Flexing a Flex Plate?

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Dusterdenovo

Dusterdenovo

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408, 727, Hughes Performance 3000 Torque Converter, B&M Flex Plate.

I am in the process of replacing my Torque Converter with an identical (?) unit. With the previous Torque Converter inserted into the back of the crank, the mounting pads sat flush against the Flex Plate no problem. Now when the replacement TC bottoms out in the back of the crank, the mounting bosses sit a bit less than 1/16" off of the Flex Plate when the bolts are finger tight.

The 2 Torque Converters are supposed to be identical (Hughes P/N 24-30), and doing side by side measurements of the 2 I can't find any noticeable differences to explain the gap, including the height of the Pilot Hub.

MY QUESTION: Is it OK to just tighten up the bolts and let the Flex Plate flex to fit?

Is that why they call them "Flex Plates"??

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yes...tighten up the bolts...make sure you use some blue thread sealant....
 
I could be wrong but it looks to be the flex plate needs to be turned around????
 
Yes - just dry fitting everything before installing the TC and marrying the Engine/Tranny.

Flex Plate is correct - just replacing the TC due to a broken tooth :(
 
If it were mine I would not tighten it with a 1/16” gap. I would get some 1/16” plate and cut a couple of rectangular pads and drill a hole. But that’s me.
 
I wouldn't do it.
I would measure the TC pilot for being too big.
And the flexplate for flatness.
More work,
I know, but..............

I wouldda just welded a blob onto the ring-gear and spent a few minutes with a die-grinder on it; in situ.
So since you went this far, I can see you're no stranger to, "more work", lol
 
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Thanks for all the input. Responses to above:

Pilot hub dimensions are same with both TCs, and the new one does bottom out in the back of the crank.


The flex plate is a little bit concave - can't say if it came that way originally.

The Hughes documentation does mention use of "high quality washers" but in this instance I was wondering if adding more mass spinning around was optimal with external balance and all that.

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That sir is indeed on backwards the gap is because your converter is touching your flex plate bolts, that is the reason for that shape.
Look how thin the heads of the bolts are that is holding it to the crank.
 
Remove it turn it over install even 2 bolts and put your straight edge over the bolt location and you will see.
 
Mr. Sinister said:
That sir is indeed on backwards the gap is because your converter is touching your flex plate bolts, that is the reason for that shape.
Look how thin the heads of the bolts are that is holding it to the crank.
Click to expand...


I say no. I say it is correct. Convex side is out towards converter. I could swear they are marked "engine side".

B&M Flexplate Install. Did I do it right?

which way does flexplate attach?

However there is NO EFFIN WAY I would run that thing "under tension" like that. Find out WHY. The converter should slide right up there "tight" touching
 
Let him take it off flip it and put a straight edge over the bolt location and you will see.
 
Mr. Sinister:

The bolt pattern on the back of the crank, with the 1 odd hole won't allow the flex plate to be flipped over.
 
Have you tried fitting the plate to the converter OFF the engine?
 
Well maybe I'm just too tired to be thinking ..... its been a looooong day. If I am wrong than my apology.:thumbsup: carry on.

Did a look in the barn mine is marked engine side and yours is installed correctly. I stand corrected sir.:BangHead:
 
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The high quality washers mentioned by Hughes would only add mass to the rotating weight but being at the four equally spaced converter bolts wouldn't affect balance. Never use lock washers in this location, they will spread and become projectiles at high rpm. But for one to seat and the other to not seat there has to be either fouling in the circumference or depth of the converter pilot or bore or the pads aren't at the same height. I'm suspecting a tolerance issue with the drive side of the converter, maybe even a warp from the welding. I would send it back and try another converter (probably a different brand, if the first one had a starter tooth fail, who knows what may go out in the replacement) before I shimmed it with washers.
 
Mr. Sinister:
No problem at all, Bud. I appreciate guys jumping in and "thinking out loud". I asked for brainstorming and that's what is awesome about FABO.

Just to completely rule it out though, I did look for my "engine side" stamp....

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Show the converters standing up next to each other. Are the pads the same height?
 
I remember a long time ago installing a new converter and the bolts wouldn’t tighten up the flexplate. They bottomed in to the front face of the converter. The pads were too short.
 
OK, so I went hi-tech with some cardboard (Grandchildren took my PlayDoh) and made a measuring template.

Turns out there is a difference in pad heights; the new ones are slightly lower.
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The **** that turns 15 minute jobs into 4 hour ordeals....

From the above, looks like the consensus on my original thought of flexing the flex plate is "don't".

That would leave washers or a different TC as the other options.

Anyone else running with washers? Any down side to that idea?
 
I would say as long as you have enough thread engagement on the bolts and use some blue locktite, using some kind of washer will cause zero problems and turn that 4 hour job right back to a 15 minute job.
 
Dusterdenovo said:
OK, so I went hi-tech with some cardboard (Grandchildren took my PlayDoh) and made a measuring template.

Turns out there is a difference in pad heights; the new ones are slightly lower.
View attachment 1715465331 View attachment 1715465332
The **** that turns 15 minute jobs into 4 hour ordeals....

From the above, looks like the consensus on my original thought of flexing the flex plate is "don't".

That would leave washers or a different TC as the other options.

Anyone else running with washers? Any down side to that idea?
Click to expand...
I successfully ran a Hughes 24-20 converter with stainless steel washers between the flex plate and the converter, LA340, 452 HP, 727 trans. Swapped it out for a 24-30 no washers needed.
 
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