TRNW-2: ZF8HP45 (850RE & 845RE) P0733

[Dan Hogan]

Marcel,

The parts sourcing for these units isn't good here in the states.  Where are you sourcing new pistons?  Even kits are not stocked in most places.

Here at least locally and at current, low mileage used units are dirt cheap.  I just looked up a job where a 60k unit was $500.

And you're right, seems like the majority of later design units are built to pitch in the trash at failure or when complaints occur if they aren't US domestic stuff (excluding FCA / Stellantis).  Ford and GM seem to be doing a decent job of making parts available and in most cases reasonable priced.  The Japanese and European designs don't want you to repair them as far as I can tell.

Challenges are always present in this industry.


---


Dan Hogan

Buster's Transmission Service

https://busterstransmission.com

704.847.5321

________________________________
From: trnw2-bounces at trnw.net <trnw2-bounces at trnw.net> on behalf of Healy Powertrain via trnw2 <trnw2 at trnw.net>
Sent: Wednesday, February 19, 2025 3:52 PM
To: pat schulte <zzyzxpat at gmail.com>; Technical Discussion Forum <trnw2 at trnw.net>
Subject: Re: TRNW-2: ZF8HP45 (850RE & 845RE) P0733

Replace the Actual Steel D Piston too when replacing the Molded D-Seal, otherwise you'll in for a repeat failure. Check the new piston for smoothness and sharp edges where the seal rides. Replace the drum Shell where the D-Frictions  eat away the aluminium (New updated drum available now from Sonnax)
As far as replacing the seal, you can do it without the tools. Make sure all is centered precisely. This thing turns at driveshaft speed!
These units are going to flood your shops, basically throw away level units ( which unit isnt these days? :o). Every possible corner is cut.  But the aftermarket is catching up, right on time.


Have Fun!

Marcel Verwijmeren
Healy Powertrain
Driveline Solutions
T 06 57745407
E info at healypowertrain.com<mailto:info at healypowertrain.com>
W www.healypowertrain.com<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.healypowertrain.com_&d=DwMFaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=smOzNWPZu5-MBJg-0tkHhHoVW9xEBKdKWsMxBeFAJDZVJI6X79ZhQVJ_erT6I9aF&m=H2sn8JJ2uT6burcB0V9196ItLitegwIqBEDzG1eVFNbpglAWmxyD4lUEdBT4sXYo&s=F18O5dZnvth8oWAszHWyhVgzHqgCTEOhj0y7_vgzE9A&e=>


On Wednesday, February 19, 2025 at 8:09:47 pm +01:00, pat schulte via trnw2 <trnw2 at trnw.net> wrote:
One thing to watch for as well, I have not seen anyone but the Transtec piston kits have a new D "piston" All the others I have seen did not carry it.

On Wed, Feb 19, 2025 at 11:02 AM Chris and Cathy Kershaw via trnw2 <trnw2 at trnw.net<mailto:trnw2 at trnw.net>> wrote:
I just watched this transtec video using their tool. Looks to me like it could be done without the tool, maybe get an old piston to make a jig for drilling the rivets. We haven't seen but a few with gear ratio or other internal problems. The vb/tcms have been on intergalactic backorder everytime I check. Used units seem to cheap & plentiful. https://youtu.be/_npBS3W3dgI<https://urldefense.proofpoint.com/v2/url?u=https-3A__youtu.be_-5FnpBS3W3dgI&d=DwMFaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=smOzNWPZu5-MBJg-0tkHhHoVW9xEBKdKWsMxBeFAJDZVJI6X79ZhQVJ_erT6I9aF&m=H2sn8JJ2uT6burcB0V9196ItLitegwIqBEDzG1eVFNbpglAWmxyD4lUEdBT4sXYo&s=2w7hqha8gxlhWTCfDxTS62H6c0IouyFoR_0Tp33WhlU&e=>

On Wed, Feb 19, 2025 at 11:47 AM tucker tuckertrans.com<https://urldefense.proofpoint.com/v2/url?u=http-3A__tuckertrans.com&d=DwMFaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=smOzNWPZu5-MBJg-0tkHhHoVW9xEBKdKWsMxBeFAJDZVJI6X79ZhQVJ_erT6I9aF&m=H2sn8JJ2uT6burcB0V9196ItLitegwIqBEDzG1eVFNbpglAWmxyD4lUEdBT4sXYo&s=QAKsD6LRqDGzZPhCPsi0I0IavDpuaSUF_yPF3G4JsJg&e=> via trnw2 <trnw2 at trnw.net<mailto:trnw2 at trnw.net>> wrote:
Group,
Does anyone know what the common cause of P0733 (gear ratio error in 3rd) on the ZF845 is?  Many times it is intermittent and works perfect on a test short drive but the P0733 comes back quite often.  We have put in about 5-6 used and rebuilt transmission, but have not rebuilt any for this common concern.  We did buy a NEW 850RE valvebody and put on one that had 60,000 miles and it did NOT correct the problem.   It also seems like the 2016-2017 are the most common years to see the code.  As for driving it here is what's weird, is the transmission has a bad shift from 3rd to 4th cold.  It flares.  Reman units from Chrysler are around 2,900, so they are almost not worth rebuilding, however now they are on backorder.  I find it odd too that Jasper, Certified, and ETE have them listed as not available.  So what are you guys doing, and what is the cause of the P0733.

Dan Tucker

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--
Pat Schulte
AAMCO Transmissions
Temecula, Ca.
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