My 2017 Beta RR 300 leaked shock fluids on my last trip. The rear end suddenly started feeling like it was all over the place, and quick test revealed that the rebound dampening was completely gone, propably due to air in the shock. The bikes got approx. 270 hours on it, and has been maintained well by the previous owner, but it turned out that the shock haven't been serviced, not even once.
The oil looked like used engine oil, and there was a small piece of anodizing missing from the inside of shock body. I smoothened the damaged area with 1500 grid sandpaper, and called it good. Otherwise the shock body was in pretty good shape. While I was at it, I polished the shock shaft, cuz why not.
As I've owned KTM's before, it was surprising that Beta only sold the full shock seal kit for around 110€'s, which was way too expensive, since I wasn't going to replace more that the seals in the seal head, and possibly the teflon shock bands if they were worn. Turned out the shock bands were in decent condition, so only the seals were needed.
This is the original disassembled seal head from bottom to top. The oil seal and dust seal needed replacement. Please note that the oil seal is upside down in this picture. The seal was an odd size, so some engineering had to be done in order to fit a traditional sized shaft seal.
The groove for the oil seal measures 6mm in depth. The original oil seal and thrust washer measured 5mm total, and the cap that holds the seal in place has a "flange" of 1mm, so the math adds up.
I then professionally turned the cap on lathe (=sanded it) so that the whole surface is flush.
And boom, we have space for traditional sized oil seals, since Sachs uses a size that wasn't even recognized by Finlands largest hydraulic store.
The seal is labeled B3 P5008, sized 16x24x5.7. Cost me a whopping 11€'s.
After that it was just a matter of installing the seals and putting everything back together according to the service manual. The whole rebuild cost me 14.6€'s for the shaft seal and the dust seal, and 12.9€'s for 5w shock oil. I tested the system with compressed air, and it is holding just like it is supposed to be. I still need to get the shock filled with nitrogen to 135psi.
Hope this helps someone who is as cheapo as I am. 😂