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Old 07-13-2010, 03:14 PM   #1
Erik@GBox
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Default Anyone experiencing a Gearbox Whine might want to read this.

Hey there everyone,

I was curious to find out how many 996 street car owners have noticed a whine in their gearbox? Sometimes you might notice that this will change in pitch or volume depending on your throttle position. Well I thought that I would address what has caused this with everyone, so that you can appreciate how important it is to get this taken care of sooner rather than later.

This gearbox has essentially 4 bearings inside of it that control the forces generated by the pinion and main shaft. Two of these bearings are the culprit of the whine that you might be hearing. These two bearings are quite pricey at about $480.00 each, however have a very important function. They essentially maintain the distancing of the main shaft and pinion shaft.

There is one on the main and one on the pinion and they look like what is shown in picture number one. These are sealed bearings, which you might think would be a good think right? Well usually this is a good thing, however, there are instances where this can also be a bad thing. While they do a fair job of keeping particulates out of the bearing races, once debris does push itself in there, this design does an even better job of keeping it there. As this bearing continues to do its work the particulates that are trapped inside the bearing also begin to work. In a very negative way, unfortunately.

Picture #2 shows the inside of one of these bearings after some of the damage has been done. As you can see the inside of the bearing is fairly pitted up. This is what is generating the whining noise that you are hearing. It is important that this be addressed sooner rather than later, as this is also generating additional heat. Heat inside this bearing is a particularly bad thing.

Picture #3 shows how this bearing is actually constructed inside. You will notice that the cage that holds the ***** in place is constructed of plastic. While this is not a bad design in and of itself, it is a bit more sensitive to increased heat. Should the internals of these two bearings get too hot, the bearing will ultimately fail. This can generate a very large repair bill, as well as potentially lead to complete failure of the gearbox itself.

Now don't get me wrong here, I am not trying to stir anything up or be overly sensational about this issue. I simply thought that you might actually like to see what was going on inside and make the recommendation that if you should notice this problem, it would be in your best interest to get it taken care of in a timely fashion, rather than wait for complete failure to occur.

I hope that this has been at least a little educational, please don't hesitate to contact me with any questions that you might have. I am always here to help. We have been building these gearboxes for quite some time, and while they are somewhat tricky they can usually be turned around in less than a week.

Warmest Regards,


Erik Johnson
GBox Performance Transaxle
(303) 440-8899 work
(303) 895-4828 cell
www.gboxweb.com
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Old 07-21-2010, 10:56 PM   #2
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Why didn't you post this a year and a half ago before I dropped a Sh*tload on a new tranny after being told that these bearings seized on the shaft. Oh well. Hopefully this will help someone else.

Any smart ideas about the front c4 differential? Being told by the stealership that the front diff is going to have problems ( I believe them, slight whine. So I keep the top down and the radio up) but that I have to replace the whole axle!!! The service guy gave me a wink and said he couldn't answer me when I asked if I can just replace the guts instead of buying the whole thing but he said he can only order the entire axle not just the inside parts. Would appricaiate any help.
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Old 07-21-2010, 11:07 PM   #3
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Ahhh the 996 with its infamous bearing problems...LOL
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Old 07-22-2010, 08:50 AM   #4
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Quote:
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Ahhh the 996 with its infamous bearing problems...LOL
Notice all of these "infamous bearings" are sealed?? Must have been a good idea on some engineer's CAD screen and on some procurement manager's BOM, but boy do they seem to be a pain to all of us "users".

I think the key is to be in tune with your car, and address these items when they become apparent (like the whine Eric describes).
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Old 07-22-2010, 09:20 AM   #5
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We should all drive around in this trusty pushrod V8 that will whine to us when it's not feeling good somewhere...

Click the image to open in full size.

On a serious note...are you talking about manual or tip?
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Old 07-22-2010, 09:51 AM   #6
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hey.... sh&t happens. Thats bottom line.
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Old 07-22-2010, 10:49 AM   #7
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hey.... sh&t happens. Thats bottom line.
Yep... I just found out my differential case is cracked. Another sealed unit that has failed

That being said my now repaired transmission is very quiet...
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Old 07-22-2010, 11:32 AM   #8
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Could anyone go into more detail about the symtoms?
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Old 07-22-2010, 11:43 AM   #9
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Quote:
Could anyone go into more detail about the symtoms?
Here is a thread about my issues

http://forums.rennlist.com/rennforum...-question.html

PM me - I have a pretty good sense as to what might be whine from the pinion bearing and could meet you to do a listen.
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"From years reading Rennlist, I've come to the realization that 951 reliability is inversely proportional to 951 modification". Luis de Prat
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Old 07-22-2010, 11:57 AM   #10
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Originally Posted by fbgh2o View Post
Here is a thread about my issues

http://forums.rennlist.com/rennforum...-question.html

PM me - I have a pretty good sense as to what might be whine from the pinion bearing and could meet you to do a listen.
I do not have this problem, but I wanted to make sure I know more about it if it ever comes up...

I need to change my rear tires first, and then I can actually get a real hear for the cars driving. Right now my tires are making an annoying noise.
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Old 07-22-2010, 01:08 PM   #11
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Mine porsche whines. If im in neutral and rev it up I here a whine. I was told this was normal for the 996
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Old 07-22-2010, 02:58 PM   #12
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Mine porsche whines. If im in neutral and rev it up I here a whine. I was told this was normal for the 996
Clutch in or clutch out? (When you test with the clutch in, wait 20 seconds for the input shaft to stop spinning.)
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Old 07-22-2010, 04:00 PM   #13
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? (When you test with the clutch in, wait 20 seconds for the input shaft to stop spinning.)
With the clutch in or clutch out. It still whines. Sounds like it is coming from the engine.
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Old 07-22-2010, 04:43 PM   #14
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Sounds like it is coming from the engine.
That's probably belt whine....
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"From years reading Rennlist, I've come to the realization that 951 reliability is inversely proportional to 951 modification". Luis de Prat
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Old 07-22-2010, 07:16 PM   #15
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two words=extended warranty
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Old 07-22-2010, 07:16 PM
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