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I'm worried that I have way to much play / slop in my v6 3rd member.
I dont notice any sounds coming from it while driving, but there does seem to be a good amount of play in the gears that i can feel when i coast and then give it throttle or go from on throttle to off.
Here is a video i took @ the drive-shaft flange showing how much slack it has.
That's way too much for a stock open differential, but it looks pretty normal for an automatic locker like the Aussie. Those types of lockers have a lot of backlash in the ratcheting mechanism. The high ratio of the 5.29 gears will make the backlash at the pinion even greater.
If I get a chance I'll crawl under my 4runner tomorrow and see how much slop there is in the front Aussie. I think it's pretty similar to what you show.
I just checked my front Aussie. Backlash is very nearly the same as what you show on your video. Yours appears to be completely normal. That's just the nature of automatic lockers, and is in fact mentioned in the installation/operators manual for the Aussie.
So that's normal for lockers? Never came across one with that much, even on Detroit lockers. Might want to pull the fill plug and see what the fluid looks like. I had the Ford dealer set up a 9" 411 gears with all new bearings because I didn't have the tools or experience at the time, it lasted less than a year and ended up with the same freeplay. The fluid was absolutely metal contaminated, wiped out everything.
Well, if we do the math we can get an idea of what's "normal". For a standard diff, proper ring gear backlash is about .008", which works out to just under 1 degree of rotation. Multiply that by 5.29 for the gear ratio and the drive shaft will have about 5 degrees of rotation.
With the Aussie, the crosspin in the ratcheting mechanism moves in a slot with V-ends, and has perhaps 1/4-3/8 inch of free movement. The length of the crosspin is about 4 inches, so that works out to about 7-10 degrees of free rotation at the ring gear, which translates to about 35-50 degrees at the drive shaft. That's real close to what I see on mine, and to what the OP shows in his video.
I don't have any experience with a Detroit - it could be tighter than that. But nothing that the OP has observed on his Aussie indicates cause for concern to me.
If the OP wants to be sure, he could send his video to Aussie. They're pretty responsive, and my guess they'll tell him it's normal.
You have to have a light touch, and differentiate (no pun intended) between what portion of the play is in the gear mesh (backlash) and what portion is in the carrier/axle components.
The backlash can be felt first, before any of the carrier components are moved.
If, in fact, any large portion of the movement is attributable to backlash, the OP does have a problem.
I do not think that RJRs' calculation using gear ratio has any validity in this circumstance.
Correct backlash figures give similar radius of motion at the pinion regardless of gear ratio.
You have to have a light touch, and differentiate (no pun intended) between what portion of the play is in the gear mesh (backlash) and what portion is in the carrier/axle components.
The backlash can be felt first, before any of the carrier components are moved.
If, in fact, any large portion of the movement is attributable to backlash, the OP does have a problem.
No argument here, but I don't think that's the issue. He was moving the drive shaft through its full range, not just feeling for the gear backlash.
I do not think that RJRs' calculation using gear ratio has any validity in this circumstance.
Correct backlash figures give similar radius of motion at the pinion regardless of gear ratio.
Not true at all. The radius of the pinion at the tooth interface is 1/5.29 the radius of the ring gear - that's inherent in the gear ratio. The actual movement of the teeth is the same for the pinion as for the ring gear, but the smaller radius means the angular motion of the pinion will be 5.29 times the angular motion of the ring gear. Basic geometry.
I fail to see how .008 backlash is different on a 4.10, or on a 5.29.
I guess that the difference in pinion radius's make a difference mathematicly, but I doubt that manual examination, by manipulating the pinion could reveal it.
I would agree that differences in the amount of pinion rotation caused by differing ratios could become more noticable with very large amounts of slop, as the OP apears to have.
First thing to do is still to make a determination of how much motion is due to backlash.
It wouldn't hurt to pull the fill plug, and check fluid level and condition. Stick your finger in there, get some oil on it, and look at it in the sunlight. If it has a heavy metallic sheen or sparkles there may be problems.
Aussie's seem to have more "slop" than most other lunch box lockers. IMO. My rear Aussie moves excessively like the the OP. It drives my nuts because I have to alter my on-road driving habits because I'm afraid I'm going to damage/break something in the drive line. I have used Quick Lock's and Lock Right's in the past and they did not have the "slop" that the Aussie does. I contacted Aussie about it and was told this is normal.
Wow, that seems like a lot to me... I'm still trying to get my imaginations behind the above discussion and trying to picture what the movement in your video translates to at the wheel end. Here is my backlash+freeplay after an aussie my buddies and I installed on my driveway. It's just about 1 -inch. I thought it was a lot, people say it's normal. It does cause some interesting situations while making a u-turn....
Not to bore this outfit with math again, but Gevo, your slop works out to almost exactly what the OP is seeing. An inch on the 12 inch brake drum is about 10 degrees of rotation, which when multiplied by the 5.29 gear ratio of the OP, is about 50 degrees at the drive shaft, which is about what he showed in his video. Pretty consistent.
well I checked the gear oil . looks fine, its only like 6 months old though.
I was the one that installed the Aussie locker into the 3rd . cant remember how much play there was at the drive-shaft before I installed it , but im sure it was less.
It was the first time i tore into a 3rd member but I was careful to set everything back the way it was before and used a dial indicator to measure the backlash on the ring and pinion and set it to what it was before i took it apart.
So it sounds like its just normal .
A by product of the looser tolerances of the Aussie locker and amplified by the lower gear ratio like RJR said
I will run it and hope that it holds up ok.
thanks for all the help !
Not to bore this outfit with math again, but Gevo, your slop works out to almost exactly what the OP is seeing. An inch on the 12 inch brake drum is about 10 degrees of rotation, which when multiplied by the 5.29 gear ratio of the OP, is about 50 degrees at the drive shaft, which is about what he showed in his video. Pretty consistent.
Math is never boring!!
I refuse to accept the amount of freeplay in my rear end is normal!! Having the Aussie out and playing with in in hand I did not see this much movement.. I always thought I had not assembled the third correctly. I am going to swap my differentials from my donor (4.88 gears) so I wasn't too worried about it... We will see how the swap goes in comparison
Well, if we do the math we can get an idea of what's "normal". For a standard diff, proper ring gear backlash is about .008", which works out to just under 1 degree of rotation. Multiply that by 5.29 for the gear ratio and the drive shaft will have about 5 degrees of rotation.
With the Aussie, the crosspin in the ratcheting mechanism moves in a slot with V-ends, and has perhaps 1/4-3/8 inch of free movement. The length of the crosspin is about 4 inches, so that works out to about 7-10 degrees of free rotation at the ring gear, which translates to about 35-50 degrees at the drive shaft. That's real close to what I see on mine, and to what the OP shows in his video.
RJR - could you bore us with a little more math? I'm trying to understand how the .008" backlash works out to 1 degree of rotation. In my head, I'm visualizing from the axle centerline (or center of ring gear) out to the end of the ring gear tooth is 4", and if the ringgear moves .008", the angle there is arctan(.008/4) which is not even close to 1 degree (more like .028 degrees). Am I missing something?
Gevo said; I refuse to accept the amount of freeplay in my rear end is normal!! Having the Aussie out and playing with in in hand I did not see this much movement.. I always thought I had not assembled the third correctly. I am going to swap my differentials from my donor (4.88 gears) so I wasn't too worried about it... We will see how the swap goes in comparison [/QUOTE]
The slop is usually between the locker and the cross pin.
Last edited by offroadnutz; 02-16-2015 at 09:39 AM.
I think we're both wrong. I missed a decimal place somewhere. I must have used .08 inches instead of .008. My apologies.
The correct answer:
arctan(.008/4)=.002 radians. Multiply that by 180/pi to get degrees and it comes out .115 degrees.
But, the calculation for the Aussie, and for Gevo's brake drum measurment, is still roughly correct.
Just as a note, you really can't get 30-40 degrees of driveshaft rotation due to improperly set ring-pinion backlash. The only way the ring and pinion can give you that much slop is if a tooth is missing somewhere. There's not enough room between the teeth otherwise even if the gears are improperly set up.
As I pointed out earlier, the crosspin in the Aussie rides in a fairly lengthy slot with V-shaped ends. The pin wedges into the V-ends to lock the side gears. Unlocking occurs when one of the side gears rotates ahead of the crosspin so that the pin floats into the middle of the notch and releases the pressure on the side gear. That space is necessary for the locker to operate correctly, but it does result in a lot of backlash.
Gevo, I predict you will find everything is "normal" inside your rear-end when you disassemble it.
02-13-2015, 06:19 PM
, but Gevo, your slop works out to almost exactly what the OP is seeing. An inch on the 12 inch brake drum is about 10 degrees of rotation, which when multiplied by the 5.29 gear ratio of the OP, is about 50 degrees at the drive shaft, which is about what he showed in his video. Pretty consistent.
