Crown Wheel and Pinion Replacement Options??

[Ross]

Thanks Peter!

[Ross]

Hi Ross,

Having read through this thread at some length, it seems you have had a lot of drama. :-(

It is not clear to me whether the original axle was ever fully stripped to determine exactly what the problem was? Was it and if so, what exactly had failed?

Cheers,
Clem

Hi Clem,

To answer your question, yes the original axle was fully stripped. There was damage to the crown wheel and pinion gear teeth. As to how the failure happened, we are not entirely certain, however we had noticed that there was a fair amount of backlash in the diff prior to failure (although I didn`t realize that it was considered excessive)...I suspect that perhaps the previous owner may have got water into the diff on a Botswana trip at some point, and this is perhaps where the accelerated wear originates from....this is pure speculation however. During my ownership the oil has always been changed regularly, and I have never had any water ingress issues.

I did an Eastern Cape overland trip late last year just at the time of the floods and the diff noise (so presumably the failure) started during that trip. Initially I couldn`t think of any situation that could have caused the failure, however in hindsight I suspect that a combination of the backlash in the diff together with working hard getting through several mud holes on the washed out roads placed enough strain to brake/chip a gear tooth....the drive home to Cape Town then did the rest of the damage.

Anyway..the above seems like the best hypothesis, as I can`t pin point a specific event where I suddenly became aware of a change, or thought at the time "gee I`m really pushing the vehicle's limits here".

[Clem]

Whew. Not good. One reason I raised all breathers (axles, gearboxes and engine) on my old Discovery high up into the A, B and C pillars. Not sure yet how it works on Patrol and whether one could do the same. Could also conceivably be the consequence of very extreme abuse in low range but doesn't seem very likely.

[Marino4x4]

Hi Clem

I am not sure about the 4.8, but in my older 4.5 all the breathers are extended and are raised to next to the air intake. If you have a look at your air intake there should be a rubber fitting with 4 or 5 rubber pipe in it. This also helps when you fit a snorkel that you extend the breathers to the top of the snorkel as your air intake. This is if everything is waterproof.

Do not think there is to much to worry about on the Patrol except maybe if it gets blocked.

Cheers

[Clem]

Thanks for that - I just learned something new!

[Stefan]

Sorry to hear Ross.

[Ross]

Hi All,

Once again thanks to all who have contributed to this now fairly lengthy thread (even if just in the way of moral support). Much appreciated...thank you!



Okay, so finally some positive news. After some negotiations I have reached an accommodation with the guy who has been doing the work on the Diff. After investigating various options I have ordered a complete new diff center from Nissan, with my diff guy contributing the difference in price between replacement parts for the original diff center (which has been lost) and the cost of the complete replacement.

Luckily there is stock ex JHB (according to the Nissan parts system anyhow...), so I hope to take delivery of a brand new diff centre for my original axle by Wednesday. Have ordered new rear wheel bearings from Bearings International (2k vs over R5k from Nissan!!!), and should have them by Wednesday as well.

If all goes according to plan (and I realize this is a large assumption based on how things have gone thus far!!!), the Trollie will be back up and running some time next week.

Holding Thumbs.

[ricster]

EXCELLENT NEWS !!!!!

[Tinus lotz]

Happy to hear that u are getting some more positive input at least your patrol is getting back on the road

[Ross]

FINALLY.....The Concluding Chapter!!

Took delivery of the Patrol on Wednesday, re-fitted with the original axle, and a brand new diff center from Nissan, and it is driving perfectly!! What a huge relief to finally be back up and running.

For the benefit of anyone who is unfortunate enough to be left in a similar predicament in future, I thought I`d share a few thoughts and lessons learned...in no particular order:

1. Be very careful of second hand parts. I think these can often be a very viable route to save costs, however in this instance it led to being badly burned even though I thought I had taken the appropriate precautions (getting it checked by a diff specialist prior to purchase).

2. Related to the above, a visual check may not be sufficient to detect issues with second hand parts (particularly axles and diffs in this case). The second hand axle proved to have a bent axle casing, as well as a bent pinion shaft, however there was no visual evidence of this. When checked on an alignment machine however the rear wheels had a toe in of 18.4mm.

3. If you`re in a tight spot, there are specialists around who claim to be able to straighten a bent axle. Before the bent pinion was discovered, the axle casing was sent to such a specialist. Their work improved the alignment reading from 18.4mm toe in, to 3mm toe in, which is a significant improvement, however I would have sent the casing back had the bent pinion not resulted in me abandoning the 4.5 axle swop. The ideal spec for minimum tyre wear would be less than 1mm, whether this degree of accuracy would be achievable if I had followed through is hard to say, but probably worth a shot if anyone has the mis-fortune of bending an axle for whatever reason.

4. Conventional wisdom seems to be that if a pinion shaft cannot bend without either cracking the diff casing, or causing visible damage to crown and pinion teeth. This is not the case! When spun up in a lathe the 4.5 pinion has a distinct wobble/run out (the cause of a bad vibration on over-run when fitted to the vehicle), however there is absolutely no other visible damage…gear teeth look brand new.

5. A H260 rear axle is a direct swop into a H233B axle vehicle, the only thing that requires modification is the propshaft, which must be shortened by 50mm to accommodate the larger H260 diff casing. The propshaft will physically bolt up, but the slip joint will be maxed which will cause problems.

6. If you bargain hard and play the dealers off against each other re discounts, a new ring and pinion for the H233B rear diff can be had for around R6800 Ex VAT….in retrospect, this is a BARGAIN!! Carrier bearings and pinion bearings should be available from the aftermarket bearing suppliers, so its probably only the collapsible spacer that you would need extra from Nissan. Faced with the same situation again, this is the route I should have gone. Not doing my homework properly with regard to the Agent prices caused me to go down a 7 month dead end!!!!!

7. Rear axle bearings are difficult to obtain from the aftermarket suppliers, and are very expensive from Nissan. Rear Axle bearings are however obtainable from Bearings International (Bearing Man swore they were agent only!), however the grease seal is only available from Nissan. Good Quality (jap) rear axle bearings cost R1k per side from Bearings International, vs R2.2k per side from Nissan. Nissan will however still fleece you another R1k for the seals!!!

8. When re-installing a diff, do ensure that you refer to the shimming procedure for the actuator, outlined within the workshop manual. If the actuator is not properly shimmed, you may not be getting a full engagement of the mechanism which will lead to a increased likelihood of failure under load.

Okay…think that’s about all I can think of for now. Hope some of the hard lessons learned over the last 7 months will save some other people some hassles.


Have ended up with the remains of the abandoned 4.5 rear axle. It is not usable as a unit, however the following component parts are available and known to be good. If they are of use to you, please PM me.

- 4.5 (H260) diff carrier with spider gears and diff lock mechanism
- Diff lock actuator
- 4.5 (H260) side shafts, with R 2k worth of brand new axle bearings pressed on.
- Various other related axle parts

Cheers,

Ross