I have been measuring the rear wheel-arch height to check whether my Model YL rear springs are sagging. At 20,532 km, the right rear measured 770 mm, just 6 mm above the reported 764 mm threshold for a free spring replacement.
While watching those numbers, I wanted to know which Model YL rear springs were actually fitted to my car. Reports from China say the part number changed from a final A to a final B. I slid under the car with my phone to photograph the labels. Here is what I found.
I recorded the latest measurements in my rear suspension recheck.
Photographing the spring labels without lifting the car
I did not jack the car up. I laid some cardboard on the garage floor, lay on it, then reached through the gap behind each rear tyre, next to the underbody cover, with my phone.
The yellow arrow shows where I put the phone. My arm could only reach so far, so I could not frame the shot by looking at the screen.
Without the phone light, the label was unreadable. I kept the light on, changed the angle by feel, then took quite a few photos.
Getting the label in focus was the hardest part. Too close and the phone would not focus; too far and the text was tiny. At around 2.2× zoom, I finally got a readable shot.
The Model YL rear springs on my car are 2188477-00-B
This is the first readable label.
It reads (P) 2188477-00-B plus (S) EBP26081500197. I take P to mean the part number and S to mean the serial number. There is also a Tesla logo plus a two-dimensional code.
I photographed one spring on each side. Here is the other label.
Its serial is EBP26081500206, while the part number is again 2188477-00-B. The serials are nine numbers apart. They look close enough that I wonder if the springs came from the same production run, but I cannot tell that from the labels alone. The photos also do not establish which serial belongs to the left or right side.
The last character was what I wanted to see: B.
What reports from China say about the A and B springs
The following details come from reports about cars in China. According to coverage based on repair records plus owner accounts, early Model YL cars had 2188477-00-A rear springs. Later cars received 2188477-00-B, with the reports describing deliveries from July 2026 onward as B-equipped. Service centres have reportedly fitted the same B part when replacing springs on cars that have sagged.
What changed from A to B has not been made public. I cannot tell whether the wire, heat treatment or something else changed just by reading a label.
Some owners reported sagging again after replacement
Several owners said the rear dropped again within one or two months of receiving B springs. One reported the same problem after just ten days.
The Chinese reports also relayed the view of two chassis engineers: permanent spring deformation may be the cause. As of mid-September 2026, the reports said Tesla was replacing parts but had not issued a recall.
My May-delivered car already has B springs
My Model YL was delivered in Japan in May 2026, a month after the model was announced here. That is earlier than the July deliveries described in the Chinese reports. I do not know whether export cars received B springs sooner or whether the production timing explains it.
The sequence 260815 in serial EBP26081500197 looks like a date at first glance. If it were one, it would fall after my car was delivered. I have not verified how Tesla assigns these serials, so I am recording the number without assigning it a manufacturing date.
What I do know is that my car has B springs. In my measurements over two weeks plus about 2,000 km, the rear moved down by 1 to 2 mm. That makes me reluctant to call B a proven fix.
The Japanese manual still says 169 mm
While researching the springs, I read reports that the Model YL dimensions in Tesla’s owner’s manual had become smaller. I opened the Japanese plus US English versions of Tesla’s Model Y manual and compared the six-seat Model Y L dimensions table.
| Six-seat Model Y L | Japanese manual | US English manual |
|---|---|---|
| Overall length | 4,976 mm | 4,969 mm |
| Overall height | 1,668 mm | 1,664 mm |
| Ground clearance, loaded | 122 mm | 118 mm |
| Ground clearance, unloaded | 169 mm | 166 mm |
The Japanese version still showed the figures given when the car was introduced in Japan. The US English version listed a height 4 mm lower, with ground clearance 3 to 4 mm lower. According to the reporting cited below, the change came after 16 June 2026.
This could have been an ordinary correction. Still, seeing a lower ground-clearance figure while owners were reporting sagging did not sit well with me. My car came with the Japanese manual, and I do not know which figure to use as my reference: 169 mm versus 166 mm.
Sources I used
The part number plus production-run claims come from Chinese media reports based on local repair records and owner posts. I could directly check only the labels on my car plus the figures in the two Tesla manuals.
The discussion began for me with this Drive Tesla post about rear suspension complaints.
- 21st Century Business Herald investigation of the Model Y L rear suspension
- Tencent News report on continued sagging after spring replacement
- CarNewsChina report on the manual revisions
- Drive Tesla Canada report on the revised dimensions
I will keep measuring
Both Model YL rear springs on my car carry part number 2188477-00-B, rather than the A part described for early cars in China.
Even with B springs, every measurement so far has moved downward. The right rear is now 770 mm, leaving 6 mm before the reported 764 mm replacement threshold. My first ride-height measurements provide the earlier readings.
If my car crossed that threshold today, it sounds as though the replacement might be the same B part. I would rather wait for a different revision if one becomes available, though I will keep measuring in the meantime.
If you took delivery around the same time, it may be interesting to photograph your labels too. I managed it with cardboard plus a phone light, without lifting the car. I want to see whether other B-equipped cars also continue to sink.
If another spring part number turns up, I will write about it.
This article is also available in Japanese.
