It was 10 years ago that I made a bespoke oil seal conversion for the rear bearing carrier using a small 55x63x5 Viton seal, and I was intending to use this on Brian’s engine. However, as I am close to the lathe it’s relatively easy to modify the rear carrier.

Brian’s original carrier was chewed by something since its last rebuild, so I couldn’t fit the rear seal mod that I designed, and was planning on using another one from my parts bin. Today, I decided I would machine the damaged portion away, and rather than use a 70mm seal, I opted to use a 72mm variant, which meant all the remnants of the SIMRIT oil channel could be removed, and leave a plain seal surface, as shown in the photo below.

I chose the 55x72x8 seal, because it was available in Viton & as a R23 variant, R23 means it has a dust seal too, but this is opened up after a short time anyway, but Viton is necessary because of the highish temperature and seal tip rotational speed.



I also cleaned up the oil hole, adding a larger internal radius and opening up the oil supply hole to match the front.



In the future, I will be doing this to all my engines, unless asked not to do so, but please note, I have no need to use a cast iron rear bearing carrier, as contrary to some beliefs, it is actually inferior, and a retrograde step to use it instead of the aluminium one.