NP242 rebuild with upgrades

[xeroOTG]

The chain and sprockets came in the mail today.

I used some prussian blue to check the contact pattern of the sprockets with both chains. They have the same tooth contact patter, even if it might be hard to see.

I tried using lithium first but it wasn't clear.

Confirmed that they are the same length next

I will have this sucker assembled tonight with any luck. I can't wait for this to be installed in my Jeep!

 

[ehall]

I found this picture of the differential collars, and it looks to me like you could move the regular 242-J collar onto the HD differential, slip it over the TW HD shaft, and solve the problem entirely?

I was looking at a 242-HD today and noticed the main HD shaft is 32-spline at the rear output. I am wondering if the 32-spline yoke from the SYE will mate onto it? It could be that a hack-n-tap is the way to go for XJ. Looking at the shafts I don't think its going to buy much but its an idea

 

[xeroOTG]

I found this picture of the differential collars, and it looks to me like you could move the regular 242-J collar onto the HD differential, slip it over the TW HD shaft, and solve the problem entirely?

The issue with that is that the HD shaft's bearing race where the differential mounts is longer. The collar being longer necessitates this, as it rides on the ridge.

I was looking at a 242-HD today and noticed the main HD shaft is 32-spline at the rear output. I am wondering if the 32-spline yoke from the SYE will mate onto it? It could be that a hack-n-tap is the way to go for XJ. Looking at the shafts I don't think its going to buy much but its an idea

No. The splines are slightly different on the 32 spline main shaft I have. They bind up, like the tooth thickness on the 32 spline shaft is bigger.

Even if you got it to fit, unless you wanted the world's longest hack and tap it wouldn't work. Then there's the issue of the lack of speedo provisions. I haven't seen a 242 HD with a speedo sensor provision. IF you found one, the splined section of my main shaft would accept the speedo drive that came with my tom woods shaft, but you would need to machine in notches for the retaining clips.

This weekend I took the 242 with the tom woods 32 spline shaft the 242ECE chain out and beat the hell out of it. I love it! I put about 100 miles of hard trails on it, and it went without missing a beat. I'm going to call my concoction a success.

 

[DieselSJ]

Do you have a part number for that upgraded chain? I decided to do this same build instead of swapping the 208 into my SJ.

 

[xeroOTG]

Do you have a part number for that upgraded chain? I decided to do this same build instead of swapping the 208 into my SJ.

(HV-061)

The only hv-061's left in the country are available at Novak. They had 5 last month and they're overpriced. I spoke to an engineer at Borg-Warner Morse who said once those chains ran out they have a vendor they work with who can make new ones which is ironic since BW is the OEM of the links that the vendor would end up using anyway. If you need those details let me know.

 

[cal]

Need to get Mike Rollins (MJR) to post up in this thread. He's been running AMG 242 hybrids in his XJ for like 12 years. He has the details on pretty much every upgrade available, including the 4:1 options.

 

[xeroOTG]

Need to get Mike Rollins (MJR) to post up in this thread. He's been running AMG 242 hybrids in his XJ for like 12 years. He has the details on pretty much every upgrade available, including the 4:1 options.

The 4:1 makes sense, since its the same front case half as the 241. What I would be curious about is 2 low and maybe 4full time low. I realize 4 full time low might be dumb since the planetaries are the weak link... Another possibility I would think is a cooler in the non-amg case. Splicing the pickup line is all that would be required I would expect.

 

[cal]

the 4:1's were custom units, I want to say that ORGS (later sold to JKS) made them but I'm not 100%. One of the nice upgrades you get from the HMMV stuff was the t-case cooler.

I'll poke him and see if he can post up some good info for you guys, he has years of experience in this.

 

[ehall]

The 241-OR that had 4:1 is a different case than the original 241. The teraflex 4:1 is fairly convoluted setup with stacked pinion gears that requires replacing the front half of the 231 case which won't work in the 242 (might be wrong--maybe you can send teraflex the case and they can replace the annulus gear). An inline doubler would be simpler and pay greater dividends, at the cost of needing new driveshafts.

The AMG cooler is basically just a finned tube that passes through the case and draws away heat passively. It makes sense if you are reusing the 242-AMG case but if you were going to the trouble of engineering something it would be far better to use a small electric oil pump and a radiator.

 

[ehall]

I tell you what I would like: a twinstick 300 in front, with the rear output into the 242 for 4WD/AWD, and the front output of the 300 turned into a PTO for external accessories.

Christmas only a few months away fellas

 

[DieselSJ]

The only hv-061's left in the country are available at Novak. They had 5 last month and they're overpriced. I spoke to an engineer at Borg-Warner Morse who said once those chains ran out they have a vendor they work with who can make new ones which is ironic since BW is the OEM of the links that the vendor would end up using anyway. If you need those details let me know.

Thanks! I missed that part number.

Here is a chunk of info that explains the strength difference -

Round Pin: Singular round pin used to articulate the chain.
Rocker Joint Pin: Two pins are utilized to articulate the chain.

Good reading here - http://www.rsgear.com/catalogs/borgwarnercat-2007.pdf

 

[DieselSJ]

Google was good to me. Found a chain for $40 cheaper than Novak. They only had 1 in stock though. The guy asked how I got a Euro spec transfer case.

 

[xeroOTG]

Google was good to me. Found a chain for $40 cheaper than Novak. They only had 1 in stock though. The guy asked how I got a Euro spec transfer case.

Hahaha! What did you tell him?

I tell you what I would like: a twinstick 300 in front, with the rear output into the 242 for 4WD/AWD, and the front output of the 300 turned into a PTO for external accessories.

Christmas only a few months away fellas

I was looking at a crawl box, or one of those "box4rocks" things on pirate. The 2.72 is nice, but a crawl box would give me 2 low without having to mess with the 242 anymore since its working so nicely.

 

[ehall]

I'm looking through that Hy-Vo PDF catalog and it shows what appears to be a rocker-joint HD chain for the (mislabeled) 242/242-WJ. The line details say "1-1/4" wide which is the HD chain, and "RJ" which the footnote expands to "Rocker Joint"

 

[xeroOTG]

I'm looking through that Hy-Vo PDF catalog and it shows what appears to be a rocker-joint HD chain for the (mislabeled) 242/242-WJ. The line details say "1-1/4" wide which is the HD chain, and "RJ" which the footnote expands to "Rocker Joint"

I talked to an engineer at work, after digging through the documentation morse has for the HV and standard inverted tooth chain they make, we decided that even with mechanical advantage of the .2" larger sprockets, when combined with the 3/8" pitch x 1.25"W rocker joint chain it would be weaker than the 1/2" pitch x 1"W rocker joint chain that is in the 242ECE.

The weakness is not the rocker joint in this case, its the pitch. The longer pitch is what makes the ECE chain stronger than the (wrongly labeled) WJ chain. I have a WJ chain sitting on my garage floor that I confirmed the measurements on.

 

[ehall]

I'm going to ask for a second engineering opinion. If HD parts could be made stronger with changes to pitch alone they would be, wider chains and sprockets cost more to manufacture, and not worth the cost if they could make even stronger without the increased material

 

[xeroOTG]

I agree it doesn't seem logical. If you have someone else who can look at it, great, but what I found was that the 3/8" pitch 1.25" wide rocker joint chain (HV-063) IS stronger than the 1/2" pitch 1" wide roller pin chain (HV-028) but not stronger than a 1/2" pitch 1" wide rocker joint chain (HV-061).

I honestly want someone to tell me which is stronger, but the math I have done and all of the hy-vo documentation I have found puts the 1/2" pitch chains at stronger than the same joint style 3/8" pitch. Just look at the links I have provided. The two strongest combos are the AMG 1.25" wide and the ECE 1" wide style due to the pitch length alone. Case and point is the number of HD cases that use either the .5" or the .5033" pitch chains, they vastly outnumber the cases that use the 3/8" (.375) pitch chains.

I suspect the ".375 (3/8) Pitch x 1-1/4 W x 98 Pitches" is cheaper to make than the 1" rocker chain because it uses shorter pitches and it was available in the NP243, NP246, NP241G2 and a very long variety of other cases on other Dodge trucks. Look through the application guide again.

Then there's sprocket compatibility, the 1-1/4" wide sprocket set shares the driven sprocket with 7 cases, as is opposed to the 1" which I only found in 2 cases. The 242HD seems alot more like a spare parts upgraded case. That being said... the drive sprocket is unique in both sprocket widths.

Am I crazy or does that make sense?

 

[ehall]

The spare parts comment makes sense. I was helping a guy in the club teardown a 242-HD for his WJ and a lot of it is the same stuff. The front output is the same 32-spline as the 242-WJ that I have in my shed (and maybe the same as the 242-J in my XJ but I don't remember). The input shaft and low-range planetary appears to be the same. AFAICT the only difference from the late-model bearing kit is the 32-spline rear output shaft bearing, which is the same as the front output shaft bearing, every other bearing is the same. Rear output housing is different and there are some differences in the seals ofc, but the only real change to warrant calling it HD is the wider chain. If it was actually weaker than the ECE chain then it seems double-stupid to use it, once for the extra engineering, and again for the extra materials

I believe you said the shaft is larger so there must be a difference in the differential but I don't know if it is actually any stronger, also should not matter as to chain issues, that little PT/FT mode selector is the weak link in the whole thing anyway and I think it is even the same

 

[xeroOTG]

Supposedly the 242D in the Durango's with a tow package had a 6 pinion low range, but the one I tore down was a 3. I did however use a combination of the differential from the 242J and the 242D because the 242D used an extra bronze syncro(?) in the top that wasn't in the 242WJ and 242J I tore down and the 242J differential had more slop. I used the shorter differential output sprocket that matched the 1" chain drive sprocket. Remember that the whole case is kinda spare parts, the front of the case is the same casting as some 241s.

As to the 1" ECE chain... AMC was involved so WHO KNOWS what the real reasoning was. I suspect in that case that since the Cherokee was a "luxury" vehicle in Europe they used it because it was quieter. My other theories include the possibility that the rocker joint was patented in the US but not Europe at the time of manufacture, so it was cheaper to use the roller joint in the US.

The 242D and 242WJ were Chrysler specified cases and the 242J/ECE were AMC. Chrysler could also have been standardizing chains to work with inventory on hand.

The only differential upgrade beyond an extra bushing is again on the AMG case. The pinions in the differential on that case have needle bearings. If I could find one with a SYE I would choose it every time, over a WJ,J,ECE, or D regardless of the availability of the Tom Woods shafts for the 1" wide chains.

The 242D (32 spline) had the same output bearing in the tail housing as the Tom Woods SYE tail housing, but the housing had a different set of oil drains. If you want pictures I can go take some. This I suspect was to help with the lubrication of the tail housing extension.

The front output is the same 32-spline as the 242-WJ that I have in my shed (and maybe the same as the 242-J in my XJ but I don't remember).

I did find 23 and 27 spline front shafts, I used the 32 from the WJ, as the J I had was a 23.

 

[ehall]

I got some time so I called Tom Woods and asked about their 242 main shafts. The "HD" shaft they sell on their site is custom machined but still only designed for regular case internals. Its heavier duty than the re-machined cores used for the "normal" main shafts, but its not designed for use with 242-HD cases.

If you send them a shaft from a 242-HD, they will re-machine it for use with their housing, $350 for the job and housing/kit.