TRNW-2: 6L90, jmdz torque converter

[Steve Everett]

   I may not have run into this particular converter before ?  I'm not
sure, I know I've run into a couple instances where the converter was not a
normal jmbx,  but don't remember if it was this particular one or not, and
don't remember what my supplier sent us to install ,  I'll have to look
into that,   if there is an issue with using a standard converter in its
place I don't want to do that,   but at any rate I would still not rerun
the original converter .
    That particular one may have lasted 140k because the vehicle was driven
mostly on the highway,  instead of stop and go city type driving,  that
makes a huge difference in how long a converter lives with the factory GM
programming

    Steve

On Wed, Oct 29, 2025 at 7:26 AM art landeck via trnw2 <trnw2 at trnw.net>
wrote:

> jmdz is a captive clutch many have successfully changed  them to a jmbx
> but i have a friend that got burned twice doing that and had a chatter he
> could not got rid of and went back with the captive clutch to solve the
> issue. Was it  just a stroke of bad luck or is there more to it. I have
> done it and it worked but not sure I would do it again.
>
> Justin Merritt via trnw2 wrote on 10/29/2025 6:51 AM:
>
> We have seen a few of these converters. They don’t seem to go down as bad
> as a jmbx. Talk to your supplier about core before deciding to use a billet
> jmbx in its place. We just use a reman jmdz when we see it.
>
> Justin
> Sent from my iPhone
>
> On Oct 29, 2025, at 5:35 AM, Fred Whitaker via trnw2 <trnw2 at trnw.net>
> <trnw2 at trnw.net> wrote:
>
> 
>   Not sure I have seen a JMDZ converter. But If I were overhauling
> it,there is no way I would use it over. ANY Transmission I overhaul with
> 140K would get a new converter. Captive clutch or not. I would simply
> replace it with a quality converter from a supplier you are comfortable
> with. I myself wouldn't mess with the programming. The first one went 140K
> with no problems.
> ------------------------------
> *From:* trnw2-bounces at trnw.net <trnw2-bounces at trnw.net>
> <trnw2-bounces at trnw.net> on behalf of John Vanklavern via trnw2
> <trnw2 at trnw.net> <trnw2 at trnw.net>
> *Sent:* Wednesday, October 29, 2025 4:14 AM
> *To:* trnw2 at trnw.net <trnw2 at trnw.net> <trnw2 at trnw.net>
> *Subject:* TRNW-2: 6L90, jmdz torque converter
>
> *Date:* Wed Oct 29 2:14:23 PDT 2025
> *Subject:* 6L90, jmdz torque converter
>
> I have a 21 chevy hd in the shop with a jmdz converter. I'm wondering what
> you guys are seeing with these in comparison to the jmbx. Are they as prone
> to failure? The main reason I'm asking is because this trans had no fwd
> with ball stuck in plate. When I called customer about it, he wanted me to
> overhaul and update trans anyway. I'm not going to argue with gravy. Trying
> to figure out if I should replace converter or reuse. trans has about 140k
> on it. besides my question, a general discussion about this converter would
> be nice. I understand it is a captive clutch.
>
> John Vanklavern
> Jvk Services Llc
> West Olive, Michigan USA
> TRNW Member Since: 5/23/2025
>
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>
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