Rear end noise (1 Viewer)

Cruiserdrew

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If the diff is original, my guess is your pinion preload is close to zero. It's normal from wear, but it will cause other problems and a leaking pinion seal eventually.

I'd say decide now. If you're doing an 80 axle FF swap in the end, do it now. If that's going to get pushed off to the infinite future, then a diff rebuild is reasonable.

Remember, you could get another differential, rebuild it, and then the full swap could be done in a day easy. And a rebuilt differential now, can still be used with an 80 series housing. My FJ60 is set up like that with a harrop and 80 FF housing it's been great.

Now if cash is really tight, then a front to rear swap will be your friend. Don't bother messing with the diff at all. Just pull the spacer and you that with the diff that's currently in the front axle. The minimal use that the front gets, usually means that's for all intents, it's still good and you can just run it and run it.
 

Spook50

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If the diff is original, my guess is your pinion preload is close to zero. It's normal from wear, but it will cause other problems and a leaking pinion seal eventually.

I'd say decide now. If you're doing an 80 axle FF swap in the end, do it now. If that's going to get pushed off to the infinite future, then a diff rebuild is reasonable.

Remember, you could get another differential, rebuild it, and then the full swap could be done in a day easy. And a rebuilt differential now, can still be used with an 80 series housing. My FJ60 is set up like that with a harrop and 80 FF housing it's been great.

Now if cash is really tight, then a front to rear swap will be your friend. Don't bother messing with the diff at all. Just pull the spacer and you that with the diff that's currently in the front axle. The minimal use that the front gets, usually means that's for all intents, it's still good and you can just run it and run it.
I might just go the front/rear swap route honestly, since I could easily do that in a weekend and money IS tight right now. If it lasts me until I can put an 80 axle in (closest full float I can find for a reasonable price is 560 miles away in Twin Falls, ID for just under $800; disc, FF, no factory locker, but I intend to put a Harrop in before swap) that's all I really need at this point. OTOH, I have yet to make sure the outer bearings are still good too, so I might be in it for that either way on my current rear.
 

Spook50

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@Cruiserdrew rereading your post, you say that the rebuilt 62 diff can be used in the 80 rear. Does this mean the diff itself can support use of a locker that would require a full float axle (I've had my eyes on a Harrop locker for when I do the 80 conversion), or as a "use as-is until the 80 diff is set up" type of deal. I had always understood the entire carrier assembly was different between semi float and full float axles (hence why I never realized I could swap my front and rear diffs).
 
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@Cruiserdrew rereading your post, you say that the rebuilt 62 diff can be used in the 80 rear. Does this mean the diff itself can support use of a locker that would require a full float axle (I've had my eyes on a Harrop locker for when I do the 80 conversion), or as a "use as-is until the 80 diff is set up" type of deal. I had always understood the entire carrier assembly was different between semi float and full float axles (hence why I never realized I could swap my front and rear diffs).
Both the front and rear axles on the 60 and 62 were all semi float in America. I’m not super familiar with the 80 series axles but as I understand it the third members are interchangable on axles from the 70’s through the mid 90’s with some variations to the castings between models here and there.

Is the 80 series axle full float? Is that why the swap is done? I have never looked into it myself.
 

Spook50

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Both the front and rear axles on the 60 and 62 were all semi float in America. I’m not super familiar with the 80 series axles but as I understand it the third members are interchangable on axles from the 70’s through the mid 90’s with some variations to the castings between models here and there.

Is the 80 series axle full float? Is that why the swap is done? I have never looked into it myself.
I do know the 60/62 front is full float, though the US rears are semi float. As far as the 80 rears, I believe some actually had a semi float early on (could be wrong there), but the majority are full float.
 

Spook50

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So this last weekend I went ahead and did the outer bearings. The old ones definitely appeared worn, but not shot by any means. Though there was a small amount of play on the passenger side when I'd jostle the wheel at 12 and 6. While I had it up I tried grabbing the pinion flange and moving it, but felt nothing. However this was with the driveshaft in place so I'll give it a feel again when I pull the shaft to do the U joints. The new axle bearings DID reduce the noise, but I can still faintly hear it during heavy breaking. I also noticed while I had it apart what looked to be a good amount of wear in the spider gears. But being inexperienced in differential work or diagnosis I'm not sure if this is still acceptable or definitely bad. What's the thought?

20210314_130048.jpg



This is what I saw as I turned the passenger side shaft after putting it all back together.
 
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So this last weekend I went ahead and did the outer bearings. The old ones definitely appeared worn, but not shot by any means. Though there was a small amount of play on the passenger side when I'd jostle the wheel at 12 and 6. While I had it up I tried grabbing the pinion flange and moving it, but felt nothing. However this was with the driveshaft in place so I'll give it a feel again when I pull the shaft to do the U joints. The new axle bearings DID reduce the noise, but I can still faintly hear it during heavy breaking. I also noticed while I had it apart what looked to be a good amount of wear in the spider gears. But being inexperienced in differential work or diagnosis I'm not sure if this is still acceptable or definitely bad. What's the thought?

View attachment 2615087


This is what I saw as I turned the passenger side shaft after putting it all back together.
Spiders look good. That lash looks about right. If you have your dial indicator you can check the gear lash while it’s atill mounted up which is what I would do next.
 

Spook50

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Spiders look good. That lash looks about right. If you have your dial indicator you can check the gear lash while it’s atill mounted up which is what I would do next.
Ring gear backlash against the pinion felt good, but definitely more than 7 thousandths. Going by what I could tell without my dial indicator I would say about 10 to 15. From my experience at my last job I can estimate pretty close in tens of thousandths, but am curious what the actual number is now. It didn't seem nearly as worn as I expected, but I think a rebuild is definitely in the near future.

This actually raises a few questions I'll post in a new thread as to the necessity of a full float axle versus sticking with my disc brake semi float, concerning actually taking advantage of the extra strength of the FF.
 

Cruiserdrew

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Agree the small pinion gears look about right but that tells you nothing about the condition of your pinion bearing where the problem likely is.

You really should measure the backlash. Nevermind, you did and it's excessive. I think you need a full diff rebuild with a new bearing set and possibly a new gearset.

If you're in it that deep, go ahead and swap the front and rear. That's the best poor man's solution you have. But if you're at high miles, you likely just need to rebuild the differential anyway.

But if you're going Full float, by all means get on it. No need to analyze further.

Edit: Thinking about this more, your front differential probably should be swapped regardless. The gearset will have much less wear and would be better for long term use when you do get around to a FF swap.

Also, I think there is no rotational strength difference between FF and SF. The Full float can carry more load, but the spine diameter of the alxe is the same 30 spline size in either, so torque strength should be near the same.
 
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Spook50

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Agree the small pinion gears look about right but that tells you nothing about the condition of your pinion bearing where the problem likely is.

You really should measure the backlash. Nevermind, you did and it's excessive. I think you need a full diff rebuild with a new bearing set and possibly a new gearset.

If you're in it that deep, go ahead and swap the front and rear. That's the best poor man's solution you have. But if you're at high miles, you likely just need to rebuild the differential anyway.

But if you're going Full float, by all means get on it. No need to analyze further.

Edit: Thinking about this more, your front differential probably should be swapped regardless. The gearset will have much less wear and would be better for long term use when you do get around to a FF swap.

Also, I think there is no rotational strength difference between FF and SF. The Full float can carry more load, but the spine diameter of the alxe is the same 30 spline size in either, so torque strength should be near the same.
I'm thinking you're spot on with your points on rebuilding/swapping the diffs. With my 62 being my only vehicle though I had to button the back end back up so I could drive it to work for now. I suppose I would do well to start collecting tools and parts I'll need and clearing out a spot in my shop to set up a press and go ahead with the rebuild. Would be nice to just full on get a rebuild done before my next road trip. What's your thought/indication that I may need a new gearset? Again, speaking from my lack of experience here so trying to get a good eye for what I'm looking for/at.

Your points on the FF lead me to stick with my plan do go that route too, since my end goal with the truck is for it to be an expedition rig. So carrying weight will be a factor down the road. IIRC I was told that the 60/62 9.5" diffs will bolt right up to an 80 series rear full float housing, so that would be nice if I've already got a fairly freshly rebuilt diff that can go right onto the 80 housing and run until time & budget allow for adding a locker.
 

Cruiserdrew

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For sure the 60 3rd will bolt into the 80 axle. I run one like that in my FJ60.

My 60 Harrop and gear install

Regarding the gearset-you need to run a paint pattern, and then consult the pictures that are on the gear install website. Ken might even comment if you ask him to.

Waste hours of your life here

I figure a very old gear set should probably just be replaced. In the grand view, it only adds $200 to the rebuild cost. Now, I'd value a Toyota factory gearset over aftermarket any day, so that's why the front would be such a desirable swap.

Swapping front and rear could be done in a weekend with an experienced helper. Especially with the front end short cut of pulling the entire knuckle and hub assembly intact. It's heavy work but can be done.
 

Spook50

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I decided rather than swap the diffs I'm going to go ahead and tackle a rebuild ASAP. Salt I don't have the funds to GI ahead with the 80 rear or the Harrop install at this point, so it'll be a straight rebuild. Plan is to attempt it the weekend following Easter. Leave work ASAP that Friday and pull the diff, then all day both Saturday and Sunday rebuilding and (what I expect to take by far the most time) dialing it in. Meantime I'll be collecting needed tools and parts.

Still need the press, carrier bearing socket, bearing splitter, inch lb torque wrench, rebuild kit itself, and going to go ahead and get a solid pinion spacer (looks like Nitro is the only one available, but correct me if I'm mistaken and if there's a better option). I'm also debating going ahead with a new gearset, but would like to reuse mine if possible. Problem is I'm not sure how to tell if mine is still good or in need of replacement. I see no damage or indication of excessive wear, but that was only based on what I could see with the cover off.

Any other recommendations from those experienced?
 
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Just my opinion, but if you're going to be in your diffs again to throw in lockers and don't see any obvious signs of wear on the gears now, I'd just hold off replacing them. Especially if money is tight.

Side note: Kinda funny the other day I watched this on YouTube. Not saying it's the right way to rebuild diffs, but it looks like all you need is a air hammer and torch lol.
 
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I decided rather than swap the diffs I'm going to go ahead and tackle a rebuild ASAP. Salt I don't have the funds to GI ahead with the 80 rear or the Harrop install at this point, so it'll be a straight rebuild. Plan is to attempt it the weekend following Easter. Leave work ASAP that Friday and pull the diff, then all day both Saturday and Sunday rebuilding and (what I expect to take by far the most time) dialing it in. Meantime I'll be collecting needed tools and parts.

Still need the press, carrier bearing socket, bearing splitter, inch lb torque wrench, rebuild kit itself, and going to go ahead and get a solid pinion spacer (looks like Nitro is the only one available, but correct me if I'm mistaken and if there's a better option). I'm also debating going ahead with a new gearset, but would like to reuse mine if possible. Problem is I'm not sure how to tell if mine is still good or in need of replacement. I see no damage or indication of excessive wear, but that was only based on what I could see with the cover off.

Any other recommendations from those experienced?
Right on! I think your gears are fine. I would reuse them. Just make sure you get the wear pattern in spec when you check everything.
Those things weigh something like 70-80lbs so eat a steak the night before. I tried using the jack to lower them and it was a pain in the arse. To lift them I ended up rolling the diff upside down on the ground beside the axle under the truck and I laid beside it and bear hugged it against my chest, carefully rolled onto my back and bench pressed it into place. I’ll admit, it was a bit sketchy... but I got to drink a beer after it was all done so it all worked out.
 

Spook50

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Just my opinion, but if you're going to be in your diffs again to throw in lockers and don't see any obvious signs of wear on the gears now, I'd just hold off replacing them. Especially if money is tight.

Side note: Kinda funny the other day I watched this on YouTube. Not saying it's the right way to rebuild diffs, but it looks like all you need is a air hammer and torch lol.
Good idea. I hadn't considered that. It would probably make it easier to get it done in the space of a weekend too.

I definitely think I'd do well to get the right tools for the job though lol. Do it right, do it once (until I add a locker).

Funny, I noticed that even though the factory ratio is 4.11, all the aftermarket gears I saw are 4.10. Very minor difference (only 0.89 degree of rotation of the ring gear), but just something I thought was interesting.
 

Cruiserdrew

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Funny, I noticed that even though the factory ratio is 4.11, all the aftermarket gears I saw are 4.10. Very minor difference (only 0.89 degree of rotation of the ring gear), but just something I thought was interesting.

Your stock diff gear is 37 x 9 teeth 4.11
80 series stock rear is 41 x 10 teeth 4.10
Aftermarket follow the 80 series convention

They are close enough, they can be run on the same truck (I do this on my FJ62)
 

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