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Installing GMPP SuperMatic 4L70E Transmission in Project EcoNova - Decisive ShiftSwapping GMPP’s SuperMatic 4L70E transmission into our E-Rod–equipped ’76 Nova From the March, 2012 issue of Popular Hot Rodding By Christopher Campbell Photography by Author
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Here’s the star of the show:... Here’s the star of the show: the GMPP 4L70E ($3,049, street price). The gear ratios are still the standard pack found in the 700-R4 and 4L-series at 3.06, 1.62, 1.00, and 0.70. The 4L70E also gets several key upgrades targeted at hot rodders: • Rated up to 480 hp • Includes friction-reducing components that send more power to the axle • Thirteen-vane pump with a heat-treated stator support • Five-pinion input and reaction carriers • Heat-treated sun shell • Heavy-duty low roller clutch assembly • Upgraded 3-4 clutch pack and a high-energy 2-4 band • Needle bearing assemblies replace conventional thrust washers to reduce power loss and heat buildup One of the key things you have to decide when you order the E-Rod package from GMPP is what transmission you’d like have: manual or automatic. Will it be direct connection or torque multiplication? Gearbox or slushbox? Three pedals or two? It’s a true moment of decision, since the calibration in GMPP’s E-Rod ECU is slightly different depending on the trans chosen, and must be matched correctly as part of the emissions compliance of the package. It’s a tailored solution. For the EcoNova project, the answer was an obvious one: automatic. Comfortable cruising is the priority, but also we didn’t feel like enduring the hassle of tracking down, restoring, and swapping in the necessary pedal assembly. Plus, with GM Performance Parts’ latest line of SuperMatic transmissions, you’re really not giving up much more than a left-leg workout. The SuperMatic designation is the retrofit kit name for GM’s 4L-series of transmissions, which all trace their roots back to the original 700-R4 introduced in 1982, and redubbed the 4L60 in 1990. The electronic shift-controlled version of the 4L60 (the 4L60E) arrived in cars in 1994, and it’s been evolving ever since with the 4L65E, and the latest and greatest, the 4L70E. The big 4L80E (derived loosely from the venerable Turbo 400) also has its own SuperMatic kit for those making big torque or horsepower. For our purposes, the highly refined and strengthened 4L70E SuperMatic made the most sense. Not only is it significantly lighter than the 4L80E and rated to handle much more power than we’ll be making, it’s also roughly the same dimensions as the 700-R4, which we already know fits perfectly in the EcoNova’s trans tunnel. That means getting it in is also similar to the familiar 700-R4 swap, since the 4L70E is based on the same architecture. Nevertheless, there’s a bit more to getting it into a vintage machine, since this trans is fully electronic. In this case that’s actually much more of a benefit than a hassle since there’s no throttle valve (TV) cable to deal with, which is great considering the E-Rod’s required electronic throttle body has no provisions for attachment. Rather than a complication, we’d call it an elegant simplification. But the benefits go much beyond that; those electronic actuators and solenoids that manage the valvebody and actuation system for the clutches and bands offer far more control over the transmission’s final performance. We’ll delve into that more down the road, for now let’s just get it installed!  On the passenger side, 700-R4...  On the passenger side, 700-R4 aficionados will recognize the blue ECU interface as the location where the TV cable would traditionally have been connected. Rather than the linear action of the cable, the electronics allow special valvebody enhancements that produce firm and fast shifts under full throttle, but smooth shifts under light throttle. The 4L70E also includes GM’s modern style quick disconnect fittings for the cooling lines, but you can still retrofit the older style tubing.  Here is the 4L70E in reference...  Here is the 4L70E in reference to the 700-R4 we removed from EcoNova. Note the strong family resemblance in the cases. The most obvious differences are the detachable bellhousing, strengthening ribs on the case, and a longer tailshaft that lacks a mechanical speedo provision.  After removing the 4L70E tailhousing,...  After removing the 4L70E tailhousing, we have a reluctor on the tailshaft that needs to be removed. We used a thin cutoff wheel to notch it deeply on two sides, then tapped it lightly with a hammer. In its place is this unique SFS reluctor that retains the Vehicle Speed Sensor (VSS), since that is used as the primary feedback sensor to make shift decisions. Note how it also adds a traditional-style speedo gear. After removing the 4L70E tailhousing,... After removing the 4L70E tailhousing, we have a reluctor on the tailshaft that needs to be removed. We used a thin cutoff wheel to notch it deeply on two sides, then tapped it lightly with a hammer. In its place is this unique SFS reluctor that retains the Vehicle Speed Sensor (VSS), since that is used as the primary feedback sensor to make shift decisions. Note how it also adds a traditional-style speedo gear.  This tailshaft kit from Southwest...  This tailshaft kit from Southwest Fabrication Services (SFS) is how we’ll remedy that speedo situation. Essentially what we have here is a special adapter developed by SFS to attach their 700-R4 style tailhousing to the electronic 4L-series transmission.  This adapter plate is the...  This adapter plate is the key to the whole swap. While it adds a couple inches in length over a 700-R4, it actually ends up being a little shorter than the stock 4L70E. The adapter uses precise machining and original GM gaskets for a leakproof seal.  To properly align the speedo...  To properly align the speedo gear, we slid the Shiftworks tailhousing into place and peaked through the speedo gear hole to ensure the drive gear was centered at the top of the hole. Shiftworks pairs your rearend drive ratio with the tire diameter to select the correct gear to send. Ours is the one required for a 3.42 ratio—the specified ideal ratio for the E-Rod calibration.  The bulkhead connector that...  The bulkhead connector that splices off of the main E-Rod harness is the interface for the SuperMatic into the E67-based engine management box. Ours is tucked inside the passenger-side fender since we opted for placing the fusebox behind the passenger-side headlight.  Getting the SuperMatic into...  Getting the SuperMatic into the car is straightforward, though if you go our route and opt for the most extreme engine setback possible with Holley’s LS swap mounts, some clearance issues may arise. Ours were minimal, only requiring a few touches from our favorite driveline swap mini sledge from Harbor Freight Tools. Every hot rodder should have one.  If you’re bolting the SuperMatic...  If you’re bolting the SuperMatic to an LS3 E-Rod, check your flexplate. The Corvette-specific one on the right is included with most E-Rods we’ve seen and is not compatible with standard automatic transmissions. The one on the left is what you need: GM PN 12602448.  Just like with the E-Rod electronics,...  Just like with the E-Rod electronics, everything on the SuperMatic kit is designed to be mounted underhood if desired, but the deletion of our factory A/C made it easy to mount it inside the cab. The grommet is the original one for the A/C wiring with an extra hole drilled in it.  We must be living right, or...  We must be living right, or we just picked the right platform for our E-Rod swap. Not only were we able to use the original trans crossmember by just drilling a new hole for the Energy Suspension trans mount, we also reused the rearward-most stock mounting holes in the subframe. To top it off, the driveshaft bolted right up. That just never happens.  Here’s something important...  Here’s something important to know: Since the 4L70E was designed with hot rodders in mind, it is the only SuperMatic kit that does not include a stock torque converter. The idea is to encourage matching the stall speed to the engine package; GMPP recommended a 2,500-stall for our package. We pursued the many options at Summit Racing.com since they had the best prices and fastest shipping around, and chose a 2,400-stall TCI Breakaway converter.  Inside, we took advantage...  Inside, we took advantage of the SuperMatic ECU’s super light weight, and just Velcro’d it to the A/C block-off plate. The system is “connect and cruise,” meaning it’s pre-programmed and ready to drive once all the connections are made. It also includes optional connections that allow adjustment of shift timing and firmness, data logging, and much more via software and laptop. Also, the system can be configured to operate in manual mode and it supports most wheel-mounted paddle-shift systems. We’ll be exploring that more when we’re up and running.  With the 4L70E in place, we’ve...  With the 4L70E in place, we’ve got two connections to make. On the tailhousing is the VSS sensor, which we reinstalled with our Shiftworks mechanical speedo kit.  Just like with the E-Rod’s...  Just like with the E-Rod’s main wiring harness covered in the January issue, it’s a good idea to lay out the SuperMatic’s wiring harness on the floor to figure out where your connections need to be oriented in the car. The harness includes electric output for tach, speedo, oil pressure, and several other connections that will need to be in the cab if you plan to use them.  Forward of that on the same...  Forward of that on the same side is the main harness connection, located in place of the TV cable.  Shiftworks has the solution...  Shiftworks has the solution for the shifting, of course. The two brackets are installed with the trans and shifter in Overdrive. We opted for the improved Shiftworks cable ($74.50, PN K100) rather than the stock GM cable (which is usable), since it offers more adjustability for fine tuning if necessary. We want 5.5 inches from the rear face of the cable mount to the center of the mount pin.  With a little hammer and plier...  With a little hammer and plier work to shape things, the horseshoe shifter bolted right up to the EcoNova’s more rounded trans tunnel. Note the factory style grommet included for the Shiftworks cable; it makes the whole thing look stock!  Here’s what will be on the...  Here’s what will be on the other end of that cable: a perfect factory-style horseshoe shifter from YearOne. Besides being one of the best looking shifters of the muscle car era, it’s one of the factory shifters supported by Shiftworks with their detent kit ($89.25, PN SC224). YearOne has them at a killer price ($219.99, PN AQ25) that made it a no-brainer versus restoring an original.  Since we had to move the junky...  Since we had to move the junky factory carpet to properly mount the YearOne horseshoe shifter, it was the ideal time to lay down Eastwood’s Thermo-Coustic Barrier sound deadener ($140, PN 12117). The dense butyl rubber membrane will kill the tinny sound reflected by our ’70s steel and dramatically reduce engine and exhaust heat. We also like how easy it lays down; with a roller, a razor, and a deadblow hammer we were done in an hour.  Shiftworks doesn’t forget...  Shiftworks doesn’t forget the details; a new factory-style shift indicator with the new Overdrive selection is available with the shifter conversion kit. We’ve got some wiring to do to get those gauges functioning with our E-Rod kit, but we’ll handle that later as we tackle the dash and get rid of the column shifter with a world-first product from ididit.  A quick 10-minute swap is...  A quick 10-minute swap is all it takes to remove the stock TH350/PowerGlide detent and replace it with the Shiftworks detent with its extra notch for selecting Overdrive.  We also took advantage of...  We also took advantage of Eastwood’s Carpet Adhesive ($9.99, PN 12743Z) to lay down the new carpet kit from YearOne that we ordered with the shifter. Yep, we’ll be switching the seven shades of ’70s tan/brown in the factory interior over to a more consistent black.  There was a surprise waiting...  There was a surprise waiting for us under the carpet; these flat pieces of steel that mounted the unidentified late-model GM seats in the EcoNova were simply welded to the tunnel and rockers, and hovered above the floorpans with no reinforcement. This isn’t safe or acceptable, and we certainly don’t love the seats enough to go to the trouble of building a supporting structure. We’ll definitely be adding new seats with legit mounts that bolt to the floorpan.  One thing about horseshoe...  One thing about horseshoe shifters: they’re intended to be used with consoles. YearOne carries the most perfect ’69 Camaro console available anywhere ($799.99, PN CA902), and we couldn’t resist the temptation since the gauges mimic the shape of the EcoNova’s speedo. Plus, it’s just beautiful and adds the right muscular touch to the interior. You’d never suspect there is a fully electronic trans on the other side.
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