E30 M3 S62 Build - Loads of queries about 4x4 drivtrains

[nando]

Yes, you'd have to have the "tone rings" used in the M5 ABS/DSC, steering angle sensor, chassis mounted accelerometers and anything else the E39 DSC uses for input.

It might not be *accurate* because of the different wheelbase and steering angles of the E30 at a given lateral g, but it would be something.

I was talking about using the X5's DSC for the transfercase, not for the M5's oil pan/pump. I don't think any of that would work with the X5's oil pan anyway.

regarding the transfercase and shaft alignmnent - I don't think it would be that much of a stretch if you didn't mind cutting into the trans tunnel. the output shaft is pretty low, almost the bottom of the engine - so even though it's 4" closer to the drivers side, it's not ilke you have a shaft running right next to your knees or something.

I don't like the idea at all of using U-joints, there's probably a reason BMW makes all their shaft alignments as straight as possible. but, sometimes you gotta do what ya gotta do. :)

[Turk]

So am I right in think diff wise you have managed to get the x5 one in BUT it fouls the various racks you have tried on the banjos?

When will you be performing the T-case Yoke-an-ectomy?

Everything you're saying make sense and no doubt I will have to head down the same path.

Which other t-cases have you looked into?

[The Dark Side of Will]

I had not considered using a DSC system, I have no idea where to even begin. Would I be able to use anything factory? wouldn't it mean integrating the correct sized wheel speed rings, steering angle sensors etc, etc?

Yes, you'd have to have the "tone rings" used in the M5 ABS/DSC, steering angle sensor, chassis mounted accelerometers and anything else the E39 DSC uses for input.

It might not be *accurate* because of the different wheelbase and steering angles of the E30 at a given lateral g, but it would be something.

[The Dark Side of Will]

My pics are on the E30tech thread I previously linked.

Due to the fact that friction due to motion is what destroys the splines in the E30, E34 and E53 T-cases, my fixed yoke would be truly fixed. Basically, it would be a short splined stub shaft as long as the driveshaft receiver hole in the sprocket is deep. The stub would be splined to take advantage of every last .001" of spline length in the sprocket. The stub would be drilled and tapped axially at the end that goes into the sprocket. The sprocket would be drilled and maybe counterbored so that a bolt could go through the back wall of the sprocket and screw into the stub to retain it in the sprocket so that it never moved at all. This is why the T-case would need to be disassembled to install the stub.

At the outer end of the stub would be a flange to which a U-jointed driveshaft like the E46 or E90 unit would bolt.

Since the driveshaft is steel, but the engine, oil pan, transmission case and transfer case are aluminum, there will be a difference of a several thousandths of an inch in the length of the powertrain and the length of the driveshaft as the engine and transmission come up to operating temperature. While this may not sound like much, if everything's bolted fast the small change in length can put very large forces on bearings and such.

So yes, I think that the front driveshaft would need a very small amount of plunge in order to operate with a fixed yoke.

I suspect that the splined fitting used in E46 T-cases has some plunge to it. For some reason, the E46 flanges seem to be much less failure prone than the E30/E34/E53 splines.

[Turk]

Any progress pix Will?

You have confirmed a couple of my fears.

I suppose the ides would be to find a t-case which has its in out shaft centres as close to the x5 as possible. I appreciate what you are saying about the centreline difference between the e3/e34 and e53 front diff locations in relation to the output of the t-case. Im guessing the x5 prop is similar to the e30 one whereby it is fixed (no u-joints?)

re chopping up the floorpan... I was fully expecting to have to do this :(

Double u jointed shafts could be made up as long as 2x correct sized flanges are available

fyi have a read of this- http://www.jeepforum.com/forum/f9/wh...nt-one-854790/

Would the prop benefit from having a splined 5/6" section to allow for a bit of push and pull?

[The Dark Side of Will]

there's always the BFH and/or a welder. :p

with the later transfercase you'll need something to control it. perhaps something aftermarket, perhaps the entire ABS/DSC off an X5.. I think that's why the other guy ended up going with a more standard GM type transfercase.

"The other guy" (me) has decided to use a GM transfer case for a number of reasons.

The biggest is what I alluded to above regarding the size of the E53 T-case.

The E30, E34 and E53 T-cases have a one piece front driveshaft with no u-joints. I comes straight out of the front of the T-case and goes straight to a guibo on the diff input flange.

In the E30 and E34, the diff is very close to the crank centerline, almost under the engine. This is possible because the I6 engines are tilted over. The oil pan rail on the left side of the block is high enough that the diff can fit under the side of the block. The floor pan is shaped to accomodate T-cases that stay very close to the profile of the RWD transmission and driveline.

In the E53, the diff is much further away from the crankshaft. This is necessary because the V8 sits upright and the left pan rail is too low for the diff to fit under. The diff has to bolt to the side of the engine. This means that it's something like 4 inches further from the crankshaft than it is in the E30/E34 cars. So to make the T-case front output line up with the diff input flange, the T-case must stick out 4 inches further than the E30/E34 T-case.

So to use a T-case that will fit into the E30 trans tunnel and the E53 V8 oil pan and diff, I need a driveshaft with u-joints. I *ALSO* need a way to overcome the habit that the E30 and E53 units have of stripping the splines from the front driveshaft and front output sprocket.

I figured out how to convert the E30 T-case to a fixed yoke front output, which would have allowed me to use a modded E46 front driveshaft. However, in order to have the best chance of success with S62 power, I'd need to start with a new sprocket, modify it for the fixed yoke and disassemble the T-case to install it. Between the sprocket sets and the custom machining and fab work for the fixed yoke, I was looking at $1500, and I would end up with a T-case that would still be marginal with 400 HP...

So to have the assurance that it will be as durable as I'd want it to be, I'd have to see if I can upgrade the 3 pinion center diff to 6 or 9 pinions, take a look at the chain, etc...

It was a deep deep rabbit hole I didn't feel like crawling down, so I decided to go with something that I had good confidence would be strong enough out of the box and that I could obtain cheaply while preserving the functionality of the original BMW T-case. I may have to carve up the floorpan, but we'll see how things fit...

[craiggroves91]

Can't wait to see this thing done

[SacE30]

oh my. this will be amazing

[The Dark Side of Will]

I don't think the E53 case will fit under the E30 floorpan.

The E53 diff is much further from the crankshaft centerline than the E30 diff is. This means that the E53 T-case is much wider than the E30 T-case in order to move the driveshaft acorrdingly.

[Turk]

I am better with the electronic tbh, But physically making bits is also interesting. Cutting and measuring and tack welding is no issue, but would have to have the proper welding done by a pro.

I had not considered using a DSC system, I have no idea where to even begin. Would I be able to use anything factory? wouldn't it mean integrating the correct sized wheel speed rings, steering angle sensors etc, etc?

If I could wire something standalone up to "hold" the centre diff in the right place offering the limited slip needed that would be fine and preferable if it means I can use the x5 TC.

If it were to be fitting the M5's dec system completely to the car I would probably try and steer away from that as it would the mean going back to square 1 re the x5/s62 sump dilemma.

[nando]

well, have you given any thought on intergrating the DSC system into the E30?

it really depends - if fabricating stuff is your best thing, then your options are pretty open. Me, I'd rather have the factory "make" the stuff, electronics are easier.

[Turk]

So what type of case am I looking for?

[nando]

it will work as an open diff but there'd be no way to limit slip

you can't weld a center diff.. it would bind insanely at speed. like a 4x4 pickup truck. if you left it open you're stuck with the same problems as the E46 case.

[Turk]

So if theres no management the basic cogs won't turn? electronic clutch? can it be removed in order to just offer straight drive maybe in the same way a welded open diff would work?

I suppose using a non bmw case isn't such an issue if the distance between centres of shafts is the same or very close to standard. I will be welding the mounting tabs on anyway so can make these up as needed.

[nando]

there's always the BFH and/or a welder. :p

with the later transfercase you'll need something to control it. perhaps something aftermarket, perhaps the entire ABS/DSC off an X5.. I think that's why the other guy ended up going with a more standard GM type transfercase.