Hi!
Here's another trick which improves a lot the CVT juddering.
Consider doing this only if your CVT fluid is recently changed and the juddering is still there.
Situation: I bought a Jazz CVT for town traffic purpose mainly. It came with a lot of small issues, but the acquisition price was good, and I accepted the challenge to fix it.
Of course, the CVT juddering was present.
Changed the CVT fluid with brand new Honda CVT-F oil and the juddering was diminished but not disappeared entirely.
After 500 Euro investment in other parts, I was starting to wonder if another 100 Euro in another fresh oil is suitable at this point, so I took on to logic, physics and chemistry to explain why and how this juddering happens.
As some of us know, the full fill of the CVT gearbox is 5.7 liters, but on service interval we need approximately 3.4-3.6 liters, so what's happening with the rest of 2.2 liters? According to physics, gravitational attraction will tend to keep the existing oil down in the different rooms inside the gearbox, so a double flush with brand new oil is indeed recommended. But what if, I can flush, filter and refill with the same oil used only for 500-600 km?
So, I took my tools, and did it and the result is a big improvement, the juddering has now decreased a lot (specific, in my case I was having 2 juddering intervals, 1st from a stand still start and 2nd when reaching ~2000 rpms. After my DIY flush, I have only the 1st juddering at a much lower intensity).
Steps for the process (assuming you all know how to change the CVT oil, if not, go to youtube and see the tutorials):
1. Search and buy or use from home a very fine and clean filter material, with very tiny gaps between bands of the filter (you can use a pair of woman tights applied in 2 or 4). I've used both (woman tights and a purchased filter).
2. Prepare 2X a clean (or brand new) empty recipient to collect the used oil and to get the oil filtered. Minimum 4 liters capacity for a good manipulation when full.
3. Try to ensure a clean environment when you do this job....as much as possible (avoid dust, particles, water or any other debris which can contaminate the oil).
4. First clean the mess around the oil cap (brake spray, soap and water, alcohol, etc.), just make sure is completely dried before proceeding next.
5. Open the CVT oil bolt and carefully retrieve the used oil in the 1st recipient.
6. Use a clean funnel on which you apply since the beginning the filter (I've used a fuel funnel which has a filter inside and I added extra my "performance" filter homemade or bought).
7. Pour slowly and carefully the used CVT oil from the 1st recipient to the 2nd one through the improvised filter. When almost finished, pay attention at the last 50-100 ml of oil, if you see debris in it, my suggestion is to accept this minimum loss and recycle it.
8. Clean the oil magnetic bolt (use brake cleaner spray is my suggestion and leave it for 1-2 minutes to get dry). Put back the magnetic bolt and tight with medium strength (1 quarter after free tightening becomes hard with the wrench).
9. Pour back into the gearbox the filtered oil from the 2nd recipient.
10. Start the engine, press the brake and switch through every gear available (P R N D S L) and allow 5-6 seconds functioning in each of them. I think a better option is to drive for few km the car, but if you are in a hurry, switching through gears will be enough.
11. Repeat the whole process starting step 5.
You will notice at the first flush metallic debris on the magnetic bolt and also some non-metallic debris at the bottom of the 1st recipient (last drops of used oil from the 1st recipient). Also, you will see some non-metallic debris on your improvised filter. I had only 500-600 km since the CVT fluid change.
At the second flush, you will see only non-metallic debris on filter and at the bottom of the recipient, but you can clean also the bolt.
I hope this saves 100 Euro from your wallet, but you should always change the CVT fluid with brand new one (only Honda CVT-F) at maximum 40K km. From my experience with this, the new oil lasts around 3 years or max 40K km before the juddering will re-appear. I think it depends much of the climate area and usage type.
Succes!
