Nissan Patrol 4x4 (Africa)

Peter Connan wrote: ↑22 Apr 2020 19:59 I have been wondering for quite a while whether these things are any good:

https://www.google.com/search?q=diff+br ... Ft-UqhOn3M

I would not mount it directly on the diff, bit up on the chassis though...

Thanks for sharing Peter. Very interesting product. And yes probably best to mount it somewhere where its protected from stones and sticks ect. I wonder what volume of air is expelled in and out of the patrol diff and whether or not they will be big enough to accommodate this. At first glance it looks like they are made for ATVs ?

Ah, you see...

Thanks Craig

I just did a quick "calculated guess", and we probably need a bellows of around 2L for the front diffs, and somewhere between 1.5 and 2.7L for the rear diff, depending on which rear diff we are talking about.
This is for a temperature change of 0C to 130C. I am not sure how hot a diff actually gets in heavy use, but I'm working on what I believe the maximum temperature oil can get to before it starts breaking down.

I still like the concept as it would mean that there would be basically no chance of getting any contaminants into the diff from the breather, but it might be tricky to find a nicely-protected area for a bellows that size. And certainly those little bellows don't look large enough.

Could these be remotely fitted in the engine bay & the additional capacity needed (as mentioned by Peter, 2L - 2.7L) made up by the lenght of the pipe extension itself?

hugejp wrote: ↑23 Apr 2020 18:29 Could these be remotely fitted in the engine bay & the additional capacity needed (as mentioned by Peter, 2L - 2.7L) made up by the lenght of the pipe extension itself?

No, I think the bellows has to have that much capacity. That is how much the volume of air in the diff can change, and therefore that is how much air movement must be accommodated. Since the volume of the pipe doesn't change, I don't think you can bring that into the calculation.

Assuming you can find a suitable bellows, and that you don't have air helper springs, the inside of the rear coils might be a good, safe place?