Sprinter 4WD Conversion Idea, GMT-800 IFS.

[luthj]

Yeah, it took a few hours to pull. I forgot half my water in the car. Should have went it got it. Nearly passed out waiting 40 minutes in line to checkout. I am a bit of a lightweight in hot weather though.

I was reading through the 722.6/NAG1 manuals and documentation.

The T1N sprinter uses the 722.681 variant. This is listed as a W5A380 by Chrysler. 5 is 5 gears, and 380 means 380nm input torque. Interestingly the cherokee I pulled the donor trans from is supposedly a W5A580. Which is strange, cause that 3.7LV6 isn't going to make that much torque... A lot of it has to do with application the trans was specced for. Regardless, I believe the cases are interchangable. And possibly a fair number of hard parts.

A few sites indicate that the sprinter and cherokee both use the same overhault kit. Supposedly all diesel applications got an extra pinion in the two planetary sets.

There are two gear ratio sets used in the USA. They are quite close, but not interchangeable due to software. The sprinter/cherokee used the same ratios though. I also hear that the sprinters K1 and K2 clutches have an extra set of discs.

Now I just need to make some room on my bench for the trans. Which means I need to get this Tcase put back together. Therefor I need adapter parts...

 

[b dkw1]

I feel your pain, there is no way I'm going junk yard hunting in Missouri in the summer. No matter how big the discount. Save that for the fall/winter. It's actually easier in the winter, stuff rolls/slides better on frozen ground. And the lack of blood sucking bugs........

 

[luthj]

This yard in on a very old auto staging facility, so its about 3/4 on "pavement". After 15 years though, all the car spots have half an inch of dirt lying underneath...


I confirmed the axle actuator pin-out. Brown is 12+, black is ground. Control is gray-black, and indication is black-white. The brown and black wires are nearly indistinguishable after 15 years. with control grounded the actuator extends, with control floating it retracts. With power removed it stays at its current position.

I think I will wire the actuator to the 4wd indicator switch on the Tcase. That way its automatic. I will probably put a manual override, as there are many situations where 2WD low is useful. So I will then have three indicator lights on the dash. 4WD, Low Range, and front axle status. I may also put a neutral light, but thats less important.

 

[luthj]

Got a few hours free, so I pulled the donor transmission apart. It looks pretty clean, but I suspect the K1/K2 parts won't mix with the sprinter. They may have more teeth on the annulus gear? Also the sprinter (supposedly) has higher clutch plate counts in the B1 and possibly k1 packs. Thus far I have determined the jeep trans has 3 single sided frictions in the B1 clutch, 5 single sided in the K1 clutch, and 5 singles in the k2 clutch (multiply by 2 for total frictions). All planetaries have 4 planets. The sprinter supposedly used 5 frictions in the B1, which is unusual, as the TranStar catalog indicates 4 is the max.

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[luthj]

I placed an order for an extension/adapter housing, and an input shaft/gear. Fingers crossed they are compatible. The trans I pulled has the intermediate/adapter shaft, which I believe is the right length.

MOPAR​	68087998AA	Transfer Case Mount	$ 43.79​	$ 0.00​	1​	​
MOPAR​	68087960AA	Transfer Case Input Gear	$ 120.79​	$ 0.00​	1​	​

 

[luthj]

Here is the FWB V 1.0 Schematic.



I also got my 30mm 12 point (not 6!) socket. So I was able to remove the output shaft nut. So the B2/3 housings came out. Here we have the whole stack minus parking gear.


IMG_20190708_201534914 by J Luth, on Flickr

 

[Wyuna]

I gotta give you credit, you don't take the easy way out.

Still enjoying the thread, i'll be following it on our trip around Aus that starts next week.

Keep up the posts, your posts of Aus and NZ along with the shipping info have been full of interesting and valuable information.

 

[luthj]

I got my parts, it was doubly surprising. That what I get for ordering without pictures!

First up I ordered a 241OR input gear. Its not compatible with the 242. bearing is wider, and it lacks the splines inside the gear to engage the mode collar. Notice the outer shaft is about 3/8" shorter, that will come into play shortly. Also note it has the standard internal splines on the input side.
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I also orderd transfer case adapter part 68087998AA. No photo on this one either. Much to my surprise, this isn't a housing, its a stub shaft. It converts from the NV internal to the NAG1 external splines. See how it engages with the jepp NAG1 adapter collar/shaft.

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So this solves the input gear problem. I won't know for sure yet without the adapter housing, but the input gear may need shortened. Its likely there is a shorter input gear available used though.

I really don't want to pay $250+ for a adapter housing though. If I am willing to drive a few hours, I can get a whole trans for 350$....

 

[luthj]

Final adjustment to the subframe are well under way. I completely disassembled the suspension parts and measured them. I made a few changes to the LCA design, which gave me more clearance than I thought I had, which was helpful. I think the GM bumpstop will work. However I will likely need to trim about 3/4" off its height. Though drilling a few lateral holes may soften it up enough. The ford UCA is good for about 30 degrees each direction I tried to adjust for 25 though just in case. That gives about 8" of travel total. Bumpsteer is acceptable at about 1/64". Final ackerman is ~45%. Not ideal, but it will do.

 

[Len.Barron]

About time to start cutting some parts!

 

[luthj]

About time to start cutting some parts!

I just need shocks... SOOOOOON.


As a side note, I was more conservative than I needed with the LCA. I was able to drop the subrame another 5/8" without impacting ride height. So there is some extra room between the diff and engine if I need it.

I am also considering shifting the diff to the left half an inch. I will probably need CV spacers anyways, and this gets the driveshaft a more direct route to the Tcase. I will check once I get the adapter housing, but I sure hope the driveshaft clears the trans...

 

[Charles R]

I've been reading your thread because it's pretty interesting, but i may have missed a few things so please forgive me if my info has already been noted.

I saw you were wondering about the NAG1 specs for the Grand. It is strange the specs are high there, but they do also use the same NAG1 in the OM642 powered version of that generation Grand Cherokee. I can't remember if they use it with the 4.7L V8, but i know they use a different trans for the 5.7 hemi.

I also see you got the input from a 241OR. I can't recall if you're needing a passenger side drop, or if it's a load rating thing that's driving your choices on the T-case because if you're after a driver's side drop, I would think it makes sense to use the 2012 and up Wrangler T-case. The 3.6 liter wranglers used the NAG1 too, so those cases are a direct bolt-in.

Beyond that, I'm pretty interested in what you end up doing with the T-case. I have the 2.72 version of the 241 in my Grand and have been dreaming of converting it to a 4:1 version that's in the rubicon wranglers. It's not a direct bolt-in though because my Grand shifts ranges electronically and is AWD, while the wrangler versions shift manually and are conventional 4wd.

 

[luthj]

I have come to the conclusion that the W5AXXX ratings are meaningless. It may sometimes reference a specific group of higher torque planetaries, but usually its just a carryover. There are some 29 variants on the NAG1, most share parts, its usually just the valve bodies and clutch plate count that vary for units made after 2002 or so. With some drum machining most can accept enough clutches to handle over 600hp.

I need a drivers side drop for the GM front diff I am using. I considered the 241OR, but the low range is lower than I want, and they don't have a full time 4WD option. I have decided on a 242HD, which is more than strong enough for my needs. With the right parts its a direct bolt up to the NAG1 from the GC.

Swapping a 241OR into a GC with electronic shift control would be a challenge. You could leave the electronic shift motor and gear indicator intact, and then just install the 241OR as a manual shift. You would just need to select the range button before shifting the tcase. The other issue is the trans. The older 4 speed trans would probably be okay with 4:1 low range, as it has an output shaft speed sensor.

The NAG1 5 speed would freak out if you used 4:1 low range, as it would see a slipping trans (it expects 2.72:1). You can apply the same fix I am using (can-can bridge) between the TCM and the rest of the vehicle. The challenge is that my program is written for Mercedes canbus frames. You would need to capture frames from the ABS module on the GC. That would let you figure out which ones are the rear wheel speeds. From there is just a matter of identifying which bits or which, and adjusting the program accordingly.

 

[luthj]

I finally have enough info to estimate my front driveshaft angles. I did a really rough calculation based on some wrangler photos to start with. Now I can place the Tcase in my model plus/minus an inch. In the lateral plane I can get the FWD UJ to zero degrees. The upper CV is at ~17 degrees. That should be well within the CV limit.



The problem is the top plane. I will know more when I get the extension/adapter housing, but currently the diff input is about 1.25" inboard of the Tcase output. That will add about 2.5 degree to the UJ. Do I need to move the diff over? Or try for a non-CV shaft setup? I don't have the final clocking for the Tcase yet, but the wrangler put its pretty high I think.




I might be able to get that down to 1.25 degrees. If that doesn't work, I guess I am stuck with some extra $$ for a double CV?

 

[Len.Barron]

my diff input is at least that far outboard from my tcase (and my elevation is greater); with a solid locked axle my driveshaft spins all the time...I run a stock dodge ram front d-shaft with a CV at the t-case, zero problems..