What is going on with this Flexplate? Out of round and bent? Yikes...

[Ackevor]

Local trans shop did a 700r4 swap a little over a year ago. Truck has maybe 1000 miles on it since. Over that past year I have been chasing down a vibration above 50 mph. Along the road I had the starter fail to engage and grind a couple times. Last week I was changing motor/trans mounts to poly and looked at starter/flexplate engagement after I got them installed.

Some pics and a link to a video below. One side of the flexplate had too much clearance between the starter bendix, the other didn't have enough causing a grinding as pictured. Shimming the starter to open the tight spot yields minimal engagement on the opposite side.

Also checking axial runout as best I can, I get almost .060" of front to back moment. Pics also show how one side of the flex plate has full bedix engagement, the other has less because of this.

My guess is this is the cause of my vibration. The teeth ring looks like it was not centered when it was welded, I can't imagine this being caused by anything normal driving 1000 miles would cause.

Thoughts?
Looks skewed

Full engagement on one side (ground spot)


Partial engagement opposite side of flex plate

These next two just show how much the teeth ring moves radially (to and from center) the indicator was zeroed on one and .060" movem on the other, understand I can't get the needle straight on because of clearance issues and I know the number is changing partially because of where it falls on the plate. But it at least shows the slight out of round by judging the position of the tip to the ring.


Ohh and fuzzy pics of the grind area from bendix.

Video link. .065" at start, then I go back to my zero at the end.

https://youtu.be/iTTvpf5nrXs

 

[cucvrus]

How about cracked flex plate at the rear of the crank? Have you checked that? The ring gear will not be a perfect circle.

 

[Ackevor]

Added video link.
Thats what I am fearing. Knowing he had to put a new plate on to do the swap, It would blow my mind that it would crack so soon. I will have to investigate but ran out of time. I would like to call the shop and see what they say before I take it apart.

 

[doghead]

Does it have three or six bolts to the torque converter?


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[cucvrus]

Does it have three or six bolts to the torque converter?


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That is a good question. Did he substitute a gas engine flex-plate?Happy Holidays Doghead.

 

[Ackevor]

Hmm... have to count when I get home, but I would guess 3 because I don't recall seeing that many.

 

[cucvrus]

The 6.2 diesel has 6 - M10 bolts from the torque converter to the flex-plate. I also believe the torque converter is internally different since the diesel engine does not run as high of RPM's as a gasoline engine. I am no expert on the subject. Lets see what Rusty Stud has to say. Happy Holidays.

 

[Ackevor]

I know he used a diesel torque converter. Never asked about the flex plate, ignorant of it at the time

 

[Chaski]

Looks like a diesel flexplate and a gas torque converter in the video. In the video you can see some of the unused holes in the flexplate since the torque converter only has three mounts. Also looks like the converter had to be shimmed out with washers. Can you turn it over one revolution to see that all three mounting points of the gas converter have the same thickness of washers?

 

[cucvrus]

Looks like a diesel flexplate and a gas torque converter in the video. In the video you can see some of the unused holes in the flexplate since the torque converter only has three mounts. Also looks like the converter had to be shimmed out with washers. Can you turn it over one revolution to see that all three mounting points of the gas converter have the same thickness of washers?

That's NOT good. That will need to be corrected. I would think that the converter with 3 holes would be clocked differently and NOT line up with any of the diesel flex-plate holes. I never tried so I don't know. Good Luck. I hope for an easy fix. But I am doubtful. Report back. Happy Holidays.

 

[snowtrac nome]

the 700 r4 trannys just had 3 holes if I had to guess they used the th400 flexplate which might balance different than the 700 r4 if you have a gen 1 6.2 diesel you might find it hard to find a flexplate for the 700 r4 seems like I thought about this once in the past.

 

[Chaski]

95% sure this is the right number for a diesel 700R4 flex plate

14077158

 

[Ackevor]

Thanks everyone for the information. I didn't get even 10 minutes to go out and check anything tonight. I know all 3 bolts have washers and I remember counting 3 bolts because I thought washers for spacing was odd. Tomorrow I have a lot on my plate again but hope to at least crawl under and verify 3 bolts and try and see if the plate is cracked around mounting region.

 

[rustystud]

The 6.2 diesel has 6 - M10 bolts from the torque converter to the flex-plate. I also believe the torque converter is internally different since the diesel engine does not run as high of RPM's as a gasoline engine. I am no expert on the subject. Lets see what Rusty Stud has to say. Happy Holidays.View attachment 655904

The GM 6.2 and 6.5 diesels are all externally balanced. If the shop replaced the factory flexplate (which it looks like they did) then they probably replaced it with a regular Chevy "Gas" engine which are all "internally" balanced. The factory flexplate should have 6 mounting holes for the "torque" converter. They could have still used the factory flexplate with your TH700R4 as they share the same bolt pattern (spacing) as the TH400. Maybe the shop still has your old flexplate. I would ask.

 

[Ackevor]

Ok broke off from my wifes car for 5 minutes and took a couple pics. Doesn't look cracked, does look new(er?). Flexplate has 6 holes for a torque converter but 3 are used. The one pic looks like the bolt/washer are off center. Also the spacers used look like run of the mill washers.

I noticed on the dust cover a nice groove from flexplate cut into it. Likely why he added washers. In any case I think its the 3 mounting points being used somehow warped it and one or more holes not being lined up or centered properly causing the tight/loose fit with starter.

I am out of town this weekend... I wish I had more time to sort it out sooner. Probably wire new fuel pump and drive it into the trans shop and see what he says next week.

 

[rustystud]

Another thing it could be is the torque converter nose or "snout" that aligns in the crankshaft. If this is the wrong size then it would not "index" correctly with the flexplate. There are "bushings" you can buy for under sized noses that are pressed into the crankshaft.
Or there could have been debris in the crankshaft pocket that prevented the torque converter from engaging fully into the crankshaft. They then tried to use spacers to make-up for the difference and bent the flexplate.

 

[rustystud]

These are pictures of a torque converters nose (snout) that must fit into the end of the crankshaft. All torque converters are aligned this way, even the big "Allisons" .
This torque converter is for a Chrysler 440 .

 

[gimpyrobb]

If it turns out to be an issue with the torque converter, I have a bunch of them sitting on a pallet for the th400. Send a pm.

 

[rustystud]

If it turns out to be an issue with the torque converter, I have a bunch of them sitting on a pallet for the th400. Send a pm.

Are they the 6 bolt ones ? and how much do you want for one ?

 

[Chaski]

http://www.tcsproducts.com/media/1/Converter_Cat1_1.pdf

good reference.

looks like there were diesel converters made with only 3 pads, and the pilot diameter is the same on them.