727 sprag

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william parker

william parker

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I have a BB 727 I picked up. Noticed when I spun it has a squeak noise. Pulled it apart and found when I spin the sprag race it squeals. Is that normal til it has fluid in? I took it apart and cleaned it and were it with fluid Put the rollers and springs back in same noise. Everything looks perfect. What yall think?
 
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Has it been upgraded to a heavy duty bolt in sprag? That's one thing I would do if not.
 
I would certainly consider that upgrade were I using a 727.

727 EXPLOSION.jpg
 
Yes that little squeak can be normal. Even with a bolt in sprag I’ve experienced the little squeal when turning the input shaft by hand. I usually just ensure I have enough assembly grease on the inner race so I don’t hear it after an assembly. And yes I’d upgrade to at least a 4 bolt 12 element sprag over the stock sprag. Especially if it’s any type of drag unit.
 
william parker said:
I have a BB 727 I picked up. Noticed when I spun it has a squeak noise. Pulled it apart and found when I spin the sprag race it squeals. Is that normal til it has fluid in? I took it apart and cleaned it and were it with fluid Put the rollers and springs back in same noise. Everything looks perfect. What yall think?
Click to expand...

Absolutely normal.
 
I don’t know how many actually know this, but the rollers in that type of sprag are not actually rollers.
They are actually in a mostly fixed position and only slide against the hub until the hub tries to turn the opposite direction, then they jamb the hub stopping it from turning via the tapered sections that the springs hold the rollers into.

That’s the basics of its operation.

The described squeak is actually more of a screech sound.
This sound is the “rollers” dragging across the smooth surface of the hub. (Not actually rolling across anything)

That is why that screeching sound is heard when turning the output shaft one way but not the other.

There would actually more likely be a problem if you didn’t hear it.
 
TrailBeast said:
I don’t know how many actually know this, but the rollers in that type of sprag are not actually rollers.
They are actually in a mostly fixed position and only slide against the hub until the hub tries to turn the opposite direction, then they jamb the hub stopping it from turning via the tapered sections that the springs hold the rollers into.

That’s the basics of its operation.

The described squeak is actually more of a screech sound.
This sound is the “rollers” dragging across the smooth surface of the hub. (Not actually rolling across anything)

That is why that screeching sound is heard when turning the output shaft one way but not the other.

There would actually more likely be a problem if you didn’t hear it.
Click to expand...
Screech is exactly it, I cleaned everything up and continued to build the trans. I did notice later if I turn the output a little faster it went away. Can't believe I've never noticed this before. Thanks for the reply.
 
71Demon528 said:
Yes that little squeak can be normal. Even with a bolt in sprag I’ve experienced the little squeal when turning the input shaft by hand. I usually just ensure I have enough assembly grease on the inner race so I don’t hear it after an assembly. And yes I’d upgrade to at least a 4 bolt 12 element sprag over the stock sprag. Especially if it’s any type of drag unit.
Click to expand...
Definitely. I had this trans I wanted to convert from shorty, build and test it while I break in the 512 I'm finishing up. I will throw in my fully built with the trans-brake in later when I get the car ready to handle it.
 
william parker said:
Definitely. I had this trans I wanted to convert from shorty, build and test it while I break in the 512 I'm finishing up. I will throw in my fully built with the trans-brake in later when I get the car ready to handle it.
Click to expand...
You know the trans brake puts a huge amount of stress into the driveline when it releases the engine torque all at once, right? I hope you put all the very best components into your trans during the build.
 
Ricks70Duster340 said:
You know the trans brake puts a huge amount of stress into the driveline when it releases the engine torque all at once, right? I hope you put all the very best components into your trans during the build.
Click to expand...
lol ya that particular trans is built and was tested over the years.
 
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