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914World.com _ 914World Garage _ 911 transmission kaboom
Posted by: Dr Evil Aug 5 2013, 07:31 PM
Cupomeat is the talent behind my rebuild DVD not sucking and actually being entertaining AND informative. He did all of the work other than what I did in front of the camera. Wouldnt it be, that the transmission that I rebuilt for his Dad's early 911 would be the first that I have ever seen break a pinion after rebuild. Of course, it was a more rare and expensive 8 toothed pinion as well 
I was a bit confused on how this happened, but it was the obvious failure and matched Meat's description of events.
Tonight I was able to get more personal with the gear stack and soon realized that there was more to this catastrophe. I first noticed that the carrier for 1/R slider was badly galled and chewed up on a face that should not have any wear:
Then I looked at what it rested against, the 1st gear race and bearing. Holy shit. The bearing fused and locked up first. Oddly enough, 1st did not break and the pinion did. This may be because the pinion is weaker having more teeth than our 7 toothed variety. Strange stuff. No idea why this happened. 
I had to beat the gear off of the race, which looked like this:
I still have not been able to get the pinion out. I will have to cut the race as it is all kinds of messed up as was the end of the pinion. What a crazy failure. I am glad that this was the only I have seen in a rebuild in 10 years. I have found others in cores, but these were neglected cores.
Gonna need some parts 
Posted by: Dr Evil Aug 5 2013, 08:13 PM
1- not my fault.
2- I was sober. 
Posted by: Dr Evil Aug 5 2013, 08:13 PM
1- not my fault.
2- I was sober.
Posted by: scotty b Aug 5 2013, 09:33 PM
Hack I'm getting Erc the 3rd (Wills) to rebuild my trannies from now on 
Posted by: Dave_Darling Aug 5 2013, 09:51 PM
1- not my fault.
2- I was sober.
You can say that again...
I think next time, you should start drinking before you start building, then.
--DD
Posted by: oldschool Aug 5 2013, 11:15 PM
....I have a cool DVD you can have. 
Posted by: bulitt Aug 6 2013, 04:35 AM
One failure in a decade and y'all throw the Doc under the bus? Whats wrong with you guys?
Um, Doc...you don't perform surgery do you??? 
Posted by: Dr Evil Aug 6 2013, 07:22 AM
I cut people, for work Is good fun.
Posted by: Chris H. Aug 6 2013, 08:50 AM
Looks like classic Fetzer Valve failure. Nothing you can do about that.
Posted by: Dr Evil Aug 6 2013, 08:57 AM
The springly sprocket encabulated. I just need to realign the eddy current transfuser and it will be fine.
Posted by: 396 Aug 6 2013, 09:52 AM
Can the above mishap be caused by incorrect tolerance during rebuild and or wrong gear oil?
Posted by: Dr Evil Aug 6 2013, 09:59 AM
Yes, but these were not factors encountered with this rebuild and run.
Posted by: Woody Aug 6 2013, 09:59 AM
Doc is slipping in his old age. ![hitfan[1].gif](style_emoticons/default/hitfan[1].gif)
Posted by: bulitt Aug 6 2013, 10:04 AM
Yes, but he is now proficient at split rail fence building 
and diaper changing! 
Posted by: Dr Evil Aug 6 2013, 10:17 AM
Fences, no. Diapers..... I can change a diaper like the guys change tires in the pit. air tools!
Posted by: Woody Aug 6 2013, 12:27 PM
Fences, no. Diapers..... I can change a diaper like the guys change tires in the pit. air tools!
sounds messy.
Posted by: r_towle Aug 6 2013, 12:47 PM
Yes, but have you been pissed on yet while changing.....rights of passage
Posted by: Dr Evil Aug 6 2013, 02:15 PM
Yes, but have you been pissed on yet while changing.....rights of passage
Well, ya.
Oh, while changing diapers. Ya.
Posted by: r_towle Aug 6 2013, 08:24 PM
Face or did you catch it in time?
Posted by: Cupomeat Aug 7 2013, 07:55 AM
The springly sprocket encabulated. I just need to realign the eddy current transfuser and it will be fine.
Its all ball bearings these days...
Posted by: tomeric914 Aug 7 2013, 06:46 PM
Its all ball bearings these days...
I don't see how any transmission in your Dad's hands can fail. He doesn't rev it past 2500 RPM. Might as well drive a tractor.
![yellowsleep[1].gif](style_emoticons/default/yellowsleep[1].gif)
Posted by: Dr Evil Aug 7 2013, 06:57 PM
Its all ball bearings these days...
I don't see how any transmission in your Dad's hands can fail. He doesn't rev it past 2500 RPM. Might as well drive a tractor.
Posted by: Dr Evil Aug 14 2013, 10:06 AM
Well, the stack has been rebuilt. I think I found the initiating failure, the inner race on the large pinion bearing was missing some pieces in the inner radius....I forgot to get a pic With this failing it placed side load on the first gear needle bearing and that seized, froze, and the pinion was broken. There was no indication that this was a risk, but that is why nothing can ever be called 100% reliable. Interesting and only took time and parts to fix. I hope to have this all buttoned up for delivery this weekend
Posted by: Dr Evil Aug 15 2013, 09:24 AM
More gore. I noted that the ring gear lost teeth, and the side cover has a nice crack in it.
I was thinking I could advertize the R/P as a special, lightened, race set like AA does 
If you look at the center of the diff, you can see the time bomb style setup where that bar is held in place with bolt nipples that wear off and that rod shoots out with amazing destructive force. I modified it last night with the upgraded style we have in our 914 boxes where the rod is kept in place with a keeper and pin.
Attached thumbnail(s)
Posted by: Bartlett 914 Aug 15 2013, 09:47 AM
It is kind of an chicken or the egg problem. Once some metal comes loose all hell breaks loose. This makes it difficult to say exactly where the damage started. It looks to me like the pinion depth was set wrong. You can see wear pattern on the outer rim of the ring gear. So much stress on the outer portion of the gear could have caused a tooth or part of a tooth to break off. Once floating around inside....KaBoom
Posted by: Dr Evil Aug 15 2013, 09:56 AM
I disagree. The pinion depth was correct, but it becomes incorrect then the pinion moves due to a failed int plt bearing. At that point it will still run but time is counting down. Then the 1st bearing seizes, the pinion stops, the ring does not, and teeth are ripped out of both and chewed up by the ring and diff bearings. A thorough autopsy and deep understanding of how these things work makes ones hypothesis about the chain of events very likely and probable.
Posted by: 76-914 Aug 15 2013, 11:35 AM
Is that a Tobacco pipe I see in that pic, Herr Doctor? Do you smoke tobacco in the same house that your family resides? Say it ain't so, Doc.
Posted by: Dr Evil Aug 15 2013, 11:36 AM
I smoke a pipe in the garage 
Dont judge.
Posted by: DBCooper Aug 15 2013, 02:03 PM
Don't judge? What are you talking about? That's why we COME here.
Posted by: 76-914 Aug 15 2013, 02:23 PM
That's too funny DB not judging you Mike. It was just a flashback. For the 1st 18 years of my life I lived with an O2 tank in my bedroom and carried an inhaler everywhere I went. When I left home at 18 my asthmatic symptoms disappeared. Didn't know about the effects of 2nd hand smoke back then. My concerns came across as a judgement of you. Not my intention! 
Posted by: r_towle Aug 15 2013, 04:36 PM
Well, the stack has been rebuilt. I think I found the initiating failure, the inner race on the large pinion bearing was missing some pieces in the inner radius....I forgot to get a pic
With this failing it placed side load on the first gear needle bearing and that seized, froze, and the pinion was broken. There was no indication that this was a risk, but that is why nothing can ever be called 100% reliable. Interesting and only took time and parts to fix. I hope to have this all buttoned up for delivery this weekend Was the offending bearing replaced with a new one at the time of the rebuild?
If so, who is the manufacturer and are there other choices in buying the bearing?
Just seems we are finding parts that are out there, but are far out of spec, or made inferior to the OEM parts....good to know what to NOT buy.
I ended up getting 5 tie rods for my BMW from a great vendor...none of the males matched the female...
He had to send the whole pallet back...they were ALL wrong.
rich
Posted by: Dr Evil Aug 15 2013, 06:19 PM
No offense taken. I thought you were just 
at me.
Mustache, no the bearing was not replaced as it was perfectly serviceable. No, there are no other vendors to go to. The replacements have now eclipsed $330 and have been back ordered from Germany.
Posted by: Cupomeat Aug 16 2013, 07:48 AM
I'd just like to say that Mike errr. Dr. Evil is awesome.
Posted by: Woody Aug 16 2013, 07:58 AM
I'd just like to say that Mike errr. Dr. Evil is awesome.
Posted by: Dr Evil Aug 16 2013, 09:03 AM
Dont be jealous, Woody.
Posted by: worn Aug 16 2013, 10:20 AM
I disagree. The pinion depth was correct, but it becomes incorrect then the pinion moves due to a failed int plt bearing. At that point it will still run but time is counting down. Then the 1st bearing seizes, the pinion stops, the ring does not, and teeth are ripped out of both and chewed up by the ring and diff bearings. A thorough autopsy and deep understanding of how these things work makes ones hypothesis about the chain of events very likely and probable.
I can't believe you said autopsy. C'mon, you must have had medical words drilled into you somewhere along the line.
At best it would have to be necropsy: except you say it ain't quite dead. To quote a Python "Not dead yet!"I was noticing the needle bearings of the first gear bearing and how they are slanted. Might one of them been missing from that bearing? Pro'ly not, but that looks squeezed real tight.
Posted by: ClayPerrine Aug 17 2013, 09:13 PM
Hey Doc!
I am in the middle of my gearbox out of my six conversion. About a month back, it started making some nasty noises at the last AX. When I pulled it apart, it had taken a few teeth off the pinion gear.
No real damage to the ring gear, though.
Well, today I was replacing the pinion gear, and found this.
That's what is left of the $305.00 pinion shaft intermediate plate bearing. And it explains why the pinion gear moved to Arkansas.
So you are not alone. It happens. This stuff is 40 years old, and the parts just break.
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