Moparts

Super sprag failure

Posted By: Ck[FIN]

Super sprag failure - 06/15/16 11:36 AM

My friends 727 broke behind his 550+cid 900hp+ big block.
It started to lock the tires after launch and i found broken sprag. Never first gear burnouts. car broke rear end last summer, maybe broke the sprag too.
valve body does have band on first gear. Also got aluminum drum.

In my opinion, the super sprag worked like it should even if it broke, didnt roll over, just got stuck and stopped the car.

https://drive.google.com/open?id=0B33OAqkGbjVpcVE2YVQ0OWY4VjRZeVM1NXE1SXBFc1B2cHVR
Posted By: turbobitt

Re: Super sprag failure - 06/15/16 01:50 PM

Hard to see but it looks like it wasn't getting any lube oil. Is that bluing on the inner race ? Do the rollers look like they have wear prior to the damage ? If there is wear due to lack of lube oil I wonder if it would have been beneficial to drill a small lube oil hole from the lube feed passage.
AG.
Posted By: JohnRR

Re: Super sprag failure - 06/15/16 05:34 PM

Originally Posted By turbobitt
Hard to see but it looks like it wasn't getting any lube oil. Is that bluing on the inner race ? Do the rollers look like they have wear prior to the damage ? If there is wear due to lack of lube oil I wonder if it would have been beneficial to drill a small lube oil hole from the lube feed passage.
AG.


I add that tiny hole on every 727 I build.
Posted By: John_Kunkel

Re: Super sprag failure - 06/15/16 06:45 PM


Me too.

Attached picture Spraglube front.jpg
Attached picture Spraglube rear.jpg
Posted By: Ck[FIN]

Re: Super sprag failure - 06/15/16 09:19 PM

Yes there is an extra lube hole. This is 4k Coan transmission, about 100passes. Front drum return springs were all over the place. Clutches like brand new.
Posted By: 451Mopar

Re: Super sprag failure - 06/15/16 10:25 PM

Not sure why it broke? Is that using a manual reverse valve body or forward pattern.

I have the A&A Ultimate Sprag, that bolts in with six bolts. I'm not sure if the super sprag is much different other than having four bolts?
Posted By: dizuster

Re: Super sprag failure - 06/15/16 10:40 PM

Just goes to show big power can break anything. Mine had rolled a stock spray with LBA a few years ago. Dame thing, never any 1st gear burnouts.

I think it's from hard launches and occasionally stick/spin launches that kill it.
Posted By: John_Kunkel

Re: Super sprag failure - 06/15/16 10:57 PM


Like turbobitt said, the burn marks are strange and extend pretty near all the way around the visible inside of the race. I'd want to mike the surviving rollers to check for flat spots.

What does the rear band look like?
Posted By: Ck[FIN]

Re: Super sprag failure - 06/15/16 11:12 PM

Its reverse vb.
I,ll take some more photos of the sprag for you to analyze.
Rear band is like new, still says hd kevlar in it.
Posted By: Ck[FIN]

Re: Super sprag failure - 06/16/16 11:09 AM

Here some more photos, looks like the color was there before accident. This car has too little tires so it spins often at launch and then gets traction. Maybe it(and the rear end failure) had something to do with this.

Sprag
https://drive.google.com/open?id=0B33OAqkGbjVpdU9OZUhuOWxnb2c

Sprag 2
https://drive.google.com/open?id=0B33OAqkGbjVpcEx1WjBrQlRCODQ

Sprag 3
https://drive.google.com/open?id=0B33OAqkGbjVpQ1JNUHlDOGd0a1E

Band
https://drive.google.com/open?id=0B33OAqkGbjVpSjlUOUZ1VDdfVmc

Case
https://drive.google.com/open?id=0B33OAqkGbjVpNDg4NnV0cm9zV2M

"Roller"
https://drive.google.com/open?id=0B33OAqkGbjVpUW9RRnZYMGhpZWs
Posted By: mafo

Re: Super sprag failure - 06/16/16 11:46 AM

No need to mike those rollers... grin
Posted By: turbobitt

Re: Super sprag failure - 06/16/16 01:03 PM

In my opinion this looks like a lube circuit failure. It appears to have a lot of wear and galling. I would start by looking at the rear roller support and make sure the seals are doing there job and contacting the appropriate surfaces. Put the tail shaft back in with the output shaft and see what is happening between the bearings, seals and relief cuts in the shaft. At this point it may be a good idea to send compressed air through the lube supply and see if there are any undesirable leaks. Then I would work my way through the system and make sure the cooler is not clogged and maybe inspect the valve body.
AG.
Posted By: Ck[FIN]

Re: Super sprag failure - 06/16/16 02:18 PM

Could be a lube problem, i'll check those oil passages and seals. Maybe a bigger lube hole also?
Posted By: turbobitt

Re: Super sprag failure - 06/16/16 02:37 PM

I don't think the lube hole is the problem and the fact that it already has one is probably overkill in a perfect lube oil situation. It just looks to me as if its not getting any oil to that hole whatsoever. It appears as if the rollers wore so bad that they eventually rolled over, jammed or ejected with the springs because of the reduction in size.
Any time a roller rear support is used carefully attention to the lube circuit and alignment of the sealing areas on the output shaft must be taken.
As a precautionary measure, I would inspect the planets and make sure the gears have minimal radial play(as an indication of needle bearing and shaft wear). If it is a lube failure and has been running like this for a while the planetaries may be starting to take a beating.
AG.
Posted By: DARTH V8Я

Re: Super sprag failure - 06/16/16 10:28 PM

Originally Posted By Ck[FIN
]Could be a lube problem

Definitely a lube problem.. yikes.
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