Adapting the
AMC 2.5L (150cid) Engine
to
GM Transmissions
This guide will show you how to replace your light-duty AX5 as found behind the AMC 2.5L I4 engine with something completely substantial, like the SM420 or SM465 transmissions. This is a more advanced swap, but the thoughtful installer will be able to do excellently reliable work.
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Parts Required
The installer will need to source the following parts. These are suggestions only and do not constitute a guarantee of fitness or applicability:
- Bellhousing, Chevy S10 Blazer. GM #15679692. This is the bellhousing that was used with the 2.8L, 60 degree V6 engine from 1985-1989. GM no longer manufactures this bellhousing, but salvage sources are an option
- Plate, cover, bellhousing lower, GM #15602627
- Pressure plate, Jeep 2.5L to AX5, 1987-2004. It is sometimes possible to purchase just the pressure plate, or to reuse the existing one if it is in good condition
- Disc, clutch, custom, 9-1/8" diameter x 10, 1-1/8" splines. Custom discs such as this can usually be purchased from companies such as McLeod, Centerforce, or possibly a local parts supplier
- Bearing, throwout, BCA #614037 is one possibility, but the best option is to use Novak's adjustable release bearing, #TB1
- Arm, clutch release, GM #15704443
- Cylinder, hydraulic slave clutch release. Try #SC103471 or Centric #13862003
- Starter motor, gear drive style. Consider the Mean Green #3212
- Adapter, hydraulic clutch release line (below)
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The Novak Kit
Novak can provide the following specialty parts to assist in completion of this conversion:
- Bracket, mounting, crank position sensor
- Pivot ball, specially modified
- Bushing, pilot, specially machined
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You may use your existing CPS (Crank Position Sensor). You will need to drill or otherwise machine your bellhousing to accept this sensor. The Novak CPS bracket and your CPS will offer you a good template for doing this modification.
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Suggested Transmissions
The ultra-low geared SM420 or SM465 transmissions will add fantastic off-road and crawling abilities to your Jeep powertrain. These are the most oft requested transmissions and will offer the best overall performance.
The SM465 is more difficult to install in that it requires that the bellhousing bore be machined to precisely accomodate the 5-1/8" retainer locator. Also, use of the suggested slave cylinder will require that one rib be machined off the SM465 on the driver's side. As such, the SM420 is usually an easier choice for installation.
We recommend that you run a 33 inch or greater tire to compensate for the loss of your overdrive gear. See our gearing page for more about this.
Transfer Case Shifter
This transmission conversion will work best with our #SK2X transfer case shifter kit. Factory shifters could be modified, but this usually results in a bigger mess than even the factory created with their shifter system.
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Transmission Shifter
Use of the OEM style transmission shifter for the transmission is easily done. The installer may opt to bend the stick to fit the particular Jeep application. The transmission shifter sits further ahead in the Jeep than the AX5 and will need to be modified accordingly.
Driveshafts
Note that you will be able to shorten your drivetrain length and lengthen your YJ or TJ rear driveshaft for better angularity and less strain and vibration. The front driveshaft will be lengthened a corresponding amount.
Engines & Engine Mounting
Your engine will remain in its factory location.
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