do it.

i get slight diff whine from about 55mph to about 83ish mph. if i cruise at about 85 (not ideal), it fades away. windows down i can't hear it. windows up with radio on helps, but you can hear it when the radio is at lower volumes.
for me personally, if its not too hot, i have both windows down. if you're one of those "auto" climate control guys that rolls around with their windows all the way up, you might be annoyed.

i still have oem dct software. when i mention clunk, i'm talking about when downshifting while coming to a stop and the car lurches a little bit because now it is mechanically slowing down in addition to brake force and it combines and now you're stopping even faster.... that sort of thing. if you're in 2nd gear and on it pretty good, then let off the throttle, then get back on it, its a little harsh (oem or not). this driveshaft combined with the bushings sharpens that. its crisp- more immediate. i feel like it doesn't make anything new, it just magnifies what is already there.
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      10-09-2017, 11:01 PM   #24
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Solid subframe bushings are one of the best mods I've done. Makes the M3 feel like a newer chassis.

Now the bad news - M Factory carbon drive shafts are on back order for 2-3 months. I asked if that was a real time frame or is it delayed indefinitely (due to the legal issues YCW were having with the carbon tube supplier), no reply yet.
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      10-09-2017, 11:07 PM   #25
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Quote:
Originally Posted by roastbeef View Post
i personally would go all the way with the bushings (solid sub, derlin diff) or don't do it.

i get slight diff whine from about 55mph to about 83ish mph. if i cruise at about 85 (not ideal), it fades away.

if you just do sub bushings and leave the diff bushings oem, you're going to transfer 100% of the shared load that was previously distributed among all of the bushings back there. understand what i mean?
Yes, got it.

Couple more questions for ya:

It seems a majority of the sound (whine), if not all, is due to your diff and subframe (solid) bushings, correct?

If so, I am leaning towards retaining my OE (new) bushings coupled with the CF propshaft. Do you think there will be any issue with using this CF propshaft with the OE (new) bushings? Are the OE bushings robust enough to deal with the more direct force of the CF propshaft? TIA
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      10-09-2017, 11:26 PM   #26
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Quote:
Originally Posted by buddalun View Post
Yes, got it.

Couple more questions for ya:

It seems a majority of the sound (whine), if not all, is due to your diff and subframe (solid) bushings, correct?

If so, I am leaning towards retaining my OE (new) bushings coupled with the CF propshaft. Do you think there will be any issue with using this CF propshaft with the OE (new) bushings? Are the OE bushings robust enough to deal with the more direct force of the CF propshaft? TIA
you are correct. the sound is from the differential bushings, not the solid sub bushings. there are people who have solid sub with oem diff bushings. i had the bushings before i had the drive shaft, so i couldn't tell you what it would be like to run the shaft alone. the shaft doesn't add noise, just feel.

i think you'll be fine with oem bushings and the carbon shaft. just not if you're supercharged or track your car a bunch.
i take it you have seen my subframe undercar video?
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      10-09-2017, 11:27 PM   #27
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Solid subframe bushings add zero NVH. And CF driveshaft actually flexes more than steel and is less harsh on drivetrain components.
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      10-09-2017, 11:59 PM   #28
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Quote:
Originally Posted by Redd View Post
Now the bad news - M Factory carbon drive shafts are on back order for 2-3 months. I asked if that was a real time frame or is it delayed indefinitely (due to the legal issues YCW were having with the carbon tube supplier), no reply yet.
When did you ask M Factory? TIA.

Quote:
Originally Posted by roastbeef View Post

i think you'll be fine with oem bushings and the carbon shaft. just not if you're supercharged or track your car a bunch.
i take it you have seen my subframe undercar video?
Found it: http://www.m3post.com/forums/showpos...12&postcount=8

Last edited by buddalun; 10-10-2017 at 12:04 AM..
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      10-10-2017, 12:13 AM   #29
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Quote:
Originally Posted by buddalun View Post
Yes, got it.

Couple more questions for ya:

It seems a majority of the sound (whine), if not all, is due to your diff and subframe (solid) bushings, correct?

If so, I am leaning towards retaining my OE (new) bushings coupled with the CF propshaft. Do you think there will be any issue with using this CF propshaft with the OE (new) bushings? Are the OE bushings robust enough to deal with the more direct force of the CF propshaft? TIA
I had solid aluminum subframe and delrin diff bushings and had significant (for me) whine. I swapped the delrin diff bushings out for purple PowerFlex polys and the diff whine is basically back to stock levels, but the rear end still feels rock solid.

For max performance, aluminum subframe and either delrin or aluminum diff is probably your best bet. But for keeping NVH to a minimum while still vastly improving rear end stability, aluminum subframe and PowerFlex purple is the ticket.
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      10-10-2017, 01:33 AM   #30
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Quote:
Originally Posted by Hujan View Post
I had solid aluminum subframe and delrin diff bushings and had significant (for me) whine. I swapped the delrin diff bushings out for purple PowerFlex polys and the diff whine is basically back to stock levels, but the rear end still feels rock solid.

For max performance, aluminum subframe and either delrin or aluminum diff is probably your best bet. But for keeping NVH to a minimum while still vastly improving rear end stability, aluminum subframe and PowerFlex purple is the ticket.
I have aluminum subframe bushings and Powerflex purp diff bushings and I get a lot more whine and whir than stock. Do you have DCT or 6MT?
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      10-10-2017, 05:24 AM   #31
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Quote:
Originally Posted by roastbeef View Post
some people complain that the oem DCT is clunky. any one piece shaft is going to magnify this feeling of clunky-ness. i feel like this effect is going to be even more pronounced with solid sub/diff bushings.
you'll see a benefit of running this shaft in a stock car, just know that the subframe and differential move around a lot... like about an inch during hard driving. i don't know if there is going to be any added effect, but you're going to be putting more direct power into the differential. you'll probably be fine.



the oem guibo does bend a little bit. i have solid sub/diff bushings and it was a pain in the ass, but i did it without touching the sub/diff. the trick was to slightly lift the DCT as opposed to lowering it. i discovered this when i was about to give up and started trying things i thought were illogical.
as we know, the oem shaft is easy as it bends and makes up for the clearance issue. i think i shaved about 1mm of material off the carbon shaft while i was muscling it into the pinion flange. i was carefull to push on the metal end of the shaft because this didn't stress the carbon. its possible, it just sucks. took me about 10 hours underneath the car (including sitting in the garage cursing) from start to finish.
After the adventure of installing the driveshaft a few months back, combined with this past weekend's replacement of a broken diff bolt, I've earned my PhD in garage cursing!
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      10-10-2017, 05:32 AM   #32
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Quote:
Originally Posted by buddalun View Post
When did you ask M Factory? TIA.
Today.

Good news is, they are gearing up to build the drive shafts entirely in-house. So if you're interested, might wanna drop them a line.
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      10-10-2017, 01:48 PM   #33
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Quote:
Originally Posted by ksteckba View Post
I have aluminum subframe bushings and Powerflex purp diff bushings and I get a lot more whine and whir than stock. Do you have DCT or 6MT?
DCT.

I would say for me it is maybe 10-15% more than stock at most. All I can say is that I almost never hear it except for a brief moment in very rare scenarios with the radio off and the car in the gear/speed combo. With the delrin bushings it was the opposite: it was pretty much there nonstop (and louder) except on rare occasion.

PowerFlex Purple was a godsend for me; bummer you aren't getting the same mileage out of it.

Edit: I should also add that I have the diff damper installed that MRF was testing on my car. However, it didn't seem to make a tremendous difference with the delrin bushings so I assumed it wasn't doing a whole lot with the PowerFlex Purple, but I could be wrong. Maybe it's the combo that is really working the magic.
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      10-10-2017, 02:09 PM   #34
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I recently installed akg red 75d poly subframe bushings and 95a black poly diff bushings. There is whine from 65-75 mph. It's not bad but you can hear it. It's diff speed dependent so a dct may differ from my 6mt. I like the improvement in rear end feel from the subframe bushings. I did the diff bushings because a few people have broken diff bolts or damaged their diffs or even their subframe. I would not go any harder than 95A for the diff. Powerflex purple is softer. I did drive a solid subframe solid diff car but it was a convertible and the top was down so I heard other sounds.
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      10-10-2017, 06:20 PM   #35
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I may have to try the diff damper...I wouldn't trade the improved feel for zero whine but if I could have my cake and eat it too I'd be psyched.

I'm one of the victims of the broken diff bolt.
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      10-10-2017, 07:34 PM   #36
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Quote:
Originally Posted by Hujan View Post

Edit: I should also add that I have the diff damper installed that MRF was testing on my car. However, it didn't seem to make a tremendous difference with the delrin bushings so I assumed it wasn't doing a whole lot with the PowerFlex Purple, but I could be wrong. Maybe it's the combo that is really working the magic.
tell me more about this diff dampener... he mentioned it a while back, but when it came down to it, i think i forgot to ask for it.

i put three 3"x8" cuts of dynamat like material on the subframe tubes and i think it helped a tiny bit in dulling the sound, but it is definitely still there. i don't expect it to completely go away, but if i can reduce it, i'd be stoked. i'm going to see malek on the 19th for some work.
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      07-23-2018, 01:28 PM   #37
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I hate to bump an old thread but it looks like the driveshaft was removed from the MFactory website. Did they discontinue it? Any news? Does another company make a carbon fiber driveshaft that uses the factory guibo? Thanks for the help!
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      07-23-2018, 01:56 PM   #38
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Last I spoke to Mike, he said it was just a matter of time before they resume production.
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      07-23-2018, 04:40 PM   #39
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Last I spoke to Mike, he said it was just a matter of time before they resume production.
Could you please tell us when the last time was you spoke to him? Thanks
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      07-23-2018, 09:00 PM   #40
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Could you please tell us when the last time was you spoke to him? Thanks
6-19-18 was the last email received from Team MFactory, VP of Sales, Michael Yip.
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      07-24-2018, 06:21 PM   #41
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Quote:
Originally Posted by TNTMYM3 View Post
Quote:
Originally Posted by Milas View Post
Could you please tell us when the last time was you spoke to him? Thanks
6-19-18 was the last email received from Team MFactory, VP of Sales, Michael Yip.
I can only wish that it becomes true. Been waiting quite a while to hear some upcoming news from them.
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      07-25-2018, 03:51 AM   #42
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^ what he said
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      07-25-2018, 06:26 AM   #43
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Bummer...I've had mine for about a year and a half now...no issues. Hopefully they start making more.
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      07-25-2018, 09:47 PM   #44
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What about this option?
https://store.vacmotorsports.com/mob...e92-p3692.aspx
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