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What could cause this Getrag cracking? by rednotdead
Started on: 03-22-2016 02:34 PM
Replies: 20 (491 views)
Last post by: Steel on 03-25-2016 01:32 PM
rednotdead
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Report this Post03-22-2016 02:34 PM Click Here to See the Profile for rednotdeadClick Here to Email rednotdeadSend a Private Message to rednotdeadEdit/Delete MessageReply w/QuoteDirect Link to This Post
My Forumla's been sitting in the transmission shop for a while now, while they (very slowly) put together Rodney's input bearing fix. Stopped by yesterday and noticed this crack:



The mechanic tried to make it out as not a big issue warranting any repair, but I told him to get it welded anyways. He's doing all this work under warranty (this is a second transmission to replace the original), so he has every incentive to cut costs and corners. Just curious - if this tranny were put back in with that crack, what could I reasonably expect to happen down the road? Also, what kind of stress could cause something like that? Defective part? Some kind of violent driving behavior?

I'm having him take a picture of the weld job after its been done - who knows if this flaky guy will even remember.
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Report this Post03-22-2016 03:31 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
That's a very odd spot for a crack. Would take some oddly placed stress over time via the fork to cause that I guess, or something coming apart and striking that area very hard.
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olejoedad
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Report this Post03-22-2016 03:33 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
Was the bushing OD checked against the ID of the bushing boss?
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Report this Post03-22-2016 04:07 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
Are you sure it's really a crack?
Getrags have a crapload of casting lines/seams/ridges/flaws. Whatever.

It kind of looks like a crack, but so do a lot of things on Getrag cases.
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rednotdead
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Report this Post03-22-2016 04:29 PM Click Here to See the Profile for rednotdeadClick Here to Email rednotdeadSend a Private Message to rednotdeadEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:

That's a very odd spot for a crack. Would take some oddly placed stress over time via the fork to cause that I guess, or something coming apart and striking that area very hard.


Yeah, I have no idea where this tranny came from - the mechanic said it looked fine inside, and from a just a quick look the gears at least seemed pristine (I am absolutely unqualified to make any judgement though).

Aside from that crack, the real damage was to the input bearing/seal/shaft, which failed and leaked oil all over the clutch. Perhaps the doner car was totaled in an accident which affected the transmission, really don't know...


@olejoedad
I highly doubt it - what is a bushing OD, and a bushing boss?

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Gall757
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Report this Post03-22-2016 04:32 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
If the brass colored part (bushing) was too big and forced into position, the aluminum (bushing boss) would crack.

[This message has been edited by Gall757 (edited 03-22-2016).]

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rednotdead
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Report this Post03-22-2016 04:34 PM Click Here to See the Profile for rednotdeadClick Here to Email rednotdeadSend a Private Message to rednotdeadEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Raydar:

Are you sure it's really a crack?
Getrags have a crapload of casting lines/seams/ridges/flaws. Whatever.

It kind of looks like a crack, but so do a lot of things on Getrag cases.


I'm not sure - its possible I'm just being paranoid and the mechanic knows what is and isn't a problem. But it didn't look superficial or just a casting error, definitely had some depth to it (even if very thin).
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dobey
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Report this Post03-22-2016 08:23 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Gall757:

If the brass colored part (bushing) was too big and forced into position, the aluminum (bushing boss) would crack.



But isn't the brass bushing softer than the aluminum, so it should have deformed first if the bushing was being forced in?
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Dennis LaGrua
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Report this Post03-23-2016 07:06 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Lets be realistic these transmissions are 27-29 years old, with a case made of cast aluminum ( a brittle metal) that has endured thousands of shifts during its life. There are crack detecting fluids that can verify if it is a crack or die line. If that line is a crack it pays to have it welded or perhaps brazed or most likely the boss will eventually crack more. I suggest brazing it, as cast aluminum doesn't always take well to welding.

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Report this Post03-23-2016 09:01 AM Click Here to See the Profile for Orig88GT-NCClick Here to Email Orig88GT-NCSend a Private Message to Orig88GT-NCEdit/Delete MessageReply w/QuoteDirect Link to This Post
I did lose a tranny for a broke journal EXACTLY were your suspected crack is.... happened without notice... major damage... replaced the whole tranny.
It was the original tran with 90k miles, no major work done, other than a clutch & bearing 6k before.
So not unheard of.
Good welding, should do the trick... would be good to look at it Before they stick it back in ..
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Report this Post03-23-2016 11:34 AM Click Here to See the Profile for Alex4mulaClick Here to Email Alex4mulaSend a Private Message to Alex4mulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by rednotdead:

My Forumla's been sitting in the transmission shop for a while now, while they (very slowly) put together Rodney's input bearing fix. Stopped by yesterday and noticed this crack:

.

The mechanic tried to make it out as not a big issue warranting any repair, but I told him to get it welded anyways. He's doing all this work under warranty (this is a second transmission to replace the original), so he has every incentive to cut costs and corners. Just curious - if this tranny were put back in with that crack, what could I reasonably expect to happen down the road? Also, what kind of stress could cause something like that? Defective part? Some kind of violent driving behavior?

I'm having him take a picture of the weld job after its been done - who knows if this flaky guy will even remember.


That most probably happened when the bushing was installed. Hammering it in created stress and did it. Maybe too much force was used, missed a stroke or there was some weak manufacturing point there already. Bottom line it needs to be fixed if possible. If it fails best case scenario is it won't shift (fork won't have leverage) and worst case it will destroy pressure plate and disc in the process and you will loose new parts.
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Report this Post03-23-2016 01:02 PM Click Here to See the Profile for hobbywrenchSend a Private Message to hobbywrenchEdit/Delete MessageReply w/QuoteDirect Link to This Post
All these comments are very relevant. Get the part penetrant checked (ZYGLO). Other comments. I think there is a clutch shaft seal. I have the pn somewhere. The bushing clearance is indeed important. I put deburred holes in the bushing and packed in grease before installing the shaft.. I considered putting in a zerk, but decided there was not enough material. I hope after weld the unit is sent to a competent machine shop for true align bore or you will have problems again.

[This message has been edited by hobbywrench (edited 03-23-2016).]

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rednotdead
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Report this Post03-23-2016 03:03 PM Click Here to See the Profile for rednotdeadClick Here to Email rednotdeadSend a Private Message to rednotdeadEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by hobbywrench:

All these comments are very relevant. Get the part penetrant checked (ZYGLO). Other comments. I think there is a clutch shaft seal. I have the pn somewhere. The bushing clearance is indeed important. I put deburred holes in the bushing and packed in grease before installing the shaft.. I considered putting in a zerk, but decided there was not enough material. I hope after weld the unit is sent to a competent machine shop for true align bore or you will have problems again.



Thanks - Ill talk it over with the mechanic and see if that's the correct/original bushing. Will the align bore be necessary even if that bushing is original/undamaged? Also, how would we know what the optical bushing clearance should be?

Is this the clutch shaft seal you refer to?
http://rodneydickman.com/ca...h=28&products_id=329
Update from mechanic on cause:
"it was caused by the collar we replaced" (referring to Rodney's replacement input bearing, I think)
Is this plausible?

[This message has been edited by rednotdead (edited 03-23-2016).]

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Report this Post03-23-2016 05:33 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
My guess is they tried to remove the cross shaft w/o removing the bushing first. You have to remove the bushing, slide the cross shaft away from the differential to remove the shaft from the bushing cup, then angle it slightly and pull it out towards the differential to pull it through the hole in the case. Looks like they might have just slid the cross shaft away from the differential and tried to pull it out with the bushing in place.
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Report this Post03-23-2016 07:18 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:

My guess is they tried to remove the cross shaft w/o removing the bushing first...


And this is why it's great having very experienced mechanics with tons of Fiero related knowledge posting here at PFF.
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rednotdead
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Report this Post03-25-2016 01:56 AM Click Here to See the Profile for rednotdeadClick Here to Email rednotdeadSend a Private Message to rednotdeadEdit/Delete MessageReply w/QuoteDirect Link to This Post
Unbelievable...

This images is larger than 153600 bytes. Click to view.

[This message has been edited by rednotdead (edited 03-25-2016).]

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Report this Post03-25-2016 07:08 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

And this is why it's great having very experienced mechanics with tons of Fiero related knowledge posting here at PFF.


True, but I think this specific issue is not specific to the Fiero, or even just the Getrag 282. The design seems to be prevalent in at least FWD transaxles of the era, until the switch to HTOB, and so any competent transmission builder should know how to repair the transaxle correctly. Sounds like a case of a general repair shop trying to do work they didn't have enough knowledge to do, and screwing it up.

And after that weld job, I'd probably be asking for at least a new bellhousing half, including cross shaft and bushing, as it looks like they didn't bother removing them before welding the crack, which may have caused even more damage, considering the different materials.
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Report this Post03-25-2016 07:35 AM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Eek.
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Dennis LaGrua
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Report this Post03-25-2016 11:02 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by rednotdead:

Unbelievable...

This images is larger than 153600 bytes. Click to view.



Do you think that there is enough weld penetration on those welds? Looks to be all lumped on the exterior.

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Report this Post03-25-2016 11:35 AM Click Here to See the Profile for hobbywrenchSend a Private Message to hobbywrenchEdit/Delete MessageReply w/QuoteDirect Link to This Post
Re align bore. The machinist should receive the welded up case, the shaft and a new bush. He will align bore the aluminum to the proper bushing fit, including clearance for bushing to shaft. A "good" machine shop might even set up a better bushing and even look at installing a zerk. Such a shop could do the welding also.You may have to search your area for such a shop and they will charge you. This job is fairly straight forward.
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Report this Post03-25-2016 01:32 PM Click Here to See the Profile for SteelSend a Private Message to SteelEdit/Delete MessageReply w/QuoteDirect Link to This Post
That's not how that's done..
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