727 Turbo Action T/C contacts flexplate to crankshaft bolts

I recently installed a new Turbo Action 10" T/C, 3800 stall. Soon after I noticed a leak from the bell housing. The front pump bushing, seal, o-ring, gasket and pump bolt washers were all replaced at this time.

I found the following upon removal of the torque converter for inspection of the leak.

The Turbo Action T/C is contacting the flexplate to crankshaft mounting bolts on a BB Chrysler. The Dynamic converter it replaced does NOT have any witness marks were it contacted the bolts and it also did not leak transmission fluid from the bellhousing.


I assume the back portion of the converters are different but if that's so I assume others with Turbo Action converters have the same problem.

Using a B&M 17203 Flex plate

Any idea why this occurred with the Turbo Action converter?
How does one correct this issue?
Anyone else run into this same issue?

Also in one of the pics I circled a wear area in red. It can NOT be felt with a finger nail. Is this from the front pump gear and is it normal?

When you first installed it, How much did you have to pull it forward to bolt it up? Looks as if it wasn't all the way back in the trans.

Common problem with some converter cores, T/As being one of them. If you don't have the thin head bolts in the flexplate to crank, you need some. If you have the thin head bolts and it's still bottomed out, you will need a washer between pads and flexplate to space converter back a bit.

The snout wear is likely BECAUSE the converter is bottomed out on flexplate

I wouldn't worry about the snout, you can clearly see where the bushing and seal were riding and it's nowhere near the spot you circled. I've had bolt witness marks on the converter. The flexplate isn't very stiff (or it wouldn't be called a FLEXplate) and the converter fluid pressure pushes the converter toward the engine. I've never worried about the marks. That haze of brown on the converter is rust from the converter snout grinding on the crank flange, possibly indicating an alignment issue. Some OE setups I've taken apart had a TON of that stuff but it wasn't really a problem. I usually use a little lube to reduce wear, but then you get a star pattern of lube on the converter.

@Monte_Smith, Do you know what converters companies or converter cores DO NOT have this issue?? Obviously Dynamic is one of them.


@@#$%&*!,
I suspect that the alignment issue is caused by the converter contacting the bolts. The witness marks on the converter are not all equal. It looks like some of the bolts made a bigger impression on the converter than others.



Thanks!

A converter should NEVER contact the bolts. If it does, there is a problem. be it the core, wrong bolts, pads too thin, core ballooning, SOMETHING and that something needs to be addressed.

In those pics, it appears they are hitting HARD. The easy fix, if you have room is some spacers between pads and flexplate pushing the converter away from bolts some. This is assuming you already have the thin headed bolts in the flexplate.

This is a common issue and one of the shortcoming of the Mopar trans. The bellhousing depth is too short and doesn't allow the use of some of the BEST cores like are used in GM trans

The fretting at the pump rotor surface is disturbing and suggests that the two contacting surfaces are experiencing a cyclic motion. Uneven pull up caused by the crank bolts?

Is it possible the converter was built for a mid plate application and you don't have one and that is why you have a clearance problem?

The opposite actually. If made for a mid plate, the snout would have a spacer and would either have been sent with spacers and or thicker pads. Both of which would space the core from the flexplate bolts. Remember, the flexplate is where it is and the converter has to be engaged in the pump lugs. So with a midplate the whole trans is back further and converter has to still engage lugs. This creates space between converter and plate so you fix it with longer snout and thicker pads.

When my son installed his turbo action converter, the instructions clearly stated to use thin head bolts.

We've been using Turbo Action stuff since 1977. I've always used a small washer between the flexplate and converter pads and have never had any problems.I also use the bolts that Turbo Action sells for the flexplate to crank and converter to flexplate.

I'm running a 10" Turbo Action converter with a 360/518 combo and haven't run into any issues in the six years it has been in the car. I did use bolts supplied by T/A though.

Thanks everyone. I'm already using the correct thin head bolts.

I guess I will have to shim the converter with washers. However, I dont like this method and never had to do this with any other 727 brand converter... Seems like a Band-Aid fix to me

One would think that instead of asking the customer to shim the converter that the core would be machined to correct this or a different core would be used by the converter company.

While it's easy to say it SHOULD be, the fact is that not every Mopar flexplate has exactly the same offset. A washer under the pads doesn't hurt a thing

I wanted to cover all possible variables that could cause this problem for me before reassembly. I performed the following of the parts I had on hand.

Flexplate: All flexplates had the same offset
B&M 10230
TCI 145200
Mopar Perf (Part Number unknown)

Torque converters:
Dynamic 9.5" 4200 stall
Turbo Action 10" 3800 stall
B&M 10" 3500 stall

Only the Turbo Action converter comes anywhere near contacting the flexplate to crankshaft bolts. See pics of B&M and Dynamic converters below. Note: There are no witness marks where the converter contacted the flexplate bolts, this is the same vehicle, same Engnie/Trans combo.

The bolts Turbo Action recommends is a joke, a milled bolt pictured below that I never should have installed. The ARP thin headed bolts will now be reinstalled.


Bolt head measurement:
T/A bolts - .188-.198
ARP bolts - .204
Stock (non-milled bolt) .250

So not only does T/A recommend to run this compromised bolt but you also may have to add washers Seriously!!
There is nothing mentioned in the instructions from B&M or Dynamic stating anything of the sort and its not needed with these brand coverters either.

I will say that the T/A converter did work as designed when installed despite the leak concern. However, I think its time T/A heads back to the drawing board on converter cores.

Most websites dont even mention the need for a different bolt or washers. So I would only assume many people buy the converter, read the instructions only to find out they now need to order a custom flexplate bolt and also need to head to the hardware store from some washers. This is something I would expect to be doing on a farm truck or tractor that one is cobbling together.

It is not real uncommon to have to use washers between the converter and flex plate to avoid converter hub to crankshaft bolt contact I have seen that with a T/A converter when switching from one of their 8 inch to 9 inch units

Dude, you are making a major deal out of something that has been a problem for 40 years. Certain cores, no matter which company makes the converter are VERY tight. These are factory cores from something. That said ALL companies are likely to use the same one for similar converters. This is not just a T/A issue

ive had many diff verts,i had to space my Ultimate out,no biggie one of the best ive had.