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light rattling noise from the rear


GTX
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Galant VR-4 org Post #: 1216276 posted 09/11/15 07:15 AM     Remind Me!  Send Private Message   Edit Post      
Hi gurus,

After installing a viscous rear diff I have noticed a slight rattling noise coming from beneath towards the rear of the car, while not under load or breaking in the gear. At first I was thinking, it would be the driveshaft as bearings were a bit loose and universal joints had almost 300k km on it. So, Ive replaced all of them. The driveshaft is like new now, but the noise did not go away. I dont see much play in the input shaft in the diff, it is within the specs. Axles also look decent. I have been told to put some LSD additive to the oil, but I wonder, if it would make any difference since it is a viscous LSD, the coupling must be sealed and isolated from the oil in the diff, eh?
I wonder if you hae any ideas before I take the diff apart.

Thanks
Alex



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2013 Honda Accord EX V6
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Galant VR-4 org Post #: 1216278 posted 09/11/15 08:15 AM     Remind Me!  Send Private Message   Edit Post      
Yep, adding an additive won't do anything as the "lsd" portion of the diff is sealed and the gear oil has no effect on it. Have you checked all your exhaust for rubbing hitting componets?



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Galant VR-4 org Post #: 1216282 posted 09/11/15 08:58 AM     Remind Me!  Send Private Message   Edit Post      
I have made a completely new 2.5 inch exhaust pipe. all the way from front to the back. It is not touching anywhere. I wonder what is the typical noise of the input shaft diff bearing? I got this diff here on the forum, obviously it is not new. I have opened the cover, changed the seals and that's about it. May be it is a shaft bearing, I don't have much experience with diffs.



1991 Galant VR4 RS Rally
2005 Subaru RS 2.5
2013 Honda Accord EX V6
2017 Honda Ridgeline EX

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Galant VR-4 org Post #: 1216287 posted 09/11/15 11:05 AM     Remind Me!  Send Private Message   Edit Post      
bearings don't typically "rattle". A better definition of the noise could help/.



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Galant VR-4 org Post #: 1216299 posted 09/11/15 03:05 PM     Remind Me!  Send Private Message   Edit Post      
Is it possible you have never heard the rattling of the latch on the cover to the passageway between the back seat and trunk before now?



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Galant VR-4 org Post #: 1216431 posted 09/14/15 09:15 AM     Remind Me!  Send Private Message   Edit Post      
No, this car does not have any seats at the back The rattling can be sensed by hand on the rear part of the floor. It happens only when you leave of the throttle for the short period of time or press the pedal, also for very short period. the tone slightly changes. I have swapped the axles with another pair I had, nothing changed. I have noticed bigger play in LSD spider gears than in the second, open diff, I have though. I'm thinking the tapered bearings in the diff might make such a noise. Besides the pinion ring only them are changing the direction of the load when you leave of or press the gas pedal.



1991 Galant VR4 RS Rally
2005 Subaru RS 2.5
2013 Honda Accord EX V6
2017 Honda Ridgeline EX

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Galant VR-4 org Post #: 1216442 posted 09/14/15 12:41 PM     Remind Me!  Send Private Message   Edit Post      
It could be the diff, but I've never heard one "rattle".

You sure the center driveshaft isn't vibrating against the mounts?



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Galant VR-4 org Post #: 1216472 posted 09/14/15 09:40 PM     Remind Me!  Send Private Message   Edit Post      
Here we go guys. I took the diff out and apart. By no means I'm not am expert in differentials, but very curious how this stuff works

I did not find anything drastically wrong with tapered bearings, all 4 of them have some wear, but nothing serious that could cause the vibrations. However I have found an interesting thing with LSD. The spider gears are a bit loose due to the gap between the spider gear assembly and the housing. Please see the pictures. My common sense tells me that this might cause the axle to vibrate when not under load since the body with spline is is loose in the housing. I wonder, what are the specs for this gap shown in the pictures. I would not mind someone to explain how this LSD works and tell me if I can take it apart, at least to access the spider gears. I see that there are two spacers inserted between the housing and the side gears. If the gap is too big (and I think it is) I could try to find an oversize spacer, or make one. Also, the splines have a gap, and they are not inline,gaps are in different places, any particular reason?




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Galant VR-4 org Post #: 1216476 posted 09/14/15 09:56 PM     Remind Me!  Send Private Message   Edit Post      
is it a little rattle like when you hit bumps ?



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Galant VR-4 org Post #: 1216479 posted 09/14/15 10:18 PM     Remind Me!  Send Private Message   Edit Post      
No, it is kind of grinding noise when not under load or breaking. If you put the hand on the floor where the rear seat should be (mine does not have one), right in the middle of the car, above the diff, you can feel it. It is enough to break a bit or accelerate, the noise goes away.



1991 Galant VR4 RS Rally
2005 Subaru RS 2.5
2013 Honda Accord EX V6
2017 Honda Ridgeline EX

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Galant VR-4 org Post #: 1216489 posted 09/15/15 12:17 AM     Remind Me!  Send Private Message   Edit Post      
Did you have a washer on each side of your Diff?
in between the diff housing and the LSD



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Edited by Olson (09/15/15 12:18 AM)

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Galant VR-4 org Post #: 1216499 posted 09/15/15 09:11 AM     Remind Me!  Send Private Message   Edit Post      
Quoting GTX:

No, it is kind of grinding noise when not under load or breaking. If you put the hand on the floor where the rear seat should be (mine does not have one), right in the middle of the car, above the diff, you can feel it. It is enough to break a bit or accelerate, the noise goes away.




The diff sits further back in the car than where the rear seat sits. Middle of car where you can reach while driving still sounds like a driveshaft carrier bearing that's worn.

I personally went through the diff before selling it to him. Nothing looked out of place and tooth contact was right where it should be. Not saying it's perfect, but all that is described really sounds like something besides the diff. If the spider gears where an issue, I think you would notice noise while cornering, or loading one side more than the other. Under straight line accel, the spiders are stationary and don't really do much.



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Galant VR-4 org Post #: 1216502 posted 09/15/15 09:49 AM     Remind Me!  Send Private Message   Edit Post      
Well, my thoughts were the same. So I replaced all drive shaft bearings and universal joints. Nothing changed. May be I'm too picky, eh?
However, my co-driver hears the same noise. I guess for the street driving it is ok, but I'm afraid if I put a bit more pressure on the diff on the stage, something might go wrong. Those spider gears are so small. I'm surprised Mitsu made them that way

Anyhow, guys, thanks for your help! I took the LSD to the local shop and we will change the shims in the spider gear unit to eliminate a extra play I found. I will let you know the outcome, so we all benefit from this experiment!



1991 Galant VR4 RS Rally
2005 Subaru RS 2.5
2013 Honda Accord EX V6
2017 Honda Ridgeline EX

Posts: 99 | From: Toronto, Canada | Member Since: 04/13/12 | IP: (108.168.26.194) | Report this post to a Moderator

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Galant VR-4 org Post #: 1216516 posted 09/15/15 01:07 PM     Remind Me!  Send Private Message   Edit Post   
Yes, the spacers are there.



1991 Galant VR4 RS Rally
2005 Subaru RS 2.5
2013 Honda Accord EX V6
2017 Honda Ridgeline EX

Posts: 99 | From: Toronto, Canada | Member Since: 04/13/12 | IP: (108.168.26.194) | Report this post to a Moderator


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