8HP90 Solenoid Kit, new and ready to install. Fits the 8HP90. Ships fast from the USA.
The 8HP90 is the heavy-duty member of ZF's first-generation eight-speed, rated for about 900 Nm behind gasoline engines. You find it behind the supercharged 6.2L Hemi in the Dodge Charger and Challenger SRT Hellcat, the BMW 760i and 760Li (F01/F02), the Audi A8 (D4) and RS6 (C7), the 2011-2018 Porsche Cayenne Turbo, and Bentley and Rolls-Royce V8 and V12 models. When one of those cars starts banging into gear, flaring between shifts or dropping into limp mode with a pressure control code, the solenoids on the valve body are usually the first suspect. This is a new, genuine ZF solenoid kit, shipped in the ZF box shown in the photo, listed under ZF kit number 1087 298 389 with 1087 298 388 as its interchange.
The 8HP has no bands. Five shift elements (brakes A and B, clutches C, D and E) are applied in combinations of three to make each gear, and every one of them is fed by its own electronically controlled pressure regulator. Sonnax's solenoid map for the first-generation ZF and Chrysler units lists the pressure regulators as EDS-1 through EDS-7: one each for elements A through E, one for torque converter lockup and one for system line pressure, plus an on/off MV-1 valve. The transmission computer varies current to each regulator to ramp clutch pressure in and out of every shift, so on a high-torque unit like the 8HP90 a regulator that sticks or reads slow shows up as a hard engagement or a flare almost immediately.
The other common ZF eight-speed complaint is a leaking mechatronic connector sleeve, which drains pressure and mimics bad solenoids. Our ZF8HP common problems guide covers both, so you do not replace a solenoid set to cure a seal leak.
Check the fluid level at temperature first; a low 8HP throws the same complaints. Then read codes with a scan tool that can see the transmission module, and note which element or regulator the code names. With the circuit board removed, Sonnax's test booklet puts these regulators at about 5.0 ohms at 20 C (68 F) and warns to use a meter that tests below 0.6 V. A reading well off that spec, or a regulator whose screen is packed with debris, confirms the diagnosis. Our pressure control solenoid guide walks through the test, and Hellcat owners can match their complaint in our Charger shift problems guide.
This kit is listed for the first-generation 8HP45, 8HP70 and 8HP90, which share a valve body family. It does not fit the second-generation 8HP50, 8HP75 or 8HP95: Transmission Digest's Gen 1 vs Gen 2 guide shows that ZF moved the B and D solenoids and changed the solenoid caps on Gen 2. If your car is a 2015 or later model, confirm which generation it has before ordering. Compare the cap colors and connector shapes in the photo against your own valve body, or send us your year and VIN and we will check it. You can browse every eight-speed part we carry on the ZF 8HP collection page.
The solenoids live in the mechatronic unit on top of the valve body, so the pan comes off and the mechatronic unit comes out. Keep the solenoids in their original positions; each bore is a different element and the module expects each regulator where ZF put it. Install every regulator with new O-rings lubricated with clean fluid, torque the retaining brackets evenly, and replace the connector sleeve while you are in there. On most 8HP cars the pan carries the filter, so plan on a new pan; Chrysler-family owners can use a replacement 8HP pan with drain plug. Refill only with ZF LifeguardFluid 8, such as our 7-liter Lifeguard 8 service fill, set the level at the specified temperature, then clear codes, reset adaptations and drive the car through every gear so the module relearns its fill pressures.
| Fits | 8HP90 |
| Part type | Solenoid Kit |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
The SRT Hellcat with the supercharged 6.2L Hemi uses the 8HP90, which is one of the three first-generation units this kit is listed for. Check that your valve body is the first-generation design by comparing the solenoid caps to the photo, or send us your VIN.
It is new and genuine ZF, packed in the ZF box shown in the photo. If you want a lower-cost option for a Gen 1 eight-speed, we also carry remanufactured solenoid sets.
No. Those are second-generation units, where ZF relocated the B and D solenoids and changed the solenoid caps. Gen 2 transmissions need Gen 2 solenoids.
ZF LifeguardFluid 8 only. ZF's data sheet limits these transmissions to LifeguardFluid 8 or 9, and a generic multi-vehicle ATF can change shift feel and clutch wear.
Yes. New regulators respond differently from worn ones, so clear codes, reset the transmission adaptations with a capable scan tool, and drive through every gear at light and moderate throttle so the module can relearn.
On a high-mileage unit most shops replace the full set, because the others have the same hours and the mechatronic unit has to come out either way. A single low-mileage failure with clean fluid can justify replacing just one.
