Is my diff stuffed?

[ozkiwi]

Jacked the truck up (both wheels off the ground) to look at the the brakes and while i was there playing around I think I Found the clunk that happens when going from reverse to Drive and the other way around.There is a lot of free play in the diff.How do I get rid of it?

[motornut]

hows the ujoints?

[ozkiwi]

Originally Posted by motornut

hows the ujoints?

a little worn but most of the play is in the diff.

[willett]

there will ALWAYS be lash in your diff, if there isn't any you have a big problem.

If there is ANY play in your U joints you should eliminate that, I can almost guarantee you tht whatever noise you are hearing is a result of pooched u Joints

[Keith Seymore]

There should be around .008-.012" backlash between the ring and pinion in the diff.

K

[PAPA KENT]

Originally Posted by willett

there will ALWAYS be lash in your diff, if there isn't any you have a big problem.

If there is ANY play in your U joints you should eliminate that, I can almost guarantee you tht whatever noise you are hearing is a result of pooched u Joints

I agree.

[motornut]

Originally Posted by willett

there will ALWAYS be lash in your diff, if there isn't any you have a big problem.

If there is ANY play in your U joints you should eliminate that, I can almost guarantee you tht whatever noise you are hearing is a result of pooched u Joints

I've had clunks and pings be the joints
have a look at where the ujoints join up can you wiggle and see the gap change?
or does it ride/look off center in the cup?

[LONGHAIR]

It depends upon where the "free play" is coming from, which you can't tell w/o removing the cover.
If the slack is from wear in the ring and pinion gears, replacement is the only option. It cannot be "adjusted" away.
The bearings can also contribute to this, once again, no adjusting to fix. Replacement is the only way.
Also, be aware that all of this is a job best left to a professional. It takes special tools and quite a bit of skill-patience to do it properly. If everything is not exactly right, it will be noisy as a best case scenario, fail miserably soon after.
Pay the money, get the peace of mind of a warranty.

[Rufton]

If rear differential is quite under load at all speeds and gear oil looks/smells normal there is a fair chance it's healthy.

[ozkiwi]

There is some play in the Ujoints and for sure it needs new wheel bearing .Will do those and see if that eliminates it and will get a specialist to check it out after that if it is still clunking.

[ozkiwi]

Originally Posted by Rufton

If rear differential is quite under load at all speeds and gear oil looks/smells normal there is a fair chance it's healthy.

Does have faint gear whine at freeway speed.

[Rufton]

Does it have any glitter in gear oil.
Do you have an IR temperature gun to measure operating temperature?

[Rufton]

6-24-13 after 90 mile trip hauling about 600 lbs load.
Temps according to IR gun:
Rear diff 165F.
U-joints=130F.
3 spd man trans=130F.
Drive shaft=105F.
Ambient approx 85F.

[ozkiwi]

Originally Posted by Rufton

Does it have any glitter in gear oil.
Do you have an IR temperature gun to measure operating temperature?

Yes I just bought one .
Thanks I will check that out.

[ozkiwi]

Almost a year later and I did nothing about it other than check the U joints which were good. The clunk now is terminal and I got a friend to but it back and forth between reverse and drive and the output shaft moves almost half a turn before the gears engage and I know the wheel bearings are badly worn as well so I figure only the diff housing is useable.
So here is my question.
If I buy a new ring and pinion in the form of a rebuild kit which comes with bearing and gaskets plus new axles and outer bearings and seals is this all I will need?
I think this diff is totally worn out and want to supply everything that is needed to the guys who will rebuild it because you cannot just run down to the auto parts store and buy parts like you can in the US. I want to do it right so there is going to be no revisit to this area in the future.

[LONGHAIR]

This is one of those "while you are in there" types of jobs. I would get the inner spindle bearings/seals, inner axle seals, and replace the axle joints too. It's a big job, so do it all....once.


Wow, had my head in 4x4 mode on this one.....lol

[Jake Wade]

It is most likely a combination of worn spider gears, cross shaft, and ring and pinion gears to have that much slack.

Sounds like you need a total rebuild.

[Chevy1966]

Back to the original question for a minute... I would sure like to know how much rotational play is normal in the diff yoke itself. I have 14-bolt corp diff. With driveshaft disconnected I can rotate the yoke by hand and there is a fair amount of free play, but what is the correct amount in terms of degrees?

[wilkin250r]

To the original poster:

I would do some diagnostics and research, first. It should only cost you some RTV and differential fluid, a whopping $20. (AUD is close to USD).

Pull the differential cover off (do a search or ask for the procedure to drain the fluid). Do NOT remove any other components, just inspect the entire assembly, and it's safe to rotate. Try to determine the exact cause and severity of the problem.

Most likely you will need a new ring and pinion, but you knew that already. What you DON'T know if whether or not you'll need new spider gears, new cross shaft, or even a complete new carrier.

In fact, because the procedure is so simple, many reputable shops will often do it for free (plus the cost of new diff fluid), or a very small fee.

In fact, because the procedure is so simple, a reputable shop will often do it for free (plus cost of new diff fluid) or at least a very small fee.

From that point, you can make an informed decision. As long as you didn't remove/change any internal components, you can just reinstall the diff with new RTV, and fill with new diff fluid. For a whopping $20 and some time, you'll be able to determine exactly which components you'll need to order and give to your shop for a rebuild.

[ozkiwi]

Went to a differential specialist who open it up with me there and he was amazed it had not let go.Everything needs replacing so I am going to bite the bullet and get a brand new 9 inch built with quality gears,axles etc and will not visit this end of the truck again I hope.Expensive but not a lot more than rebuilding the gm 8.5.

[ozkiwi]

Went to a differential specialist who open it up with me there and he was amazed it had not let go.Everything needs replacing so I am going to bite the bullet and get a brand new 9 inch built with quality gears,axles etc and will not visit this end of the truck again I hope.Expensive but not a lot more than rebuilding the gm 8.5

[hatzie]

You racing it at high HP? a built 9" is some pretty serious stuff.
You could get a known good condition 12bolt around here for about $100 used that will run for many many trouble free miles.

[KQQL IT]

9" rears are tough. And usually cheaper in the long run.

[ozkiwi]

Originally Posted by hatzie

You racing it at high HP? a built 9" is some pretty serious stuff.
You could get a known good condition 12bolt around here for about $100 used that will run for many many trouble free miles.

Around here is Australia a 12bolt would be a very rare item and go for about $800-$1200 .Just the parts I need to rebuild my current diff from summit racing landed here would be $1200 then I would have to get someone to rebuild it.The 9 inch is overkill for my weak little crate 330hp motor but then again I love this truck and will be driving it till the day I drop at which time the new owner will have a nice rear end he wont have to worry about.The 9 inch works out to be $800 more than any other option.