I built a turbo into my differential
Yeah right, but anyway, at 2100 to 2200 RPM at the input shaft of my rear diff, I hear a turbine frequency gear whine. Not a howl, but a wine and at a very limited RPM range. The gears have about 60 miles on them so far.
The background: I put together my 5.29 ARB V6 differential using yukon gears. The pattern looks great. (sorry, no pics) Anyway the pattern is centered tip to root and covers about 80% of the drive and coast sides with a slight concentration on some, but not all teeth toward the toe on the drive side. The coast side shows a cocentrations a litte to the heal. The pattern is too centered heal/toe to be called "competition" pattern.
Their seems to be more pattern variation from tooth to tooth than I have seen on some other gearsset I have built. Maybe these are the "economy" yukons?
I can keep my hand on the axle housing after a 15+ mile run at about 45 MPH. It is hot for sure, but not TOO hot.
I was concerned about the noise and the heat so I took it all apart today. Pattern still looks great on the ring gear. In fact, you can start to see the "real" wear pattern working the black stuff off the gear faces and it too looks great. The pinion wear marks seem pretty darn close to the beginning of the teeth and end about 1/8 of an inch from the end of the tooth. Engagement point seems a little too low, but the pattern says if anything, I can add a little MORE pinion shim which would engage the pinion even sooner.
the pinion preload was a little tight, so I added .001 shim to the solid spacer. Total pinion preload is still a bit high (per Toyota) at 9 inch pounds. (including seal drag, so I bet it is really only 8. ZUK runs even more than this though, so I think I'm OK there.) Besides, have you seen the size of the V6 pinion bearings? There is slight chatter on the pinion bearings which bothers me some. maybe 1 inch/# difference. And here is why:
There was debris damage on the end of 1 carrier bearing race so I replaced both bearings and races. (they were reused carrier bearings, and I guess I stirred up a little metal in there. This infected the big pinion bearing and put a few dings in the rollers. I left them this way though.
Put it all back together and had a nice dinner with Lin.
Total preload was also a bit high at 20 inch pounds, but I'm not surprised. I went the ZUK route and cranked 100ft/#s of torque on the carrier bearings (while maintaining backlash) I get the best pattern at .006 backlash which is still in spec. (one checking point runs all the way up to .007)
So, The gears are set on the tight side, with the carrier bearing preload cranked up and the pinion pre-load about .001 too tight too.
What did I do to induce the whine? I'm guessing the damage to the pinion bearings? simple harmonic of new, rough gears? cheap gears?
How many of you would go in a third time and replace pinion bearings/races? How many would drive on, just try not to go the annoying 43 MPH and wait to see if they break in OK and hold up on the trail. :)
I'll try not to smoke this new diff on my 30 mile commute tomorrow. This is the only time I''ve ever WISHED for a traffic jam!
I vote 3rd time, 'cuz I wanna see more of your entertaining (and educational) posts
I vote to run it for a week, varying speeds, don't let it overheat. You didn't say what kind of oil you run- dino? Synth? Blend? If it still makes noise then, go in and have a lookee see.
Man, .001" adjustments... you make *me* look non-anal. Truly doesn't sound like the pattern. I know some folks were talking about off-brand Yukons (not Precision, nor US Gear), but if it checks out, it checks out. .001" variation doesn't sound like anything to lose sleep over. Guess the proof is in the wear.
Gettin' good at the Toyota bench press routine yet? Sheesh, I swear the chunk gets heavier every time I'm in there.
I almost did the ZUK 100ft/lb. thing, but jeez Louise those bolts don't LOOK like 100 ft./lb bolts. So many people run 60 ft./lbs... so I did too.
Sumtin' else to worry about as I fall asleep...
If you ARE living on the edge, you aren't taking up ANY space.
Cuz you probably fell off.
Or slipped into an alternate universe, or bought a Jeep or sumthin'.
What I need is a dirty ol' digital garage camera that I can get greasy and take pictures with so you can share visually how much fun I have in the garage. Like...standing up under the spare tire carrier and ALMOST giving myself a black eye yesterday. Just a little scrape or 2 and a bruise.
That would be PEAK entertainment, eh?! Seriously, I'll work on the 'garage camera' idea.
Toyota Bench press
Yep, I think you are onto something, RedChilli. I am running only el cheapo GL-5 conventional 75/90weight oil with a tube of BG gear concentrate additive.
Considering the low price I paid for the yukons, I bet they are the "economy" yukons too.
Talked to a good ol' wrench turner here at Autoaves and he asked the same question. "What weight oil you runnin'? Synthetic? Ford is now specin' 85/140 synthetic." He knows it is a toyota, but listened to my problem and right away thought wrong oil.
The sound is also barely audible at 53mph. It is probably just pinion bearings and most people would probably never hear it or think it was just a 43mph wind whistle. (That is what it sounds like really.).
I just got back from Boulder. 10 miles in traffic and then about 20 miles at 55-60 MPH. Yeah, the diff was hot when I stoppped, but again, I can keep my hand on it for about 5 seconds. My transmission shifter gets almost that hot! No smells, no smoke, no leaks, no other bad noises. I think it will be OK and will probably quiet down when I change the oil at 500 miles and switch to 85/140 and maybe even synthetic at that point. 5.29 is a pretty steep gear. I'm sure it generates a bit more heat than a 4.10. We'll know if I did something wrong on the next trail ride. or the next 200 mile highway run!
20 inch pounds seems high, 12 would be closer to what I'd shoot for. Normally you expect a higher preload with new bearings than simply reassembling with old bearings, but that just seems like a little more shim would have been what it would have wanted.
I run 140wt in my rear w/lunchbox, but 85w-90 in open diffs. I am inside things too often to spend the extra on synth.
I agree with Bill, drive it for a week or so. If it get's worse, yank it, if it doesn't it'll probably just wear in and be fine.
If it was a 35 year old FJ40 you'd probably never even notice any new sounds :-)
I think 85/140 is a bit thick for minitruck diffs. Thick != lubricity nor shear strength, just more stuff to sling. Do the calcs: how many *millions* of miles have been put on minitrucks (even running 5.29s!) using dino 80W90, with NO issues? Now add BG MGC, and use Valvoline dino 80w90 or Valvoline Durablend 80w90 (not a bad price at all), and you have... a winning combo IMHO. I happened to use Redline Heavy Shockproof (still 80w90) cuz I had a gallon sittin' around just looking expensive. Valvoline wuz gonna go in there.
It could be a combo situation too, with tire tread, u-joints, splines and just the right amount of something in the diff, made audible by all the (appropriate) play in the driveline. Put the diff in another truck and you might have silence. Plus, put your hardtop back on and you might hear... nothing. Add a different shim and alter your driveline... same outcome.
Run it for 500 miles varying speed and temperature, do the hypoid drain maneuver, and check your drain plug for chunks. No chunks, no increase in noise (beware the audible hallucination dynamic when you are looking for something and are 'just sure' you heard it), run whut ya brung.
Like I said, *you* make *me* look non-anal! And that is an accomplishment of which to be proud. I just completely disassembled a diff and locker, chasing what turns out to be an emergency brake cable issue. *THAT* would be *anal*.
turbo whine updates
Well, I can still put my hand on the diff after 30 mile commute including 20 miles at 59 MPH so it isn't getting TOO hot.
Total miles on unit= 200 already
Noise is still present, but no louder, maybe a bit quieter.
Thanks for the encouragement and the gear oil recommendations. But how many mini-trucks run 5.29 gears? Those are pretty steep teeth!
The sound persists and yes, my rear driveshaft slip yoke is pretty much cashed and my pinion angle doesn't quite match my t-case angle, and I watched my driveshaft spin while up on jackstands and the slip yoke appears to be put on the driveshaft at a slight angle (It just doesn't look right going round 'n' round!) Maybe the yoke is bent or heat warped. so yeah, that might be part of it, but it sounds like pinion bearings.
Since I have not yet burned up the diff, I think it is going to be just fine.
Asked my dad, "The RudeMaster," and he says, "Build a whiner and it will whine forever. It might just be the gearset. Buy a commuter car."
At 500 miles I'm going to go synthetic. not sure what weight yet, but it would appease my psyche to have something in there that can handle higher temps without film failure. In the race car world, we'd see a few diffs burn up a year on conventional oil. 1/year on mobil 1 and never burn one up with redline. Why? :)
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