[andreu12qw]

Curious in updates as well!

Which solid subframe bushing did you go with? Any upgraded diff bushings?

[Drifter2090]

Damn that's a big update!

[tetsuo111]

I've been away. New job, new interests.

While the E91 continues to entertain, a seductive Italian is competing for attention. This is a carbureted, pre-FI Ducati. She's fast, raucous, with flashes of temper. Love the machine, and learning new skills.

[tetsuo111]

Originally Posted by andreu12qw

Curious in updates as well!

Which solid subframe bushing did you go with? Any upgraded diff bushings?

RSBs: Turner in this car, MRF in the last one (BTY, MRF is a real pleasure to work with).

Billet / solid AL rear subframe bushings are mandatory in my experience, based on two cars. They add no NVH whatsoever, and significantly tighten up control. Do the rear sway bar while the subframe is down, so you won't need to do the job twice.

Diff bushings: Turner Delrin in this car, Turner AL in the last car.

The billet AL diff bushings in the last car tighten up the drivetrain, but do add noise, transmitted from the diff pumpkin to the rear subframe and into the car. The noise sounds "turbine-like".

The Delrin bushings in this car also tighten up the drivetrain about equal to the AL bushings, with a bit less turbine-rush.

The difference is not dramatic, but is enough such that I personally prefer the Delrin. This is subjective and there will be as many who prefer the solid AL versions.

[tetsuo111]

More on bushings.

Drivetrain bushings should be upgraded as a group, to avoid concentrating forces at one location. Drivetrain bushings consist of: engine mounts, trans mounts, and diff mounts. Upgrading one or two bushings to firmer than OEM without upgrading the others will / may result in more stress at the non-upgraded positions.

Solid RSBs can be done independently without negatively affecting the drivetrain. Solid RSBs are all upside, no downside, aside from the cost to install. There is no additional NVH resulting from solid RSBs. Solid RSBs should be the first performance bushing upgrade on E9X platforms, before any others.

IME the order of precedence is:

1) Solid RSBs. In two cars, solid RSBs add significant control, with zero downside impact on NVH. In fact, the sole downside to solid RSBs is the cost of labor for the job. This is due to the scope of work and time needed to drop the rear subframe. You should do the rear sway bar while the subframe is down, or the job will need to be repeated.

2) Drivetrain. Do all three positions at once. IME, engine mounts may add subtle NVH depending on design and stiffness. You may or may not object. I found poly engine mounts too stiff for a daily. The guy using them today loves them! The trans mount is far and away the position most responsible for adding NVH, followed by diff bushings, and lastly engine mounts.

Control arm / suspension bushings are an entirely different topic.

[mashimarho]

Looking good!

[tetsuo111]

Lovin' motorcycles! I have another Ducati, this a 2005 S4R. Only 5 years separate the bikes, but they're worlds different in personality. The M750 is air-cooled and carbureted, and runs with a deep, throaty growl. It's loud, brash, and raucous. The S4R is powered with the same motor from the 996 superbike, with almost twice the power as the 750, and a more capable suspension. The S4R still appears on lists of fast production bikes, 15 years later. The dry clutch sounds beautifully analog and mechanical. In comparison to the 750, the S4R feels like a weapon. These bikes differ enough to keep both! The 750 is fun for moving around town, and the S4R is thrilling for covering ground quickly.

In memory of the late, great, justpete.

[tetsuo111]

It's been a long while since I've posted. There's a variety of reasons for this, mostly.... Italian bikes (although BMW's R Nine T is growing on me, too). There are others as well, for instance, the suspension and brake installation was strongly unsatisfactory and I haven't felt like tackling a remedy until now (more to follow). There's also family life, COVID-19, etc.

In any case, I'm getting reacquainted with my car again after a long dormant winter.

[tetsuo111]

The E9X M3 has many bits and pieces that are unique. One of these are a pair of rear chassis stiffeners.

Since a stiff, rigid chassis is the foundation for the entire platform, enhancing the chassis is a priority. These parts are not listed in RealOEM, nor anywhere else I'm aware of.

Note that the bottom chassis hole isn't threaded. A threaded nut was added.

Results: After adding these, the marginal benefit is similar to that of replacing the non-M front strut brace with the stiffer aluminum M version. The car feels "tighter". The improvement is subtle but feedback is noticeably better.

Interesting useless factoid: the insulation in the M3 is a sort of wool / fibrous matting. In my non-M, it's a gray spongy rubber-like material.

Recommended.

Pic 1 - Rear fender arch and chassis. Notice the bottom hole isn't threaded
Pic 2 - Nut added behind hole, for fastener
Pic 3 - Welds being cleaned (not me in picture)
Pic 4 - Stiffening plate, installed. Right side.
Pic 5 - Stiffening plate, installed. Left side.
Pic 6 - stiffening plate inside an M3

[cbryant514]

Originally Posted by tetsuo111

It's been a long while since I've posted. There's a variety of reasons for this, mostly.... Italian bikes (although BMW's R Nine T is growing on me, too). There are others as well, for instance, the suspension and brake installation was strongly unsatisfactory and I haven't felt like tackling a remedy until now (more to follow). There's also family life, COVID-19, etc.

In any case, I'm getting reacquainted with my car again after a long dormant winter.

After so much research on the Nitron suspension, I would very much like to know what was so unsatisfactory. Was it the product itself, the way it was installed, or some other subtle detail? Sorry it did not turn out as you hoped, buy I thank you for once again setting a high bar for my E91!

[Phil325i]

Originally Posted by tetsuo111

The E9X M3 has many bits and pieces that are unique. One of these are a pair of rear chassis stiffeners.

Since a stiff, rigid chassis is the foundation for the entire platform, enhancing the chassis is a priority. These parts are not listed in RealOEM, nor anywhere else I'm aware of.

After adding these, the marginal benefit is similar to the experience of replacing the non-M front strut brace with the stiffer M version. The car feels "tighter". The improvement is subtle but feedback is noticeably improved.

Recommended.

P.S. Not me in the picture

Thanks! You clearly have an amazing knowledge of what makes an 'M'. I imagine the impact of this bracing would be less significant in an E90 or E92 than in the wagon(?). Apart from this and the strut brace, any other 'M' stiffening parts to recommend?

[tetsuo111]

Originally Posted by cbryant514

After so much research on the Nitron suspension, I would very much like to know what was so unsatisfactory. Was it the product itself, the way it was installed, or some other subtle detail? Sorry it did not turn out as you hoped, buy I thank you for once again setting a high bar for my E91!

1. The problem is with installation, not product: IME, people either care about doing a good job, or not. In this case, management was less than confidence inspiring, but I took a chance on a new employee who impressed me with her background. She's a BMW factory trained master tech who races in her spare time. More importantly, her perfection and attention to detail is remarkable. Sadly, she was terminated by management on this, her first assignment, because they felt she was taking too long working on my car. Consequently, the management completed her work in a manner aligned with my expectations. The result was predictably catastrophic - one of the teflon-lined spherical bearings failed. When I examined the part, the evidence was clear. Only 4 - 5 threads were engaged on the end mount, because they used this as a shortcut to adjust ride height. Thus the mount failed and disconnected from the damper body while the car was in motion. Morons.

2. The product itself is confidence inspiring, with the caveat that the new suspension has only been lightly exercised since the repair was finished at the end of January. The materials, finish, and build quality are among the best I've experienced, on par with or better than Ohlins TTX. The build quality is noticeably superior to JRZ RS. They are also a better product than the TCK / Koni Sports, although the TCK / Konis are at a lower price point, are only single adjustable, and IMO are one of the best values in a performance-oriented adjustable damper.

3. Nitron customer support is remarkable. When the apes repaired their handiwork, Nitron responded immediately, requesting a couple of pics to confirm the correct part, then shipped from the UK in two days. This is not a one-off event. Nitron customer support came through when one part was missing from the original shipment, delivering the missing part overnight. The customer service is among the best I have experienced.

4. The apes delivered the car to me after repair with the suspension grossly mis-configured. I don't remember the settings as delivered. I do remember the ride felt more like a high school student's slammed Civic (hard as a rock, bumps felt "square"), and less like a performance car. I barely drove the car until May, when I decided to remedy the mess. With 3-way dampers, it takes more attention to make things work rather than screw-up. In the past 5 weeks or so, I've adjusted the ride about where I want. The feeling now is very soft and compliant, with very little roll and pitch, while still damped and controlled. Traveling at 90 - 100 mph feels like moving around 50 - 60 mph - so composed. The Third World streets in Seattle make tuning a challenge, but probably no more or less than many American cities.

5. The local tracks are just opening. The car has not yet been driven at speed on track. I expect dialing in the damper adjustments for track will take a similar amount of time as setting them for the street. Can't wait....


Nitron Dampers Tech


Pic 1- Rear coilover conversion. You can also see the Bimmerworld lower camber arm bearing installed in the rear subframe.
Pic 2 - Rear suspension, exhaust, and luggage conversion (for diff cooler)
Pic 3 - Camber plate and rebound
Pic 4 - End mount failure
Pic 5 - Failed end mount. Only 4 - 5 threads engaged.

[tetsuo111]

Originally Posted by Phil325i

Thanks! You clearly have an amazing knowledge of what makes an 'M'. I imagine the impact of this bracing would be less significant in an E90 or E92 than in the wagon(?). Apart from this and the strut brace, any other 'M' stiffening parts to recommend?

Thanks. Probably reveals more of my OCD tendencies than anything else.

These rear underbody stiffening rods are unique to M3s on E-9X cars. They're easy to find on Ebay and an easy job to install. I didn't feel the same improvement here as from the strut tower bar and rear chassis bracing.

There is also a massive aluminum stiffening plate beneath the motor, also unique to M3s. This does help stiffen the front end up.

[Phil325i]

Thanks. Funnily enough, mine's in MSport trim and has the two 'V' under chassis stiffening rods and the under-hood braces fitted as standard. The M reinforcement plate is very difficut to fit to non-M cars if you want to retain the plastic protective undertray to keep the engine bay clean.

I've increased stiffness by bolting (front) and bonding (rear) extra cross braces, converting the 'V' rods effectively into 'A' braces.

[cbryant514]

Originally Posted by tetsuo111

1. The problem is with installation, not product: IME, people either care about doing a good job, or not...

Wow - what a frustrating experience! Thank you for providing a clear and thorough explanation / update of your progress. It sounds like you are very close to the results you seek, so I hope you enjoy your HPDE tuning sessions!

[rothwem]

I would be pretty nervous about doing that full coil over conversion on something that is not a racecar with a roll cage reinforcing the rear shock mounts.

As for the sound deadening material, I think its actually an E90 vs E91. I seem to recall that my sedan had the wooly stuff in the trunk but my wagon is the rubbery stuff. Probably needed more heavy duty sound deadening because the cargo area is open.

[tetsuo111]

Originally Posted by Phil325i

Thanks. Funnily enough, mine's in MSport trim and has the two 'V' under chassis stiffening rods and the under-hood braces fitted as standard. The M reinforcement plate is very difficut to fit to non-M cars if you want to retain the plastic protective undertray to keep the engine bay clean.

I've increased stiffness by bolting (front) and bonding (rear) extra cross braces, converting the 'V' rods effectively into 'A' braces.

Thanks - I didn't know that about M-Sports. That's a nice trim package!

It did take some creativity to fit the under-motor reinforcement plate, but nothing too inconvenient. I added thread nuts to existing matching holes in the front subframe, then had a pair of billet AL stiffening rods added for extra security. I posted a thread about this, I think in 2018.

[tetsuo111]

Originally Posted by rothwem

I would be pretty nervous about doing that full coil over conversion on something that is not a racecar with a roll cage reinforcing the rear shock mounts.

As for the sound deadening material, I think its actually an E90 vs E91. I seem to recall that my sedan had the wooly stuff in the trunk but my wagon is the rubbery stuff. Probably needed more heavy duty sound deadening because the cargo area is open.

Good point. Research shows rear shock towers were a weakness on the E46. My understanding is that the E9X chassis was reinforced to remedy. I haven't come across instances of ruptured shock towers on our platform, but that doesn't mean it can't happen.

[Phil325i]

Originally Posted by tetsuo111

Thanks - I didn't know that about M-Sports. That's a nice trim package!

It did take some creativity to fit the under-motor reinforcement plate, but nothing too inconvenient. I added thread nuts to existing matching holes in the front subframe, then had a pair of billet AL stiffening rods added for extra secutiry.

Thanks. Two things:

1. Way back in the thread you said you'd fitted E30 gearbox mounts. Did you mean E30 (as in 1980's) or F30?

2. A while back you showed a tease pic of a diff back plate with cooling fins. Did you ever fit it? And if so was it easy? And what's the part number pls?

[tetsuo111]

Originally Posted by Phil325i

Thanks. Two things:

1. Way back in the thread you said you'd fitted E30 gearbox mounts. Did you mean E30 (as in 1980's) or F30?

2. A while back you showed a tease pic of a diff back plate with cooling fins. Did you ever fit it? And if so was it easy? And what's the part number pls?

1. E30 (or E21), NOT F30 transmission mounts. The benefit of the older mounts is greater stiffness compared with E9X, while remaining street friendly. It's simple to see, based on the parts geometry. The E9X mounts are intended to flex more, for comfort.

E21 mounts should be stronger due to larger mounting bolts, but these require enlarging the hole in the chassis to fit the mounting bolts. E30 mounts fit without modification. There is NO increase NVH comparing E30 to E9X mounts.


2. The finned differential cover was never used because my old LSD, with the same finned cover, came back to me. The cover fits the pumpkin w/o modification. But, it might be necessary to shave a couple of fins due to interference with some other part under the car (can't remember if it was the subframe or a suspension component).

Remember to have the pumpkin machined for any bungs for a cooler or temperature probe. I didn't do this the first time, but will the next time.

Here's a write up, with part #:

Finned Differential Cover Finally Arrived

[rothwem]

Originally Posted by tetsuo111

Good point. Research shows rear shock towers were a weakness on the E46. My understanding is that the E9X chassis was reinforced to remedy. I haven't come across instances of ruptured shock towers on our platform, but that doesn't mean it can't happen.

You haven't seen ruptured shock towers because the stock design doesn't put all the suspension forces through sheet metal that's only 1.5mm in cross section!

I mean, its your car. I'm interested to see how it holds up. If it cracks, it seems like you've got plenty of resources to weld repair and reinforce it.

[ornicar]

Originally Posted by tetsuo111

The interior is mostly finished after the addition of a M3 6MT kombi. I was accessing hidden menus to monitor coolant temps. The new cluster includes a temperature gauge and aesthetic details. Several miscellaneous bits and pieces are needed to convert the interior.

Turner 60A poly motor mounts were also installed recently. The last car had 034 Motorsports 50A rubber mounts. The 034 mounts were perfect for a dual use car. They're clearly less compliant compared with stock, but have zero NVH penalty. All upside with none of the hassle. In contrast, the 60A poly mounts are less compliant than both the 034 and OEM mounts. But NVH is a challenge when the motor spins less than 750 RPM. Furthermore, the nature of the NVH is different between rubber and poly. Rubber has a more forgiving nature, while poly seems to transmit more undesirable frequencies to the cabin. Even above 1k, the vibrations go away with the 60A polys, but there still seems to be a "hardness" to the NVH character.

More chassis strength and stiffness are ALWAYS welcome. The M3 has many chassis reinforcements, and most of them are invisible unless one knows where to look. The largest brace reinforces the front subframe with a large and strong aluminum panel. Non-M cars don't have this panel and use an "A-frame" truss instead. I was able to install the M3 aluminum reinforcement panel by adding 4 OEM blind rivets to the subframe. There are already holes in the frame for a perfect fit. In addition to this panel, I'm having an aluminum reinforcement bar fab'd to connect the subframe to the unibody.

"In addition to this panel, I'm having an aluminum reinforcement bar fab'd to connect the subframe to the unibody."

Can you please give us further details on your custom reinforcement bar?

Thanks