Around 6 or 7 years ago, some of the long-time members here may remember that I was rebuilding shifter linkages with thrust bearings (the linkage on the transaxle itself) to alleviate slop due the plastic coupler wallowing out. In 2016, I designed an entirely new coupler which can be 3D printed and houses the correct bearings. That was before I had a 3D printer myself... KVDR on here kindly printed me a sample. I'm happy to report that after almost 2 years of abuse in our team's rallycross 944, it has has held up great.

So I'm taking the next step - looking for 4 volunteers to run these in their 944 and provide feedback before I put them up for sale. Just pay shipping ($7.80 flat rate USPS envelope within USA or whatever it is now). I will send you everything you need for a full installation. It's your part after that, and you don't need to return it.

Let me back up and explain what this is: it's a bearing housing that replaces that plastic bit on the linkage assembly. This removes most shifter slop originating from the transaxle. These are made with PETG plastic, which is durable and allows some margin for flexing - compared to a brittle failure mode of ABS or PLA materials. Temperature and UV tolerance are up there as well, I expect this part to be quite overengineered for the loads it will see. Update: see post #13 which shows destructive testing!

A lot is explained in this installation guide I made:


So if you are interested in beta testing this part, please drop a line in this thread. I do have some "fine print" however, no way around it:

• Needs to be clear that using this part is at your own risk. The intent of this study is to get data points beyond the 1 car that currently has this installed, even though there have been no issues with it on that car. If you aren't comfortable with swapping in your old linkage on the side of the road if this part were to fail, don't bother, for your own sake. No crybabies please... this is a test of the part, not a giveaway.
• This is not a part that sits on your shelf untouched for months or years. If you contact me about testing this, the expectation is that you install it sooner rather than later. I understand we are all busy but I am limited on how many I can send out as test parts: when you see how much the bearings alone cost on McMaster Carr you will understand how this adds up for me. When one guy takes months to get round to installation, that's 25% of my study missing. My heart goes out to the guys with project 944s on jackstands who want an upgrade part for their stash, but again, defeats the point.
• Perhaps most importantly: I need you to provide feedback! Please don't ghost after you get the part - I need at least a few check-ins to see how it's holding up for you, any challenges you had, improvements or complaints, that sort of thing. Ideally every few weeks, just drop a line, even if it's just to say "hasn't broken, all good."

Sorry if the above comes off as harsh or negative - not my intent, just need to set the ground rules so there is no confusion. I'm doing the testing at a loss, and will probably not be able to sell the final product for any meaningful profit later on. I'm doing this because I think it's fun as a mechanical engineer, and I love the 944 platform. If you feel disqualified by what I said back there, reach out to me anyway: I have some test samples that I can give away, you just need to provide your own bearings (that is where the real cost is). I am also not trying to keep this locked down, as though it's a top secret patent... you can print it yourself, I made the STL file free to download. Again, just provide your feedback (and do not print this in PLA at 20% infill or something dumb!)

If I get more than 4 serious volunteers, I will need to decide based on who got there first, but also by your involvement/history on this forum. That's why I posted this on Rennlist instead of the facebook groups: nothing personal, I just need to see assurance that you're being serious.

Cheers,
Michael

 

That's really cool! I'm not a good candidate to field test your new kit but I'd like to tighten up my linkage in the next year or so. I thought I'd probably go with the all metal kit by only944 kit, which I believe also shortens the throw, but maybe yours is the better solution.

 

The Only944 part can be adjusted to give something close to a stock throw. However it's $100 more or less, I was hoping to sell these for something like $25 or $30 as complete kits. Ideally as a contract to a parts vendor. I wouldn't say they are better than the Only944 part, it's just aimed at a restoration / fix rather than a total replacement.

 

Hi Michael,
As luck has it, I’m pulling my ‘88 NA out of winter storage today. The repair is to fix the slop in the shifter. Last fall I redid the shifter in the cabin and was planning on looking underneath asap.

I wrench on my own so I can also Gucci feedback on installation.

Let me know.

Ed

 

I'm interested, primarily for my 968, if you think that would work on that car. I have the more common thrust washer upgrade that I did on my S2, which I'd be happy to replace and use as a test bed as that car is maybe closer to running reliably than the 968 and, if it works in the S2, could probably be moved over to the 968 at a later date.

Let me know, I'm happy to help out and help defray costs.

Cheers

 

Ed, thanks for volunteering! PM me your shipping address and I'll get one sent your way.

The 968 has a different mechanism. I've never seen one in person, but it looks like this part may actually fit fine. Are you going to be driving the car often? I'm happy to get the parts out there but for the 4 test parts, I'm mainly targeting people who daily drive their 944 or at least use it regularly. If you aren't really driving it that often, I can still send you the parts at cost - however I was hoping to see some real-world feedback before shipping these out. But if you are driving it quite regularly I can put you in the test group and it will be just shipping cost.

 

Hi Michael,

First, please include information so I am able to pay for shipping. Thanks.

Ed Petry
715 Lawson Drive
Westerville, OH 43081-4644

Can't wait to have a good shift again...😄

Ed

 

Hi Michael-

Keep me on the list for if you don't get enough volunteers. The 968 needs a new oil pump sleeve so it's not going to be seeing daily driver duty for a while. I'll keep up with the development; I love these kinds of projects.

Cheers

 

I would be interested. I already did the cabin shifter. I had a short shifter installed but had to remove it because of a manufacturing defect and have been looking to get rid of the slop back there. I you look at my build thread you will see installing it is not a problem for me. Currently the car is on the road and 99% of the bugs are worked out. I built this car to drive it, not park it! Since it gets the best mileage of all my cars it is my go to.

 

Roger that! Will PM you when I am ready to send them out later this week.

Absolutely. I am happy to send an engineering sample if you want one just to play with, if you get the bearings separately.

Awesome! Welcome to the team!

As a general update to everyone interested in this project: I have been doing destructive testing of several different designs of this part (different materials, infill ratios, infill patterns, layer angles, etc). My buddy came out over today to be a second set of hands. Made a test rig with a 944 transaxle, long lever arm (the black rod that goes along the torque tube), a roundsling, and a fish scale to record load. Goal was to test a stock part as the baseline, and assess the strength of this part. The findings are really interesting. A lot failed, but there is one design concept that is just as strong as stock. Spoiler: the plastic part is not the weak link! Even for the stock design, other parts failed first when subjected to a bending load condition. Will upload the footage in the coming days when I have time.

 

Let me know when you are ready and we can exchange payment/ information

 

Will PM you. Still don't have 4 people, was going to ship them when I had that. I will give it until end of today, then, will link this thread to the Facebook pages if nobody else on here is interested.

 

Finally merged all the clips together - here is the destructive testing! It's a bit of a lengthy watch, but around a dozen samples end up being tested, all with different characteristics, to dial in the design.

 

Looks like all test samples have been delivered in the last few days - curious to hear y'alls feedback on the installation process and first impressions.

 

Hi Michael,
Yes, received the kit. My plan is to install this coming weekend.

I'll definitely tell you what happens when I install.

First impressions are good. Don't expect any issues as your instructions appear complete. My plan is to follow as written and let you know.

Thanks again.
Ed