The valve body of the ZF 5HP-24A consists of four main aluminum housings that are screwed together.
The pressure regulator is installed in the housing that’s at the lower front of the valve body, as installed in the car. Here is a picture of the housing plus internals when separated from the other housings of the valve body:
Prudence dictates that this pressure regulator should, after 100,000 miles or so, be renewed, lest it allow a fluid pressure spike that blows out the rim of the clutch “A” drum, necessitating a transmission removal and repair. This is a classic failure pattern for this type of transmission. After this happens, the clutch “A” drum slips, hence the transmission slips in 1st, 2nd, 3rd and 4th. The transmission control computer then senses this and limits forward motion to 5th gear.
Even when the transmission and valve body are still in the car, there’s an easy way to remove this casting. It’s the front-most, lower-facing casting in the valve body, so it’s relatively easy to access, hence it’s not necessary to remove the valve body from the transmission, in order to remove the casting. Also, no wiring is involved.
Tools required: a 5mm Allen wrench and a Torx T-27 driver, and some ratchets and extensions to turn those. You basically drain the transmission fluid, drop the transmission oil pan and remove the housing. That’s all — nice and simple, and yet it prevents a repair bill that can be upwards of $4,000.
This approach makes sense only when the transmission hasn’t failed yet and the work is being done as preventative maintenance.
Buying a used unit is risky. It might have 15 years’ worth of wear and tear on it, and there’s no viable way to predict when it’ll let a pressure spike through to the clutch “A” drum. In fact, it’s so risky that we refuse to sell these units as used parts.
What we are, however, willing to do is to sell them as cores that we ship on your behalf directly to the ZF distributor (nice people) in Connecticut, for their renewal process.
When they have cores in stock, you don’t need us. They would simply charge you a core charge and then later when you ship your old part to them, they refund the core charge. The problem comes in when they don’t have a core in stock. Then, you have to take the part off your car, send it in, wait for it to come back, and your car might be out of commission for a week or two. In such a situation you might be better off buying the core from us, we send that the ZF distributor directly on your behalf, they renew it, they send it to you, and then you install that in your car. Downtime for your car might be only a few hours, in that scenario.
For $35 plus shipping (which is less than $15) we would send in only the casting, no internals. The ZF distributor would then precisely bore out the pressure regulator area and install a Sonnax oversize piston, charge you for that work, and send the end result back to you. Contact them for pricing, tell them you’re working with us as to a core, make it clear that you’re presuming you’re sending them a core from us — just the bare 1058427022 casting, without any internals — and then ask them what they’ll charge you to install a renewed pressure regulator.
Once the item arrives from them, you would then remove that housing from your car, transfer the various internal parts (but not the pressure regulator, of course) from the old housing to the renewed housing, and then you would install the renewed housing, containing the internals from your car.
Fair warning, the internals have been described as the sort of spring-loaded items that can easily fly all over the room if you’re not careful, so transferring the internals from the old housing to the renewed housing is no trivial task. You might decide to avoid the risk and hassle involved, and buy from us a core that also contains the internals. For that we charge $75 (instead of $35) plus shipping (which is less than $15). When you send in an entire unit like that, then the ZF distributor tends to be willing to dismantle it, renew the pressure regulator, clean it and reassemble it. If anything looked suspect he’d let you know. This approach buys you a reduced hassle and reduced risk, and the internals are assembled by someone highly skilled. The core costs you $40 more (which you pay to us) and the more-involved process means the ZF distributor would charge you more too. It might well be worth it. This way, it’s a low-hassle and low-risk process for you. You get the item shipped to you from the ZF distributor, you install it, and you’re done.
As to its structural internals, the ZF 5HP-24A had two main versions, an early version (used on the early D2 A8 Quattro 4.2 V8) and a late version (used on the C5 A6 Quattro 4.2 V8 and the later D2 A8 Quattro 4.2 V8). You know you have an early version if the valve body has five green solenoids; that is the most obvious visual cue.
The early transmission type has letter codes of “DPZ” or “DSM” or “DTE” — all for the Audi A8, production date through 12/98. The housings (and part numbers) for the early and late types are identical, as to the castings. So, if you’re doing the $35 deal, I don’t need to know whether your transmission type is early or late. You can order the $35 core (casting only, no internals) from our D2A8parts.com website here, or our C5A6parts.com website here, and pay with PayPal or a credit card (via PayPal).
As to the internals, there IS a difference and ZF keeps these two separate; one doesn’t supersede the other. So, if you’re doing the $75 core deal, I DO need to know whether your transmission type is early or late. You can order the early-type core with the casting plus internals from our D2A8parts.com website here, and pay with PayPal or a credit card (via PayPal). You can order the later-type core with the casting plus internals from our D2A8parts.com website here or from our C5A6parts.com website here. Either way you can pay with PayPal or a credit card (via PayPal).
We emphasize that what you pay us is just for the core and shipping the core, and that we are only willing to ship these cores directly to the ZF distributor. They would charge you over and above what we charge, for the renewal work, and for shipping.