Everything You Need to Know About a ZF 8HP Swap Kit

ASE now builds ZF 8HP conversion kits for five engine families across four transmission sources. This is the overview — which variants exist, which engines are covered, what is in a kit, and how to get a combination added that is not listed yet.

Watch the overview

Why there are suddenly so many options

ASE built its first 8HP adapters — K-series and JZ — around two years ago. At that point the BMW transmission was realistically the only 8HP you could control, so it was the only one worth adapting to.

What changed is TCU support. As standalone controllers started covering more variants, the cheaper and more plentiful transmissions became viable. That is the entire reason the Dodge, Jaguar and EcoDiesel kits exist.

The BMW units mostly turn up in diesels, Mk5 Supras, and newer BMWs running B58 and S58 engines. They cost more, but they carry a noticeably smaller bell housing, which is worth paying for when tunnel clearance is tight.

Current kit coverage

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Coyote and VK kits are in development. Both engines are on the stand and already scanned — they are waiting on R&D workflow rather than on anything unresolved.

How a new combination gets added

If your engine is not listed, it has not come up the priority list yet. It is not a refusal.

The real constraint is access to an engine. A live engine on site is preferred for final fitment and for filming the install guide, but what is strictly required is a very high quality 3D scan of the crank side of the engine.

Scan quality is the deciding factor. Rolled edges and poorly defined transmission and crank holes are not usable. The ASE scanner resolves to roughly two microns, and that level of edge definition is what produces the fit and finish on the finished plate.

Every transmission ASE has already adapted has been scanned — all the Dodge 45s, the 70 and 90 series, most of the BMWs including the V8 units, and the Jaguars. If you have a good engine scan and the transmission is one already covered, that combination can move quickly. Get in touch.

What is in every kit

Billet flex plate with a brand new starter ring gear

Full solid pieces with everything integrated. ASE avoids reusing factory flex plates on any kit where it can be avoided, and so far that means brand new ring gears across LS, JZ and K-series.

On the JZ specifically this is not a preference, it is a judgment about the market. Factory JZ flex plates are old and they crack. Street car power has moved: what was a 500 to 600 horsepower aspiration six or seven years ago is now routinely 800 to 1,000.

Stainless hex-drive dowel pins

Threaded rather than pressed, so they screw into the hole and seat down. You cannot bend them on installation the way a pressed dowel bends, and if one is damaged it can be replaced as long as the stud has not snapped off. Both common sizes use an 8 mm hex drive.

Fitted to everything except the BMW kits, which still use factory BMW dowels. That may change.

Converter centering hardware

The K-series to Dodge kit uses a 1 inch thick plate with a detachable centering ring for the pilot stud. It clears the ARP flex plate bolts and is located by precision machined dowels, so it pops into position and centers the converter spud without separate adjustment.

An adapter sleeve drops into the center bore to reduce it, which is what allows one kit to cover both Dodge converter diameters found across second and third generation transmissions. Remove the sleeve for the larger spud and the same plate handles it.

The JZ to Dodge flex plate uses the same sleeve system, with two threaded holes for 8-32 socket head bolts if you want it positively retained.

One detail worth calling out, because it is the kind of thing that only matters later: the sleeve sits on a machined lip that keeps it elevated off the full surface, with three relief points around it. If it ever seizes in place after load and heat cycling, a punch or screwdriver taps it straight back out. Serviceability is designed in rather than assumed.

Engraved torque specifications

Most current batches of flex plates and motor plates carry the torque specs laser or machine engraved directly on the face.

The documentation and install videos are on the site, but having the numbers physically in front of you during assembly means you are not stopping to email on a weekend — or worse, asking the wrong person on a forum and paying for that answer with a teardown.

In-house 6061 billet machining

Every plate is CNC machined in house from 6061 on ASE equipment, in deliberately small batches. If a tooling issue appears, it costs one or two parts rather than fifty, and revisions can be rolled in between runs.

The LS / LT kits

These work with both LS and LT engines — the upper bolt hole is integrated to cover both. They include a partial dust shield: that material is normally removed and discarded entirely, so leaving some of it in place on an application where it does something useful costs nothing.

The billet flex plate works with both 70 and 90 series torque converters and carries a brand new GM starter ring gear.

LS kits are available for both Jaguar and Dodge based transmissions.

Why the BMW small case is a two-piece assembly

On the small case BMW transmissions — the M50 and M57 — the smaller torque converter overlaps the area where the starter ring gear needs to sit.

You cannot run a bolt through the ring gear teeth, and removing enough material to clear it would leave a part that cracks. So that kit is built as a two-piece assembly, located by a precision machined alignment spud that drops into the center.

Alignment method varies across the range: machined into the plate on the JZ and K-series kits with a top mounted arrangement, or a spud that presses into the crank much like a pilot bushing. Whichever the application needs is supplied in the kit.

SR20 and the global picture

SR20 conversions are not especially visible in the United States, but demand is real across the Caribbean and South America, where these transmissions are readily available. ASE has done three different SR20 based conversions, including SR20 to Dodge and SR20 to the BMW V8 units — the N63 family, with concave slope torque converters and a larger bell housing case.

It is the same pattern as the 4G63 and the DSM crowd: not every platform is popular in your immediate circle, and the demand is there globally regardless.

Supporting hardware

A swap stalls on the small things. Transmission coolers, thermostatic adapters and driveshafts are all listed.

Driveshafts are made to order, the same as the T56 Magnum and CD009 shafts, so length is not a constraint. A custom driveshaft listing is in progress that will let you select your transmission output, your rear differential, and your overall length, and add driveshaft adapters within the same selection so the whole combination price-builds in one order.

The scenario that drives that: everything is in the car, you reach the final steps, and you are missing one intricate component.

Getting a question answered

If you are considering a swap and want to know whether it is viable, use the contact page on the site or send a message on social media.

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