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Telly
10-14-2012, 11:49 AM
Decided to pull my 78 FJ40 front diff while I'm waiting for my seal/bearing kit to arrive. I'm doing this to clean up the housing and gears. I assume there is no issue with blasting everything with brake cleaner? Better suggestion? Thanks. Doug

Telly
10-15-2012, 08:52 AM
To be more specific, I seperated the diff from the axle housing and I plan to spray brake cleaner to clean all the grey soup off the ring and pinion, bearings, ect. I don't see this as a problem but thought I'd double check. Thanks.

subzali
10-15-2012, 09:32 AM
I don't see any reason to go to that effort. The problem for me is that I wouldn't want that solvent to get into places where it can hide and prevent your fresh oil from doing its job. If there's goop and stuff on the ring and pinion I would just wipe it off with a rag and call it good.

On the other hand, some folks would check gear backlash, runout, and all that good stuff, so in that case yes I suppose you need to do a pretty thorough cleaning. Just depends on how much work you want to do.

Telly
10-15-2012, 04:14 PM
I'm with you on this. I've gotten most of the goop out already with rags. I'm going to change out the fluid after 200 miles of 4x4 use, which should get most of the other gunk out with the drain and fill. Thanks.

Rzeppa
10-17-2012, 05:42 PM
Personally, I am of the school where you clean all residual lubricant out with solvent (brake cleaner if it is a trail fix, mineral spirits if it is my parts tank at home), blow everything out with compressed air (which gets most of the solvent out) and then fresh lubricant. If you are planning to do a lubricant change after a couple of hundred miles, then all the better.

The rationale is that that old lubricant, whether grease or oil, carries a bunch of abrasive dirt and stuff in it and you want all the stuff gone gone.

Tommy the Cat
10-18-2012, 01:46 PM
You certainly aren't going to hurt it by cleaning it too much but it isn't absolutely necessary either. I would wipe it off as much as possible, hose it down with some brake clean then install it and fill the diff with the cheapest gear oil I could find then run it in 4WD for a while and change it. I might even mix the gear oil 50/50 with ATF and get it good and warm before I dumped it.

You're really over-thinking it, it's just a diff!

Telly
10-19-2012, 07:26 AM
I dropped the diff off at "The Diff Shop" in Colorado Springs. He is going to dip it in his cleaning tank and check clearances for me. Might as well since it's out of the rig. It's going to cost me $30 bucks (if no adjustments are necessary). I plan to reinstall this weekend.

Tommy the Cat
10-19-2012, 09:50 AM
That sounds like it is for the best and a really reasonable price. Our third members are the easiest to adjust so it really shouldn't cost much if it does need a little tweaking. So easy in fact, I would do it for free if you were closer.

Telly
10-19-2012, 10:01 AM
That sounds like it is for the best and a really reasonable price. Our third members are the easiest to adjust so it really shouldn't cost much if it does need a little tweaking. So easy in fact, I would do it for free if you were closer.

One of these days I need to learn how to set-up gears...I really don't like taking anything to a shop.

Tommy the Cat
10-19-2012, 09:24 PM
Bring it with you if you pick up the birfield and we'll go through it together if you would like.

Telly
10-21-2012, 03:01 PM
Thanks for the offer but I already picked up the diff (no adjustments were necessary) and reinstalled in my rig. Did no read your offer until i was done. Thanks again. Doug

Air Randy
10-21-2012, 09:49 PM
You may also want to consider extending the vent from your front axle to minimize water intrusion. You said the goop that was in the diff was gray, so it probably had a fair amount of water in it. Could be a leaky seal too.