Thread: R380 rebuild after 5th gear failure

Originally Posted by awabbit6

Here's a photo of my bearing for comparison,

... ....

Not quite as bad as yours.
The thing that I noticed that was interesting was the difference in width of the wear across the bearing race. Mine is wider. It would indicate slight differences in the width of the rollers.

Your photo makes a comparison easy.

Mine certainly has noticeably more pitting.

My original comment about yours being worse was based on the impression I had that a deeper groove had been worn in the inner race. Your photo gives the same impression. It seems to have a deeper, smoother groove, although that may not actually be the case.

Something that encouraged me to believe that your bearing had worn more than mine was the notion that I had that it would take more play than there was in mine to create enough load on the teeth to break them. However that is based more on my need to believe that my gears were not in danger than any actual data.

I had a bit of time to today to look at the R380 and work out what to do avoid this box failing again.

Well that layshaft bearing is definitely the culprit for these failures, as alluded to in previous posts. My bearing whilst still in one piece was extremely loose, nearly 2mm overall deflection which has allowed the layshaft to deflect, changing the contact location between the 5th gear cogs. De-meshing has afforded the torque transmitted the opportunity to develop a bending moment sufficient to strip the teeth on the larger gear.


And what to do about this? The Ashcroft reco kit (and most online suppliers) contains exactly the same bearing, from the same manufacturer, as a replacement. Considering the rest of the bearings in my box were all very healthy (154k old) I'm not to keen to swap like for like in this case. Tomorrow I'll start chasing an equivalent bearing from Timken or the like.

Cheers,

Jas

definitley interested to hear how you go re bearing. There was word of another larger OD bearing being available, but would require case machining I think

good luck, iirc rhp made these for this application, and no other supplier is currently manufacturing, either. at least this is what my research told me when i tried to get another brand.

jc

I recall Dave Ashcroft saying not to use a different brand

Originally Posted by djam1

I recall Dave Ashcroft saying not to use a different brand

...yes probably also due to inferior copying out there in pattern parts land..

jc

Yes, RHP is genuine fitment and as good as they get, the copies are rubbish,

Dave

As Justin and Dave suggested, I drilled out the screws holding in the oil pump. They are quite soft and drilled easily.





I've cleaned everything up and painted the main casing. All laid out ready for reassembly.



I've found that Queensland Diesel Spares carries Castrol Syntrans so I'm changing to that rather than the Valvoline. By all reports it is the oil to use and I would really like it if I never have to pull this gearbox out again.

Hopefully the next update will be when it is back together