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oltom 11-29-2012 11:53 PM

D-G Drum failure Root Cause
Hello ALL
This post for info only. If previously posted please forgive. Just purchased a 2001 530i with 77K on the clock. Transmission is working fine with NO codes present. Before purchase I knew of this problem area. Before being left on the side of the road I decide to tackle this problem. After talking with numerous associates from ZF transmissions this is what I learned. Yes the D-G drum is light weight and needs to be replaced but the root cause is in the main valve body. Pull up the explode view of the trans. valve body. Find the main valve body part number. Find part number 50.010 or ZF part number 1060 327 138. Locate bore number 50.100. This is the modulation pressure port. It's job is to regulate transmission pressure and does so by continuous rapid cycling. Over time the piston laps or wears the bore of the valve body making it egg shaped, as a result constant pump pressure (approximately 850psi) slips past part 50.100 and puts constant pressure on the clutch pack. The end result BAM! If you've installed a new D/G drum and did not address this, it's only a matter of time.
The good news is that you don't have to pull the tranny to change this part. Drop the pan, the lower valve body plate the neck of the transmission filter goes through is the culprit. When swapping out the piston components no o rings are required. The best price I could find is $140 at CTSC (California transmission supply company). If you don't have a $140 look up Valve body's is all they do. They have a modification fit which includes a reaming fixture tool to over bore the port and an over size piston for the hole. Price for this tool unknown to date.
This also appies to Audi, VW Passet, Porsche, and several others.
My contacts: Lory transmission (ZF rep) Miami, Fl.
Eriksson Industies Old Saybrook, Conn.
Need a new tranny... check out Trans Specialties Wayne, NJ.,
Price $2000 plus tax, shipping $125, and $750 core. This tranny indules ALL modification/upgrades and includes a torque converter.
Good Luck and pass this on.:):thumbup:

vavet5308 11-30-2012 03:23 AM

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This is interesting. Good detective work there.

I think this is the the ZF 5HP19 transmission. If so, here's a page out of the manual that shows the parts numbers for others to reference.

I'm a little unclear on what you're telling us. I think what you're telling us is that the piston wears out the bore, which also wears the piston. The fluid is eventually able to bypass the piston. This causes the transmission failure. The solution to this is to replace the piston. Is that the essence of this?

oltom 11-30-2012 06:22 AM

sorry for the misunderstanding. Lets try again. No the piston doesn't wear out. The high rate of modulation or cycling actually wears the valve body out at the 6 o'clock position, ie the bottom of the bore. The hole in the valve body that excepts the piston becomes egg shaped in the bottom of the bore allowing fluid to bypass the piston on top or 12 o'clock position. The repair has to be made one of two ways. Replace the valve body housing with a new one to the tune of $150 min. All the pieces in the old valve body should drop right in the new valve body no soft wear will be disturbed. The other fix is reaming the bore with the tool I mentioned from Sonnax. When purchasing the reaming tool a new over size piston is provided as part of the kit I think or may be sold separately. The over size piston diameter is matched to the diameter of the reamer. The 2 choices are replace the valve body or repair the old one. If you want to find out the condition of your existing valve body pull the piston out of the bore in the hole marked as 50.100. Then stick your finger in the bore. If the vale body is shot you will feel a ridge or step inside the bore. Example; have you ever taken a motor with high miles apart? At the top of the cylinder (combustion chamber) there is usually a ridge worn in the top of the cylinder where the compression ring stops. Any good mechanic doing a engine over haul has a tool called a ridge cutter for cutting the ridge out of the engine block cylinder. This is the same principle that happens in the valve body. That's what this reamer tool from Sonnax does. It's kind like punching out a cylinder bore to install over size pistons or cutting the ridge off the top of a cylinder to save the engine block. Hope this clarifies it. Got a little long winded. Sorry. PS you may have trouble trying to get the piston out of the valve body. Use compressed air from the back side and blow it out. It goes without saying when pulling these vale bodies apart make sure all the springs and things go back in the correct order. Good luck. PSS; This tread also applies to 3 series bimmers and possibly 7 series. The key to this is a ZF 5HP 19 transmission. It doesn't matter what car it's in, it's still a ZF 5HP 19 tranny.

oltom 11-30-2012 06:31 AM

Again no need to replace piston unless you can see that the anodized coating on the piston lands is worn off.

vavet5308 11-30-2012 07:04 AM

Thanks for the clarification. I looked through the ctsc website. There is a lot of good information there.

I want to clarify one other thing. If you wait to do the repair until the transmission has failed, does it damage anything else? Your use of the BAM! in the first post is scary, but from what I understand about the internal workings of automatic transmissions(limited), it's not going to do any permanent harm.

oltom 11-30-2012 07:35 AM

Tried to open your link to the PDF chart and couldn't. For all go to Scroll to page 24. You'll find what your looking for there. Additional info. when replacing the d-g drum. After reading several threads I guess finding o rings for the piston plate in the D&G clutch pack is trouble. My understanding is you have to buy a base line rebuild kit. They run about $230-$250. Now I know you can buy a D-G drum for about $110 on the low end. Then you have to start piece mealing every together. When I talk to Lory transmissions (Miami, Fl.) they quoted a price of $230, upon reluctance to purchase, they came down to $195 for just the drum. I still wanted the o rings. After talking with Scott and explaining my tranny wasn't blown nor did I have any fault codes and my objective was to just replace the D-G drum this was the offer. A D-G drum kit which I had never heard of for $250 plus shipping. I took it. When the package arrived this is what I got; steels for the D-G drum assemblies, orings for the D-G clutch packs, the up graded D-G drum, a forward seal, o rings for the forward pump housing, a filter and pan gasket. Granted some of this I won't use (clutch pack steels including snap rings), but over all I think it was a pretty good deal. Lory didn't have the valve body ZF
part number 1060 327 138 it's coming from CTSC in Calif. FYI; CTSC will not talk to you on the phone or discuss transmission problems. CTSC is email only and that is strictly limited to buying parts. They won't help you looking up a part number or anything else. It's like this, fill out the order form to include part numbers, and give m your credit card number. That's it! Do not pass go,do not collect $200, go directly to jail. That's it. They do have a return policy but for the most part know what your buying before pulling up the order form. But hey this valve body every where else is like $250 or more. I got it for $140 plus shipping. For that price go ahead and slam the door in my face, who cares.

oltom 11-30-2012 07:43 AM

The problem with Bam is this for the most part the D-G drum is directly over the top of the valve body. For the most part the metal falls directly into the oil pan and is secured there, because ZF like any other transmission has magnets in the bottom of the oil pan for just that purpose. The worry is the o rings in the D drum, if they disintegrate, pieces could migrate to the torque converter or else where if they become deposited on the up stream side of the filter. If the o ring parts drop to the oil pan they'll stay there or get caught in the filter.

oltom 11-30-2012 03:34 PM


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