Diff rebuild by "pro" not going well

[alcyon]

Yeah its right on the edge.
I don't like how many 0.1 measurements were in there though.

Do you have around 0.001" of runout on the ring gear when you spin it in the case?
Might be something to check as well.

Yes max runout on ring gear was 0.07mm or 0.0027". Toyota says runout should not be more than 0.1mm or 0.0039", So i guess this is ok.
I am going to take the risk and button up as is, as on previous rebuild, I had no clunk, then eventually the clunk came back after some time, I correlate with the backlash opening up. Hopefully this would get rid of the clunk for at least several years.

 

[alcyon]

Ok looks like I now have one additional problem. Since preloads are good, I then removed companion flange to install the front seal. Oiled the lip, installed companion flange with new toyota Nut. Went 147ft lb, then used a breaker bar and got another 1/10th of a turn. Now I am measuring a total breakway of 22inlb, or 3inlb increase, but a drop in rolling torque to 8inlb, previously was around 10 or 11.
I have a feeling its the resistance from the new nut, as during setup I used a steel nut which seemed to have less resistance. I did put anti seize on the back of the nut washer. Should I go tighter on the nut another 1/16th and try get rolling torque to at least 10 in lb ?

 

[Piratetip]

Preload is too high then, this does sometimes happen with a new unused nut.
Threads are stronger than an old used one.

Starting in/lbs is the number to target @ ~12-13in/lbs once the nut is fully torqued down.
Re-do the shim stack and try again.

 

[Piratetip]

Are you lightly oiling the bearings with gear oil before readings?

 

[alcyon]

I did not disasmble the bearing, carrier or the pinion, i just removed companion flange, installed seal, oiled seal, and reinstall companion flange with new nut. The increase I measured is including the carrier, not pinion preload only. So I think the seal stiction is causing the increase in breakaway preload, and from the lower rolling torque, I think perhaps its just the nut is not tight enough due to the "false" tightening torque?
Yes all bearings were oiled before, since I did not remove the bearing, I did not re oil. Right now I am inclined to leave it as it is instead of trying for for rolling torque.

 

[Piratetip]

Ohh, sorry I thought you meant just pinion.
You should be good to go then.

 

[alcyon]

I got my used prop shaft and installed it with the diff. Just went for a test drive. A 7km trip to breakfast and 7km back home.
There is a small amount of noticable noise. It is mostly on light acceleration over 35kmh. Its like a hum /whine. on decel at 60 to 20kmh its hardly makes any noise I can hear. At very low speed coasting, under 20kmh, a faint clacking can be heard.
I think its all gear noise. The gear was ran for a 1000 miles on a shallow pinion depth 0.09mm/0.0035" than it is now, so I guess the gears have worn a bit on the shallower side, and now its moved deeper, its probably touching near the flank that the pinion never made contact with. Yeah I kinda expected it to be quiet right away but I guess that's unrealistic given that it ran shallow for a 1000 miles.
I have not exceeded 60kmh and the noise is loudest at 60kmh on light cruise. As soon as i let off its silent.
Overall the diff feels solid and doesnt feel like its gonna seize or fall apart. It is also seems to be better noise wise at very low speeds than before rebuild, but at cruise its much louder than before. So I am gonna go through the whole 9 yards of light break in. Short tripping for 10 to 15km round trips, cool off repeat a few weekends. Gonna run about 500km and then change the oil. Let's see how this goes.

Edit : went for another short drive, on load like climbing a mild slope, accel noise can hardly be heard, its almost silent, its only on light cruise or very light accel there is a hum.
I guess the only way to have a silent diff at this point is new gears. But this is highly wasteful at this time. Gonna give this set a chance for 1000+ miles and see it if quiets down.

 

[Piratetip]

Drive it for awhile.
It should quiet down.

 

[alcyon]

Yes I hope so. I went for another drive which is a bit longer. 10km + 10km to the city center. parked and returned.
It was a large highway so had to go at least 80kmh for 1km. The noise was loud at 59 kmh and kept getting louder and louder till 77 kmh, then after that to 80kmh, almost no sound, all light throttle. Parked at home, got my temp gun , hottest part of the diff is 140 F.
Should I continue break in with short tripping or some highway cruising.
Overall this build feels better than what the shop did. with his setup it was grinding almost all the time. With my setup, at least its quiet more than half of the time.
It also feels smooth when coasting, I don't feel any extra drag or bogging down. Same goes for accelerating from a stop.

 

[Piratetip]

Either is fine, if on the highway just vary the speed.
Key is allowing the gears some heat /cool cycles.
So they don't overheat, short trips.

 

[alcyon]

Update, it's a week later, drove 35km to work and 35 km back Diff casing temp was 152 F. , and some short distances on the next day 5km to 15km .
The noise has gone down in some conditions and went up in some.
The whine/groan at 59kmh onwards is still there, but the high level of groan goes down at 70kmh, previously it was still noisy at 77kmh.
Starting at 70kmh, the noise is noticably down, and gets lower at 80kmh, i can still hear the gears grinding at 80kmh but its very faint.
I have no idea why it makes so much noise between 59kmh to 69kmh.
Next at coast it used to be almost quiet after letting off throttle at 65 kmh, now there is a bit more noise (still not as loud as drive side)when letting off the gas at 65kmh, and the noise goes down gradually.
At very low coast speeds of 20kmh and under, can still hear the gears grinding faintly, but I think its not really coasting at that speed, I believe the drive side of the R & P is engaging.
I plan to drive the car on some short trips not exceeding 50km at one go in the coming week for several more days, from wednesday to sunday. I think I can total up 500km. So far I only made 140km.
It seems next week, I need to drive to a sounthern state that is 350km away 1 way, So i plan to swap out the diff oil on Sunday. I bet there will be a lot of metal gunk in there. On the long drive I plan to not exceed 100kmh, so far i have not exceed 80kmh.

Edit 22 June 2023. I have been driving roughly accumulated distance of 350km thus far. Today is a particularly hot afternoon, and while I was closing in to my workplace, at low speed coasting I could hear the gears grinding. It wasn't this loud when the oil was cold. I have a baaad feeling this break in will not quiet down the gears. Gonna go up to at least 1000km before I make decision, but If I had to change a new ring and pinion, I would sent the carrier out to a machine shop to skim the mounting surface to get back a runout of 0mm vs the 0.07mm. I need to make a quick decision because my workplace will be shifting somewhere else by end of the year. Once that happens no more self rebuilds.
This whole fiasco is delaying my plan to change new JDM wheels and tyres, of which I will not do until this problem is settled along with the 70mph vibration.

 

[alcyon]

Update, after roughly 700 km with no improvement and a lot of metal in the oil, I pulled the diff apart and decide to rebuild with new gears.

My new gears are coming tomorrow. I pulled the diff off the car on Saturday the 8th of July.
I removed the ring gear and did a runout check on the carrier. Indeed there is a 0.07mm runout.
I labeled the high spot and the lowest spot is 0.


I have arranged for my machinist to cut from the high spot ,inwards by 0.1mm up to the radius.

After this there will be 0 runout, and a consistent backlash
Due to the high rate of metal shedding, indicated by noise that isnnt improving, the bearings show signs of metal particles circulating through all 4 bearings.




Next update will be in several days to show the gear pattern with the original shim of 0.076" or 1.94mm. I strongly believe the stock shim will give the same good pattern as before since this is OEM gear with same ratio.
In the meantime, will be prepping the housing for new bearing shell install, removing rust, and repainting in the meantime.
Hopefully with stock shims and new gears and consistent backlash this would be the final rebuild.

 

[Dave 1jz]

This kind of bearing damage can also be the result of too high bearing preload.

 

[alcyon]

This kind of bearing damage can also be the result of too high bearing preload.

Thanks dave, but I am pretty sure preload is not too high. I was very careful not to exceed the preload I set in the 3rd rebuild. In the 4th rebuild, the breakaway wasn't that much higher than rotating. I will be equally careful on this 5th rebuild.

 

[Piratetip]

How do the gears look?

 

[alcyon]

How do the gears look?

Frankly, I can't tell thats anything wrong with it, just like the second rebuild. But there are bits of metal on the ring gear surface as well as the pinion.


On pinion there are some gasket material I sanded off the diff case and some metal bits

 

[alcyon]

I didnt mean to post anything till I get my gear pattern, but something came up..as always. I received my gears today, and to my horror, there are two chipped areas on the pinion tooth. However I think this wont affect the pinions function or cause noise, notice the red lines i drew, they are the borders of the lapping area on the pinion.

Since they are outside of the lapping area, this chips shouldnt cause any noise. Correct me if I am wrong.
Here is a close up of one of the chips.

I set the preload, and after the 3rd try got 14inlb breakaway and 7inlb rolling.
The ring gear also has chipped tooth.

These are very light chipping

Coast pattern can be seen here

Drive pattern

I will dremel the chipped edges on the pinion and ring gear, but the chips on the tooth face on ring gear I will lightly sand.

 

[Piratetip]

You have some bad luck with these gear sets.
Where did you get this one?

 

[alcyon]

You have some bad luck with these gear sets.
Where did you get this one?

From RHD Japan always.
I just checked the runout, it seems its still there, I think maybe the casing is the problem. Anyway. I got a backlash reading

I then checked gear pattern. Left pic is previous pattern, right side new gears, both are with 1.94mm shim

Close up of new drive pattern

Coast comparison. left previous, right new


Not too sure if this is ok, but it seems like its a tad deeper on coast than previously.maybe I am wrong should I reduce shim to 1.90mm and try ?
Reverse painted drive side below

It does seem ok to me.
Pinion pic


Carrier Bearing cage has some sound, but otherwise smooth.

 

[alcyon]

I pulled the pinion shim of 1.94mm and changed to 1.90mm. It looks better to me especially on the coast.
The drive looks almost the same,.

On the coast its a bit more spread out

Pinion at 1.90mm


I am leaning towards 1.90mm pinion shim.
One additional problem appeared. It seems I probably damaged the new carrier bearings. They are making a ticking sound. I will remove the carrier and confirm that the sound is from carrier bearings. Worst case I will re use the old carrier bearings, I will confirm the old ones dont make this ticking noise first.


Sunday Edit..the noise is pinion bearings not carrier bearings, the carrier bearings are silent.
I am not sure why the pinion bearings are making the cage noise, because the shells look ok. I got a good setting now just thinking on what to do with the pinion bearing noise. Maybe it would quiet up bathed in oil ?
Here is the video of pinion bearing noise.

I will investigate the sound tomorrow. This is the main thing keeping me from finishing this.

Edit 17th July . Replaced bearings with newer ones, very carefully transported (in a bag full of clothes) carefully and gently installed, pinion bearing ticking no longer there. Now the preload is a tad too high at 18inlb breakaway. Will adjust to 13 or 12 inlb breakaway, then decide on backlash.
Leaning towards 0.048" average as previously. Gonna try one step difference in carrier shim to open up backlash and compare the difference. Once I make up my decision will Install.
Edit 18th July, added 0.03mm to shim for pinion preload, and got 11 inlb breakway and 6 inlb rotating. That's a good figure and sticking with this.