Project Special Reserve

[Scott Cee AKA 2drx4]

I guess I had better post this here, since I made a forum for people to post builds and then didn't post my own.

This story started with somebody sharing a FB ad... And being that I'm somewhat mentally suspect I was instantly intrigued and had to check it out.

FBMJscreenshotcropped.jpg (132.73 KiB) Viewed 3791 times

Well, it turns out it was in Nazko. Which is close, but really not close.

Anyways, if you're going to drive all the way out there you might as well take cash. So I bought it.

By the time I had a chance to actually do much with it the weather had turned (I don't even know what happened to that entire year of my life ).

And man, what a score. No straight panels, rust, 2wd, probably a blown up 4 cylinder, ignition was punched, steering jacked, rear bumper gone, tailgate pushed in 6"+. It was perfect.

[Scott Cee AKA 2drx4]

Somewhere during that entire year I lost (seriously, if anyone knows what I did that entire year, I'd love to know) I pretty much sketched up an idea of what I wanted to do with it. Basically, I want to build a replacement for my other Comanche.

The other Comanche:


I honestly felt I had the build fairly right with that one, based on what I actually wanted it to do, and what I wound up doing with it. It did have some deficiencies. That said, I took the (at that time) 30 year old pickup on a 5000km road trip and experienced zero mechanical issues. However, I didn't like that it had small brakes, used wheel adapters to run the JK wheels, has a lunchbox locker in the front (Lokka, it works fine, I'd recommend one any day for their intended use, it's just that it is a lunchbox locker and I am outside of the intended use), lacked range (60L tank is meh at best, even with the Renix 4.0L), short arms in the front (ride sucks), a little too light of springs in the rear, crap window/mirror combination (anyone who spends a lot of time in early XJs knows the mirrors are useless), the rear brakes do weird things, and some other things among them being the bodywork was heinous and not worth fixing.

So to address these issues I figured I'd swap an OM617 diesel into the thing. Since you know, that totally was the problem with the last build.

And to that end I picked up a nice Mercedes for way too much money and butchered it.

[Scott Cee AKA 2drx4]

I guess I should admit this build was never meant to be put on a forum, since there wasn't really one I cared to put it on at the time, so there isn't pictures of most of it. There is video of everything though, which I'll post the link to eventually.

Anyways, I took zero pictures of stripping out the car. But I did take some of the truck.

Cleaning out the engine bay:

Basically everything was to go for now, because everything was either not needed or would be in the way:

I left the brakes and a few other things, as I still wanted to be able to roll it around. The 2.5L and 2wd AX-5 went to the metal scrapper. I should have pulled a few things off of it but it was in the way, so it just got tossed.

Gas tank out:

Surprisingly it's actually good on the inside. I'd rather not use it though, and the aftermarket repops are a little thinner. I'd like to use a Dakota tank but I haven't had much luck finding one.

Floor is meh at best:

I haven't pulled the rubber floor up yet but I already know it's going to be bad. There was a large hole clean through the windshield, and it's been sitting for 10 years... Not a recipe for intact floors.

[Scott Cee AKA 2drx4]

I also built this temporary bumper thing just so I could move it around with my plowtruck wrecker abomination or with the LBP XJ.

[Scott Cee AKA 2drx4]

Video that pretty much explains things to this point:

https://youtu.be/zpztBi8Z9rw

[Mr.gutsy]

You are a mad man. But i love oddball swaps so i really dig this.

[Scott Cee AKA 2drx4]

You are a mad man. But i love oddball swaps so i really dig this.

This has been a complete rabbit hole of a swap. Sooo yeah. There's definitely some insanity in this.


I'll try to update the rest of the thread to basically where things actually are at tomorrow.

[Sterlingfire]

In!

[Scott Cee AKA 2drx4]

So part of why there was no movement on this project for so long was the first adapter I bought was too sketchy for me to be willing to run. After all this build was supposed to be reliable, I want to be able to take this truck on 5000km roadtrips like I did with the last one. I hadn't been able to find much info on the adapters, and the company that sold them had a totally shit website with zero info. I knew some people had managed to make the Jeep to AX-15 adapter work, at least for the short term (long enough to post pictures of it and the odd video of one being driven a bit), so I just ordered it and hoped for the best.

It was NOT good.

This is from Mercedes Diesel 4x4. www.mercedesdiesel4x4.com and the P/N is A-MB202 adapter. He's updated the website since I bought it, but the link is here: http://www.mercedesdiesel4x4.com/product_p/a-mb202.htm

This adapter allegedly will work with the later AX-15, NV3550, and TJ NSG370. I'd argue it actually works with none of these transmissions.

I am putting this info in here in the hope that anyone who contemplates this swap will find it via Google search or the like, and realize NOT to buy this trash.

This is basically what you get:

It's a basic steel adapter plate, and a steel crank adapter with an oilite/bronze/whatever pilot bushing in it. Not pictured was a bag of cheap hardware, and he may have provided printed instructions or maybe I printed them.

Okay, so what's wrong with it?

Starting with the adapter plate, it's plasma cut. Which includes the absolutely tolerance critical dowel holes.

Mercedes side dowel holes:

Jeep side:

These holes need to be located correctly to within a few thousandths at worst, and they need to fit the dowel with a mild press or at worst tight slip fit. There is no way a CNC plasma can hold the definition required to produce that sort of result. With none of these holes being that close, you run into a real risk of tolerance stackup resulting in the engine to transmission being a long ways out of concentric. This will result in rapid and unusual clutch wear, outright clutch failure, rapid pilot bushing (or bearing) failure, excessive vibration, poor shifting or jamming in or out of gears, excess or unusual wear on the transmission bearings (specifically the input), and quite possibly even detonating the rear main bearing in the engine. If it was an automatic it also will likely cause the flexplate to crack. Finding more people who used this kit, it turns out MOST of them experienced one or more of these problems.

When I had ordered the kit I has assumed these holes would be cut on a CNC mill. Well, assume not!

[Scott Cee AKA 2drx4]

Oh, I forgot to mention, the hole edge distance on the one Jeep dowel hole is completely unacceptable. The camera angle doesn't quite capture it, but it's got maybe an 1/8" of material. The other hole is a little better, but not great. Again, this is stuff that's not just asking for trouble, it's demanding it at gunpoint.

Here's a picture of why it's such a concern. There is a flaw in the cut right at this point (they started or stopped the torch here I guess?).

[Scott Cee AKA 2drx4]

Okay, so the next problem with the adapter plate was the thickness.

It's 5/16" thick... Which isn't right. There's no way it can be that thin and work with the needed stickout for the crank and crank adapter. This means it's pushing the flywheel and clutch about 1/8" or so (I'm not looking at my notes, just take my word for it, I measured two different 4.0Ls for block to flywheel dimensions and arrived at this) deeper into the bellhousing than it should be. Okay, so, why does this matter? Well for one the starter will not engage the ring gear correctly, they sorta make up for this by not providing you with a dust shield/shim for the starter, but it's still wrong (you should have the shield/shim on it too, it's there for a reason). The other issue is that Jeep clutches are finickity at best, and you're just asking for trouble with moving it in this far. I do not think you would ever get away with this if using an internal slave transmission, although with the external one you could probably make it work. It still isn't right.

Also to save costs (which is what most of the problems with this kit stemmed from) there is an access hole for torque converter bolts cut in the adapter. By doing this the same plate could be sold for the automatic kits as the manual ones. Again, no cover or dust shield is provided. This is asking to pack the clutch up with crap if you wheel in anything sloppy.

Also by making the plate this thin there was no way to countersink or counterbore for the attachment hardware. This means there is little to no clearance between the hardware and the flywheel. Any inconsistency in the flywheel may result in contact.

[Scott Cee AKA 2drx4]

On to the crank adapter.

It's nicely machined carbon steel. I'll give them props on the machining for sure. CNC lathe obviously, and then probably put into a CNC mill for the holes. Beautiful surface finish throughout, tolerances are bang-diddly-ang on.

Adapter side towards transmission/flywheel:

First thing I'm going to pick on is the pilot bushing. Yeah, I'm swapping an archaic engine in, no, that doesn't mean we need to go backwards on things unnecessarily. Pilot bearings are the choice by OEMs for good reason, being they actually last, and they have been the choice since the early to mid 80s. Plus any transmission input that's been run with a bearing inevitably tends to be in too poor of shape to be run with a bushing, as any damage to the surface will result in it effectively machining the bushing in short order. Been there, my other Comanche has a bushing because it's an early 4.0L crank with a later transmission, if I ever have it apart again I will machine a sleeve and install a pilot bearing since the bushing doesn't last that long and plays hell on the clutch and tranny as it wears out. Which brings me to wondering why they didn't just machine this to the correct size to accept a pilot bearing? Obviously the advantage of the bushing was they could make multiple bushings to fit different applications, and have only one crank adapter... But at the same time the bushing costs money to machine, and the material isn't the cheapest either, so I'm not sure how much money they saved over either providing sleeves or machining the adapters differently to accommodate different pilot bearings. Maybe they just figured you'd like a bushing because you're swapping in archaic stuff anyways. I have no idea.

Back side of the adapter/towards engine:

Flipping the adapter over reveals the start of the real trouble, and this is what absolutely killed any chance I'd run this kit as it was built. The transmission potentially not being concentric could actually be solved by measuring the runout and machining offset dowels as required. The clutch issues could possibly be lived with given I'm using an external slave. This problem can not be solved as the kit is offered, at least not at all easily. And what is that problem?

Well, those holes that have negative edge distance on the raised portion of the adapter, those are for the bolts that hold the whole schebang to the Mercedes crank.

They intend for the Jeep flywheel to be installed on top of the adapter, and those holes drilled through the Jeep flywheel, so bolts will go through the Jeep flywheel and the adapter, and then into the crank flange.

Not exactly AutoCAD rendering of where these holes will land with the flywheel on the adapter:

So? What's the big deal? Well, the Jeep flywheel is not the same thickness as the raised center of the adapter. In fact I don't believe the thickness of the Jeep flywheel is spec'd as a super specific tolerance, there seems to be variations between manufacturers, as it wouldn't really matter in the stock application. In this case it means the 6 bolts that are to be installed here will have only roughly half of their head supported. This means they will be horribly unevenly loaded, and in an application that sees high vibration, shock loading, and possible massive temperature swings and differential between the parts. The other issue? Well, Mercedes actually used 12 bolts to hold their flywheel to the crank. Admittedly this is probably a little overkill, but given they used coated and stress relieved hardware with extra fine threads, I think they must have had some concerns about longevity. Since the Jeep flywheel pattern interferes with half of the MB flywheel bolts, Mercedes Diesel 4x4 simply chose to omit them and not come up with a workaround for this.

So, to fix this you could probably bolt the adapter to the flywheel and then mill/face the seating area of the bolts so they were at least flush. That said you have two different materials (cast iron flywheel, low carbon steel adapter) in an application that is also subject to a ton of heat... Could you make it last? I don't know, and I have zero interest in finding out. Again, searching around on the internet I managed to find people who had sheared crank bolts off, or had them come loose and trash other things in the process.

Backside picture of crank adapter on flywheel:

That's just another view to show you how the holes would have to be drilled into the flyweel with zero to negative edge distance.

[Scott Cee AKA 2drx4]

Here's the sort of failure this adapter typically has.

[Scott Cee AKA 2drx4]

One last pic of the MD4x4 trash.

Here's the bag of bolts they give you:

Like come on. Pennies in price difference for bulk hardware that's good versus that shit.

[Scott Cee AKA 2drx4]

Okay, so with that out of the way... I totally let the project sit while trying to figure out what the next move was. I honestly had no motivation to even work on the chassis given that I was at an impasse that would potentially massively change the direction the project progressed. I debated just throwing a "LS" 5.3 or something in it instead. That seemed boring though, and wasn't the direction I wanted to go from the beginning. I debated trying to fix the adapter's issues, or at least modify it to the point that it would be reliable. The problem was nothing about it was really right. I didn't trust the adapter plate to template for a thicker one that could allow for proper flywheel placement, and I didn't feel any modification to the crank adapter would acceptably solve the problems it had.

I think if I HAD to run what I'd bought, I would counterbore the flywheel and the crank adapter, and at least allow the 6 crank adapter bolts to seat correctly on only the adapter. I determined that VW actually sells some flywheel bolts with the correct thread and a suitable length. The pilot bushing could be removed and replaced with a sleeve that would properly locate a pilot bearing. From there the adapter plate would basically just have to be run, put it on there and build a tool to check it was concentric (fairly easy to do using a stripped transmission case and a dial indicator) and make offset dowels if need be. The clutch spacing would be a bummer, but probably could be reliably solved be modifying the throwout lever. I think you could build something that would work out of that.

However, given I was dragging my feet so much (and going to work a ton), it meant enough time passed that another company decided to build an adapter. This company is Doomsday Diesel, and they (or he, it's really a one man show) has made adapters for Toyota R151 or W56 or whatever it is (I speak Japanese better than I speak Toyota) transmissions for a while. So naturally he was able to figure out a reasonable solution to all of this given what the known issues were.

This kit costs way more... But at least you're getting something. And apparently I never took a picture of the whole thing.

Adapter plate and start shield/shim:

It's aluminum. Water jet cut for the non-critical dimensions, CNC mill for everything else.

Close up of holes:

Crank adapter:

Steel, two piece design. I don't have a picture that is usable (again, all of this was NOT meant to be turned into a build thread, so pictures are lacking), but the cover comes off and there's 12 counterbored holes for attaching it to the crank. The cover centers the flywheel on the adapter, and a new larger bolt pattern is included in it to mount the modified Jeep flywheel.

Flywheel:

It is the same as a regular HO 4.0L flywheel, it just has a second wider pattern drilled into it, and the surface has been faced so the bolts will seat properly.