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Old 08-15-2010, 11:51 AM
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Torque converter binding?

I just installed new Summit brand turbo 350 and Summit torque converter to a new stock 350 flexplate but I hear some knocking in that area now when running it. The knob on the torque converter appears to be really tight inside the center hole of the flexplate/crank area. I had about 3/8 inches of space between torque converter mount holes and flexplate and when I rotated the torque converter at that distance it move freely in the hole except for appeared to catch in one small spot and turned there with some difficulty. When I pushed the torque converter up against the plate, the knob appeared to snug into the hole tight but the converter now wouldn't rotate freely when flush to the flexplate. I bolted it together and it began knocking in that general area when running. Knob binding? Add washer shims? Thanks.

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Old 08-15-2010, 04:08 PM
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If you had 3/8" of space between the converter bolt pads and the flexplate, then pulled it back to the flexplate you likely pulled the drive neck lugs out of the front pump and that is where the knock is coming from. Converter pilot should be a decent snug fit into back of crank. Anything more than 1/8" or so between the converter lugs and flexplate will require shims to fill the gap.

Hopefully it didn't ruin the front pump if this is what happened.
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Old 08-15-2010, 09:01 PM
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Torque converter binding -- now what?

Hi,
Thanks for the reply. Does this mean the transmission is screwed? Or can I just unbolt the flexplate and add shims to get the proper distance on torque converter to pump? I don't want to pull this tranny again because it is a replacement for a bad one Summit sent last week, along with this torque converter. The car does move forward and backward.
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Old 08-15-2010, 10:06 PM
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You should pull the trans as it will be hard to inspect the front pump for problems just by looking at it from the outside. About all you can do at this point is to unbolt the converter and see if it will slide right back into the trans. If it will easily, it is a good sign that the drive lugs did stay engaged with the pump and nothing was hurt. If it won't slide back it means that the drive lugs have pulled far enough out that it is just the face of the converter neck driving the pump and the pump will have to be removed and inspected to assess if it is torn up.

Some easy checks to start with are to make sure none of the converter bolts are loose, that none of them are contacting the lip of the block, and to look for a cracked flexplate or flexplate loose at the crank flange.

If the gap between the flexplate and converter is too large like you said in the first post, you will need to shim it at the converter bolts.

all you can do at this point is check things over, fix the shim problem if it passes the other checks,and try starting it again to see if the knock persists.
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Old 08-16-2010, 07:01 AM
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If you pulled the converter into the crank with the bolts you may have cracked the flex plate. You said it makes noise so you obviously ran it. Did the transmission go into gear or did you not try it
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Old 08-16-2010, 11:20 AM
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Eric, I'll try just the minimal inspection on how or if the torque converter slides back into tranny and inspect for flexplate cracks or loose bolts. I'll add some shim/s to get proper distance and try this without pulling tranny to see if noise stops. If noise persists, out comes t350 for third time. Thanks for tips. T-bucket: i'll check for flexplate cracks. And yes, i did run it forward and backward a few feet OK, but with noise and vibrations at my feet, all difficult to sort out when it's running open manifolds. Thanks, man.
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Old 08-16-2010, 12:24 PM
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Cracks in a flexplate can be hard to see but they're easily heard- along w/visually checking it, tap it lightly w/a rubber mallet around its circumference. If there's a crack, you'll know. You'll want to do this w/the flexplate attached to the crank and disconnected from the TC.
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Old 08-16-2010, 02:27 PM
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Quote:
Originally Posted by 68HellCo
Eric, I'll try just the minimal inspection on how or if the torque converter slides back into tranny and inspect for flexplate cracks or loose bolts. I'll add some shim/s to get proper distance and try this without pulling tranny to see if noise stops. If noise persists, out comes t350 for third time. Thanks for tips. T-bucket: i'll check for flexplate cracks. And yes, i did run it forward and backward a few feet OK, but with noise and vibrations at my feet, all difficult to sort out when it's running open manifolds. Thanks, man.
If it moves you didnt break the pump
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Old 08-16-2010, 03:04 PM
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So here's the update. Inspection found no flexplate cracks, but 2 of the bolts to torque converter were not tight and one was quite loose. The torque converter slid back to the tranny easy enough, so I measured and had 5/16 between it and flex and decided to put shims in to take the gap down to 3/16. Then I cranked everything super tight several time over and fired up. No noise for about 1 minute, noting forward and backward wobble of flex plate and torque converter looked excessive. Then came a high-pitched whining or screeching sound. Yikes, i shut it down. Sucks. Now what?
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Old 08-16-2010, 03:55 PM
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That sounds like the Pump gear may have just broken & is destroying the Pump. Are you sure the Converter nose slide back into the Pump lugs correctly?
Disconnect a Trans line at cooler, Have someone check for flow while you start the engine momentarily and then shut it off.
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Old 08-16-2010, 04:01 PM
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Make sure the nose of the starter gear is not hitting the flex plate. I have seen this a few times and it make a terrible screeching noise. This is especially true of the high torque replacement starters.

Edit: you may want to check that the mounting bolts for the flex plate to the crank shaft are tight also.

Disconnect the torque converter, push it back, start it and see if the noise is still there. There should be no run out in the flex plate. If there is it is either loose, bent or broken.
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Old 08-16-2010, 04:24 PM
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Thanks about starter pinion stick and pump blowup suggestions. The pinion was free and I drained fluid from pan plug and found no particles of shrapnel. I called Summit tech and they said it sounds like torque converter is out by sound of loud screeching noise. I asked if I should be concerned about tranny pump and he said look for shrapnel in fluid but that it is likely just the torque converter. They are sending another torque converter. This comes after they replaced bad tranny. Should I inspect the pump once it's down, and if so how? I would check to see if it's pushing fluid out lower line running but that screeching noise is evil. Dare I? Thanks again ...
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Old 08-16-2010, 05:23 PM
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I don't blame you I would want to hear it anymore either.
Do the check Chet mentioned above.
If it's the TC it will send metal thru the Trans if it's ran long enough. May already be inside filter.
When you drop the Trans or unbolt the TC from flexplate, spin the TC & listen. "If you find metal anywhere, TC or pan I'd want a new Trans & TC." You'll need to flush the cooler lines before installing them also.
You may be able to pop the front Trans seal out & look at the Pump gear lugs to see if they're broken. I've heard of several having trouble with Summit Trans & TCs. Most say they didn't get what they paid for, stock build for high price.
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Old 08-16-2010, 07:48 PM
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I pulled lower fluid line and fired up car. It shot fluid and kept pumping it out. Car went into gears. In drive, I revved it a little bit and whined higher and louder. It appeared to whine in all gears and park. Is the pump OK on this tranny and is it just a torque converter replace? I don't want to do this five more times, tranny in, out. Have new TC coming ... Thanks.
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Old 08-16-2010, 08:02 PM
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Only way to determine if the pump is unhurt and the problem was all in the converter would be to remove the pump and disassemble the two halves and inspect it. Anything else would just be a guess. The pump can be scored inside and still pump, it will just continue to eat itself up and make noise when put back into service.

Probably not what you want to hear, but doing anything else would just be taking a chance on having to pull it out yet again. I personally would not put it back in without a pump inspection, but I am lucky enough to know how to do it myself, the average person can make more of a problem by not knowing how to work in a TH-350. You might want to consider having a local trans shop take a look, or if you know someone who knows what they are doing.

To confirm what SSedan said, I have also heard grumblings around the web about Summit transmissions and converters but I don't know how much of it is installer/user error
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