roostaz24

Hi,

I am in the process of putting a Trailblazer SS powertrain (LS2/4L70E) into a 1984 C4 Corvette that came with the manual 4+3 trans.

I will periodically update findings I have had along the way for those that are interested. I don't believe I have seen anyone convert a 4+3 car using these components, most start out as auto 700R4 trans. Most people also do not start with a 4WD 4L70E.

Major Highlights to Date:

1.) Switched out truck intake to Corvette intake and fuel rail - led to a domino effect of unusable Trailblazer accessory drive parts. First, new intake is now right in the way of the Trailblazer SS idler pulley. Replaced alternator bracket to fix - this led to needing a Corvette specific alternator (TBSS won't bolt in, too short) and PS pump (TBSS pump bolts in but is not in alignment with belt). As a result of this change, all accessories need to be replaced since Corvette accessories are about 1 inch closer to the engine than TBSS. Replacing the water pump then led to ditching the TBSS 87mm throttle body due to interference, resulting in the need for the LS2 Corvette throttle body. Up next will be replacing harmonic balancer and switching oil pan over to a batwing Corvette pan.

2.) Removed 4L70E AWD transfer case, front driveshaft, and front diff. Original 4WD tailshaft is too short to be used with a 2WD tailhousing. So trans is over now getting rebuilt with the 2WD shaft which will allow enough length to get a 700R4 tailhousing on there (with a 6 to 4 bolt adapter between trans and tailshaft housing).

3.) Wiring on LS2 side near complete, pinned out full harness to ensure all wiring was good. Rewiring a few items now that got cut off with the body harness, such as fuel pump, front end fan, gas pedal, fuel tank pressure and fuel sender, speedo and tach info, A/C, etc. Cleaned up the Trailblazer SS fuse box and removed lots of fuses I didn't need.

4.) Since the 1984 only (both auto and manual) came with a Dana 36 rear end, bought a 1988 C4 manual trans Dana 44 rear end to accomodate new powertrain. Since Dana 44 is an inch longer than the 36, I probably cannot use the 700R4 driveshaft and will require a custom driveshaft.

5.) About to move on and start pulling old powertrain out of the vette to prep for install.

roostaz24

Last photo out on the road before rebuild...

buddhaz06

iTrader: (8)

Awd vette will be nasty

roostaz24

Original accessory configuration and truck intake and alternator bracket removed containing idler pulley, truck alternator, and truck ps pump

roostaz24

Check fitment of new alternator bracket from a 2004 Corvette. Note that the block is machined to accept both configurations of the bracket, but the holes that need to be used require a different set of bolts.

roostaz24

Attempting to re-use the truck power steering pump reveals the pump cannot be drawn in enough into the bracket due to top of pump interference. This pump is a no go. Delco 36-516306 was the solution (the Vette PS pump).

eric5678

different gen, different engine, etc.

still might help somehow. The car has been around for 6-7 years now, there's bound to be more info out there if you dig.

http://forums.corvetteforum.com/c3-t...ngray-awd.html

http://www.syty.net/forums/showthread.php?t=37000

roostaz24

Bird's eye view of the old truck PS pump on the new bracket proves the corvette accessory drive is a good inch closer to the engine than the TBSS accessories. The LS2 Vette throttle body's interference the truck water pump was the straw breaking the camel's back. The entire accessory must be changed over to Corvette LS2 accessory.

roostaz24

New LS1 water pump, LS2 Corvette alternator, bracket, tensioner (on left) and idler in place. I was able to re-use the water pump bolts but needed to order the PS pump and alternator bolts from a Chevy dealer.

Still need to replace the harmonic balancer and secure the new PS pump pulley, which was also ordered separately. A/C comp will likely also be replaced with the recommended LS1 compressor for ease of fitment into the C4.

roostaz24

Comparison of new 2WD 4L70 tailshaft (Delco 24238748) with purchased 700R4 corvette tailshaft housing to the old 4WD tailshaft still on the trans. The new shaft should buy a few inches necessary to secure the 700R4 housing to the 6 to 4 bolt adapter (not shown) and leave enough spline outside of the housing to connect up the driveshaft.

roostaz24

Typo here. I meant to say that with the new LS2 Corvette throttle body that it interfered with the old truck water pump. So that was the reason the truck water pump had to be replaced to the Corvette LS1 water pump.

roostaz24

Trans is back from the shop with the new 2WD tailshaft installed. Everything had to be removed inside the trans to change out the shaft, so I elected to have it done to save time. It is officially a 2WD 4L70E now. Everything looks good and is the right length. Waiting for the 6 to 4 bolt adapter to sandwich between the trans and the 88 700R4 tailshaft housing.

roostaz24

The '08 wiring harness rework is pretty much complete. From the pics you can see I added several paths (blue and red conduit) to complete the body side of the harness that was cutoff when I received it. The red conduit lines include 5 wires - fuel tank pressure 5V ref, fuel tank pressure signal, and fuel tank pressure low, fuel sender (fuel level) and fuel pump power from the fuel pump relay to power the pump. There is probably too much wire here but will cut it down after it is in place.

The next set of conduit (in blue) includes the 6 wires for the gas pedal and the single wire for the brake on signal, which will go to the ECM and then subsequently will go to the trans (ECM to trans was part of original harness, nothing needed there).

The third set of conduit (in blue) includes signals for the cluster and ignition (tach, speedo, crank wire to the steering column, MIL signal). I'll likely have to add 3 more wires later for oil pressure, oil temp and coolant temp so I can populate the cluster with these but am not ready yet for that.

On the fuse box side the picture with lots of relays is the original TBSS fuse box from '08. The reduced fuse box is the final product of what is needed for the build, including all relevant ECM and TCM signals. Since the TBSS was not pinned for electronic fans, I decided to use the WSW (winshield washer) relay and WSW fuse to control the fans. I'll likely re-use the trigger from the '84 Corvette to command the fans on. The control signals I labeled with "C's" on the relay so I remembered the orientation.

roostaz24

Another couple of shots of the underside of the fuse box. Note that I removed all wiring to the off-white, gray and middle black sections before the rework minus one wire - the starter signal in the middle (orange/black). The wires shown in the off-white and black section now are what is needed for the build. Note there are no wires going into the grey section now. I also added two wires to the far right white section for AC (the white and light green wires headed to bottom right corner of screen). Far left (orange - fuel pump relay control out, pink is power to fuel pump), middle (brown is cooling fan control out, small pink cooling fan control in, thick pink cooling fan power, solid orange is TBC IGN (theft), orange/black is the starter wire, and grey is the crank wire).

roostaz24

the new wire marriage point

85MikeTPI

iTrader: (9)

So you're NOT building an AWD car? Have you been over on http://forums.corvetteforum.com ? The basic C4-LS swap threads there would have already saved you tons of time re-inventing the wheel..

roostaz24

No, this will be a RWD only setup. The goal of this forum is to provide details on how to convert the Trailblazer SS powertrain into a useable format so as to follow Corvette Central's guide on the LS swap, and going into more detail in some areas than they have shown through the website and Dec '07/Jan '08Corvette Enthusiast magazine.

roostaz24

Got the adapter kit in from Advance Adapters. I have found a few comments online about this but these pics show that I will not be able to use the reluctor ring that comes in the 50-0405E kit. If you try to use their reluctor in the position they give on the adapter for the VSS sensor, the reluctor ring sits between the two diameters of the shaft and will not bolt down securely.

I spoke with Vette Works and they also recommended not using the reluctor from 50-0405E. Instead, order the reluctor to a 4L60E and use the VSS from a '96 Corvette to replace the VSS in the C4 tailshaft housing.

www.youtube.com/watch?v=F1-wYZIePEI "Reluctor Ring VSS Installation 01.avi" shows heating up the reluctor and tapping it onto the shaft into the correct position. I will be doing this as soon as the new reluctor and VSS come in the mail...

roostaz24

Teardown is nearly complete. I am after as much weight savings as possible so I will be removing much of the old wire harness and re-doing the insuation with a lighter weight more water resistant material.

I decided to blow away the evaporator to make room for the Trailblazer SS underhood fuse box I will be using. I'm thinking about being crafty and still re-connecting the heater somehow while using the evaporator's original space for the fuse box.

roostaz24

The tailshaft assembly is complete. Essentially all that is needed from Advance Adapters Kit 50-0405E is the 51-0405 adapter plus (2) 716079 22 mm plugs. The two plugs are to close up the holes made to allow a VSS to go into. However, the VSS position for the kit won't work on the 4L70E tailshaft, so I plugged them both up.

I used a 4L60E reluctor ring (aluminum) and tapped it onto the tailshaft in the correct position using a piece of pipe the diameter of the ring to be the "middle man" between the ring and the hammer. The inside of the tailshaft housing required some Dremmel tool trimming so that the reluctor ring would not hit the case. I made sure to trim enough to allow for some room on the shaft moving about within the tailshaft housing. I then used Loctite adhesive on the 1996 Corvette VSS sensor to secure it in place. The conversion cost was just about $250 between the adapter, reluctor ring, and VSS sensor.