[Cliff R]

WAY back when I got into this hobby I'd have to fart in my pocket to have a cent. I was only able to buy "bottom end" converters and every single one I purchased had issues of one sort or another. They ranged from "shaking" at certain RPM's, poorly coupled under heavy load, noise, or WAY too much stall when hit with full power.

Even blew one up and trashed the transmission when it pumped it full of ground up needle bearings.

One I got the family raised up and considerably more funds for my toys I started buying much better converters. By far and above the very best improvement one can make to one of these vehicle per dollar spent.....but only the "top shelf" varieties are going to make the grade in all areas, especially behind a high torque/low RPM Pontiac engine build You loose in two ways with these engines, they make TONS of power and can kill a converter that's not built with good internals. Also, any "shelf" variety is unlikely going to be well coupled enough to effectively transfer power to the wheels thru the usable RPM range. Some are OK, but I've tested converters that some folk on the Forums use and recommend, like the Hugh's BOP varieties. They are just OK, but not on par anyplace with a top shelf custom built unit and I have the test time and track numbers to prove it......FWIW......Cliff

[lust4speed]

I've lost track. Have we discussed whether the engine was internally or externally balanced? Stock flexplates have additional holes drilled to compensate for the necessary external balance, and the only welding you see on them is the beads that hold the ring to the body. Then we go and have our engines internally balanced and the shop doing the balancing is either going to drill holes on the other side of the flexplate to get it back to neutral or they are going to weld on steel tabs on the hole side. Just wondering how the old flexplate was balanced and if the new ones were balanced the same?

[glhs#116]

Originally Posted by lust4speed

I've lost track. Have we discussed whether the engine was internally or externally balanced? Stock flexplates have additional holes drilled to compensate for the necessary external balance, and the only welding you see on them is the beads that hold the ring to the body. Then we go and have our engines internally balanced and the shop doing the balancing is either going to drill holes on the other side of the flexplate to get it back to neutral or they are going to weld on steel tabs on the hole side. Just wondering how the old flexplate was balanced and if the new ones were balanced the same?

But the engine plus flexplate doesn't vibrate. Only when the TC attached

[lust4speed]

Very good point. That should effectively rule out the flexplate.

[steve25]

if it's not the motor and the converters are / have been balanced properly then that points to the tranny input shaft no?

[glhs#116]

Originally Posted by steve25

if it's not the motor and the converters are / have been balanced properly then that points to the tranny input shaft no?

Hope not. The thing is, the old damaged converter wasn't vibrating. It literally started upon installation of the new one. Anyway, the "new new" one just arrived. Hopefully I will know soon.

Sam

[steve25]

Are you 100% sure the End of the Crank is locating the snout of the converter properly?

["QUICK-SILVER"]

Did you check this?

Originally Posted by steve25

Are you 100% sure the End of the Crank is locating the snout of the converter properly?

Saw your comment on the old thread and guessing the "new new" converter has the same vibration.

I've seen the back of cranks wallowed out where engines got ran with broke flexplates.

Also seen converters that used a ring on the snout to center them in the back of the crank.

You have to check for up down movement with the bolts out.

If there is up down movement....Could be the noisy converter was centered close enough just by luck.

Got to know or at least rule out to know how to proceed
Clay

[glhs#116]

Originally Posted by "QUICK-SILVER"

Did you check this?



Saw your comment on the old thread and guessing the "new new" converter has the same vibration.

I've seen the back of cranks wallowed out where engines got ran with broke flexplates.

Also seen converters that used a ring on the snout to center them in the back of the crank.

You have to check for up down movement with the bolts out.

If there is up down movement....Could be the noisy converter was centered close enough just by luck.

Got to know or at least rule out to know how to proceed
Clay

Your comment is fair. Here's what I know that leads me to think of something like the input shaft being at fault:

• Crank newly reconditioned by Paul Carter. I measured no runout. Didn't notice any deformation in the end of the crank when putting on my flexplate. It's an aftermarket thick plate and not at all cracked. Very good condition.
• Original install of engine in car didn't have the converter vibration. Revved smoothly. Just had the dastardly ticking noise
• But old converter was betrayed as noisy / dying as soon as ticking noise was eliminated (it wasn't a surprise since this converter had a bit of a dry startup when first installed a few years ago)
• When replacing the converter I was initially trying to slide the trans far enough back to swap it without fully dropping the trans. Was trying to avoid removing the crossmember which is a pain to remove and reinstall in my car
• In the process I know there were several times when we nearly succeeded. This meant the full weight of the converter on the end of the input shaft and maybe even a little trying to pusuade it to come out
• Obviously eventually just had to drop trans and swap normally
• Vibration started with the new converter and went away when it was unbolted so my logical conclusion: the converter isn't balanced
• When I swapped in the new replacement I had the same vibration again. Now unbalanced converter was less likely but I also noticed the flexplate was not spinning true. Sure enough, the mounting pads on the converter were uneven. About 40 thou shimming needed on the low pad (I made up some shim washers). Thought I had it fixed but when the converter and flexplate were true (and the flexplate spun true) the vibration was about the same

So, that's where I figured probably something in the trans input side got tweaked. Input shaft bent? Bushing shifted or galled? Anyway, something that spins with the converter (like the input shaft).

So that's where I'm at and what I'm trying to solve. To me the tipoff was that the vibration is harmonic in character. It gets worse at certain engine speeds and then better again in between. A simple balance issue should just get worse linearly with RPM. That's when I was thinking, "but I KNOW the crank isn't warped!" But then I thought, "that's not the only spinning shaft in the equation." A spinning warped shaft would have a harmonic vibration, no?

Anyway, I defer to anyone's experience.

And as for the seating in the crank business.. Well, the converter I took out didn't have any paint worn off around the button. And, honestly, before these troubles I've never had an issue. I would have thought if the crank hole for the button was galled it would have given the first converter an issue and that never had one. And, since I was also thinking about it maybe not centring right, I did (with both this converter and the previous) first attempt to unbolt, ensure not binding, and then finger tighten all bolts before tightening.

But I love to learn. Especailly the kind of learning that doesn't cost me money!

Sam

[glhs#116]

So, I am guessing this isn’t that common but I still need to address it.

Good news is, I was able to get it to and through testing. It’s legal and insured for another year. The bad news is that I dare not drive much until I fix this

I am sort of thinking of getting an input shaft, bushings and gaskets and taking the trans out again. I just hate to do that sort of thing without having everything ready because it takes so long to order things.

Has anyone had and resolved this issue?

Sam

[steve25]

Everything points to something with your Trans being the issue at this point, I just wish I could help ya narrow it down more!

Here' s a thought though, if you jack up and lie under the car with the motor running and the flexplate shield off , if someone brings up the rpm slowly do you see the converter wobble at all?

Does the tranny bell housing have any cracks in it starting off from any of the locating dowls?

[johnta1]

When you are putting the converter bolts to flexplate in, how do you rotate the engine to get to the next bolt hole?

Put all bolts in then tighten?
Put one in tighten, then next in line?
How are you rotating the flexplate?
By flywheel tool?
By the front crank bolt?

I still believe the cause may be the converter is not centered when tighten.

[glhs#116]

Gentlemen! We are back!

Many many many thanks to Cliff for some big big help. First in giving me the confidence that it really really could be two bad converters in a row. Second for giving me an idea where to concentrate on the transmission R and R. During the overhaul I found part of the retaining clip for the direct accumulator in the pump body. Basically, on the rebuild I did some years ago where I beefed up the transmission with parts that would hold behind the 455 I found that this clip was broken. I found a replacement clip in town but it was visibly thinner softer metal but it was all I could find. This clip clearly came apart so I knew I needed a genuine replacement this time. Cliff went above and beyond to track me one down as well as supplying a good torque converter at a decent price.

This clip (next to a BETTER aftermarket one than the one that failed on me) was pulled by Cliff from one of his transmissions


...that allowed me to put back together this on the evening that the clip arrived


...along with this converter which, surprisingly, doesn't shake my fillings out


...all of which meant that the following day I was at work in my car!!


So.. Yes, it really has been 18 months. A full year and a half! But she is back on the road.

I couldn't have done it without all of you. Thanks again so much for the great practical help of Paul in working to prepare me a crank with remote ghetto rod weight numbers. Thanks again so much to Cliff for the TC and clip assistance. Thanks again to so many of you like Steve and dataway and others who just kept giving me the benefit of their experience and encouraging me.

Sam

[johnta1]

Congrats!

It is great that the TA is back on the road.

[steve25]

Great to hear this news finally, and I will make a toast to your perseverance tonight even though where a few thousand miles apart!🤗
It also very well illuminates how two new parts can be bad!

[dataway]

You have inspired me!
Excellent you are back on the road.

Any details on the torque converter?

[glhs#116]

Originally Posted by dataway

You have inspired me!
Excellent you are back on the road.

Any details on the torque converter?

Thanks, dataway!

Cliff sells it as his "street" 13". Only driven to work and back two days but it seems to be going well. It's certainly chunky. It's basically about 1/8" away from scraping the front of the transmission all bolted in place (although my flexplate is a thick aftermarket unit so that probably contributes). But it does seem to be properly balanced. It couples pretty well.

Mine came with a bright neon sticker saying "Metric" which meant I had to go get some metric bolts to attach it. I assume they make the 13" units with salvaged old stock converter shells so I'm guessing it's luck of the draw whether you get SAE or Metric but I'm glad they put the label to alert me. The 3/8 x 16 bolt that is SAE standard will thread into the M10 x 1.5 holes without any trouble but the fit is loose and they would strip when tightened. Without the warning I could have made a bad mistake so the sticker was a nice touch.



Sam

[glhs#116]

Originally Posted by steve25

Great to hear this news finally, and I will make a toast to your perseverance tonight even though where a few thousand miles apart!🤗
It also very well illuminates how two new parts can be bad!

Truth. But it's hard to make those gambles with all the extra lead time and shipping cost on top of the regular burden of dropping the gearbox to swap it. I'm really grateful for all the help.

Sam

[JSPONT]

Awesome, glad you never gave up!

[grivera]

Great news - good for you sticking to it. How does it drive? We need a video!!

BTW - awesome picture