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SB TF727 issue - lost third and reverse

Posted By: 471Magnum

SB TF727 issue - lost third and reverse - 08/15/10 06:37 PM

In route to Mopar Nationals, my Roadrunner broke down. We were cruising down the interstate at 60 mph or so and the transmission just downshifted to second.

No sign of any slippage. Throttle linkage was set right and it seemed to have plenty of throttle pressure. No leaking and fluid looks and smells clean.

Still shifts through first and second, but no reverse either. Guessing I lost a band or clutch pack.

I'll be pulling the transmission this week and probably bringing it to a friend for repair, but I'm looking for some advanced pre-diagnosis.
Posted By: dOc !

Re: SB TF727 issue - lost third and reverse - 08/15/10 06:51 PM

You probably BLEW OUT the rubber seal in the front clutch piston.... a 50 cent seal
Posted By: 1_WILD_RT

Re: SB TF727 issue - lost third and reverse - 08/15/10 07:06 PM

Quote:

You probably BLEW OUT the rubber seal in the front clutch piston.... a 50 cent seal



Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/15/10 07:26 PM

So... what causes it to blow out? Mis-assembly?

Do I need to remove the transmission and tear it down to replace the seal, or can it be done in car? Got a part number for the seal?

Point me to the right page in the FSM. I'm flipping through looking for it.
Posted By: 70AARcuda

Re: SB TF727 issue - lost third and reverse - 08/15/10 08:51 PM

Quote:

So... what causes it to blow out? Mis-assembly?

Do I need to remove the transmission and tear it down to replace the seal, or can it be done in car? Got a part number for the seal?

Point me to the right page in the FSM. I'm flipping through looking for it.



the converter got to come out..the front pump is got to come out..the front drum with clutch pak is gotta come out...

get the idea...
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/15/10 09:01 PM


Dangit. Thought I might get lucky on that one.
Posted By: dOc !

Re: SB TF727 issue - lost third and reverse - 08/15/10 11:11 PM

Quote:



So... what causes it to blow out? Mis-assembly?





From this statement you made .. this trans was supposedly redone a short time ago ?
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/16/10 01:47 AM

Quote:

From this statement you made .. this trans was supposedly redone a short time ago ?



Only owned the car about a month. PO claims it has a few thousand miles on it.
Posted By: 451Mopar

Re: SB TF727 issue - lost third and reverse - 08/16/10 06:43 AM

You might want to pull the VB first and check it, I had a valve body that cracked the wall on one of the fluid passages and did what you describe. Probably the same fluid path as the front clutch like described by everyone else.
Posted By: fox

Re: SB TF727 issue - lost third and reverse - 08/16/10 07:36 AM

It should have dropped to first.
If it actually went to second something else happened.
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/16/10 06:38 PM

Anyone else have an opinion?
Posted By: Alikazam

Re: SB TF727 issue - lost third and reverse - 08/17/10 12:53 AM

I had a weird problem with a different make transmission where it wanted to be in 2nd and 3rd at the same time... was a stuck valve in the valve body. I'd definitely look at that first. Good luck!
Posted By: JohnRR

Re: SB TF727 issue - lost third and reverse - 08/17/10 06:27 PM

if you lost first and reverse it would be the front clutch, either the inner seal let go or you have a fluid path leak , and it would be a huge one. As said drop the VB and with a rubber tip air gun you can test the clutch pack , if you hear a loud air rush you have a blown seal or crack in the case , or the front pump and/or gasket , be prepared to get covered in trans fluid.

If this happened after a 1000 or so miles I would just bite the bullet and pull it and go thru it , auto trans repair shops will reuse whatever parts they can, clutches and seals included.
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/17/10 07:16 PM

The bullet will get bit.

Plan to pull the transmission tomorrow night. I'll bring it to a trusted friend for repair.

I've got a good spare 727. Unfortunately, it's a BB unit, but if I've got some broken hard parts, it will make a good doaner.
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/19/10 05:58 PM

Got the transmission out last night.

Lots of metal in the pan. It's headed over to a friends for a complete tear down and rebuild.
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/22/10 08:28 PM

Quote:

You probably BLEW OUT the rubber seal in the front clutch piston.... a 50 cent seal



Give the man a cigar.

Just got the word that it was the piston seal. $.50 plus $133.50 in labor.

Actually, a few more parts went into cleaning it up and putting it back together, but the damage was 134 bucks, not including my labor doing the R&R.
Posted By: dOc !

Re: SB TF727 issue - lost third and reverse - 08/22/10 10:36 PM

Ceegar ? ... THX ... but I quit smoking back in 1991 !!

Was that seal hard and brittle(and break-apart) ...or did it just roll-over ?
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/22/10 11:06 PM

Quote:

Was that seal hard and brittle(and break-apart) ...or did it just roll-over ?



Actually, I spoke too soon. No cigar.

It was actually the front piston lip seal. Apparently the guy that rebuilt it previously got a little careless.
Posted By: dOc !

Re: SB TF727 issue - lost third and reverse - 08/22/10 11:13 PM

That IS the rubber seal .... so what do you mean ?
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/22/10 11:20 PM

No. It was a cast iron seal. I may have the description wrong.
Posted By: dOc !

Re: SB TF727 issue - lost third and reverse - 08/22/10 11:26 PM

So it BROKE ? .... that is a rare-bird on a new part.
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/22/10 11:58 PM

Suspicion is that it got broken when the pump was installed during assembly at the previous rebuild. It just took a while to come apart completely. Just my luck it came apart on me, and not the previous owner.
Posted By: dOc !

Re: SB TF727 issue - lost third and reverse - 08/23/10 12:04 AM

Quote:

Suspicion is that it got broken when the pump was installed during assembly at the previous rebuild. It just took a while to come apart completely. Just my luck it came apart on me, and not the previous owner.



THIS is what he told you ?

If the sealing RING broke upon installation .. it would have leaked THEN.

This whole deal does not sound right ...
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 08/23/10 12:20 AM

Kind of a moot issue at this point. It's a theory, wrong or right.

Ring was broken. I had to pay someone to fix it.
Posted By: PDFrogman

Re: SB TF727 issue - lost third and reverse - 08/23/10 01:38 PM

Quote:

No. It was a cast iron seal. I may have the description wrong.


that will cause no third, no rev. my concern is... did the broken ring damage the sealing surface in drum or the reaction support?
I wonder how the builder was able to seat the pump and torque it down with the broken ring?
Posted By: Anonymous

Re: SB TF727 issue - lost third and reverse - 12/14/11 08:42 PM

Where in the wide, wide web (or world) can ya score the 0.50 seals without buying the 39.95 overhaul kit???

I just know one or more of my front clutch piston seals is leaking and its well past time to go in after it.
Posted By: RodStRace

Re: SB TF727 issue - lost third and reverse - 12/14/11 08:48 PM

Did your builder find the cause of "lots of metal in the pan" too?
Better to find and fix the root cause now...
Posted By: 471Magnum

Re: SB TF727 issue - lost third and reverse - 12/15/11 12:57 AM

This issue was resolved over a year ago. No issues with the transmission since.
Posted By: JohnRR

Re: SB TF727 issue - lost third and reverse - 12/15/11 04:01 AM

Quote:

Where in the wide, wide web (or world) can ya score the 0.50 seals without buying the 39.95 overhaul kit???

I just know one or more of my front clutch piston seals is leaking and its well past time to go in after it.



Transtar
Posted By: Anonymous

Re: SB TF727 issue - lost third and reverse - 12/15/11 12:10 PM

I looked at the 2011 Transtar Chrysler catalog yesterday - they dont list the front clutch piston seal seperately. So far have only found one place on the web that claims to have them seperate which makes me suspicious.

Ya think I'd get anywhere at the dealership parts counter with a 30 yr old p/n?
Posted By: JohnRR

Re: SB TF727 issue - lost third and reverse - 12/15/11 06:10 PM

Which seal , inner or outer ? What year is the trans ?

Inner is 13310 , inner for the over cut groove is 13310A

outer is 62-71 3272L , 71 up is 13309
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