Miata Wood Nardi Shift Knob Restoration

At times while shifting gears my Nardi shift knob makes a terrible screeching noise. I found out after closer inspection that the outer wood layer of the knob was rotating on the stationary chrome base, causing the noise. The base of the shift knob will stay still at times, causing the noise, and other times it will rotate with the rest of the shift knob. Either way, the knob needs some attention. If your Nardi shift knob is squeaking, squealing or just feels loose even after tightening it Here is a video of the problem:

https://youtu.be/sM0iHvzqkZM

It doesn’t matter how much I tighten down the shift knob, the outer layer of wood will always be loose enough to rotate. This problem occurs because of overtightening the shift knob and also adhesive failure over time due to age or heat. As much as I would have loved to just buy a new shift knob, they are discontinued, and when they come up for sale used, 9/10 they are in worse physical condition than mine. The shift pattern is all intact on mine still, which is common to fade/rub off, and the wood is in great shape. So I figured I would try my hand at restoring this one. I reached out to a few of my friends and eventually was referred to a gentleman by the name of Bill. Bill provided me with the following picture to educate me on the structure of the knob as well as some guidance on how to remove the outer shell.

https://i.imgur.com/EjuZ55X.jpg

The knob consists of two main components: The outer layer of wood that you see and the base/core of the knob. The base of the knob is only partially exposed at the very bottom of the knob when fully assembled. There is a plastic sleeve on the inside of the metal base/core of the knob that has the threads you use to attach your shift knob to your car. Most times the wood separates from the metal core rather than the plastic sleeve separating from the metal core, but it is a possibility I suppose. The main goal is to take the wood sleeve off the metal core, clean the mating surfaces, and adhere with some fresh adhesive. Let me tell you... easier said than done because the ribs on the outside of the metal core make it very difficult to remove the two pieces.

Here is what you need to do to remove the outer wood shell from the base/core:
Buy a long M10x1.25 bolt
Bench vise
WD-40
Degreaser
Isopropyl alcohol
Clear Gorilla Glue (non-expanding)
Rubberized gloves (optional)

The first step is to remove your shift knob from the car and thread your long bolt from the hardware store into your shift knob. You are going to want an M10x1.25 bolt that is at least 100mm in length. Once you have the bolt securely threaded into your shift knob, clamp the bolt head into your bench vise. Here is the lovely simple part… pull, pull, pull! This is one of those “It's a marathon, not a sprint” situations because the shift knob is most likely going to take a lot of effort to properly separate from the base. What I did was take turns with my buddy and I while we hung out in the garage. Whatever you do, do NOT try and use any type of pry tool to remove the shift knob. The wood is soft and you will end up just denting/gouging the wood rather than removing it off the base. The hardest part is getting the initial gap started but once you start to get the wood to move, you can add a little bit of WD-40 into the gap to help. Be careful not to add too much or else the wood knob will become too slippery.

https://i.imgur.com/j61kOtE.jpg

https://i.imgur.com/HEheNOd.jpg

https://i.imgur.com/Gd6m7e7.jpg

https://i.imgur.com/yImFC3Y.jpg

Eventually, you will end up with the two pieces successfully separated (I believe in you) and now it's time to clean them up and put them back together for good. I began by cleaning all the WD-40 from the surfaces with some degreaser. Then I lightly scuffed the inside of the wood sleeve with some 400 grit sandpaper to remove any of the old adhesive that was loosely attached (don't worry about removing all the old adhesive, some of that stuff is really stuck on there and it’s not worth it).

https://i.imgur.com/FhgNx5W.jpg

https://i.imgur.com/BYQfGJK.jpg

Next, I hit the mating surfaces with some isopropyl alcohol. Now all the prep work was done. The last thing before putting them together was threading the core of the shift knob onto the car and mark the rear-facing center point so I knew which orientation to put the wood sleeve back on. That way when the shift knob was tightened all the way, it was nice and aligned. Once I had the core marked, I took it out of the car and back to the workbench. Finally, I applied a thin laying of the clear, non-expansive gorilla to the side of the wood sleeve and the outside of the core. I left the shift knob rest for 2 days while the glue cured fully before installing it into the car.

https://i.imgur.com/5BSNkvm.jpg

https://i.imgur.com/kAbYhz2.jpg

And there you have it, good as new :)

If anyone has any tips or tricks when it comes to keeping my shift knob in good condition I would love to hear it. Any polishes or techniques are greatly appreciated. The last thing I want is for the numbers to rub off on the shift pattern so I'm thinking about getting it wrapped in some clear vinyl, having it clear coated, or using some type of protective coating.