252k - transmission gave its last

[sdeeter19555]

So I started getting a wierd vibration in 6th at low rpm about a year ago, odd resonating; figured it was an exhaust noise (that's what it felt like too).  Fluid looks perfect, just changed it a couple weeks ago.  Turns out that odd resonation was probably the converter slipping...

 

So Monday it started surging in cruise.  I could control it if i didnt run cruise...all other gears seemed ok.  Get about 150 miles from home and I can tell it's the converter clutch slipping because it does it on a lugging pull in 3rd as well.  Drives fine when the converter is unlocked and if I'm light on the throttle.  Drove it back there (300 miles round trip) again Tuesday no change...

 

Funny thing is it only does it when lugging, it does it a whole lot less in tow/haul because it shifts earlier and its at a higher RPM.  

 

Any idea on what I might be looking at cost wise for a rebuild?  Southeast Pennsylvania if that makes a difference...

[CamGTP]

Might be hard to say with labor rates and all that. But a new transmission from GM is probably around $4,200, just like the one in this link here. Prices may vary depending on dealership and such, then add labor.

 

https://www.gmpartsdirect.com/oem-parts/gm-automatic-transmission-assembly-19431754?c=Zz1hdXRvbWF0aWMtdHJhbnNtaXNzaW9uJnM9YXV0b21hdGljLXRyYW5zbWlzc2lvbiZsPTUmbj1Bc3NlbWJsaWVzIFBhZ2UmYT1jaGV2cm9sZXQmbz1zaWx2ZXJhZG8tMjUwMC1oZCZ5PTIwMTImdD1sdCZlPTYtMGwtdjgtZ2Fz

 

I can bet a rebuilt unit from a good transmission shop is going to run at least $3,000-3,500 then add labor to install. Going to guess at $100-150 an hour for labor, so add on another $1,000-1,500.

 

Around me there are a few places that advertise online and on marketplace that they do rebuilds for $2,000-3,000 but you have to do all the labor work of removing it yourself.

[Grumpy Bear]

If the clutch is slipping then replace the converter before it kills the transmission? 

[richard wysong]

With that mileage if you pull it to do the converter it would be foolish not to rebuild it

[Grumpy Bear]

On 10/11/2025 at 5:25 AM, richard wysong said:

With that mileage if you pull it to do the converter it would be foolish not to rebuild it

 

I can think of a few thousand reasons ($$$$) it isn't. 

[KARNUT]

What foolish advice. Anyone with any automotive knowledge knows the odds of any transmission life after 250K miles. Is a crapshoot. You’re already paying for R&R of the transmission. You’re changing the converter. A likely transmission failure is inevitable. So let’s trash the new converter with contamination and schedule time for the job again. And R&R the transmission. Sometimes people like to be contrary for no reason. Rebuilt the thing. 

[sdeeter19555]

Right now, looking at $4800 for a complete rebuild with all available upgrades, custom converter (same guy who did my ultra low stall for my old Dodge), and new computer (stops the converter from locking until 5th and 6th).

 

I didn't think that was horrible considering my 47RE was $3200 nearly 20 years ago...

[sdeeter19555]

$4800

 

Custom converter with better clutch, new pump and pump mods, new sprag, all new bearings and bushings, new clutches, new valves in valve body, new plugs with orings, among other upgrades.

 

1-2-3 clutches looked good, 4-5-6 were worn but not bad.  It was the converter that was causing the issue and that caused the pump to wear.

 

Not bad for 252k miles...