MyE28.com

Well guys, I've just about given up on my 524td chassis for various reasons. Looks like I'm going to pull the motor, transmission, diff, and junk the rest.

Top of my list right now for a new shell is a E30 iX. Specifically a 4-door with manual transmission *fingers crossed.* So on to the notes:

M21 will not fit in the E30iX in stock configuration.
iX front differential mounts to and the passenger side axle passes through the iX oil pan.
M21 and iX similar oil pan bolt patterns with the exception of the iX block having two "long" oil pan bolts just above the oil pan axle tube on the driver side which would have to be drilled and tapped into the M21 for added support.
iX and non iX M20 blocks and oil delivery systems differ slightly. Standard M20 has a threaded relief valve port right next to the pressurized delivery port. The iX variant block has an incompatible flanged port in the same location which a "branch" of the iX oil pump bolts to, and the oil pump has an integrated relief valve.
M21 has an oil pump with an integrated relief valve, but no relief "port" in the engine block. A flat area exists in the casting (milled flat with the oil pan surface) which mirrors the M20 port locations, however I'm not sure whether it would have an oil channel in it if I were to drill it out.
iX oil capacity is 4.75L.
M21 oil capacity is 5.25L.
M21 oil filter housing is a bottom-load cartridge housing and would need to be relocated. I've seen adapter plates for M30s which allow remote oil filters, doesn't look like it would be hard to make one for this engine.
No boss on the M21 engine where the iX dipstick goes.
iX oil pump rotates in the opposite direction the M21 oil pump rotates. This is due to the cut of the helical gears on the intermediate shaft the meshed gear on the pump drive. These parts seem to be physically interchangeable.

That pretty much covers all the main issues I can come up with right now. Just on visual inspection of the M21 and iX version share all of the same bolt holes and mounting points seem to be in place, only downside is I will probably need a vehicle with a fully intact engine (at least long block) to get all the little bits I would need.

All I'm hung up on the relief valve and the oil capacity right now. I'm sure there might be a way to double-back the pressure into the iX oil pump relief valve I just have to see how it is set up in person. And since diesels typically have large oil capacities due to things like soot contamination I will probably just have to step-up my oil change interval a bit. I also plan on installing an onboard centrifuge to protect the engine and whatever turbocharger ends up going on this thing.

What do you guys think?

Subscribed.

The oil relief port could be an issue, but i've never dealt with the m21 and very little with the m20 so i can't speak to those problems.

The oil capacity issue is easy to solve. You are talking about doing a remote mount oil filter, which sounds like a great idea. While doing this plumbing you could simply plumb in a fairly large oil cooler. In south florida the temps will normally be high enough to warrant oil cooling anyway and the extra oil residing in the lines and cooler should more than negate the .50l difference if capacity matters that much to you. Is there any reason you want an e30 ix beside the cool factor? The parts specific to the ix are terribly expensive and getting harder to come by. If you are planning a move to a northern state i can understand, but in s florida do you need the awd? Also, it will cause slightly lower fuel economy (not a big deal with a diesel) and will be a completely one-off project. The problems you are likely to run into if you have a break down far from home could be hard to deal with. Imagine you were visiting the middle of georgia for a weekend and the front diff went out, locking up and cracking the oil pan in the process... where would you get parts to fix it and could you afford to tow it back home?

a standard e30 converted to diesel doesn't face the same challenges. sure diesel parts aren't the most plentiful, but i'd imagine easier to come by than e30 ix parts. plus, other than the engine, parts for a normal e30 are everywhere in junkyards and all over craigslist. Just something to think about.

That said, cool project!

Well as long as there is a relief valve somewhere I don't think it really matters, I could tap threads into the oil pump housing and mount a standard M20 relief valve or something. The M21s blank feedback port for the pressure relief makes me think that the relief port popped by head pressure alone at or around the pumps gears.

Now that I think about it, between a large oil cooler, large oil filter and that centrifuge I should be fine on capacity, too.

Why AWD? Well, the cool factor is one part. I wouldn't mind playing around in an amateur rally or rallycross circuit either. What also drew me to it was just how much damn power I plan to pump out of this motor. MLS, 12mm head studs, ARP fasteners to hold the lower end together, mains girdle, knife-edging the crank which is already forged.. To add to that larger injector nozzles, swapping out the injection pump components for 5.9L Cummins performance parts. I think we're looking at about ~500ft/lbs of torque and ~400HP before we start pushing the physical limitations of this engine. - ANYWAY - My thought was, that is a lot of power to try to hook up with the ground on just one or two tires, but what if you could lay it out to all 4 tires? It's occurring to me however that the iX components might not be able to take that stress. It's the viscous coupling I'm worried about the most.

And I hear what you're saying.. I would never take this thing across country anyway. It would probably be my local/daily driver to work and on erands just due to the size and the fact that the Beetle is my girlfriends car. As taxing as all the AWD components would be on fuel economy.. I so still expect mid to high 30s in fuel economy. And if we want to take a trip, we take the Beetle. Can't argue with 48mpg.

We won't even get into the Cummins El Camino project yet..that will be my play car on weekends.

3.91 diffs.
You may be able to find the euro 3.64 diffs, but that still means your low revving diesel will be geared to the moon.

why not just use a....you know...normal gasoline engine

Gaso..what? You mean those things with sparkplugs?!

seriously just use a non outdated gas engine, the TD stuff is painfully slow and is just reinventing the wheel. A 325i will have way less maintenance and less ridiculous parts to buy if something goes wrong...not to mention way more room to work in, everything is so much cheaper.

So what's wrong with the E28 chassis?

mooseheadm5 wrote:So what's wrong with the E28 chassis?

Do you mean mine specifically? Front QP, rear QP, rear door, hood, misc dents, fried paint, some frame damage, rebuilt title from accident (I bought it as a rebuilt), bad suspension all around, bad brakes, bad wheel hub bearing, rust, door seals, worn, faded/ripped/torn seats, cracked dashboard, cracked tail lights, cracked grille, cracked front indicators, fire damage - and damage from the dry chemical extinguisher used to put it out - under the hood.

Even with all that, it isn't an insurmountable task. However, nothing I do will ever get that "rebuilt" title lifted. For a fraction of the cost spent on any of that I could probably find a 528e or something in much better condition and do a direct swap.

I said the iX is at the top of my list. An E30 sedan wouldn't be so bad, or as I said another E28. The E30 cabriolet isn't too bad either.. but for now I just want the engine on a stand or bench to build into something really mean. That will take a while, and I don't feel like paying for a tag, registration and insurance on a beat up old rusty shell in my driveway while the motor is out.


I just love diesels. I can't really explain it. Running biodiesel and having not looked at a gas station price board in a few years has been nice too. So the M21 is outdated, so is the OM617 by MB but people are pushing crazy power numbers out of that engine in Europe.

When people are like "I can't believe gas is $4.12 a gallon!" I'm not entirely sure if it is a good or bad price.

That explains the reason to ditch the chassis, but like I said, you only have two choices of diff on the ix, and neither is ideal for your motor.

you wont be able to run the TD engine in an ix chassis

Damn. I did some more digging into the differentials and found that not only are the ring and pinion fundamentally different from any other BMW diff I've ever seen but even if I was able to find a way to shim, shave, modify, whatever and make a different ring and pinion gear set fit..the damn helical mesh on the front iX gear is out of phase with every other BMW diff. it would make the front tires spin the opposite way of the rear tires.

The only way I can think of to get around it would be to modify the transfer case so that there is an intermediate ilder gear rather than a chain which changes the output rotation or put a T-case from a newer Xdrive vehicle on it. Check it:

Old style:


New(er) style:


So this project is possible, just not practical unless I want to start taxiing large aircraft.

Just because something can be done doesn't mean it should be done. By the time you are done assembling this frankenstein-car, for the money and time you will have in it to try to make it anything approaching reliable, you can easily go buy a VW diesel, or maybe even an MB diesel. You would also be better off finding another 524td.

reinventing the wheel
Get a small 4x4 truck if you wanna be a mud-bro, and pick up a 24 pack of odouls to complete the look.

Bimmerguy2002 wrote:reinventing the wheel
Get a small 4x4 truck if you wanna be a mud-bro, and pick up a 24 pack of odouls to complete the look.

No, Coors light with a confederate flag waving somewhere.

its obviously possible in some form
http://www.youtube.com/results?search_q ... .303.6.6.0.

Of course just because a crazy Scandinavian can do it doesn't mean anyone can.

mooseheadm5 wrote:Of course just because a crazy Scandinavian can do it doesn't mean anyone can.

This is a good point really.

Subscribed, because it sounds like you're just as much a stubborn jackass as I am. You're likely going to hate this whole project, but I'd love to see what you come up with.

Just throwing out that a gear driven t-case won't fix the rotational direction issue you were talking about. The shafts still turn the same way as if they were joined with a chain. Front ring and pinion sets are always reverse cut. You'd have to get a custom reverse cut gearset for the front diff if you wanted a reasonable ratio. Either way, you'd blow the front diff sky high with that much power.

tsmall07 wrote:Front ring and pinion sets are always reverse cut.

Didn't Jeep have an issue with running some that weren't at some point?

mooseheadm5 wrote:

tsmall07 wrote:Front ring and pinion sets are always reverse cut.

Didn't Jeep have an issue with running some that weren't at some point?

I've not heard of that issue, but it is possible. Sometimes you just have to shake your head at some of the stuff Jeep did. If you ran a standard gearset in the front and reversed the driveshaft rotation, wouldn't that cause the drive side of the ring gear to be opposite? I know some guys do it in 4x4 rigs but they flip the axle over instead of changing the driveshaft rotation. That is so they can make a low pinion axle into a high pinion. It's fairly common to make a "609" axle, which is a Ford 9" upside down with dana 60 outers welded on to make a front axle. Those are all low speed applications, though.

99% of the time front ring and pinion sets are reverse cut.

CoyoteStarfish wrote: My thought was, that is a lot of power to try to hook up with the ground on just one or two tires, but what if you could lay it out to all 4 tires?

Honestly I think this is the biggest issue with your plans. If you want to find a way to make a diesel work because you like diesels, great! I love oddball projects that don't make a lot of rational sense. Heck, if you really just wanted to build an AWD BMW diesel in an E30 chassis because you liked the idea and didn't mind spending the time and money to re-engineer things, great. But if you think that an ix drivetrain is really going to help you put a lot of power to the ground, I think you're mistaken.

Especially if you can get that engine to produce 500 lb/ft of torque, I think the only thing it'll put on the ground is small pieces of the drivetrain and several quarts of fluid.

On the other hand, there are ways to get massive power down to 2 wheels in an E30 if you really want to. If you really want a big-power diesel '80's BMW I think sticking to RWD is your best bet.

Have I got the vehicle for you:

http://charlottesville.craigslist.org/c ... 23076.html

M21 will bolt right in, but you may need to mod the oil pan.

I think you should do a diesel e24.