Huh... It would appear that the forum website software here is friendlier for posting, than the software over at LXForums.com. Perhaps I shall continue my build thread over here, then...
20 Mar 2015:
At 220,000+ miles on the clock, my Magnum's transmission finally decided to give out. My Magnum (the Karen-mobile) was "blessed" with the 42RLE 4-speed transmission, which, as everyone here knows, has next to no aftermarket support whatsoever. There is no autostick support to speak of, reprogramming options are practically non-existent, and it's a real PITA to change rear axle ratios (if you don't have a StarMobile with the CDA software package and relevant ENG files, don't even bother trying).
So, I apparently lost 2nd gear and reverse, physically in the transmission. Those two gears now act like neutral. If I can keep the PCM from going into limp-in mode (which it will, eventually), it will shift correctly into 1st gear, then act like it's in neutral when it attempts to go to 2nd gear, then will actually (sometimes) shift into 3d gear. Haven't tested 4th gear, nor do I plan to. I learned about the 1st/3d gear thing while trying to nurse the Karen-mobile back to the house.
Did I mention that I lost 2nd and reverse? Yah... when the PCM does go into limp-in mode (which it will reliably do now), the Karen-mobile will not move at all under her own power. Nor will the Karen-mobile move under her own power if I yank the TCM relay in the front power distribution center to force limp-in mode. Well... Actually, the Karen-mobile will kind of slowly "oooze" forward, if I try to go into "D" and rev the engine.
The CEL is on, and the key dance reveals a P0700 code.
My StarMobile reports that there are also a P0720 (Output speed sensor circuit), P0734 (gear ratio error in 4th), P1790 (Fault immediately after shift), and P0732 (gear ratio error in 2nd).
Haven't yet pulled CVIs, but I don't see much reason to do so, at this point.
So... my options at this point are to either find a junkyard 42RLE and hope for the best, take it to the local transmission shop and pour about $2000 into labor and a reman'ed 42RLE, or... do the NAG1 5-speed swap.
08 Apr 2015:
Been giving this some thought, and...
To hell with it - I'm going to swap in a manual transmission, instead.
17 Apr 2015:
I have in mind using a NSG370 transmission out of a 2WD variant of a 2008 Jeep Wrangler with the 3.8L V6. The bellhousing-to-engine bolt pattern is identical, and there is a machined boss where the crank sensor goes. The flywheel has the NGC crank tooth pattern on it, and should bolt right up to the 3.5l crankshaft in place of the existing driveplate.
The case is provisioned for a hydraulic clutch setup, which "should be" fairly easy to install and route.
Weird thing is, the NSG370 case itself is identical between the 2WD and 4WD versions, but the 2WD version has a different output shaft.
I received the transmission a few days ago, and am waiting on other parts to arrive.
26 Apr 2015:
So... I have the flywheel, clutch disc, pressure plate, clutch fork, master and slave cylinders, throwout bearing and adapter, engine wiring harness from a manual-equipped 3.8L engine, an LX brake pedal assembly, and a Jeep Wrangler transmission mount.
Still waiting on the shift tower, oilpan, LX transmission mount, and Jeep Wrangler clutch pedal.
The NSG370 case is about 3.25 inches shorter than the 42RLE case.
Looking at having a custom driveshaft flange fabricated, as the 2WD Jeep Wrangler flange is substantially different. That appears to be a CV flange. The output shaft has 30 splines, and i will have to work up a decent engineering drawing of what i want the flange to look like. I had wanted to have no custom machining done at all, but apparently that is not to be. Oh, well...
Considering getting a RWD NAG1 driveshaft to see if it is longer than the 42RLE driveshaft (I think it is), and how much the length difference is. This will figure into my custom flange.
The Karen-mobile has been jacked up to two feet, and is resting on jackstands that are each rated to 6 tons. Those were the only jackstands I could find that would go that tall. She has been sitting like that for a week.
Went to start tearing down the Karen-mobile in preparation, and had lots of fun with the exhaust flanges. Apparently, after 220k miles, the nuts and studs will corrode in the most interesting ways. The first stud i tried, just snapped off. Its diameter, right at the lower right-hand exhaust manifold, had shrunk by about 50%. Almost everything else came off normally, which was a surprise.
The final nut had somehow shrunk such that the nut body went from 13mm to about 12mm, but the nut end (where it had contact with the steering rod heatshield) remained at 13mm. This, of course, easily rounded itself, making it impossible to remove with a normal socket. I will have to go to Hazard Fraught tools tomorrow and get a nut extractor set. I will also have to get a set of impact torx sockets for the driveshaft.
Here are some pics, from a bit over a week ago, to today.
Unloading the new tranny...
The new tranny!
The Karen-mobile, 2 feet above the ground
Exhaust flange hardware
Exhaust flange stud close-up
30 Apr 2015:
The NAG1 pattern 3.5L oilpan will not fit the NSG370.
Based on the fact that the Jeep Wrangler 3.8L engine was equipped with a 42RLE transmission and the NSG370 transmission, and that the structural collar that goes between its engine and transmission has the same part number for both transmissions, I'm going to theorize that I may not have to modify my oilpan.
The driveshaft flange shipped out today. Once the NSG370 is in the Karen-mobile (hopefully this weekend or next), I can take some measurements and see about getting a driveshaft fabricated or modified.
The shift tower came in a few days ago.
03 May 2015:
Some more progress...
Adjustable brake pedal assembly from an LX
Non-adjustable (base) brake pedal assembly from an LX
The Karen-mobile is kind of an oddball, in that she has a base SXT rear-wheel drive trim, but somehow managed to pick up adjustable pedals as a factory option. I was rather surprised at this discovery, as I could not figure out why there was an extra switch at the front left of my driver's seat. Went to play with it, and the pedals moved! Weird.
Once I get the car on the road, I figure that I might take a whack at making the clutch pedal adjustable, too. However, first things first...
Wiring harness from a Jeep Wrangler 3.8L engine with the NSG370
I only really need the backup lamp connector, and I might need the CKP connector. Otherwise, it's a source of replacement fuel injector connectors, and other interesting bits. Apparently, the engine harness comes apart using a heavy-duty wiring connector, with a main harness section, and a smaller secondary section that contains the fuel injector and ignition coil pack connectors.
Exhaust system removed, in one piece
Had to intentionally twist off two more studs on the exhaust manifolds. One of the studs had somehow rust-welded itself to the cat-side flange, and I could not get a good bite on the nut on the other side. Oh, well... I can either pull off the exhaust manifolds and repair them, or I can get a set of JBA shorty headers. Hmmm... decisions, decisions...
Driver side exhaust manifold, showing one good flange stud
Passenger side exhaust manifold, with both studs twisted off
The driver side outboard stud had that strange shrunken nut on it, and I could not get any good bite on it with my nut extractors.
Rear driveshaft sections, NAG1 (bottom) and 42RLE (top)
Front driveshaft sections, NAG1 (bottom) and 42RLE (top)
The Karen-mobile has (had?) this slight center support bearing noise for as long as I have owned her. I had meant to replace the bearing, and to do so, I bought a complete driveshaft almost two years ago and replaced the center bearing on that shaft. I was not aware at the time that the NAG1 and 42RLE driveshafts were different lengths, though. Had I attempted to proceed with replacing the driveshaft last year as I had intended to, I would have been in for a rather nasty surprise, I think. Fortunately, I did not go through with that plan.
I could observe that while the rear driveshaft sections appear to be identical in length, the front sections differ by about 5.25 inches. The 42RLE front section is about 30 inches long, while the NAG1 section is about 35.25 inches long. In addition, the original driveshaft appears to have become frozen together - the front and rear sections will not move at all, let alone come apart.
Rear of 42RLE
Driveshaft tunnel, with differential at top
I am going to replace the 3.64 differential with a 2.87 differential that I have laying around. Would like to use a 2.65 differential, instead, but that would mean having to install a mounting bushing in the rear crossmember, and I am not sure how to do that at this time.
Took a couple of measurements of the bottom two bolt holes on the transmission bellhousings of both the D-E-D 42RLE, and the NSG670 replacement. On both transmissions, the bottom two bolt holes appear to be a little over 4 inches apart... This looks really promising!
It appears that the shift tower will enter into the Karen-mobile's cabin at about where the ash tray now sits. I could lose the ash tray - it depends on whether there's enough height between the actual tunnel itself, and the spot where the ash tray now sits.
The pressure-plate-to-flywheel bolts have the exact same part number as the transmission oil pan mounting bolts.
11 May 2015:
No actual vehicle time is noted this past week.
I did, however, delve deeper into wiring diagrams and such. PCM Plug 1 Pin 12 controls power to the 42RLE TCM section of the PCM. Removing power from this pin will effectively remove the 42RLE TCM from the vehicle network, so a replacement PCM/PCM reflash *should not* be necessary. This information was derived from when I tried unsuccessfully to make the Karen-Mobile think that she had AutoStick, over a year ago. I was able to get as far as enabling the AutoStick display on the instrument cluster, but that was it.
The NAG1 TCM takes the park/neutral switch as an input, and apparently spits that out onto the CAN C bus. The NAG1 shifter assembly apparently spits the reverse position onto the CAN C bus. The 42RLE TCM section presumably does the same thing, but by reading the 42RLE TRS instead.
I will get a CAN bus shield for an Arduino, and program an idiot TCM that will spit out the necessary park/neutral, reverse, and drive bus messages onto the CAN C bus.
12 May 2015:
Did a bit more research, and came to find out that the NSG370 that is found in the Chrysler Crossfire shares about 95% of the same parts as the NSG370 found in the Jeep JK Wrangler. The differences relate to the rear case, output shaft, input shaft, front case, and shift fork assemblies. There may be differences in the countershafts, but the differences only appear to be related to the shift fork assembly differences. The gears on the input shaft, countershaft, and output shaft have identical part numbers. The bearings have identical part numbers. The synchronizers and other miscellaneous hardware also share the same part numbers. The bolt patterns on the rear case appear to be identical.
The rear case itself appears to be two inches shorter on the Crossfire version, as compared to the Wrangler version. This shows promise, in that the Wrangler NSG370 was already about 3.25 inches shorter than the 42RLE. I might be able to get away with using the NAG1 driveshaft, without any modifications needing to be made to it. Only thing I'd have to fab would be an adapter plate for the transmission mount.
So, the plan is now to swap the Crossfire rear case, shift fork assembly (possibly the countershaft), and output shaft assembly onto the Wrangler front case. Assuming this will work, and I am fairly sure it will, I will dub the creation, "Franken-tranny." (er, maybe not? Somehow sounds wrong.)
Crossfire ZH NSG370
Side by side comparison of Crossfire ZH NSG370 and Jeep JK NSG370
15 May 2015:
Just got off the phone with... Hemituner? If he can help me, that would be a huge plus. Would save me much coding time, trying to come up with that idiot TCM.
The idiot TCM would have to be able to do the following, from what I have read so far in the LX FSM:
- Pass along gearshift states
- Send driveshaft speed to the FCM and ABS
- Send some sort of status messages to the FCM, PCM, and ABS
- Send acknowledgements to the FCM, whenever the A/C clutch is cycled on
Maybe it would have to do more than this - I don't know at this time. Finding out would involve a lot of packet sniffing (hence, data logging). It can be done - I'm just lazy, though.
Otherwise, won't be doing very much this weekend - going to be doing a short-notice visit to family.
Studied both a 2004 Crossfire FSM and a 2007 Wrangler FSM, for transmission disassembly/overhaul/reassembly, and still see no show-stoppers.
Am going to have to purchase a starter, since apparently the NSG370 flywheel is about 2 inches in diameter wider than the standard 3.5L/2.7L driveplate that accepts the 42LE/42RLE/41TE series of torque converters.
Considering purchasing a new brake pedal/clutch assembly for a Challenger, but not sure about the swept volume of the clutch master cylinder that bolts onto it.
20 May 2015:
Well, Hemituner never returned my call. Doesn't really matter why, as I never included the possibility of his help in my swap plans. This is not a show-stopper... Started code planning for the idiot TCM. Going to use an Arduino UNO with a CANbus shield for the hardware. Will write the C++ code from scratch, using the CANbus shield code library as a reference. (hey, I could have an... iTCM!)
25 May 2015:
Some more progress...
Comparison of front case internals for JK NSG370 and ZH NSG370
Comparison of rear case internals for JK NSG370 and ZH NSG370
Cracked open both of the NSG370 transmissions, and confirmed my suspicions that the internals are almost identical. I will need some sort of sleeve that the ZH shift rod slides in, and it apparently retails for about $4.20 or so. I will also need to purchase the seal that covers the countershaft securing bolt, within the bellhousing.
Other than that, the rear cases will match up to the front cases, regardless of intended application. This means that it could be possible to have a AMG 3.2L V6 with an NSG370 power a Jeep Wrangler 4x4, for all the good that would do.
42RLE driveplate and torque converter
The 42RLE is out. Pulled the rear speed sensor, and it was coated with irregularly shaped bits of metal. This gives further evidence that the 42RLE ate itself. Oh, well... Had to cut the cooler lines - it was just as well, for most of the lines appeared to be so badly rusted that they probably would have burst open in another 50K miles or so.
Managed to snap two more bolts - Two out of the four bolts that hold the transmission cradle to the frame. Those will be somewhat fun to yank out. Also appears to be some very slight galling on the upper 4 transmission-to-engine-block bolts - nothing that can't be cleaned up, I think.
Tried removing the starter per the FSM - it would not clear the exhaust manifold in 30 minutes of trying to get it out, so in the end, I just gave up and proceeded with the rest of the transmission removal. Hm... once the 42RLE was removed, the starter came right out.
Visual inspection confirmed that the JK NSG370 flywheel is about 2 cm larger in diameter, as compared to the LX 42RLE flexplate. It's good that I bought that starter, after all. The spacer ring from the driveplate matches up exactly to the flywheel, as I thought it would. Almost all of the bolt holes match up exactly between my engine and the JK NSG370 bellhousing. The only two that don't are the bottom two oil pan structural collar holes. The 42RLE and NSG370 holes are mismatched about 1/4 inch in the vertical direction - they match up in the horizontal direction. Kind of a head scratcher. Thinking about pulling off the oilpan, and machining the two holes and surfaces to move them up by the required amount.
My titanium ceramic coated JBA shorty heaters should be coming soon, as well as the Challenger clutch pedal assembly. Pulling the exhaust manifolds ought to be a metric butt-ton of fun, given that all of the bolts holding the manifold heatsheilds in place are about as badly rusted as were the manifold studs that I snapped off last month, and DaimlerChrysler didn't exactly provide a whole lot of room to work in. At least, with the transmission out, I can get somewhat better access to that area. Heck, I might even be able to sit upright in that space!
Bare rear end of engine
28 May 2015:
Got a few things in the mail today. Plan for this weekend is to at least install the flywheel, clutch, clutch pedal, and headers. Can't do much else with the transmission until I get a shift shaft bearing and a seal.
Challenger brake pedal assembly, compared to base 2005-2008 LX brake pedal assembly
JBA Shorty headers!