Catastrophic Input Shaft Failure (T56) ****Pics**** What happened?!
04-13-2014, 11:01 PM
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Catastrophic Input Shaft Failure (T56) ****Pics**** What happened?! What the hell happened?!
Here's the run down... Turbo LQ4 Miata... 660rwhp, 750rwtq.
Transmission started whining... REALLY REALLY loud... got worst as I did full power runs on it...
Took the transmission out, gave it to a trans shop, they put bearings in it but didn't really see anything wrong with it other than that.
Got it back, put it in, same noise! Actually got even louder.
Took the trans out again -_-
Gave it back to them, they said they don't really know what it is but they found an irregular wear pattern on the input shaft gear.
They replaced the input shaft, and I threw it back in.
Noise is gone! Success!
Put the car on the dyno, started to do pulls on the dyno, of course in 4th gear, and got the tune all finished up
Put down 660rwhp and 751rwtq @ 15psi (76mm)
Unstrapped her from the dyno and jumped on the highway
(remember, we haven't performed ANY pulls on this new input shaft OFF the dyno, only ON it)
Cruised and jumped on the highway... 60mph, downshift to 3rd and did a data-log test hit.. went to 6800rpm, pushed the clutch in, put it in nuetral and let off the clutch.
The engine INSTANTLY stopped and went to 0rpm in maybe half a second!
Got off the highway and this is the result:
What the hell happened?!?!?!
The ONLY thing I can think of is improper input shaft pre-load caused the bearing to fail. (to tight?)
Called the trans guy, sent him the pictures and he states that either the transmission fluid was low, or the engine thrust bearing is allowing the crank to push against the input shaft.
*I filled the trans with Synthetic Dexron 3 until it came out of the fill plug, and the trans has NO leaks.
*The end of the crankshaft has NO marks from any evidence of "crank to input shaft contact" and the pilot bearing looks perfect! I tried pulling back and forth on the crank and it has NO forward to back free-play.
*** Please note: those marks on the pilot bearing in the picture below is caused by the install, not by the input shaft/trans.****
*The transmission does have the bellhousing to block dowel pins in place, and the transmission to bellhousing dowel pins are also in place.
*Clutch is perfect, everything looks in line, ALL bolts are TIGHT on the bellhousing and the transmission.
**Bellhousing and all transmission case components are F-body OEM parts, no aftermarket bellhousing or anything...
Any ideas on what happened?!
- It CANNOT be a failure due to the fluid moving back from hard acceleration and allowing the input shaft to dry up/heat up because it was a SINGLE GEAR PULL on the highway on a brand new input shaft... very very first pull.
Thats the car in question.
Any input would be greatly appeciated!!
Here's the run down... Turbo LQ4 Miata... 660rwhp, 750rwtq.
Transmission started whining... REALLY REALLY loud... got worst as I did full power runs on it...
Took the transmission out, gave it to a trans shop, they put bearings in it but didn't really see anything wrong with it other than that.
Got it back, put it in, same noise! Actually got even louder.
Took the trans out again -_-
Gave it back to them, they said they don't really know what it is but they found an irregular wear pattern on the input shaft gear.
They replaced the input shaft, and I threw it back in.
Noise is gone! Success!
Put the car on the dyno, started to do pulls on the dyno, of course in 4th gear, and got the tune all finished up
Put down 660rwhp and 751rwtq @ 15psi (76mm)
Unstrapped her from the dyno and jumped on the highway
(remember, we haven't performed ANY pulls on this new input shaft OFF the dyno, only ON it)
Cruised and jumped on the highway... 60mph, downshift to 3rd and did a data-log test hit.. went to 6800rpm, pushed the clutch in, put it in nuetral and let off the clutch.
The engine INSTANTLY stopped and went to 0rpm in maybe half a second!
Got off the highway and this is the result:
What the hell happened?!?!?!
The ONLY thing I can think of is improper input shaft pre-load caused the bearing to fail. (to tight?)
Called the trans guy, sent him the pictures and he states that either the transmission fluid was low, or the engine thrust bearing is allowing the crank to push against the input shaft.
*I filled the trans with Synthetic Dexron 3 until it came out of the fill plug, and the trans has NO leaks.
*The end of the crankshaft has NO marks from any evidence of "crank to input shaft contact" and the pilot bearing looks perfect! I tried pulling back and forth on the crank and it has NO forward to back free-play.
*** Please note: those marks on the pilot bearing in the picture below is caused by the install, not by the input shaft/trans.****
*The transmission does have the bellhousing to block dowel pins in place, and the transmission to bellhousing dowel pins are also in place.
*Clutch is perfect, everything looks in line, ALL bolts are TIGHT on the bellhousing and the transmission.
**Bellhousing and all transmission case components are F-body OEM parts, no aftermarket bellhousing or anything...
Any ideas on what happened?!
- It CANNOT be a failure due to the fluid moving back from hard acceleration and allowing the input shaft to dry up/heat up because it was a SINGLE GEAR PULL on the highway on a brand new input shaft... very very first pull.
Thats the car in question.
Any input would be greatly appeciated!!
Last edited by 1SIKZ31; 04-13-2014 at 11:21 PM.
04-14-2014, 07:26 AM
#3
^yep nearly all taper roller bearing failures are not enough preload instead of too much...
what does the race look like in the mid plate? what about the rollers? I see the inner race looks fak'd but its probably from it eatting the cage.
If it got too hot I think you'd see more colors.
stupid question(maybe) but was the input engaging the pilot? I see you have the smaller needle bearing pilot.
With the standard f-body bellhousing you would need the needle bearing pilot but I'm not sure about the lq4. I think some of them had longer cranks?
Just trying to brainstorm for you...in the end you may never figure it out exactly especially if it was improperly shimmed.
what does the race look like in the mid plate? what about the rollers? I see the inner race looks fak'd but its probably from it eatting the cage.
If it got too hot I think you'd see more colors.
stupid question(maybe) but was the input engaging the pilot? I see you have the smaller needle bearing pilot.
With the standard f-body bellhousing you would need the needle bearing pilot but I'm not sure about the lq4. I think some of them had longer cranks?
Just trying to brainstorm for you...in the end you may never figure it out exactly especially if it was improperly shimmed.
04-14-2014, 10:38 AM
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what brand atf you running? and i would say you are getting into the power levels of needing a pump. it only took me one pass on a brand new build to hurt mine at 700whp back before a pump but not destruction like u have just lots of whine
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04-15-2014, 07:32 AM
#8
I don't see a lot of evidence of heat, so it doesn't seem to be a lube issue. You may never know what caused it (I'd guess improper/loose shimming), but I'd put a good new timken bearing on the input, properly shim the main/counter, replace your pilot bearing and make sure the input is seating fully in it. Make sure nothing else got torn up from that bearing shrapnel. I do agree you're probably at the level that a pump would be a good idea while it's apart.
04-16-2014, 02:50 PM
#9
http://www.timken.com/EN-US/Knowledg...ence-Guide.pdf
don't overlook improper install and damage of the cage when installing.
if there was excessive preload on that failed bearing, there would be evidence of overheat on the rollers and race. if there's no evidence of heat then i think a more likely cause is damage of the cage upon install, then the bearing saw runtime on the street (it saw little time on the dyno) and let ago.
i think the biggest problem is in your first description: transmission started whining- replaced bearings- still whined. that proves you have some kind of gear misalignment causing the whine. what caused the misaligment?
and you said, "gave it to a trans shop, they put bearings in it but didn't really see anything wrong with it other than that.".
on the old bearings, what evidence is there that something was wrong with them? and then what caused whatever was wrong with them?
9/10 times bearings just don't wear, you cannot just slap a new set in and call it fixed then blame the follow on problems on a owner and claim low lubrication, that is b.s.
don't overlook improper install and damage of the cage when installing.
if there was excessive preload on that failed bearing, there would be evidence of overheat on the rollers and race. if there's no evidence of heat then i think a more likely cause is damage of the cage upon install, then the bearing saw runtime on the street (it saw little time on the dyno) and let ago.
i think the biggest problem is in your first description: transmission started whining- replaced bearings- still whined. that proves you have some kind of gear misalignment causing the whine. what caused the misaligment?
and you said, "gave it to a trans shop, they put bearings in it but didn't really see anything wrong with it other than that.".
on the old bearings, what evidence is there that something was wrong with them? and then what caused whatever was wrong with them?
9/10 times bearings just don't wear, you cannot just slap a new set in and call it fixed then blame the follow on problems on a owner and claim low lubrication, that is b.s.
04-16-2014, 11:38 PM
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The Pilot bearing is NOT in backwards. It is correct.
The ATF being used is out of a reel. it's a "world class" synthetic fluid, and Dexron 3 is one of the fluids that are in the specification. (don't know brand.)
I'd rather not name the shop due to problems and finger pointing.
Why is it best to replace the pilot? It'll be a bitch to remove, and it looks perfect and all the rollers are smooth and nothing looks damaged.
But if its best, then I will. They're cheap. and its free labor (me).
Last edited by 1SIKZ31; 04-16-2014 at 11:54 PM.
04-16-2014, 11:42 PM
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http://www.timken.com/EN-US/Knowledg...ence-Guide.pdf
don't overlook improper install and damage of the cage when installing.
if there was excessive preload on that failed bearing, there would be evidence of overheat on the rollers and race. if there's no evidence of heat then i think a more likely cause is damage of the cage upon install, then the bearing saw runtime on the street (it saw little time on the dyno) and let ago.
i think the biggest problem is in your first description: transmission started whining- replaced bearings- still whined. that proves you have some kind of gear misalignment causing the whine. what caused the misaligment?
and you said, "gave it to a trans shop, they put bearings in it but didn't really see anything wrong with it other than that.".
on the old bearings, what evidence is there that something was wrong with them? and then what caused whatever was wrong with them?
9/10 times bearings just don't wear, you cannot just slap a new set in and call it fixed then blame the follow on problems on a owner and claim low lubrication, that is b.s.
don't overlook improper install and damage of the cage when installing.
if there was excessive preload on that failed bearing, there would be evidence of overheat on the rollers and race. if there's no evidence of heat then i think a more likely cause is damage of the cage upon install, then the bearing saw runtime on the street (it saw little time on the dyno) and let ago.
i think the biggest problem is in your first description: transmission started whining- replaced bearings- still whined. that proves you have some kind of gear misalignment causing the whine. what caused the misaligment?
and you said, "gave it to a trans shop, they put bearings in it but didn't really see anything wrong with it other than that.".
on the old bearings, what evidence is there that something was wrong with them? and then what caused whatever was wrong with them?
9/10 times bearings just don't wear, you cannot just slap a new set in and call it fixed then blame the follow on problems on a owner and claim low lubrication, that is b.s.
The actual FIX to the noise was the replacement of the input shaft.
I took the transmission to another guy and he said the front plate is fucked because the race is seized in there and he said that the counter shaft gear is fucked because of the wear pattern.
He noted that maybe the irregular wear from the old counter shaft gear and the new gear from the input shaft gear were binding and caused the shaft to "****" and ruined that bearing, but that's just a theory...
Last edited by 1SIKZ31; 04-16-2014 at 11:47 PM.
04-17-2014, 12:26 PM
#12
Your first problem was fluid, hence the input. Get pumped.
It "feels" good to replace bearings but the input would have been obvious if he had looked. The countershaft will look less damaged but needs done too.
Get the right welding on that race, it will shrink and come right out of the front plate.
Going forward, deal with someone like TDP instead of your rookies.
It "feels" good to replace bearings but the input would have been obvious if he had looked. The countershaft will look less damaged but needs done too.
Get the right welding on that race, it will shrink and come right out of the front plate.
Going forward, deal with someone like TDP instead of your rookies.
04-17-2014, 04:16 PM
#13
Was it a new input shaft they installed? Was the race installed into the back of the input? I've seen this happen with people doing Lt1 to Ls1 input swaps and never notice that new inputs don't have the small race in it. Allows the input to walk up, down, side to side and tears up the front bearing. If it is, I would make sure it's seated all the way down.
As for the midplate being no good, I am sure it is still o.k.
*Mod Edit* Removed non-sponsor contact info.
As for the midplate being no good, I am sure it is still o.k.
*Mod Edit* Removed non-sponsor contact info.
Last edited by MeentSS02; 04-18-2014 at 09:29 PM.
02-23-2015, 06:41 PM
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Was it a new input shaft they installed? Was the race installed into the back of the input? I've seen this happen with people doing Lt1 to Ls1 input swaps and never notice that new inputs don't have the small race in it. Allows the input to walk up, down, side to side and tears up the front bearing. If it is, I would make sure it's seated all the way down.
As for the midplate being no good, I am sure it is still o.k.
*Mod Edit* Removed non-sponsor contact info.
As for the midplate being no good, I am sure it is still o.k.
*Mod Edit* Removed non-sponsor contact info.
03-01-2015, 06:14 AM
#16
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Was it a new input shaft they installed? Was the race installed into the back of the input? I've seen this happen with people doing Lt1 to Ls1 input swaps and never notice that new inputs don't have the small race in it. Allows the input to walk up, down, side to side and tears up the front bearing. If it is, I would make sure it's seated all the way down.
As for the midplate being no good, I am sure it is still o.k.
*Mod Edit* Removed non-sponsor contact info.
As for the midplate being no good, I am sure it is still o.k.
*Mod Edit* Removed non-sponsor contact info.
Certainly sounds more viable than the nonsense suggestions about oil or pumps.
It is absolutely an install problem, whether the bearing itself, pre-load or even an issue with the new input shaft not being correct ( was it OEM or aftermarket piece ? )
03-03-2015, 09:38 PM
#17
Based on my bone head mistakes with tapered wheel bearings, I would say too much preload/ pressure on the bearing in the race. Too much pressure and that bearing doesn't want to rotate and will fall apart like that. Lubrication would prevent discoloration, especially in a quick failure. Bearings usually fail from lack of lubrication or mis-alignment. I think there was installation error here.
Which bearings were replaced? If he did the countershaft too, check brand there.
Op is right, the pilot is installed correctly and even if it wasn't, it would still work backwards.
Which bearings were replaced? If he did the countershaft too, check brand there.
Op is right, the pilot is installed correctly and even if it wasn't, it would still work backwards.
03-04-2015, 05:28 AM
#18
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An extreme possibility....if the engine/trans is mounted at a bad angle pointing rearwards, and the trans was run low in oil for an extended period. I guess that would also be a maybe...but it really is clutching at straws
As nobody would be daft enough to run it low in oil for starters.
As nobody would be daft enough to run it low in oil for starters.
03-04-2015, 01:29 PM
#19
An extreme possibility....if the engine/trans is mounted at a bad angle pointing rearwards, and the trans was run low in oil for an extended period. I guess that would also be a maybe...but it really is clutching at straws
As nobody would be daft enough to run it low in oil for starters.
As nobody would be daft enough to run it low in oil for starters.
If the fluid level was decent, that's not the problem. That like saying hard acceleration or driving up a hill would deprive bearing to the point of failure. The gears turning would whip fluid all over. Common denominator here, recently messed with the bearings.
