Harmonic Vibration

[Frankenchevy]

I think @shiftpro may be on the right track, but I won’t know right away. I pulled the inspection cover and started the truck. Noticed what to me seems like excessive rollout in the body of the torque converter. I took a long ratchet extension, braced it against the trans pan and placed the tip against the outer housing in two places. I get a skipping rather than a smooth drag across the surface.

Hughes Performance is sending me out a new converter.

edit: disconnected TC from flexplate and the flexplate itself has a serious wobble. I used new ARP flexplate bolts with locktite and they all seem snug... this is awesome.

 

[shiftpro]

All fingers crossed...

 

[Frankenchevy]

@shiftpro check this out. Seem normal?

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[Frankenchevy]

Ordered this guy from the local(ish) speed shop.

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[HotRodPC]

I got my SFI flexplate from Advance Auto IIRC. Seems it was about $60 or so a few years ago. For a 454 the stock flexplate only had the Th400 Converter bolt pattern. I wanted to be able to run my Th350 3000 stall converter someday so the SFI also had dual pattern.

 

[Frankenchevy]

The flexplate came in today. The torque converter will be in Wednesday.

 

[yevgenievich]

I have been following this as been pretty much down the same road with my 91 v2500 suburban. Did steering, wheels, driveshaft and still have similar vibration come and go 70-75mph. Goes away below or above that speed range. Torque converter and flex plate were on my next things to check. Very different drivetrain but simptoms similar.

 

[Frankenchevy]

Very different drivetrain but simptoms similar.

You mean you have a 4l80 vs my th400 I’m assuming...

The speed shop I purchased the newest flexplate from said he’s had many problems with all the big name torque converter manufacturers—Hughes Performance, B&M, etc. Said QC is no good and when he goes to Summit in Nevada, it seems like he sees a few Hughes/B&M boxes on the return shelf.

He gave a recommendation for a local TC builder if the newest Hughes replacement doesn’t remedy the issue. Said it’d probably be cheaper than the $300+ I paid for the Hughes TC.

And if all that doesn’t fix it, it’s back to the rear diff. I’ve been researching carrier swaps on the 14bff and it’s supposed to be one of the easiest diffs to set up. Time is short these days, so I’ll likely still have a shop do it.

 

[Frankenchevy]

The parts are gathered for this weekend’s truck project. TCI flexplate has a tiny rock on the TC. Don’t really have a reliable way to tell if it is the fp or the tc. The rock is audible, but not really visible. Probably the thickness of a baseball card or less of movement. Rotated it to all three positions with about the same movement...

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[Frankenchevy]

I believe the new TC may be a more carefully built unit as it has no external weight, only two small weld dimples. While the older ones had a weight several inches long.

New

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Old

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[shiftpro]

@shiftpro check this out. Seem normal?

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**** I don't know what's normal anymore.

But umm, why did they call it a flex plate in the first place?

 

[Frankenchevy]

**** I don't know what's normal anymore.

But umm, why did they call it a flex plate in the first place?

I guess because it acts as a damper between the crank and TC.

 

[Frankenchevy]

How to jerry rig a trans and t-case into position alone.

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It takes a decent amount of effort just to swap a tie que converter and flexplate.

 

[Frankenchevy]

My 84 has a grease zerk in the front driveshaft

I can't imagine the military wouldn't have some way to lube the front driveshaft and just relied on a boot. The military has done stranger things though.

Just looked over my front driveshaft real good. No grease points anywhere. It’s on my list of things to rebuild in the near future. May go with a Tom Woods custom shaft that uses the bigger U-joint in the front with the U1 long travel slip yoke. The new springs are supposed to have pretty decent negative travel droop.

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[Frankenchevy]

Almost got the truck buttoned up. I was laying under it and heard a pig grunt.

Some people get stray dogs in their yard, I get stray pigs, lol!

I’d put it in with mine, but it may be carrying something I don’t want to expose my pigs to. I would’ve given it a home in a freezer, but mine are all full.

Had a neighbor come put it on a livestock trailer and take it home.

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Oh well, back to work.