[odonnell]

Hello all, I'm an imposter from the 944 world. Wanted to share a part that I whipped up for a friend on here, for his xDrive E90. My understanding from him is that a good (stiffer) aftermarket part isn't available, except for a solid unit which leaves a lot to be desired as far as NVH.

This design is a simple insert, made from 95A Shore hardness thermo-polyurethane (TPU):



Here is a video of the bushing, and installation:

I mainly wanted to feel out the interest for a part like this. I'm not necessarily trying to profit from this - I figure that if a 2 or 3 were sold (which would offset my time/materials) then I would be happy to open-source this part are share the files. Just reckoned it would be better than making a one-off part.


If anyone wants to be part of the testing, drop a line. I can ship a few at cost, probably $10 + $8 flat rate USA shipping.

[mikest]

Thanks for posting (and making this part). I'm super interested! Unfortunately I'm too much of a lurker to have established permissions to PM you.
Is this offer still open, I'd love to take you up on it...

FWIW, I've already installed UUC short shifter and Turner poly shifter arm bushings to improve shift feel. There's still room for improvement, and this could really help.

Edit:
A couple of hardness datapoints from this thread with folks experimenting with filling their transfer case mounts:

• poly, 80A = "horrible vibration and noise"
• 3M WindoWeld, ~60A = "feels great...slight added NVH"

Granted that an insert probably doesn't transmit NVH as completely as a filled bushing, but my gut says that folks willing to do the work necessary to create the above two datapoints likely have higher NVH tolerances that the wider market for an insert. Can you cast 60A-or-lower poly?

[odonnell]

Sorry, I haven't checked this thread in ages. I'll add a few notes, after shipping almost 50 of these (in various hardness levels) since my original post, and receiving feedback.

To start with: I want to be transparent about my manufacturing process. These are 3D printed from TPU, at whatever hardness / stiffness has been requested. However, there isn't much in common with a normal 3D printed part which you may be imagining. These are made completely solid, and then annealed in a baking soda cast for several hours at 200 C. This fuses everything together, making it a solid and isotropic part. It is virtually identical to polyurethane except that it will begin to melt at around 200-250 C. However, this is not a risk, as you would have bigger problems if your transfer case mount was getting this hot. Even before the annealing process, it is virtually impossible to break the layers apart. It is very tough - ask anyone who has purchased one. I am a mechanical engineer by trade, and run a very tight ship as far as quality and acceptance criteria.... been designing and shipping custom Porsche 944 parts for almost a decade.


Next - a breakdown of the different hardness / stiffness options:

• Shore 95A
• Shore 98A
• Shore 64D
• Shore 75D
• Others can be made on request, within reason!
• Edit on 7 December 2023: I have purchased 75A and 83A material due to a customer request. I can now also offer these as softer options, 75A is not much stiffer than the original rubber of the mount.

The 95A insert is most appropriate for 90% of people. Daily drivers, enthusiast driving, etc. It removes a lot of slop from the driveline (rotational / torsional) without sacrificing too much for NVH. However, there is still a slight NVH increase. A few people have noted that cold starts are rougher, and raised the idle by ~100 RPM to compensate, which did the trick. There is also a very slight amount of gear whine at certain speeds, but nothing crazy.


The 98A insert will turn everything up a notch. Expect an even more direct driveline response, but also a little more NVH. I would personally use this in an autocross car or an otherwise dedicated "fun" car.

The 64D / 75D inserts are approaching a solid piece, but obviously not quite as rigid as the Twisted Tuning billet part. The only reason I listed these are because a few racing teams have special-requested them from me, so I made the investment in the raw material and made profiles for them.

As far as track record, I have shipped around 30 of the 95A versions with overall positive feedback. Maybe 4 or 5 of the 98A version with good feedback. I never heard back from the guys who bought the 64D / 75D parts, but they were apparently installed in a few track-prepped cars.


As far as pricing: my initial engineering time, material cost, power usage, and post-processing time leads me to $55 USD + shipping for the 95A and 98A versions. Increase of $20 for the 64D and 75D versions purely due to raw material cost. Each kit comes with the insert, installation tool, packer shims, and printed installation instructions.

I am located in Texas, so shipping is generally ~$9 for a flat-rate padded envelope. For international customers, I will take $10 off the price, because I feel bad that the shipping is sometimes almost as much as the part, and I don't want to leave you out. I have shipped around 10 of these internationally to Norway, UK, Sweden, Netherlands, Canada, etc. It was $30-40 each time.

Please feel free to reach out with any questions,
Michael O'Donnell

[odonnell]

Originally Posted by mikest

Thanks for posting (and making this part). I'm super interested! Unfortunately I'm too much of a lurker to have established permissions to PM you.
Is this offer still open, I'd love to take you up on it...

FWIW, I've already installed UUC short shifter and Turner poly shifter arm bushings to improve shift feel. There's still room for improvement, and this could really help.

Edit:
A couple of hardness datapoints from this thread with folks experimenting with filling their transfer case mounts:

• poly, 80A = "horrible vibration and noise"
• 3M WindoWeld, ~60A = "feels great...slight added NVH"

Granted that an insert probably doesn't transmit NVH as completely as a filled bushing, but my gut says that folks willing to do the work necessary to create the above two datapoints likely have higher NVH tolerances that the wider market for an insert. Can you cast 60A-or-lower poly?

Hi, I can certainly make a much softer version. Feel free to reach out to me! The 95A part leads to a slight increase in NVH, but is still daily-driver friendly, based on feedback from around 10 people. But I can make it even softer if requested.

[mikest]

odonnell You've got more/better data points than those I referenced, sounds like the 95A would suit me. Price seems more than reasonable. Could you post or send the installation instructions along with preferred payment method?

[alex35i]

pm'd

[odonnell]

Originally Posted by mikest

odonnell You've got more/better data points than those I referenced, sounds like the 95A would suit me. Price seems more than reasonable. Could you post or send the installation instructions along with preferred payment method?

I've uploaded the instructions here:

https://drive.google.com/file/d/18J1...usp=drive_link


As far as payment, I mostly use PayPal (send as goods and services, it's the right thing to do, and protects you as a customer). But I can also work with Venmo, Zelle, Apple Pay, etc.


To get in touch, I should get an email whenever I get a PM on this forum. But the best thing is just to directly email me. Let me try and put my email here in a way that won't get harvested by all the scraper bots.... (sorry for being weird)

midodonnell at gee mail

[ACJBMWPVD]

This is a great product! Please help me understand the shore ratings above...

It sounds like the 95 is softer than the 98 but the 74 is firmer...I am confused.

Is the firmness rating not linear? Thanks for doing this and educating us! I want something more firm for a track car build that is driven on the street too.

Thanks again!

[HondaRC51]

Originally Posted by ACJBMWPVD

This is a great product! Please help me understand the shore ratings above...

It sounds like the 95 is softer than the 98 but the 74 is firmer...I am confused.

Is the firmness rating not linear? Thanks for doing this and educating us! I want something more firm for a track car build that is driven on the street too.

Not necessarily. It depends on what "Shore Hardness" scale the Poly is rated for. This might help to explain

[odonnell]

Originally Posted by ACJBMWPVD

This is a great product! Please help me understand the shore ratings above...

It sounds like the 95 is softer than the 98 but the 74 is firmer...I am confused.

Is the firmness rating not linear? Thanks for doing this and educating us! I want something more firm for a track car build that is driven on the street too.

Thanks again!

There are several 'scales' for Shore hardness. 'A' and 'D' are the most common. You can find an equivalency graph here:
https://www.smooth-on.com/page/durom...ardness-scale/


One of the most common questions from customers is the equivalency of this insert versus a different type of mount, for an example, a motor mount. 95A sounds quite hard compared to aftermarket / stiffer mounts which may be only 70A to 80A. So how can a 95A insert be appropriate for a daily driver, when 80A motor mounts give you significantly more NVH?

The key here is understanding the composite system stiffness. Ultimately, the insert is reacting to the load in series with the original rubber of the mount. So in reality, your "effective" hardness is somewhere in the middle between rubber and 95A (or whatever hardness was selected). Hard to calculate the exact value without a fancy FEA model, but this is what's going on. As a ballpark estimate, the 95A insert makes the overall mount behave like an 80A part, if you imagined that the whole mount was homogeneous and solid.

[J828BROWN]

Hello I just joined the page and still trying to figure things out. Michael O, I saw your video on YouTube and sent you an email. let me know if you are still making these inserts.

[N54_Sauce]

pmed

[Jeffman]

Feedback: I finally installed the OP’s 95A hardness insert this week. It’s too stiff. Too much NVH. I needed to raise idle from 650 to 900 rpm to make it bearable while idling, but driving is still rough and not refined. As well during pulls I’m getting lots of timing drops and transmission noises. I removed it and went back to stock.

[bshambam]

I did mine w/ 95A harness but it is not solid fill. Driving and shifting is much more direct, not much slop at all.

[Jeffman]

The OP @odonnell just did an amazing thing - he replied to my email and told me that he heard similar feedback (too stiff / too much NVH) from others about the 95A hardness inserts. So he very kindly offered to send me softer 75A inserts to try *for free*. Now that’s what I call customer service!

[theoforest]

Originally Posted by Jeffman

Feedback: I finally installed the OP’s 95A hardness insert this week. It’s too stiff. Too much NVH. I needed to raise idle from 650 to 900 rpm to make it bearable while idling, but driving is still rough and not refined. As well during pulls I’m getting lots of timing drops and transmission noises. I removed it and went back to stock.

What do you mean by timing drops? Timing correction ?