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Old 10-19-2011, 06:46 PM   #1
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Default Xray 2011 ball diff

I replaced my ball diff with ceramic balls and ceramic thrust bearing. Now it keeps loosening during a five minute run.

Does anyone know why? All the thrust washers and cone washers are in the right spot. The plastic piece is in the male side of the diff housing too and isn't stripped. I pulled it out and tested it with the screw and it won't thread all the way thru. I suppose it's tapered but the screw fits nice and tight.
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Old 10-19-2011, 07:10 PM   #2
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Well, I'm not sure exactly what your problem might be, so hopefully the answers you give to my questions will help sort it out.

Your cone washers are oriented as: )()( , correct?

Are any cone washers flattened?

On the thrust bearing, are the cut races facing the balls? [I've found the diff to be smoother when I install the races so the smooth side is facing the balls]

What are you lubing the thrust bearing with?

What are you lubing the diff balls with?

Any bearings in the assembly not spinning smooth, without noise?

How tight is your initial assembly?

What is your diff break-in method?

Is the snap ring deformed at all?
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Old 10-19-2011, 07:32 PM   #3
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Originally Posted by HarryLeach View Post
Well, I'm not sure exactly what your problem might be, so hopefully the answers you give to my questions will help sort it out.

Your cone washers are oriented as: )()( , correct? Yes

Are any cone washers flattened? I think one maybe so I've ordered new ones.

On the thrust bearing, are the cut races facing the balls? [I've found the diff to be smoother when I install the races so the smooth side is facing the balls]
mine are smooth on both sides. No groves on either sides.

What are you lubing the thrust bearing with? Stealth lube

What are you lubing the diff balls with? Stealth lube
Any bearings in the assembly not spinning smooth, without noise? Nope all are smooth

How tight is your initial assembly? Just medium to stiff.

What is your diff break-in method? I hold the middle shaft and move one tire in the forward direction for a minute or so.

Is the snap ring deformed at all?
no

Last edited by jgraham37128; 10-19-2011 at 07:33 PM. Reason: Answer
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Old 10-19-2011, 08:14 PM   #4
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Alright, I think your main issues are that your initial assembly is too tight, and your break-in is not long enough.

I use thinner lube for the diff balls [actually use the XRay diff lube], but that shouldn't be a problem using stealth lube.

Did you re-prep the diff rings at all?


At any rate, on your initial assembly, tighten the diff just enough that there's barely slippage. On the car stand, run the drivetrain at about 1/4 throttle while holding the left tire for around a minute, then do it again while holding the right. You'll feel the diff loosen up quite a bit while running. After doing this with each wheel, tighten the diff 1/4 turn and do it again, alternating between each wheel. After that, the diff should still be very smooth, and you can slowly tighten the diff so that you can't slip the pulley when holding both wheels.

Then it's ready for the track, checking every minute or two to make sure everything is staying smooth and you don't have any slip.

If, at any time after the initial 2 minute run-in on the car stand, the diff feels notchy, you have something that needs attention.

Since you've had the diff loosening on you on the track, you should inspect the diff rings for any scoring from the diff balls, and inspect the diff balls carefully for flat spotting as well.
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Old 10-20-2011, 06:20 AM   #5
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Originally Posted by HarryLeach View Post
Alright, I think your main issues are that your initial assembly is too tight, and your break-in is not long enough.

I use thinner lube for the diff balls [actually use the XRay diff lube], but that shouldn't be a problem using stealth lube.

Did you re-prep the diff rings at all? Yes, I place lube on both sides very thin but plenty all the way around.


At any rate, on your initial assembly, tighten the diff just enough that there's barely slippage. On the car stand, run the drivetrain at about 1/4 throttle while holding the left tire for around a minute, then do it again while holding the right. You'll feel the diff loosen up quite a bit while running. After doing this with each wheel, tighten the diff 1/4 turn and do it again, alternating between each wheel. After that, the diff should still be very smooth, and you can slowly tighten the diff so that you can't slip the pulley when holding both wheels. Yes, I do leave it loose intitally and tighten after a lap or two on the track. I may have just got these too tight and flattened the washers enough that they aren't rotating like they should. I'll know for sure when my new ones arrive.

Then it's ready for the track, checking every minute or two to make sure everything is staying smooth and you don't have any slip.

If, at any time after the initial 2 minute run-in on the car stand, the diff feels notchy, you have something that needs attention.

Since you've had the diff loosening on you on the track, you should inspect the diff rings for any scoring from the diff balls, and inspect the diff balls carefully for flat spotting as well.
I did check and they look fine. Just a small groove like normall=. I sanded it out before I rebuilt with my old thrust to see if this was the problem but it did the same thing.
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Old 10-20-2011, 12:15 PM   #6
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Have you had a chance to try with a longer bench break-in yet?

One thing I've noticed with diffs of all brands on newer cars is that loosening during a run seems to be more the diff freeing up, giving the feeling that the bolt is backing out, when it really isn't. With a longer break-in at lighter pressure, you allow everything to wear in smooth without damaging anything, and get closer to your final tension before you get the car on the track.

If all else fails, get some Vibra-tite [available at most motorcycle / Harley shops] to coat the diff bolt threads for a little bit extra hold, without locking it in and becoming un-adjustable as loc-tite would do.
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Old 10-20-2011, 01:31 PM   #7
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There is a small difference in the outer diameter of the two thrust bearing washers. The washer with the smaller outer diameter should be on the outside, in contact with the diff screw. Could this orientation have been swapped during your rebuild?

- Bryan
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Old 10-20-2011, 02:08 PM   #8
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There is a small difference in the outer diameter of the two thrust bearing washers. The washer with the smaller outer diameter should be on the outside, in contact with the diff screw. Could this orientation have been swapped during your rebuild?

- Bryan
Nope, that was double checked. 3.0 on the outside and 3.2 in the inside (closest to the cone washers)
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Old 10-20-2011, 02:10 PM   #9
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try adding some loctite to the screw before screwing it into the nut , maybe the plastic has streached slightly

failing that , BUY A GEARDIFF !!!!!!
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Old 10-20-2011, 02:14 PM   #10
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Quote:
Originally Posted by HarryLeach View Post
Have you had a chance to try with a longer bench break-in yet? After a minute it's so loose it's just free wheeling.... So longer test time won't change anything. It only takes a minute at 1/4 throttle and holding one wheel for it to completely back off 100%.

One thing I've noticed with diffs of all brands on newer cars is that loosening during a run seems to be more the diff freeing up, giving the feeling that the bolt is backing out, when it really isn't. With a longer break-in at lighter pressure, you allow everything to wear in smooth without damaging anything, and get closer to your final tension before you get the car on the track. I know what your talking about but this diff loosens up to the point where it's 100% loose. you can spin a wheel one at a time like the pinion is missing.

If all else fails, get some Vibra-tite [available at most motorcycle / Harley shops] to coat the diff bolt threads for a little bit extra hold, without locking it in and becoming un-adjustable as loc-tite would do.
yes, this may work but something is wrong...... I really need to fix it not patch it up... I'm thinking it's the cone washers...I will know for sure when my new one's arrive in the next day or so.
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Old 10-20-2011, 02:16 PM   #11
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Quote:
Originally Posted by sidecarphil1 View Post
try adding some loctite to the screw before screwing it into the nut , maybe the plastic has streached slightly

failing that , BUY A GEARDIFF !!!!!!
Is the plastic nut tapered? I noticed my screw won't go all the way threw it. It will stop right before it comes out the back side.

I hear you on the gear diff. I've never used one but might use one very soon.
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Old 10-20-2011, 02:21 PM   #12
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Quote:
Originally Posted by jgraham37128 View Post
After a minute it's so loose it's just free wheeling.... So longer test time won't change anything. It only takes a minute at 1/4 throttle and holding one wheel for it to completely back off 100%.

yes, this may work but something is wrong...... I really need to fix it not patch it up... I'm thinking it's the cone washers...I will know for sure when my new one's arrive in the next day or so.
Alright, chances are one or more of the cone washers are flattened, which makes the tension on the diff bolt higher than the thrust bearing wants and lets it work free.

Let us know how it goes when you get those cone washers replaced.
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Old 10-22-2011, 03:34 PM   #13
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Default ball diff

Ok, all parts arrived today as planned. I installed a new screw, all new cone washers, and still same problem. It keeps backing off when you hold one tire while under power. I guess the only thing left is the female end of the diff, everything else is brand new. What a frustrating experience.

JG
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Old 10-22-2011, 03:43 PM   #14
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Does it matter which tire you hold?

Before you buy new diff halves, I would try vibra-tite or some other non-hardening screw lock compound. It would really suck to spend the money and have it make no difference.

I know I asked once already, but both ball bearings are good? Center pulley bearing and the thrust side diff half bearing?

Something really screwy is going on, I've never had this problem with any TC ball diff, even if the locking insert for the screw was borderline wore out.
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Old 10-22-2011, 04:02 PM   #15
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The thrust should be packed with black grease, not stealth lube.
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