questions about surface rust on ring and pinion (1 Viewer)

[edwards_rljr]

I have a '78 FJ40 and I posted here a few weeks ago about my rear differential that I was having trouble with and I ended up buying a used front 3rd member off ebay that was listed as being in 'good used conditioin' ... I paid around $185 shipping and all... I got it the other day and have been working on the job this weekend... the used 3rd was pretty grimy so I was cleaning it up and noticed that there is some rust on the ring gear as well as some that I can see down in there on the pinion too... there is not any rust like this on mine that I'm trying to replace and I'm guessing this is a sign that there was water in the differential and it was sitting for a while or something like that but I don't know if this is a common problem for front diffs or not ? I used a wire brush and mineral spirits to clean it up and there is some slight pitting of the surface of the metal. I am wondering how much of a problem this may be or is likely to become in the near future if I go ahead and do the swap ? I don't want to do all this work and install this used 3rd if it's only going to end up being a problem in a short time because of this pitting of the metal on the ring and pinion. The pitting doesn't look that deep really but obviously the surface is not smooth anymore. Is this pitting likely to cause the ring and pinion to wear more and damage the gears because the metal surfaces are not completely smooth ? pictures below, any advice and opinions would be appreciated.. thanks

 

[Pin_Head]

It is not unusual, especially in the front and I have seen and run worse.

 

[cruiser88]

oh heck put the cover on and drive down the roadjust dont forget the gear oil

 

[edwards_rljr]

thanks for the reply... I've heard that you are the landcruiser guru so that makes me feel a lot better about this since I really did not want to have to deal with trying to send this thing back and find something else... I guess I'll go ahead with it.

 

[OffRoad911]

Hi Gents, Need some urgent advice. My mechanic has opened my BJ40's front diff and has spotted water ingress. There are visible signs of rust (see images). He has asked me to source a used a complete front end to replace it with but I am concerned why I need to change the whole thing. The images above are pretty bad compared to mine and I wonder why I should change the whole front end. Will appreciate some feedback please.

 

[Pin_Head]

While it looks ugly and you wish it wasn’t there, it is not going to hurt anything. If your mechanic is pissy about it, get another mechanic.

 

[71FFJ40]

Hi Gents, Need some urgent advice. My mechanic has opened my BJ40's front diff and has spotted water ingress. There are visible signs of rust (see images). He has asked me to source a used a complete front end to replace it with but I am concerned why I need to change the whole thing. The images above are pretty bad compared to mine and I wonder why I should change the whole front end. Will appreciate some feedback please.

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Based on your pictures......nothing suggests the need to replace your front end.Completely clean,degrease and rebuild? Yes- no need to replace the entire front end.

 

[OffRoad911]

Based on your pictures......nothing suggests the need to replace your front end.Completely clean,degrease and rebuild? Yes- no need to replace the entire front end.

Reading your response gives me confidence to tell the workshop not to replace the front axle and diff. Many thanks