There has been much debate as to which transmission to use for the swap. Transmissions play a very big part in the selection of a block to work with. As you may have read in the Sirius history, there are two types of bellhousings available: wide and narrow. Here is a photo of the 2 types overlayed:
These two bellhousings are sometimes denoted as 13.25" lower bolts (Wideblock) and 12.25" lower bolts (Narrowblock). These are not the only differnces though. The upper bolts are also both different as are the starter bolt positions. This difference can open and close windows very quickly for your swap. Choose wisely and read this site to help justify your decision.
There are many differnet ways to mate a transmission to the Sirius Engine. Here are just a few of them:
- D50/Arrow/MightyMax transmission with Starion Extension housing.
- D50 tranny with Starion Extension housing and Starion internals.
- Starion 2.6L transmission with a wideblock motor.
- Mazda B2600 Bellhousing w/ RX7 transmission using a wideblock
- T56 using an adapter plate, custom flywheel on a wideblock
- Toyota W58 using Pierce
- An adapter plate/custom bellhousing to use with a transmission such as the W58
- Dave Burscher's Powerglide automatic transmission.
These will be discussed in more detail below.
The Mitsubishi KM-132
To understand the relationship between the D50 and Starion transmissions, we need to do a quick lesson on the KM132 transmission.
The KM-132 was used in several RWD and 4WD Mitsubishi Vehicles. The Starions, 2WD and 4WD pickups, and even the montero used this transmission. The transmissions are far from the same though. The tailhousings can be of different lengths, including ones with a tranfercase hanging off the back. The major difference that we need to pay attention to is the bellhousing pattern. This transmission is offered with both patterns so switching is very simple. More details area available below.
|KM132 Gear Ratios||Car||1st||2nd||3rd||4th||5th|
Because the DSMs come with a narrow block 4G63, many of the swappers coming here will be looking to use this transmission. It is truely the budget choice at first glance. The small trucks also known as the "Dodge Ram D50, Mitsubishi Mighty Max and Plymouth Arrow" came equipt with several engines: the 2.0L 4G63 (G63B), the 2.4L 4G64 (G64B), and 2.6L G54B. Depending on year and type of transmission, the 2.0L trucks may have a narrowblock. The narrowblock bellhousing transmission is basically the same KM-132 that is found in the Starion, only with a narrow bellhousing! This allows you to bolt the transmission up to the 4G63 and use the stock Starion transmission crossmember and driveshaft... or so you'd think. The shifter location on the truck transmission is 2" forward of that of the Starion. This is easily remedied by swapping the tail housings between the two transmissions.
The D50 transmission is also a pull-cable type setup. Because of this you will need to make your own hydrauilic setup or adapt the cable mechanism. On my first swap I chose to make a hydraulic setup. Wilwood (the brake company) makes a small hydraulic clutch slave cylinder that works well. Prices for this are around $60. You will also have to make brackets and modify the swing arm being careful that no binding will occur. More info on the slave cylinder setup can be found here.
The biggest problem I have found with this transmission is that the input bearing does not like to handle the high input RPMs of the 4G63 engine. I have killed 3 of these trasnmissions in a year. Never have I broken a gear or shaft. Each time the input bearing failed.
The Clutch for this setup is fairly easy to obtain. You need to use the FWD version of the flywheel. AWD flywheels have a smaller ring gear and thus, the starter will not align properly. You can use the pressure plate from whichever flywheel you are using, but you will need to specify the spline pattern to use. The DSM spline pattern is 7/8" 20 count. Most clutch companies can easily (and for no extra charge) rivit a 225mm clutch disk to a 1" 23 count spline center. If you are really on a tight budget, the 215 (or smaller) flywheel/disk combo can be used from the pickup trucks.
Moving the shifter back 2" is going to be required with the D50 transmission. This is easily accomplished by swapping the tail housings between the Starion and the D50 transmissions. Be sure to test out the shifter before you say you're finished. It will usually take several attempts. Just get a good mental image of what is going on inside and you will be able to feel your way around literally with your eyes closed.
Less imporant is the bottom cover. The Starion uses a "waffled" cast aluminum cover which seals with a reusable o-ring. This can help the rigidity of the case as well as oil cooling compared to the stamped steel piece of the D50 transmission with replacable cork gasket. Since you'll be using the Starion box to donate the tail housing, you might as well steal this as well.
The Starion transmission is slightly better than the D50 unit. Also known as the KM132-M-CNL, the SQ transmission has a few benefits over the D50's KM132. The bearings are better, but the gears themselves are basically the same. Same ratios too. Reverse is heically cut rather than straight cut for a quieter reverse. Reverse is also synchronized in the Starion unit. This option is good for those who will be sourcing and rebuilding a block. This transmission requires a wideblock. Since you will be rebuilding, why not buy forged pistons! Since you're buying forged pistons, why not just get 2.4L pistons! You can see this train of though will lead quickly to this transmission, but also opens up a suprising alternative.
D50 / Starion Hybrids
Some intelligent (and brave) souls have actually swapped the Starion internals into the D50 case. Well known names such as Eric Phlebani and Alex from www.dentsport.com come to mind. I, however, tried to swap these internals and it was a total failure. The integrated bellhousing/cases were actually slightly different. Shimming of the bearings is required. The shafts also varied. Certain bearings would need to be kept with the case and others with the shafts. The real challenge is finding the correct combination. Eric P. apparently has figured this out. I would love for him to contribute to the pool of knowlege, but he has yet to show an interest in sharing this info. Sadly, the Dentsport transmission died within one season of racing. There are many contributing factors to its death, but the ultimate failure was in the bearings. This failure resulted in Alex tossing the 4G63 to use the popular Nissan SR20DET.
Toyota W58 on a narrowblock
This method has been documented somewhat by Jason aka "PiercedJD" in Port Charlotte, FL. He's had this drivetrain in several of his vehicles including a Conquest and a GMC Sonoma! Here is a quote on how he did this:
The bellhousing bolt locations have been moved.
The very very simple version of how to do this... use a DSM starter plate. Make a new starter plate and bolt it to the engine and locate the center of the crank shaft on the plate with it bolted to the engine and drill a pilot hole.
Locate the center of the plate on the transmission input shaft and clamp the plate to the bellhousing. Relocate the old bellhousing bolt locations to match the new locations which you are taking from the starter plate. Make sure the hole diameters are the same, as the two lower bolt holes also house the guide dowels. Do the same for the starter opening/bll and bolt locations. You can leave the old starter bell where it is, or cut it off and add a piece of aluminum). Your bellhousing is now complete.
Modify your flywheel (DSM FLYWHEEL)to accept a pilot bearing of the correct size. Whatever car your transmission came from, buy the pilot bearing. Take the flywheel and pilot bearing to a machine shop and hand the proprioter both pieces. tell him make this (pilot bearing) fit into this ( flywheel).... come back in about an hour. Your flywheel is now complete.
Purchase a 225mm clutch disc that will fit your transmission input shaft. Assemble.
Currently, a member of Zero G is working on this combination and will be supplying photos and info for a future write up.
A shop in Australia has actually put together a partial kit for adapting the Supra transmission to the Mitsubishi wideblock (for the 2.6L Starions). It can be found here. The part number is "AP 20". Here is a picture of this transmission installed in Kris Heefners awesome Starion (G54B wideblock)
Mazda RX7 Transmission
How the hell will an RX7 transmission work? This came as quite a suprise to me as well. Here is the background. Mazda built the Mazda B2600 for several years. During two of those years ('87-'88... 12/86-6/88 to be exact), the carburated engine blocks were the 2.6L G54B! The other "2.6" engine produced during this time was called the G6. This is also known as the MPV block. Here is an image comparing the bellhousings:
Mazda, during this time was using the same basic transmission in its vehicles. This "Model R" transmission was used in the following vehicles:
|'R' gear ratio's||Car||1st||2nd||3rd||4th||5th|
TT = 3rd Generation "FD" RX7 Twin Turbo
Click here for a detailed page with information on the RX7 transmission.
Custom Stuff - Adapter Plates
This option may be one of the most flexible options available. There is alot of doubt in my head of just how easy some make this out to be. It involves making adapter plates between the block and the bellhousing. Theoretically, you need to get the center lines almost perfect. This seems very hard to me, but I have heard many stories since starting this site of people who "just welded them together". If you don't want to be quite so DIY with this part, there are hotrod shops all over the U.S. that offer services backed with years of experience and techniques. Please send in some pictures if you have ever done something like this. We would all love to find out more on this method.
T56 on a wideblock
Chad Samuel is making an adapter kit for the wideblocks. It will use the legendary 6 speed T56 transmission from the Camero LT-1 Camaro / Firebird (93-97). Other makes/models require too much fabrication to be $$$ feasable. This kit has been in development for over a year and we are finally starting to see some parts. Here are some pictures of some adapter flywheels. These adapt the Mitsubishi 6 bolt to the 11" GM clutch: Here are some images of the "Stock" Fidanza next to the T56 flywheel from the face and the back.
I can't wait to see how all this turns out. It is being installed on
- Intake Manifold = Retail $550
- Adapter plate for GM trans = Retail $300
- Motor mounts = $150
- Oil filter housing = $50
- Optional Fidanza flywheel for T56
- Optional Flexplate and Torque converter
Buschur Racing Powerglide Kits
One custom RWD alternative was developed by Bushur Racing in the late '90s. Lots of money went into research to develop this kit. If you are building a HIGH power drag car, this is the best option available. You can purchase many of the parts from Buschur's Website. I have seen this install in person and it looks very nice. The obvious downside to this is the price of some of the components. While it seems high, it really is not as bad as it may seem. You have to do it once and there are very few mistakes to make.
"Myself, Plebani, Brent Rau, Mike Simon, Albert Lioe-a-tjam, all of us and many more use our adapter. Silly to design and make something when what is out there is perfect." ~David Buschur
© 2006 Bowman Cybernetics