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If the transmission control module is built into the trans, do you even need such a sophisticated aftermarket controller? 馃殮
 

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Discussion Starter · #22 ·
You got me interested, that trans is something. I wonder how the HTC controller interfaces with the 8HP, at the end of this video, he says the TCM is built into the valve body. A great watch, when you have time.

So rebuilding one is basically like a 727, you take your arm and scrape the parts off the bench into the case, cuss and bang the case on the floor until the pump fits, chunk the extra bits in the trash and you're done...... I don't think I want to buy all the special tools and clutch pack compressors needed to tackle one. That and I no longer posses the required patience. Great video, thanks for posting it.

Can't say on the controller, from the pics of these I've looked at there is a box mounted to the driver's side of the case. I assumed it was the TCM. Much research to be done in that aspect before I try to install one. The Hemi 8 bolt flex plate and the 6 bolt LA crank is another minor detail.
 

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You got me interested, that trans is something. I wonder how the HTC controller interfaces with the 8HP, at the end of this video, he says the TCM is built into the valve body. A great watch, when you have time.

I watched this and man that guy knows his stuff. A true great video in deed. I am impressed on how sophisticated this trans is using planetary gears. .
 
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Discussion Starter · #24 ·
Pickup 8HP70. I assumed that box was/is the TCM.
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Discussion Starter · #25 · (Edited)
Just got off the phone with Sound German Automotive in Washington state and he answered basically all my questions. His controller generates CANBUS signals to fool the factory TCM. Inputs needed are TPS, a digital tach signal, [can't derive the signal from the coil neg, too noisy] a brake switch signal and an 8 speed shifter knob from a pickup or the stick from a Charger/Challenger. That's it. That sounds promising.

He also says my 208 will bolt up without issue, or any 23 spline 6 bolt t-case, so that's saves a chunk of change. He recommended a 2018 or earlier trans, said things got more complex on the 2019 up models. They can be made to work but there's more crap involved.

The mystery box on the side of the trans in the pic above contains a temp sensor and a heating element, and a coil for circulating hot coolant to warm the trans fluid in the great white north. He said if so equipped, take it off and chunk it.

So....that leaves figuring out the torque converter/flex plate/starter interface. Hemi flex plates are 8 bolt crank flange, the LA is of course 6 bolt, and the crank flange standoff is a bit different. That will take a little home brewed engineering to work around. I have an idea on that if an of the shelf option can't be found. It would require some custom machining but my work has a machine shop. Things are looking up.
 

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I watched this and man that guy knows his stuff. A true great video in deed. I am impressed on how sophisticated this trans is using planetary gears. .
Yea, he is great. It was his video on how the Pacificas 9 speed trans works, that convinced me on buying the pacifica. Then later I saw his video on the ECVT used on the hybrid, and along with some good folks on the Pacifica forum, convinced me to trade the gas version in on a hybrid. Since, I have watched most of his videos. I like the ones where he explains how the power flows through the trans, too bad he has not done that for the 8HP series yet.

So rebuilding one is basically like a 727, you take your arm and scrape the parts off the bench into the case, cuss and bang the case on the floor until the pump fits, chunk the extra bits in the trash and you're done...... I don't think I want to buy all the special tools and clutch pack compressors needed to tackle one. That and I no longer posses the required patience. Great video, thanks for posting it.

Can't say on the controller, from the pics of these I've looked at there is a box mounted to the driver's side of the case. I assumed it was the TCM. Much research to be done in that aspect before I try to install one. The Hemi 8 bolt flex plate and the 6 bolt LA crank is another minor detail.
I do not see any wires on that. also looks to have coolant lines, so not sure what that box is.

I have not looked into the rebuilding, but I think it is easier, in that you do not need to worry about end clearances near as much. I would not be surprised if you build it as a stack, then slide the case over the top.

I saw a pic of the back end, and it does not have a bearing near the endn of the case like the 46R series, so you 208 should bolt on with that adaptor.
 
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Discussion Starter · #27 ·
Who makes custom flex plates? Talked to Advance Adapters, they ain't interested.
 

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Discussion Starter · #28 ·
I have about a dozen numbers to call in search of getting a flexplate made, but if that falls though I have an idea on how to mate off the shelf parts. Give me your thoughts and feedback on it.

First, neutral balance so no indexing issues need be addressed. Considering taking the 5.7 pickup and 727 flexplates and setting on a fixture with the same OD as the register on the crank. The 727 flexplate would have a pattern of holes drilled on a dividing head, and excess material trimmed off leaving just the center section with the 6 bolt pattern. The drilled holes would then be plug welded to the 5.7 flexplate. Then chuck it up in a lathe and cut the center out of the 5.7 flexplate exposing the LA 6 bolt pattern. The plug welds would also get trimmed flush on the lathe to prevent balance issues. I've also considered possibly using alignment pins and bolting the pieces together if there are no clearance issues with the bolt heads hitting the block or converter. I have the rev limiter set at 5000 with no extreme rpm intended.

Am I inzane?
 

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Pics might help me visualize this better. Do you need the ring gear on the flex plate? If not, why not just redrill a B&M 318 flexplate to fit the new TQ.

What is the difference in the bolt pattern for the two engine cranks?

Instead of replacing the center section, what about welding the center of the 727 FP, to the center of the 8 speed, then drill the holes through. you would end up with with a double think center hub, but then you are not reyling on welds to hold the torque.
 

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Discussion Starter · #30 ·
Pics might help me visualize this better. Do you need the ring gear on the flex plate? If not, why not just redrill a B&M 318 flexplate to fit the new TQ.

What is the difference in the bolt pattern for the two engine cranks?

Instead of replacing the center section, what about welding the center of the 727 FP, to the center of the 8 speed, then drill the holes through. you would end up with with a double think center hub, but then you are not reyling on welds to hold the torque.

The 8HP uses three sets of two threaded bolt holes in a triangular pattern, can't symmetrically align the square four hole LA flexplate. No starter ring gear on the converter, has to be on the flexplate. The late hemi has an 8 bolt crank flange, the LA has 6.

What would be the difference between welding to the converter or welding the center of the flex plates together? Still relying on a weld to transmit the torque. And I'm thinking centering the flex plate to the converter would be a challenge given the design of the converter hub. My concern with welding either way is hardening the metal leading to cracks.

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Discussion Starter · #31 ·
Windows Paint rush job, but here's the basic idea.

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Discussion Starter · #32 ·
............... then drill the holes through. you would end up with with a double think center hub, but then you are not reyling on welds to hold the torque.
I'm slow but sure lol. Missed the drill/bolt it. But I don't think it would be easy to center. Runouts need to be .005" max.
 

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I think the centering is about the same for either idea.

In the end, the next thing that needs to be answered, is what is the hole pattern, and center hole size for both flex plates?

Have you looked for an adapter to mate the two? or is it possible to get the crankshaft filled, and redrilled for the new flex plate size?
 

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Discussion Starter · #34 · (Edited)
I think the centering is about the same for either idea.

In the end, the next thing that needs to be answered, is what is the hole pattern, and center hole size for both flex plates?

Have you looked for an adapter to mate the two? or is it possible to get the crankshaft filled, and redrilled for the new flex plate size?
Note how the converter hub is undercut. Making a fixture that would stay square on all axis would be much more involved, likely a counterbored two piece bolt together affair that would center on the two different sized OD's of the hub. Even after it was made there'd be some indicating and tinkering to get it turning true. Much easier to build a T shaped single OD fixture that fits the center hole of the flex plates.

From what I've read the center register size on the cranks are the same, 5.7 and LA. Possibly B/RB too though I haven't verified.

Nothing but OEM design parts are available for the 8HP. There are aftermarket flexplates for it, but none with an LA pattern or 6 to 8 bolt adapter. Even looked at early hemi stuff. The bolt circles of the cranks are close, although I haven't found that specific dimension. I suppose one could possibly make an aluminum hub to bolt to the crank, with a larger circumference bolt pattern around the periphery, cut the center out of the hemi flex plate and drill it to fit that pattern. Space possibly being the issue, the LA crank sticks out roughly .090" farther than the 5.7 so you're already down a bit on real estate in relation to the converter face. Could possibly counterbore the crank flange side of the adapter a bit to gain that back. Starter bendix alignment to the ring gear has to be considered as well, can't really move things around much without opening a can of worms.

Mounting the 5.7 flexplate to the block side of an LA flexplate would gain back most of the .090" difference. That helps on the trans side but may make the converter bolts hit the block or some other unforeseen issue. Won't know until I get into it. Not too interested in making an aluminum plate to sandwich between the trans and block to gain space for some kind of adapter hub, just more work and expense. I don't really see the advantage of making an aluminum hub vs using the center of an LA flexplate to accomplish the same thing. Either way the center would have to come out of the 5.7 flexplate.
 

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Discussion Starter · #35 ·
Did some more looking at the PCS controller, it's made here in the U.S. SGA in Washington state is is a dealer and specializes in trans swaps. PCS supplies electronics and other parts to the OEM's, plus their aftermarket line of products. Chances are pretty good that it's a fairly reliable quality piece not something hacked together by some kid with a soldering iron like the ones from Poland. I'd already blew those guys off.
 

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If they specalize in trans swaps, ask them about the flex plate, I think they may at least have some expeirience, and may lead you better then some old fart in Colorado.
 

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Discussion Starter · #37 ·
If they specalize in trans swaps, ask them about the flex plate, I think they may at least have some expeirience, and may lead you better then some old fart in Colorado.
I've always appreciated your input and perspective George, and the rest of the guys here. As far as I can tell from interweb searches there's one other guy that's tried the 8HP to LA swap but he hasn't made any headway in a while, he bolted one to a 318 in his shop floor but never went any further on getting a flexplate figured out. It's one thread on For A Bodies Only that pops up and that's it, so far anyway. May be a good reason for nobody doing it that I haven't run into yet?

These transmissions are fairly cheap in a boneyard and if controllers are coming on the market the LA might get some aftermarket support, might not. The LA's and Magnums are dinosaurs now, and at almost 60 so am I for that matter, all the kids want hemis and LS's these days. Can't blame them, they're good engines and make good power. In hindsight I probably should have late hemi swapped my RC instead of spending a small fortune on my small block, but then I'd be just another lemming following the other lemmings over the cliff. Hell, easy ain't no fun.

I'm going to call SGA Monday and talk a little more in depth with Russell [?] about things. I still have questions about how they keep the TCM out of limp mode, their unit's diagnostic capabilities etc. I'll get his thoughts on the flexplate.
 
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I would like to see someone else weigh in on the welding. Looking at tons of pics, the only spots I see welded, are for a ring gear. very few had any welding towards the center, where any flexing would occur.

Any idea how the ring gears compare? thinking out loud, but maybe use the B&M LA flex plate, and weld a ring gear to it, and drill for the 6 bolt 8 speed pattern.
 

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Discussion Starter · #39 ·
I would like to see someone else weigh in on the welding. Looking at tons of pics, the only spots I see welded, are for a ring gear. very few had any welding towards the center, where any flexing would occur.

Any idea how the ring gears compare? thinking out loud, but maybe use the B&M LA flex plate, and weld a ring gear to it, and drill for the 6 bolt 8 speed pattern.
I agree on the welding, not sure that's the best way to go. Thinking bolts would be better if there's room.

LA's have an available 130 tooth ring, the Hemi is 131. Don't know if the difference is in diameter or gear pitch.

Ran across an interesting tidbit today on a Ford industrial site. Some guy had pulled a Marauder engine out of an old Ford truck and found it to have a two piece bolt together flex plate. It seems some early Ford and Mercury engines briefly used a common center section with different outer sections that bolted to it. The thought behind it being that different balance and ring gear requirements of their various engines could be bolted to it.

Nothing new under the sun is there?
 

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I bet you saw this in your searching. Damm impressive. He has a hemi turning the 8 speed.

 
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