I decided to pull my diff cover after I noticed a loud growling/grinding noise and found a few interesting things. I don’t have any experience with axles or differentials and was hoping to y’all’s opinions. I hope to open the fwd one also.
Differential opinion (1 Viewer)
- Thread starter B1oodyBuzzard
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Your ring and pinion is toast. The entire thing has to be gone through and Inspected to find what happened. Did you find any pieces of metal in the case or drained lube? What does the pinion look like?
- Thread starter
- #4
I’ll try and get more photos. The yellow metal on the inspection cover looks like the cover was cracked and brazed by a previous owner not telling how long it’s been like thar. The guy I bought the truck from inherited it and parked it
Whats your estimate on cost for parts lol
Whats your estimate on cost for parts lol
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GA Architect
SILVER Star
Last year, I purchased a good used set of 3.70's from Georg ( @orangefj45 ) @ Valley Hybrids / Cruiser Brothers. They were set up with new pinion seals and drive flanges to match my '77. I think for those parts shipped from the West Coast to the East Coast was around $500 (+/-).
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I would guess between 100 and 200 for a good used stock one. Maybe someone here has one for you on the low end. They’re heavy as you know. What are they out of?
I've seen used diffs for under $100 that could probably be dropped in an run. If you're looking at a rebuild (new bearings, ring and pinion, etc.) then it's about $400 in parts. If you're paying someone else to set the new differential up, plan on doubling the cost of parts for labor, at a minimum.
In short - depends on how far you want to take it. $100-$1000.
Just make sure if you buy a used differential it's the same gearing and splines as the one that's coming out.
I would also confirm that the growling noise is definitely coming from the differential.
Since you didn't find any fragments there's a "possibility" the ring gear chip and cover damage was dealt with and you have a bad axle bearing. Or two. If you haven't already, get it up on stands, spin the wheels and listen close up.
Since you didn't find any fragments there's a "possibility" the ring gear chip and cover damage was dealt with and you have a bad axle bearing. Or two. If you haven't already, get it up on stands, spin the wheels and listen close up.
- Thread starter
- #9
Took another look at it after work and found the metal using a magnet. (edited the previous comment) the remaining oil that was still pooled in the bottom was magnetic and found part of the chip from the ring gear. I also took a couple videos but can't get them uploaded yet cause the iPhone screen my crapping out. Seems too be a fair amount of slop when I turn the drive shaft/pinion gear and the ring engages, occasionally sticking. Probably won't be able to jump too deep into it during the week so I'll be parts hunting. Haven't told the wife yet 
this is a Feb 1980 FJ40. Ring gear has 10X37 on it.
this is a Feb 1980 FJ40. Ring gear has 10X37 on it.
- Thread starter
- #10
I checked out their sight and didn’t see the gears for sale. First place I normally look for parts is SOR. I also came across a brand on ebay called Nitro, but I’m weary because most of ebay is just knock off crap.
I’m thinking of cleaning it up the best I can and putting new oil in just to get it to a local shop to do the work. I’m afraid I just don’t have the time to really adjust lash and set everything on my own with a limited garage space
I’m thinking of cleaning it up the best I can and putting new oil in just to get it to a local shop to do the work. I’m afraid I just don’t have the time to really adjust lash and set everything on my own with a limited garage space
- Thread starter
- #11
double post
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pb4ugo
SILVER Star
I maybe wrong, but, In reading your last response, i'm not sure you understand what others are saying. Your complete third member(pumpkin) can be removed from the axle housing. Then you can install another used third member with the proper gear ratio back in to the housing. If you go this way there is no need to buy and set up the ring and pinion and backlash. A used third member can usually be found for $200 or less. All you have to do is remove the axles then unbolt the cast portion from the front of the housing. Third members can be found in the classified section or from some of the folks that were mentioned earlier. Usually they like a phone call.
- Thread starter
- #14
Nope, wasn't picking up what ya'll putting down. I was thinking the guts for that price not the whole pumpkin as you say.
What years would that be interchangeable with???
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pb4ugo
SILVER Star
You stated the ring gear was stamped 10x37, which means you should have 37 teeth on the ring gear and 10 teeth on the pinion. That equates to 3.70:1 gear ratio, 37÷10. All fj40 pumpkins/3rd members will fit the housing, but you will want a 3rd member with 3.70 gears in it. I believe stock 1979 and later fj40's and fj60 pumpkins are that ratio. 1978 and earlier 40's and fj62's will have 4.11:1 and will not match you frt end gearing.
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Generally speaking, front diffs are in better shape due to the lack of use. It certainly doesn’t solve your problem, but if you’re in a bind for time/money, perhaps you could swap your front and rear diffs and just not engage the transfer case until you sort things out. That is, unless a previous owner beat you to it...
- Thread starter
- #18
Not that it changes anything. The above links are the videos I took of the gears.
The repaired hole in the cover may indicate that it was run without oil until they discovered the hole, and then repaired the hole. IMO, you'd be best off with a good, used 3rd member.
- Thread starter
- #20
for other people that find this in a search, I found this in regards to shipping info
Third Member Weight?
Third Member Weight?
