Technical Speaking of Chevy flywheels or flex plates...

I have an issue with my SBC flex plate/torque converter/transmission/ engine block. The block is a new bow tie, the transmission is a new 400, the converter is a recently new 600 miles) Hughes piece and the flex plate is one I got from a friend that raced the same setup on an 8 second car.
The problem that I see is there isn’t enough room between the converter and the flex plate. Yes, the converter is all the way into the front pump on the transmission. Yes, the flex plate is bolted on correctly. No modifications have been made to any of the pieces but there is still not enough room between the two. I can lightly use persuasion to get the converter in place to install the bolts, but it creates undue backward pressure on the converter towards the front pump on the transmission.
In between the raised bosses on the flex plate where the bolts go, I have some space and the converter moves freely until it hit the raised bosses on the flex plate.
Then force is required to line up the bolt holes.
I know this isn’t right. It’s already cost me a transmission rebuild so I want it to be right this time.
The thing is, I can’t figure out where the problem exists.
Check out the pictures.



I know there should be about an eighth of an inch space between the plate and the converter before bolting it up. I don’t have that. It’s like everything is setup for a mid plate without the mid plate, but it’s not been setup for that.
I’m wondering if I should make an eighth inch spacer to go between the block and the transmission...
Ideas?
r


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Tell us what you know about the converter. That's the first thing I'd suspect. Sometimes they are built to work with a block plate, and if that's the case, it will do just what you are experiencing. Perhaps there's a number on the converter, you can call Hughes and ask about the stack height?

 

My question is the flex plate bolted correctly to the crank? I have that same setup on my 34 Chevy and something doesn't look right. One picture looks like the flex plate has the indent towards the block and another picture shows the indent to the converter. Was it a 168 tooth flex plate?

 

It looks like the flexplate is on correctly. The pads are not lined up with the bolt holes, because it's a tight fit when they are, from what I understand.

I wonder about that little round part on the pads, was that a spacer that was added to the pads? Maybe if you remove them, it'll work? hard to see what they look like though, with the converter in the car.

 

G'day, Two things come to mind. The mandrel on the front of the converter is not fully meshed into the back of the crankshaft or that the converter is not fully messed into the pump. A friend was helping my dad and they tried to "pull" the converter to the flex plate. They broke the new pump on the transmission.

I have had to take emory paper to the mandrill of a converter to get it to mesh properly before. As the converter has been used before that does seem likely.

 

Are we sure that the converter is FULLY engaged into the trans? Could be one click away,then-bingo!
Just asking.........

 

Me also thinks the converter is for use with a block plate.. Here is a shot of a STOCK converter in a 1 ton with a SBC (engine getting rdy to pull)



Notice just a flat ear..

 

I agree , probably made to use with a block / mid plate .

 

The converter is NOT all the way in.

If it were, you should not be able to get your finger in here:

 

I agree with Mr Gimpy .

Tommy

 

I’ll try to get the converter farther back but I took the converter with me when I picked up the transmission from the builders just so I could make sure it was in all the way into the transmission. After we slipped it in, he was agreeing that it was in all the way since we couldn’t get our hand in between the converter and the bell housing at the top. The converter was purchased from Summit and was not listed as being for a motor with a mid plate...
r


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Did the converter come back out a bit, during transportation to your place?

 

Will be checking that today.
r


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I like to feel a CLUNK CLUNK when I install a converter. I made up a small bracket years ago, like a fork that holds the converter all the way in. I use one of the inspection pan bolt holes to secure it.

 

If it is set up for a block plate the center hub where it slips in the trans will probably have an adapter(extension) ring on it also.

 

Also possible the pump gear is backwards if it’s a fresh rebuild.


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Did the converter come off a transmission that went bad........since you mention it only has 800 miles on it? Nothing to do with your current problem but if it came off a transmission that failed, I would be hesitant to use it. Hope that isn't the case.

 

This is my thought.

 

Should be a clunk, clunk, clunk. You have to align the input shaft, stator, and the front pump.

 

This distance between the converter and the transmission housing is only about 3/4”. I messed around with it today and that’s as far back as it will go. It’s a hard stop and I believe that the converter is against the pump cover.



This is the distance between the block and the flex plate (7/8”).



Flex plate.



Distance from the bolt mount face to the end of the pump sleeve (6 -26/64”).



Distance from bolt mount face and notch in pump sleeve (5 -52/64”).



Distance between bolt mount face and end of min (1 -1/16”).



Distance between transmission face and converter bolt mount face (31/32”).



Hughes converter.

r


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The converter came off this combination after it ate the front pump because of the same issue I’m confronted with now.
r


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Pull the converter and look at the pump gear, the tangs should be reassessed.

This would be the front of the gear^

This would be the back side of it.

 

If you had another converter laying around you could compare the measurements between them and rule that out .
You might try pulling the front seal and looking back in there with a light to confirm the gear is in correctly.
Is this a completely new transmission,,built by a different guy,,,,,since you say this happened before ?
I feel it has to be one or the other,,,the converter or the gear .
Your measurements leave almost no clearance,,,the flexplate to the block,,,,and the converter to the front of transmission case are almost the same .
Good luck man .

Tommy

 

That makes it scary

 

Yep that’s the rule I’ve always followed. Push on it while turning it until it clunks 3 times then you know it’s in properly.

 

Why does your block have extended alignment dowels?

 

It's a 283 that came with a cast iron Powerglide, of course.

 

If the pads are back almost an inch and the flex sticks out 7/8ths, then it should bolt up.
Did you try the converter pilot in the crank, without the transmission? It looks like the pilot has been in the crank already
Your overall stack height is off somehow. With the converter hub sitting on a flat plate, the distance from the pad surface, down to the plate , should be 6.150 or slightly less.
That converter has been re-hubbed. I don't mean to suggest that The Big Red Bomb Converter Company would ever get one wrong, but you need to re check the stack height.
It seems to be okay if the converter install at almost an inch depth.

 

Who knew they made a new Bow Tie version of that?!

I learn something new every day!

 

The smaller the converter body, the longer the pump drive hub needs to be, to engage the pump.

Based on where the mounting pads for the flexplate are, this is not a small body converter, yet the hub looks long.

I think this converter was made wrong, but I cannot get to a stock on until Saturday.

Small converter, long hub, off-body pads:

Large converter, short hub, on-body pads:

It looks to me like you have a mixture of incorrect parts welded on to that converter.