Leaking 700R4--help please!

[galong05]

Hi guys,

My first day on the site as a member.  I'll keep it simple, but hope to meet some really informative nice people here.

I have an 83 Chevrolet C10 Scottsdale with a rebuilt 700R4 transmission in it from Monster.  Shel's only got about 500 miles on her.  Well, the output shaft seal was replaced about two weeks ago, but now it is dripping tranny fluid out of the side.  I put a photo attached to this post for you mechanical gurus to look at.  I'm just hoping that somebody tell me what this piece of the trans is and why it may be leaking from there.

Thank you guys.  I appreciate it.

[zieg85]

That piece corrects the speedometer.  There is a plastic drive gear and driven gear that is paired with your rear end ratio and tire size.  If the leak is severe enough just remove it and try to find another.  The speedometer will be off a bit but a GPS will help you until you find a replacement.  BTW welcome to the site from NW Indiana

[galong05]

Thank you sir.  I appreciate it very much. 

[bd]

Welcome galong05, from Central California!!

There's no tranny fluid in the ratio adapter (pictured).  The ratio adapter is not the source of the leak.  Fluid is leaking past the speedometer driven gear seal in the transmission.  To fix it, you need to unscrew the speedo cable and ratio adapter from the transmission, remove the Y-clamp retainer that holds the aluminum speedo gear support bushing and then remove the support bushing.  A small amount of fluid will drain out.  When you pull the support bushing the colored plastic driven gear will come with it. 

With the gear still in the support bushing, wiggle the driven gear side-to-side - there should be no more than ~0.003" to 0.005" of radial play in any direction.  Now, pull the plastic gear out of the support bushing and inspect the shaft of the driven gear - it should be smooth except for a shallow 'spiral' groove that wraps the length of the shaft to provide lubrication and "thread" fluid away from the seal.  If there is more than ~0.005" of side-to-side play between the gear and the bushing - replace both the gear and the bushing.  If radial play is 0.005" or less, but there is a concentric groove worn into the shaft about 1/4" from the cable end of the gear (or many concentric grooves along the length of the shaft), replace the driven gear. 

In either case, replace the driven gear soft silicone lip seal (P/N 1240382) and support bushing o-ring (P/N 15552872).  Don't lose the wire snap-ring that retains the lip seal.  Install the silicone lip seal so the 'lip' points toward the transmission.

See this thread for additional details...  speedo gear leak

Edit:  images

[galong05]

Thanks BD!

[bd]

You're quite welcome.

[frotosride]

Welcome galong05, from Central California!!

There's no tranny fluid in the ratio adapter (pictured).  The ratio adapter is not the source of the leak.  Fluid is leaking past the speedometer driven gear seal in the transmission.  To fix it, you need to unscrew the speedo cable and ratio adapter from the transmission, remove the Y-clamp retainer that holds the aluminum speedo gear support bushing and then remove the support bushing.  A small amount of fluid will drain out.  When you pull the support bushing the colored plastic driven gear will come with it. 

With the gear still in the support bushing, wiggle the driven gear side-to-side - there should be no more than ~0.003" to 0.005" of radial play in any direction.  Now, pull the plastic gear out of the support bushing and inspect the shaft of the driven gear - it should be smooth except for a shallow 'spiral' groove that wraps the length of the shaft to provide lubrication and "thread" fluid away from the seal.  If there is more than ~0.005" of side-to-side play between the gear and the bushing - replace both the gear and the bushing.  If radial play is 0.005" or less, but there is a concentric groove worn into the shaft about 1/4" from the cable end of the gear (or many concentric grooves along the length of the shaft), replace the driven gear. 

In either case, replace the driven gear soft silicone lip seal (P/N 1240382) and support bushing o-ring (P/N 15552872).  Don't lose the wire snap-ring that retains the lip seal.  Install the silicone lip seal so the 'lip' points toward the transmission.

See this thread for additional details...  speedo gear leak

Edit:  images

Great info....