bolt in sprag failure
#272189
03/31/09 01:31 AM
03/31/09 01:31 AM
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Joined: Dec 2006
Posts: 4,647 aotearoa
rebel
OP
master
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OP
master
Joined: Dec 2006
Posts: 4,647
aotearoa
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just when my racecar is going great the auto has a failure. last run went bad, big revs, no real power. change gear & the shift light stays on. it has all the good parts. an A&A ultimate LBA brake, steel drum, billet servos, reds, steels, deep pan, bolt in sprag etc... when it was pulled apart the bolt in sprag has failed & fallen apart & the case has broken where the bolt in sprag is fitted. with a LBA brake i thought the sprag is not under any duress so what would cause this? the bolt in sprag not in tight? any educated opinions out there? oh yeah. the car weighs 2950lbs, engine produces 700 hp, has a fan assisted cooler that stays under 200* auto is freshly built. it has been passing a lot of fluid out the breather since the rebuild but not too much to run out of fluid on a run, maybe a mouthfull if you could imagine that much.
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Re: bolt in sprag failure
[Re: 451Mopar]
#272192
03/31/09 07:52 AM
03/31/09 07:52 AM
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Joined: Aug 2005
Posts: 760 Southington Ct.
turbobitt
super stock
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super stock
Joined: Aug 2005
Posts: 760
Southington Ct.
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A failure like this makes me wonder if it was damaged during installation. I think the A&A outer race is powder metal or at least it looks that way. If it wasn't drawn in evenly it may have cracked.
1970 Challenger w/572 Hemi street car and my pride and joy.
1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno.
1976 Cee Bee Avenger Jet Boat - 460 Ford powered.
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Re: bolt in sprag failure
[Re: turbobitt]
#272193
03/31/09 08:02 AM
03/31/09 08:02 AM
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Joined: Aug 2003
Posts: 11,179 Atco NJ
DJVCuda
I Live Here
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I Live Here
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Posts: 11,179
Atco NJ
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Mopar Enthusiast has an article in this months issue covering this - It's a free read onthe internet right now starts on page 41 www.moparenthusiast.comthe A&A sprag race is made from billet steel and not powdered meta.
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Re: bolt in sprag failure
[Re: 451Mopar]
#272194
03/31/09 08:11 AM
03/31/09 08:11 AM
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Joined: Aug 2003
Posts: 11,179 Atco NJ
DJVCuda
I Live Here
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I Live Here
Joined: Aug 2003
Posts: 11,179
Atco NJ
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Quote:
Was that the 4-bolt 12 roller sprag or the 6-bolt 16 roller sprag? Any idea where the sprag failure point was?
It sounds like a 12 roller, since the high revs leads me to believe that the sprag rolled over, the 16 roller design does not allow that to happen. Bolt in sprags fail, they just dont take a steel drum out with them, and make them explode, the shaft is still spinning 2.2x rpm speed and will take out the next weakest link, in this case the case itself and sprag race.
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Re: bolt in sprag failure
[Re: rebel]
#272198
03/31/09 12:41 PM
03/31/09 12:41 PM
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Joined: Jan 2003
Posts: 16,928 NC
440Jim
I Live Here
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I Live Here
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NC
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Quote:
change gear & the shift light stays on.
This makes me think other things got broke, and your disassembly confirms it. If only the sprage wasn't holding, shifting to 2nd should have been OK. Also the LBA
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Re: bolt in sprag failure
[Re: rebel]
#272206
04/01/09 12:51 PM
04/01/09 12:51 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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A while a go there was discussion about doing a burnout in second. If you have a low horsepower car maybe but I have been doing a burnout in high gear only with no issues at all. I'm not say this is why you had a failure but you never know! Quote:
trans man tells me i've been off n on the pedal all the time but i'm not. he even says i shouldn't start the burnout in 2nd. i'm no john force on the burnout. i start in 2nd & as soon as i see smoke by the window i shift into 3rd & release the linelock & ease off the pedal. does that sound right? slicks still have depth dots @ the end of season so i'm not overkilling it. burnout limiter is set @ 6500 on a 5500 stall converter. when daughter gets home i'll take a pic & post it. it was a 4 bolt sprag.
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Re: bolt in sprag failure
[Re: 451Mopar]
#272207
04/01/09 12:56 PM
04/01/09 12:56 PM
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Joined: May 2008
Posts: 1,131 Thigh-Gap Junction
@#$%&*!
New user name, Same old jerk!
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New user name, Same old jerk!
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
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Quote:
I have been told the 12-element sprags (4-bolt) really are not any better than the stock one, and they were supposed to be a fix for sprags that were loose in the case?
I guess I wasn't being a total dilweed when I bolted in the original one without taking it out. And once I had 4 bolts in, adding the other 2 wasn't much more work. So far so good.
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Re: bolt in sprag failure
[Re: rebel]
#272208
04/01/09 03:37 PM
04/01/09 03:37 PM
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Joined: Aug 2005
Posts: 760 Southington Ct.
turbobitt
super stock
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super stock
Joined: Aug 2005
Posts: 760
Southington Ct.
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Is it just me or does this thing look like it got hot ? Maybe lack of oil lub somehow? Is there any galling on the mainshaft or governor support(or whatever they call it)? Allan G.
1970 Challenger w/572 Hemi street car and my pride and joy.
1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno.
1976 Cee Bee Avenger Jet Boat - 460 Ford powered.
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Re: bolt in sprag failure
[Re: 540dust]
#272213
04/01/09 09:07 PM
04/01/09 09:07 PM
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Joined: Nov 2005
Posts: 656 Kokomo, IN
540dust
mopar
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mopar
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Posts: 656
Kokomo, IN
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Quote:
This makes me think other things got broke, and your disassembly confirms it. If only the sprage wasn't holding, shifting to 2nd should have been OK. Also the LBA
What does the front planetary splines to the output shaft look like ?
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Re: bolt in sprag failure
[Re: 493_Scamp]
#272216
04/02/09 08:22 PM
04/02/09 08:22 PM
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Joined: Aug 2003
Posts: 11,179 Atco NJ
DJVCuda
I Live Here
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I Live Here
Joined: Aug 2003
Posts: 11,179
Atco NJ
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Quote:
So the low band slips? I thought it would be capable to handle the load by itself without slippage. Am I correct in my thinking that the sprag only moves a fraction of an inch before it locks or does it slip a measurable amount.By hand they appear to lock instantly. Doesnt the THM 400 use no roller and a band only for first? I know my 727 needs an aftermarket front drum to be safe but I was thinking the LBA was going to make it bulletproof at least as far as sprag failure. I'm footbraking in the 10s with no LBA and factory drum,with factory sprag I drilled and bolted myself.
and you are risking a drum explosion!
www.moparenthusiast.com
Read this months issue - it has a 727 article that will explain alot of this.
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