Big Bertha is having surgery
We bought Big Bertha with a known problem… the front axle wheel hubs had a small oil leak. This required David to periodically top up the front hubs with oil, but unfortunately this has disturbed a second gasket and has caused a more severe leak.
Our options were to replace these outer gaskets (cheap) and continue periodic top up, or tackle the root cause and dismantle the hubs to replace the offending seals (expensive).
We were very fortunate to be introduced to Raul by our new overlanding friends Mar and Luis (BB was stored at their house in Madrid while we holidayed in Indonesia). Raul works at MAN in Madrid and has looked after Big Bertha for us. After some discussion and estimated costs, we decided to tackle the root problem, after all, it would only get worse over time.
After dissembling, the problem became clear. The front drive shafts have an external universal joint between the axle and the wheel hub housing the planetary gears. The axle and hub seals are fixed to the axle and hub respectively and ride on sleeves that have an interference fit on the drive shaft. The hub sleeve was very worn and no longer presented a smooth surface against which an effective seal could be made.
It’s not clear why, but it’s likely that dirt has entered the sleeve/seal interface and caused the damage. Given it’s a 4×4 truck with less than 250k km on the clock, it does not seem a very satisfactory design!
Unfortunately, new sleeves had to come from Germany and Big Bertha spent Xmas and New Year in the MAN garage (probably BB’s idea of heaven!!).
We can report surgery is now complete and Big Bertha is under observation with hopefully little chance of remission.
Drive shaft with universal joint. The sleeves fit either side (over the shiny bits)
Secondary leak caused by me over-tightening the hub filling bolt – you can see where I squeezed the gasket out.
Great detail Dave, wonderful explanation.
Hope all is well with BB for the next 250k kms!
Thanks Nigel
Looks like you definitely made the right choice to deal with the root problem. Hope its smooth driving for the forseeable future.
Thanks Anne, I very much hope so!
Good to get the seals sorted. Trust you to over-tighten the filler bolt – tut tut David!
Happy New Year to you and Francine. I look forward to receiving your blogs and reading about your adventures.
Thanks Mike!
Hi Dave and Francine,
Very useful info for this wannabee overlander. 😉
Glad you could have it checked out and wishing you and BB all the best for 2019.
Thom
Thanks Thom. Next time I’ll go DIY – if the weather is a bit warmer.
Hhhh best wishes to her♥️
Thanks Fatin. Big Bertha is out of ‘hospital’ and has fully recovered!!
Glad you went for the more permanent solution. Looking after BB’S wheels is as important as you two looking after your feet on such an epic trek! x
Very true Ania – we hope that if we look after BB, she will look after us!!
axle and hub seals ,sleeves that have an interference fit on the drive shaft, hub filling bolt… a whole new universe opens up to me…. fascinating 🙂
Cheeky Lady 🙂
Don’t forget the inter- planetary gears! 😂
Happy New Year, Francine and Dave. What an amazing expedition. This is not what I thought you had in mind when you talked about a mobile home! Very enjoyable blogs even if most, OK – all, of the latter went over my head.
Happy New Year Allison! Ha ha – all over my head too! 😉 x
I wondered how long it would be before you started dismantling BB.
Good news! Luis & Mar are great.
Your “Big Baby” 🙂 🙂 is ready to conquer Africa!
Thanks for the update, Dave. I think that my truck/engines related vocabulary is now substantially broader in English than in Spanish! I hope everything is fixed now.
Ha Ha!!
Happy New Year. Hope it’s plain sailing now. X