Transaxle trouble Options

[Hank914]

I earlier added to the "what you did today thread" but I thought I would start a new thread with some more details on my transaxle troubles.

So I recently installed by rebuilt tranny after the PNW tranny clinic. I also converted from tail to side shift, and all the bushings. The previous owner (40 yrs) rebuilt the engine after 97k miles in 2007, but afaik did nothing on the tranny. The bushings were shot. Last weekend, after logging 120 test miles around Central Oregon, I thought I'd take her down to the Bay Area. About 130 miles into the trip, I hear a loud bang and spin a 360 into the ditch. During the fun, I figured I had a blowout. But not tire problems just a locked up rear differential.

I pulled the tranny and this is what I saw. (Please excuse the large photos, but it adds detail)




So I opened up the tranny case and found some interesting stuff.

Pictures to follow...

[Hank914]

Here are some more pictures of the damage...



Looks fine on that side...

But not so much on this picture.

[Hank914]

Here are a couple more pics...



And a close up...

[Hank914]

So, any ideas on...

1). (IMG:style_emoticons/default/WTF.gif) made that piece decide to come off?

I was in 5th gear doing about 65mph. I use this car (1.7L) as a commuter. I don't push it very hard at all. I did switch to Fuchs 4 lugs with 205's instead of the 165's the PO had on it.

2). How often does this happen?

3). Why does this happen?

Any other thoughts?

Thanks.

[Dave_Darling]

2) Not very often!
3) In very high-torque applications, galling develops on the pinion teeth. After some time, it gets bad enough that the teeth start to shear off.

I'm pretty sure that's not what happened here.

Could the pinion shaft bearings be loose enough that the pinion was not held engaged properly to the ring gear? Any foreign objects in the trans? Anything that looks like it might have come adrift from somewhere else and gotten jammed into the R&P mesh?

That trans case is.... scary.

--DD

[chads74]

I had the transmission on my high school 914 lock up and send me into a ditch also. Just pulled it and sent off for a rebuild, I never found out what the cause was. Hopefully you came out injury free, besides maybe some new undies.

[6freak]

PNW tranny clinic (IMG:style_emoticons/default/beer3.gif) ...theres always someone with an issue`s after one of these clinics, (IMG:style_emoticons/default/drunk.gif) your the someone this time ..thats sucks IMO the lash was not set proper on the R&P.. .I have a case in Tacoma if ya need one? just come get it good luck

(IMG:style_emoticons/default/smile.gif)

[Dr Evil]

Not sure what 6freak is talking about, but to address your qustions.

This is not common. I have seen one come to me to be repaired out of over 300 I have had my hands in. A few things to note regarding yours:

You have new bearings and they were fitted just fine. You did not have any galling on your pinion, this was inspected at time of rebuild and I had parts on hand to swap if there was. This is most likely due to metal fatigue from 40yrs of use, but I can not be sure. Pinion was not reset and did not need it. It would need to be way out to be the cause of that.

It would appear that the guts are in good shape for the most part, and we can work with that.

One possibility is that with the rebuild there was a change in how stresses in the transmission were communicated to the parts and it found the weakest spot. However, I am speculating.

I'll help you get this sorted out with as little pain as possible.

[0396]

Here are a couple more pics...

And a close up...

I'm no expert but a simple logical person (IMG:style_emoticons/default/piratenanner.gif) .
If it was me, I would simply start with a new core trans.. Trying to reuse most of the parts one would have to really inspect and make sure there no metal wedge between the gears. Once that happens, the gears will never mesh 100%. Thus why take a chance. Then it's just me...do it right once ...and don't Mickey Mouse it for the long term. Good luck (IMG:style_emoticons/default/piratenanner.gif)

[jkb944t]

I don’t see any gulling of the remaining section of the pinion so it wasn’t a setup issue.

It was either an inherent defect in the gear that was there from manufacturing that unfortunately decided to give out now or something foreign was floating inside the transmission and locked up in between the pinion gear teeth.

Jeff B

[Hank914]

I don’t see any gulling of the remaining section of the pinion so it wasn’t a setup issue.

It was either an inherent defect in the gear that was there from manufacturing that unfortunately decided to give out now or something foreign was floating inside the transmission and locked up in between the pinion gear teeth.

Jeff B

(IMG:style_emoticons/default/agree.gif)

I looked pretty closely to see if there was any foreign floater object that I could identify as the reason. I found nothing but smaller bits of metallic shrapnel and the one larger "tooth" that broke off. Hence I think it is an inherent defect from the beginning.

And that's why I started this tread. How often? Sounds like 'not very' is the consensus answer.

[Dr Evil]

I am wondering what the diff guts look like. There is a possibility that the diff seized and that cause the pinion to lose a tooth. I would need all the parts here to do a post mortem.

[Jonathan Livesay]

I am wondering what the diff guts look like. There is a possibility that the diff seized and that cause the pinion to lose a tooth. I would need all the parts here to do a post mortem.

I broke the diff ring gear on a 944S that I used to own and it cracked the case just like that.

[jkb944t]

I am wondering what the diff guts look like. There is a possibility that the diff seized and that cause the pinion to lose a tooth. I would need all the parts here to do a post mortem.

A locked diff does seem to be a very good possibility and would explain the crack in the side of the case.

Jeff B

[Tbrown4x4]

Did you experience any tire slip and then regain traction suddenly? That could transmit the kind of shock load that could damage the pinion. How did the ring gear look?

[nine9three]

That seal looks really high. Was it like that before the damage?

[Hank914]

Did you experience any tire slip and then regain traction suddenly? That could transmit the kind of shock load that could damage the pinion. How did the ring gear look?

After the loud bang, both rear tires locked solid. Laid two solid black stripes on the pavement. Never regained traction. I'll see if I can take some detailed picks of the diff. I'm sending it off to the DrEvil for a post mortum.

[Tbrown4x4]

Well, I'll be following this with great interest.

I assume you were towed home. You never mentioned if the tires were still locked up when it was put on the flatbed.

What seems really strange to me is the torque applied to the ring and pinion should be at its lowest in 5th gear. Just the opposite of a hard launch in 1st.

(Like when my kid brother was popping wheelies in my Corvair powered sand rail. Lots of little pieces came out of the drain plug that day!)

[Dr Evil]

That seal is high. Not out of tolerance, but not where I like it. I wonder if it was pushed out as I would not have let that seal pass inspection.

[6freak]

Not sure what 6freak is talking about,

just saying with the party type atmosphere (IMG:style_emoticons/default/drunk.gif) it could be easy to miss details.. your still at 99.5% to the good (IMG:style_emoticons/default/lol-2.gif)

if its man made it can break,even when new
(IMG:style_emoticons/default/smile.gif)