bolt in sprag failure

Posted By: rebel

bolt in sprag failure - 03/31/09 05:31 AM

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.

Posted By: CRIKEY

Re: bolt in sprag failure - 03/31/09 09:34 AM

any pics?

I have seen the outer sprag ring break when fitted incorrectly, is it possible it could have been cracked?

Posted By: 451Mopar

Re: bolt in sprag failure - 03/31/09 09:40 AM

Was that the 4-bolt 12 roller sprag or the 6-bolt 16 roller sprag? Any idea where the sprag failure point was?

Posted By: turbobitt

Re: bolt in sprag failure - 03/31/09 11:52 AM

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.

Posted By: DJVCuda

Re: bolt in sprag failure - 03/31/09 12:02 PM

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.com

the A&A sprag race is made from billet steel and not powdered meta.

Posted By: DJVCuda

Re: bolt in sprag failure - 03/31/09 12:11 PM

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.

Posted By: B G Racing

Re: bolt in sprag failure - 03/31/09 12:20 PM

Replaced more bolt in sprags(over running clutchs)than stock.Just changed out a bad super sprag in Dave Ross's Coan trans.Although it had more rollers and springs,the rollers/springs were much smaller than the stock ones as well as the ramp ring housing.Many of the springs were broken or flat and the inner race(ring) had obvious chatter(flat grooves)markings.Go figure

The only time I use a bolt in overrunning clutch is if the stock one is bad.Having a bolt in one does not guarantee it won't break.

Posted By: dizuster

Re: bolt in sprag failure - 03/31/09 12:55 PM

What's interesting is that the LBA should have still held the drum, even after the one-way roller clutch failed.

Posted By: 65dragnet

Re: bolt in sprag failure - 03/31/09 01:39 PM

evidently the LBA and the steel drum did their job ! He didn't mention any broken or torn up feet. Sprags tranny's or engines are not indestuctable

Posted By: 440Jim

Re: bolt in sprag failure - 03/31/09 04:41 PM

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

Posted By: MR_P_BODY

Re: bolt in sprag failure - 03/31/09 04:53 PM

Does the torque converter still hold at the same RPM

Posted By: rebel

Re: bolt in sprag failure - 04/01/09 04:42 AM

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.

Posted By: 451Mopar

Re: bolt in sprag failure - 04/01/09 05:21 AM

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 don't have any information on the valve body you are using, but a stock valve body will apply the low band when in manual low, but if you place the selector in 2nd or drive the trans starts in low/breakaway without the low band apply?

I have read some articles that alaways say to do your burnout in second gear, but this seemed to be when using a reverse manual valve body?

Posted By: rebel

Re: bolt in sprag failure - 04/01/09 06:22 AM

pics at last

Attached picture 5133596-01-04-09_18331.jpg

Posted By: rebel

Re: bolt in sprag failure - 04/01/09 06:23 AM

another

Attached picture 5133598-01-04-09_18311.jpg

Posted By: rebel

Re: bolt in sprag failure - 04/01/09 06:24 AM

the sprag. the rollers(not shown) all have flat spots on them????

Attached picture 5133599-01-04-09_18321.jpg

Posted By: DJVCuda

Re: bolt in sprag failure - 04/01/09 11:12 AM

she sure rolled over - thats for sure!

Posted By: Anonymous

Re: bolt in sprag failure - 04/01/09 04:51 PM

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.

Posted By: @#$%&*!

Re: bolt in sprag failure - 04/01/09 04:56 PM

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.

Posted By: turbobitt

Re: bolt in sprag failure - 04/01/09 07:37 PM

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.

Posted By: 493_Scamp

Re: bolt in sprag failure - 04/02/09 12:03 AM

Correct me if I,m wrong but with LBA the sprag doesnt hold any force because the band holds instead,then in 2nd gear the sprag overruns(releases and freewheels).So with LBA the sprag only functions during the 1,2 shift overlap when the LB has to release to let 2nd work.So I'm thinking the LB isnt actually working to have that much failure of the sprag.

Posted By: 540dust

Re: bolt in sprag failure - 04/02/09 12:41 AM

That doesn't look like the last Ultimate Sprag I installed, I think maybe someone was blowin' you smoke. The A&A Ultimate is a 16 element 6 bolt, not a 12 element like that one. It's a much better quality piece and would be much less susceptable to the roll over that you encounted. LBA, or the bolt in sprags still do not guarantee no failure but definitely help. That sprag looks like the old "striped out case" fix it, which used to be all that was availabe. Now the Coan Super sprag and the A&A 16 elements are superior to those old 12 elements.

Posted By: 540dust

Re: bolt in sprag failure - 04/02/09 12:44 AM

This is the A&A Ultimate Sprag....

Attached picture 5135811-22961L.jpg

Posted By: 540dust

Re: bolt in sprag failure - 04/02/09 12:47 AM

Ok, excuse me, I read more closely, and you did not have the 16 element sprag.... you had the ultimate LBA brake...pardon me.

Posted By: 540dust

Re: bolt in sprag failure - 04/02/09 01:07 AM

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 ?

Posted By: John_Kunkel

Re: bolt in sprag failure - 04/02/09 07:22 PM

Quote:

Correct me if I,m wrong but with LBA the sprag doesnt hold any force because the band holds instead,

The sprag is in the "partial hold" mode when the rear band is applied, due to its smaller size the rear band has limited holding power.

Posted By: 493_Scamp

Re: bolt in sprag failure - 04/02/09 11:52 PM

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.

Posted By: DJVCuda

Re: bolt in sprag failure - 04/03/09 12:22 AM

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.

Posted By: rebel

Re: bolt in sprag failure - 04/03/09 09:40 AM

Quote:

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.

HOT!!! oh yeah. went thru the traps had a quick scan of the guages & thought"damn, trans temp guage is f....." it was reading zero. on the return road i looked again & saw it reading 220* & dropping. the needle was held back from going around again by the zero pin. it was still full of fluid & the debris was two big chucks of alloy & the sprag springs ground up in the pan @ the back. cooler only had 3 specs of alloy after flushing. no damage to anything else except 1 band has a lil alloy in it too. i'm guessing the being low band was why i could still drive back to the pit??