Shim Torque Converter?

[EngineerDoug]

Thanks for your ideas on this. I realized after I posted the question....duh why don't I just ask the converter manufacturer?

So I called Dynamic and they indicated the gap between the flex plate and the converter should be between 1/8" and 3/16". This is with the converter seated. Note the flex plate is bolted to the crank flange, but the converter is a slip fit into the trans. When I said "shimming" I meant adding a washer between the flex plate and the lug on the converter. This effectively seats the converter deeper into the transmission. If the gap is too big, and you take up all that slack with no shimming, the converter may not seat far enough in the trans = damage.

The bottom line is that shimming is OK, according to Dynamic (I checked with Hughes as well). Use hardened washers and mike them all so they are equal thickness. So now I am off to double check my measurement to confirm the existing gap is indeed > 3/16".

 

[steve340]

Shim it I was not bullshitting you. Just make sure you do it right but it is not rocket science.

 

[Babyblue66]

Thanks for your ideas on this. I realized after I posted the question....duh why don't I just ask the converter manufacturer?

So I called Dynamic and they indicated the gap between the flex plate and the converter should be between 1/8" and 3/16". This is with the converter seated. Note the flex plate is bolted to the crank flange, but the converter is a slip fit into the trans. When I said "shimming" I meant adding a washer between the flex plate and the lug on the converter. This effectively seats the converter deeper into the transmission. If the gap is too big, and you take up all that slack with no shimming, the converter may not seat far enough in the trans = damage.

The bottom line is that shimming is OK, according to Dynamic (I checked with Hughes as well). Use hardened washers and mike them all so they are equal thickness. So now I am off to double check my measurement to confirm the existing gap is indeed > 3/16".

Done it and seen it on different cars. Haven't had to on a mopar, but it won't hurt anything if you do. My old boss shimmed his on his drag car that ran 9.50s.

 

[RemCharger]

Good to see you engineered it out

 

[69 GeeTeeX]

What torque converter and flex plate are you using? I'm assuming both are aftermarket with the larger 7/16" ARP bolts? Does the converter slide forward all the way against the flex plate like it's supposed too or is the converter hub bottoming out in the back of the crankshaft leaving a gap between the flex plate and converter bolt lug?

That's why I asked you what combination of components you're using. I've built several 505 strokers using eagle 8 bolt crankshafts, B&M flex plate with PTC 9.5" torque converters and had to use a 1/8" (.125") grade 8 hardened washer between the converter lug and flex plate to fill the gap while keeping the converter depth in oil pump within specification and converter hub depth in crankshaft within specification. It's so small it doesn't have any effect on starter to flywheel engagement. That's what it takes when using this part combination.

 

[EngineerDoug]

Thanks again, folks - turns out my initial measurement was FUBAR. This time I used more light (the engine & trans are in the car), more coffee, and a dial caliper to measure 0.140" gap. So no shims required, but hopefully this thread will help somebody else down the road with a similar question. BTW I am using a 440 source stroker crank, B&M flex plate, and a Dynamic converter with ARP 7/16 bolts. And yes, the converter slides all the way forward to meet the flex plate.

 

[Lefty71]

Thanks again, folks - turns out my initial measurement was FUBAR.

I pulled a 727 BB trans last night..... thinking of you, I pushed the converter back, as soon as I took the flexplate bolts out, just to see how much farther back full engagement was. By eye, it moved back into the trans just about the thickness of the flexplate, so pretty close to 0.150". No surprises, as these were almost all factory parts. As other have said tho, when everything is after market ( crank, converter, pump, flexplate, midplate, etc.), you'd be smart to be the thinking man and check everything. HTH, Lefty

 

[AR67GTX]

Thanks again, folks - turns out my initial measurement was FUBAR. This time I used more light (the engine & trans are in the car), more coffee, and a dial caliper to measure 0.140" gap. So no shims required, but hopefully this thread will help somebody else down the road with a similar question. BTW I am using a 440 source stroker crank, B&M flex plate, and a Dynamic converter with ARP 7/16 bolts. And yes, the converter slides all the way forward to meet the flex plate.

It's hell being an engineer and failing the old measure twice - cut once rule. I won't bore you with my recent story of trying to cut shelving boards to fit into a closet - it wasn't pretty.

 

[65wgn440]

My trans builder cautions me almost every time I take him a trans ( mostly GM's) to check gap and shim if necessary or pump failure could result. Have only had to shim a couple. Depends on the convertor.

 

[66Satellite47]

My trans builder cautions me almost every time I take him a trans ( mostly GM's) to check gap and shim if necessary or pump failure could result. Have only had to shim a couple. Depends on the convertor.

OK, stick with GM thinking. Mopars are different.

 

[dvw]

I've shimmed mine. Also made spacers between the block and the case. What ever it takes to get it correct. I've had 2 Mega blocks. Both required the shim.
Doug

 

[oldkimmer]

Shim it I was not bullshitting you. Just make sure you do it right but it is not rocket science.

The starter will chew the teeth off the ring gear. Also then the hub is not seated into the crank, so then no support then and u will probably end up with a cracked/broken flex plate and a pump failure. I have never once in 45 years ever had to shim a converter on a Mopar. Or taken any shims out from someone else putting them in. So to the original poster U have this guy agreeing with u so shim away as that’s is what u wanted to hear. 1guy agreeing, 20 disagreeing. What’s the odds that 1 guy is right and 20 are wrong. Kim

 

[steve340]

The 20 are wrong - read some of the other posts.
Especially the one by the original poster who contacted the manufacturer of the torque converter.
And the dummies who made it told him to shim it - not to mention the other guys who have shimmed.
I think some of them even shimmed a Mopar - the fools!!!!!!!!!!!!!!!!!!!!!!!!

 

[vintage chromoly]

It isn’t a Mopar vs. GM thing!

it a “is my converter located correctly” thing.


the same guys telling you that you don’t need to check converter depth are the kind of guys who just match the dots on a cam and crank gear when installing a cam. “No need to degree a Mopar cam! This ain’t no Chevy!

 

[Fran Blacker]

If you shim as said earlier with hardened washers. Another thing regular washer vary in thickness, never checked hardened washers so check to get 4 the same.

 

[Moms68]

If you shim as said earlier with hardened washers. Another thing regular washer vary in thickness, never checked hardened washers so check to get 4 the same.

I’d be curious if the washers will affect the torque setting.

 

[66Satellite47]

I'm still unsure why with a Mopar, with a good flexplate installed correctly why shim would be needed. I've used at least10 aftermarket converters and a couple stock ones. Never had an issue that looked like needing a shim. I've use a couple early B&M's, numerous Turbo Action's, Coan, Lupo Dynamic. Never had a shim issue. I do recall my Chev buddy had one shim issue, but the GM flexplate & mounting is different especially going from TH350 or TH400 to a Glide.
MHO.

 

[RemCharger]

I can see how using shim-bandaids looks great in a time of despair .... but the actual issue is the converter was built wrong. Maybe the last time it was freshened . I would be concerned with hub engagement as oldkimmer pointed out.

 

[oldkimmer]

There is atleast 2 different pad thicknesses. Kim

 

[66Satellite47]

The pad thickness depends on which converter case it is. The key is the pad thickness and the hub being in the proper dimension. I have used about a dozen converters over the years, from about 6 manufactures and numerous flex plates. Never had to use a shim.