The Lab Rat - SFR's R&D Comanche

Prefer shrooms.

Ok back to business. To answer the earlier question, yes I decided to convert to discs. I have a strong hatred for drums and after some discussion about how simple the swap is I was convinced. Not a lot of arm twisting was involved, though Cal may have regretted the suggestion as within an hour I was dragging him to the junkyard to grab the caliper mounts from an Explorer.

I had 2 perfectly good, complete 8.8s sitting in the shop, but decided not to pillage them for parts. I feel like such a responsible adult for that one. Anyways, Cal offered up the old rotors and calipers from 4643 that were removed before KOH so all that was needed were the caliper brackets/backing plates. These were pretty easy to find, and cost roughly $30 at the junkyard, making it not very worthwhile to ruin one of my complete axles.

The bolt pattern on the 8.8 has just a little bit more horizontal spread to the holes, so there was some slight modifying to be done. Thankfully the parts were pretty easy to fixture onto the mill so I didn't have to resort to using a die grinder.





In case anyone is wondering I slotted all the holes .130 towards the center and everything lined up.



I also took the opportunity to clean them up and shoot a little fresh paint on to make em pretty.

With that part done it was time to move to the axles. I got a nice new set of Ten Factory shafts, which came with bearings, and seals, but not the shaft retainer plates (which is normal). I had both of the stock retainers, but one is on a complete good shaft that I didn't want to take apart, and both of them were kinda warped and flimsy (also normal). I decided to cut some new ones on the plasma table from 3/16" plate to make them a little less flimsy. Since the new backing plates are a bit thicker you also need to add a ring to the retainer to keep pressure on the seal. Matt had brought some down a while back, and since they are a pain in the ass to get into place when they are just loose on the shaft I went ahead and TIG welded them to the retainer plates.



With those all made up I was then able to press the bearings, seals and retainers onto the shafts and install the shafts into the housing. I sure am glad I welded the rings on too, because there is just no space to get your fingers in there with the parking brake shoes in place. That would have been a nightmare.



Last steps were pretty simple. The rotors center holes were just a tiny bit too small so I had to use a drum sander on a die grinder to open them up just a touch to fit right.



After that the rotors slid on and the calipers bolted right up. I also had Crown Performance make me some custom soft lines to connect the calipers to the axle. Hopefully it'll be going in to the truck soon!

Very Nice!

While I was building the rear axle the front was just sitting there waiting for a new diff cover before the steering could go back on. Got that sorted and time to seal it up.




Now here's an important step for anyone stepping up to alloy shafts. The ears on a lot of shafts have a bit more meat to them than the stockers. If your steering stops aren't set right you can bind them up at full turn. Crashing yokes at full turn is the fastest way to break a U-joint or shaft so you wanna make sure everything turns freely. Many companies will not warranty a shaft if they see signs of this as well. If you look closely at my steering stop bolts you'll notice the heavy washer I added to keep things from going too far. I would have just adjusted the lock nut, but it had been tack welded to the bolt. They didn't crash much, but anything is too much if you want things to live.

This my friends is a torque wrench, and today we will be learning all about why we use one. We will also learn what happens when you don't, AKA how to send Dallas into a full day rage. I actually had to wait a few days to post this update because otherwise this post would have violated the forums language rules.



Let me explain. I had an NP242 transfercase, but really wanted a 231. I knew someone with a 231 who wanted a 242, so we made a trade. Seemed pretty simple, except for this minor detail. It seems that this 231 had been opened up before. This was pretty obvious when I saw that one of the tabs on the top that the case half bolts go through was broken and there was RTV smeared all over in a rather non-factory fashion. This should have been a warning sign. You see it seems that whoever opened this case up in the past reassembled it using an impact gun instead of a torque wrench. When I took it apart not only were certain bolts in the wrong places, but they were all at very different levels of tight. Some were barely finger tight, others were tight enough I was surprised those mounting tabs hadn't broken. This was mildly annoying, but not the end of the world.

The reason I was taking the case apart was to install an Advance Adapters SYE kit, and it all went quite smoothly and easily, right up to installing the new tailhousing. This is where mildly annoyed turned into.......really not happy. You see there are only 5 8mm bolts that hold the tail housing on, and 2 of the holes were stripped out from...you guessed it.....over torqueing. Worse yet they were the 2 bolts on either side of the shift rail section of the housing meaning they were next to each other, but the farthest ones apart. Essentially the housing could now only be held on by one side. This definitely would not do.

So off to the store I go to buy a rather not inexpensive solution. Helicoils. These little buggers can really save you when someone does something like this, but they are kind of a last resort. Once I had them in hand I had to drill out the holes, however those holes go all the way through into the case and I really didn't wanna tear it all apart again, nor did I want metal shavings inside. So I used an old trick I learned somewhere, grease on the drill bit. Go slow and the shavings all get stuck in the grease.



Just like this!



Next step, tap the holes with the supplied tap.



And finally, use the special tool thingie to thread in the new helicoil thread inserts. As a final step to make sure I didn't leave any bits inside from all the drilling and tapping I filled the t-case with fluid after reassembling, sloshed it all around, spun everything, then drained it again.



And now we have a complete NP231 with SYE installed, and all it cost me was an NP242, half the junkard cost of a 231 and most of a day of frustration.

People always assume that torque wrenches are designed to tighten something to spec.

They don't realize it's there to prevent you from being an idiot and going past the material's ability to function.

Yes, the torque spec given for those bolts was 18-20ft.lb. Pretty sure you don't need an impact for that.

What is the spec on the Helicoil you used, I'm pretty sure I have at least one bolt on my case that is leaking for that very reason..

Torque spec stays the same. The Helicoils are sold based on thread size, and it's an M8x1.25 bolt. No idea what the hole gets tapped out to, as the tap doesn't say on it, but since it comes with the kit it doesn't matter all that much.

FYI another point about the Heli-Coils is they are not made for through-holes, there is a different, far more expensive product for that. You can use Heli-Coils on through holes, though, if it's a deep enough hole. To do this when you drill it you stop short, only drilling to the depth of the coil itself. Then you tap it the same and all will be good.

If you drill and tap all the way through you end up running the likely risk of the whole coil spinning out the backside of the hole. Found that one out the hard way years back. :-/

GSequoia said:

FYI another point about the Heli-Coils is they are not made for through-holes, there is a different, far more expensive product for that. You can use Heli-Coils on through holes, though, if it's a deep enough hole. To do this when you drill it you stop short, only drilling to the depth of the coil itself. Then you tap it the same and all will be good.

If you drill and tap all the way through you end up running the likely risk of the whole coil spinning out the backside of the hole. Found that one out the hard way years back. :-/

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At least you were trying to do it the right way. I watched a kid in shop class use JB weld as a gasket maker on a briggs 5 hp since one of the mount holes was stripped.

Though not optimal, they are available, and in this case they got the job done. Not optimal, but they stayed in place while torquing so they should be fine for the life of this case.

It does seem like some helicoils are better than others. These ones went in pretty tight, I actually had to use a 1/4" drive ratchet to run them in. The bolts then threaded in nice and smooth by hand. I have seen inserts that just wanted to float in the hole though. Seeing as this set was $40 I wasn't willing to spend even more for a more optimal thread fixer. At that point I'd just go to the junkyard and start with another t-case and cut my losses.

RedHeep said:

At least you were trying to do it the right way. I watched a kid in shop class use JB weld as a gasket maker on a briggs 5 hp since one of the mount holes was stripped.

Click to expand...

Hey man, they say that stuff can be drilled and tapped :roflmao:

GSequoia said:

FYI another point about the Heli-Coils is they are not made for through-holes, there is a different, far more expensive product for that. You can use Heli-Coils on through holes, though, if it's a deep enough hole. To do this when you drill it you stop short, only drilling to the depth of the coil itself. Then you tap it the same and all will be good.

If you drill and tap all the way through you end up running the likely risk of the whole coil spinning out the backside of the hole. Found that one out the hard way years back. :-/

Click to expand...

Or put some red Loctite on the outside of the coil when you insert it, but the tapped hole needs to be clean and dry for that to work. I tend to do that as a matter of principle so the coil doesn't back out if I ever need to disassemble the part anyway.

Whole discussion makes me sad as I'd had a lot of stuff off of my '99 and now it's going away... I get to start all over with an '00 and I'm sure I'll get more practice with my Helicoil and rivnut technique...

any particular reason you didn't just drill and tap the case?

Hey SFR, I just read through your entire thread on the MJ, can't wait for parts, as these trucks don't get love like the cherokees do. Anyways, just a word of advice. I have a MJ D44 in the rear with the explorer disc swap, and I'm using a ZJ rotor, didn't have to do any grinding. Just advice for anyone who stumbles across this thread. Great work so far!

I already had these rotors, otherwise may have considered something different. Either way it was literally .025" worth of sanding. Took all of a couple minutes.

rockclimber said:

any particular reason you didn't just drill and tap the case?

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Did you miss that whole part where I DID drill and tap the case. I assume you're being a bit pedantic and suggesting I use different hardware though. I felt that building it with the proper hardware at the proper torque was the proper way to do it. I also didn't feel like drilling the holes in my brand new output housing larger to accept the wrong hardware.

StinkyFab said:

Did you miss that whole part where I DID drill and tap the case. I assume you're being a bit pedantic and suggesting I use different hardware though. I felt that building it with the proper hardware at the proper torque was the proper way to do it. I also didn't feel like drilling the holes in my brand new output housing larger to accept the wrong hardware.

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fair enough.

I meant without helicoils.

I just dislike helicoils. I would much prefer 2 different size bolts on a part that almost never gets unbolted.