I think I am experiencing this symptom, although from what I've read up as much as I can about it, I'm not sure I should be experiencing it with my setup.

I have a TH-350 with a 8" 3600 stall Vigilante converter on it. It is not a lock-up converter, and what I've read leads me to believe that "shudder" is caused by the lock-up clutch chattering rapidly.

I felt this symptom before on my previous motor, but thought it was an engine misfire or something - but I never got a misfire code, and A-Tapping the PCM said the motor was running fine.

Well, I've since replaced that motor with a completely new one (hydro-locked the previous one), and the vibration/shudder problem is not only still there, it's much worse. Through much trial and error, we were able to eliminate the new motor as the source of the vibration (it is new after all), but I didn't know if the problem was in the TC or the tranny, although the shudder was still present during a converter stall test.

I'm trying to find the answer as to where the problem is - TC, tranny, or both - and just found out about "torque converter shudder" - and the symptoms of it matches all my symptoms, but I don't have a lock-up converter, so I'm still not sure if the problem is in the TH-350 or the TC.

Also, what causes it? Tranny getting too hot? Should I add a 2nd tranny cooler? Or is it because of normal tranny wear (clutch packs)?

Thanks in advance for any help on this!

Dean

 

Man, I wish I could help. I have "shutter" in the stock '98 trans, but here goes-
1. In the stock tranny the shutter is usually when o.d. is appplied, that's to be expected in stop n go traffic.
2. In my TCI 'Vertor on the '67, shudder is non-exist when I hit the powerband (3500-7000).
3. On the GN (which was also an OD) it did not exist. Left the light at 2750, hit boost at 2900, and everything was smoothe after that.

I'd say it's OD without compensating for RPM's, but in your case, maybe a higher stall and earlier "leap" into functioning powerbands. With your TH350?400 I would say just jump in sooner. That's my input.

 

I should mention one other detail that I left out before...

The "shudder" is present at all speeds and all RPM's, as long as I'm in the gas pedal. When I let off the gas, the vibration subsides substantially to almost non-existent.

Also, when the car is cold, the vibration is nowhere near as bad as when the car has warmed up.

I sure hope the description of these symptoms rings a bell with someone!!


Dean

 

Weird but could be a bad balanced converter. Try throwing the stock converter in and see what it does. Lots of work, but it'll rule out the Vig.

 

Have you ruled out other driveline problems like
large pinion angle, or suspension related hopping?

 

Yes, the vibration is present even if I stall test it - with car stopped, hold brakes and give gas to bring RPMs up to ~3500. The driveline is stationary at that point so cannot contribute to vibration.

Anyhow, I pulled the tranny oil pan off, and found "glittery", metallic flecks all in the bottom of the pan. The tranny filter had the glitter in it too, but also trapped big chunks of what looks like asbestos - I think that's the clutch/band material.

I'm pretty sure I need a new converter now, but I'm also sure I need to overhaul the tranny at the very least to replace the clutches/bands and to flush out all of the contaminants floating around in there.

 

Hi Dean,
I sounds like you have torque converter vibration...not torque converter clutch shudder. You can simply unbolt the converter without pulling it out of the car. Start the engine up and see if the vibration is still present. If it goes away, you know that it was converter vibration.
Kevin