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Diesel conversion, VW TDI 1.9 ALH


couttsdesign

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I know that my '75 also had a steel return line under the car. Not sure when they started having them, but I think it have have been a smog related part to help reduce excess fuel going into the carb... I know I read about it somewhere when I first got into '02s but I can't remember where.

Tinker Engineering - 2014

 

Mica - 2000 BMW 323i - The one that started it all

Fiona - 1975 BMW 2002 - The Definition of Project Creep

Heidi - 1988 BMW M5 - The piece of BMW history

Silvia - 2013 Subaru WRX - Stock, for now

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One of the most important requirements for this swap is to get the gearing right. Given that the ALH diesel engine redlines at about 4800 RPM's I need to figure out how to get the RPM's low, especially for highway cruising at 80 mph. The way I will be doing this is to run an E30 differential, 2.93 ratio, and that is where I currently am in this project. However, as you may know this requires total fabrication of the rear subframe carrier and half shafts to work....or fork over $2200 and use the Autohaus plug and play kit. Pictures to follow soon......

1973 3.0 CS sahara

2000 VW Golf TDI

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Guest Anonymous

The rear end fab isn't very difficult. For the halfshafts you just need the later 02 style with 1980+ e21 or e30 inboard tripods. It fits perfect, I was working on this last winter but my account vanished along with my project blog and all my posts. I haven't touched any of my cars since early march, but hopefully will be back at it shortly(tomorrow is my first day off in almost a month).

Anyways, the fab work should easily be with in your abilities if you're sticking the diesel in. Since two minds are better than one, here's how I went about it.

1. cut an old driveshaft u-joint end off and bolt it to your diff(still attached to the subframe).

2. weld a brace securely holding that cut off joint in place, remove the diff and cut about 2/3's of the factory diff support plate off, or the full thing minus where the u-joint end is welded on temporarily.

3. Carefully support and bolt up the e30 medium case diff to the welded on u-joint.

4. E30 Factory is <1/8" steel for the monocoque portion, iirc it was 0.100". I started using a mix of 3/16" and 1/4" for my diff support "box", better safe than sorry.

5. assemble halfshafts with one e30 tripod. This is where my memory is kinda foggy because I tried every combination(early, mid, late '02, 77-79, and 80-83 e21 halfshafts, and e21/e30 tripods). I believe the late e21 tripods are the same dimensionally as the e30 medium diff because I recall being annoyed at myself after scrapping them and finding one later/noticing it was the same as the e21 ones I had. Small case diff e30 halfshafts were 8mm, the same as the '02 vs the 10mm m20 and late e21.

6. Purchase e36 medium case diff cover, it's a twin ear setup vs the e30 single ear. I got one for $60 shipped.

Food for thought. This way will leave the diff in the same location as the factory 02 diff; however, the e30 diff is larger all around. You will have a slight angle to the halfshafts(about 5 degrees iirc, well with in their range of motion). The diff is taller too, so you'll have to modify the trunk floor. Alternatively you can do some fancy jig work and mount the diff lower and forward like 02haus did, but with the tools I have available I was much more comfortable with my method. That way I know the differential is aligned correctly. The car I'm putting mine into is so far from stock that I don't give a second thought to cutting the floor up.

Another aside in case you didn't know. With e30 medium case differentials a 2.73 ratio was available in the first year of the eta m20s, 2.93's are super common and in all other etas.

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manimalnotsignedin wrote;

(Alternatively you can do some fancy jig work and mount the diff lower and forward like 02haus did,)

This information is incorrect. A lot of effort and planning was taken to make sure that the location of the output flanges of the e30 differential are at the same height and front to back location as the stock setup. We believe it is important to closely maintain the original geometry as much as possible and if changes are made, there are positive tested results, not guess work.

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It would be a lot easier to put the diesel from an old 5 series in it. I know it probably isn't as good a motor but it would be very similar to an m20 swap. Heavy though.

Not as good as a motor? I had an e30 324td touring and put 200.000km on it before i sold it with 380tkm. And i had an e30 saloon 324td with 60tkm on it. It's an awesome engine when you're talking about diesels from that period. 6cylinder engine, not diesel-sounding as long as you're driving, more like a turbine, great efficiency, a lot of torque and you could easily add an intercooler if you wanted.

I'd take the M21 out of an e30 though, because it has the more modern electronically controlled injection pump.

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Guest Anonymous

This information is incorrect. A lot of effort and planning was taken to make sure that the location of the output flanges of the e30 differential are at the same height and front to back location as the stock setup. We believe it is important to closely maintain the original geometry as much as possible and if changes are made, there are positive tested results, not guess work.

My statement wasn't meant to offend anyone, you just misconstrued what I said. The "fancy jig work" part referred to what someone with out access to a mill would have to do to mount the diff "lower and forward like '02haus did". That said, I did not participate in the construction of his subframe, though it sounds like you did(I highlighted the "We").

So, with that said, I just went to the garage and measured a stock diff and medium case. It's quite easy to figure out where the diff would have to me moved to. Square the input flange to a flat surface and measure the center of input flange to the surface, likewise for the output flanges. The stick the square on the input flange and measure to the center of the output flange for the length. If you want to be nearly 100% correct, don't forget the pythagorean theorem to correct for inclination. It's really not helpful though since a 1" rise over 10" run only changes the measurement about 0.05". Measurements from the stock diff are ~9.4" run and ~1.1" rise, medium case is ~10.5" run and 1" rise(+/- 0.1" since I was using a measuring tape). So it actually needs to come up 0.1" to have the output flanges at stock height, roughly 1.1" forward too.

Now for my assumptions. To make this a bolt in unit the diff needs to clear the floor, thus 02haus's unit moved the diff forward and down. Immediately it needs to move forward to clear the reinforcement between the shock towers. This is no problem since it will help bring the flanges towards the OE location. Unfortunately the diff is still too tall, so it must come down, which brings it further from OE specs. Really, this is no big deal though. Even if you dropped the diff 1" with 15-16" long half shafts, the angle of inclination changes by 3.8 degrees. At full compression of the suspension it still won't get into the "danger zone of self destruction" with an additional 3.8 degrees of inclination.

Now the advantage of what I did is the relocation of an 83lb mass, 1" further back. In the scheme of things this is inconsequential though, so I would never tout it as an advantage. Actually, after making those measurements I might machine out a 1" spacer. A totally random aside, unrelated to this build, but moving the diff 1" forward makes a the trans output flange to diff input flange length almost identical to that of an e30 325e when using a 3pc Getrag 265 behind the M10 in a 2002. So there, nearly bolt-in driveline good for 400ft-lb.

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I like your project that is a great engine with plenty of power and the potential to easily add a lot more. I have a 2004 tdi and it really runs well. I have gotten as much as 65 mpg on the hwy and average around 45 mpg. I will be watching your progress. I will be in So Cal in January and would like to see it if that could work out. This thread is about your car and should be kept that way. Keep up the good work!

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Thanks Manimal for your expert information. I'm pretty much in agreement with most of your comments. I'll get to why I agree with you in a moment, but here is what I have done so far....

I have access to a digital scanner at work, so I was able to manipulate the stock diff and the e30 diff in the tube. Also, I scanned the diff carrier.

This is a digital comparison of the two diffs with the axis of the inputs aligned and the axis of the output flanges aligned.

diffs_planviewcopy.jpg

diffs_side_01copy.jpg

Notice how when the input flanges are aligned the e30 diff is a bit taller than the stock diff. This created a problem with clearance to the floor of the 02 and also accessing the two bolts at the top of the diff carrier was impossible. Honestly, the fit was tight and probably could have worked with a 10mm spacer between the carrier bushing and the body of the 02, and a couple of holes cut out of the trunk floor to access the bolts to drop the diff.

This all probably sounds confusing, and it is...so here are some more pics to rest your mind...

IMG_7304.jpg

IMG_7305.jpg

IMG_7311.jpg

IMG_7319.jpg

So the last pic was the test assembly, just tacked together for a test fit. As I said earlier, the diff was too close to the floor of the 02 and I elected to lower it about 20mm. Here is the schematic of what I am planning on next...

diffs_side_02copy.jpg

Note the yellow colored diff is the same as the above pic (red e30 diff) but I have lowered it 20mm. In order to do this, I will have to cut a channel into the stock differential carrier and then weld my fabricated e30 bracket into the channel. Still in process and pics will follow.

So, In my opinion, the main take away from this long post is the last pic. The e30 diff input will be LOWER and FORWARD compared to stock. The e30 output flanges will be LOWER than stock. Stay tuned....

1973 3.0 CS sahara

2000 VW Golf TDI

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It would be a lot easier to put the diesel from an old 5 series in it. I know it probably isn't as good a motor but it would be very similar to an m20 swap. Heavy though.

Not as good as a motor? I had an e30 324td touring and put 200.000km on it before i sold it with 380tkm. And i had an e30 saloon 324td with 60tkm on it. It's an awesome engine when you're talking about diesels from that period. 6cylinder engine, not diesel-sounding as long as you're driving, more like a turbine, great efficiency, a lot of torque and you could easily add an intercooler if you wanted.

I'd take the M21 out of an e30 though, because it has the more modern electronically controlled injection pump.

One of the main goals of this project is to get INSANE mileage. I believe with the light weight of the 2002 and the modern efficiency of the ALH engine, 50 mpg/combined will be achievable. I just checked fuelly.com and there are a couple 524TD's registered with an average fuel economy of 28.7 mpg. Granted the 524 is a heavier car, so I'm not sure how much better that figure would be in a lightweight 2002.

Also, MUCH broader support for VW diesel in america compared to BMW diesels. VW just has many more years of selling diesel in the USA and hence, a much more knowledgeable population and vendor support for diesel.

1973 3.0 CS sahara

2000 VW Golf TDI

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I like your project that is a great engine with plenty of power and the potential to easily add a lot more. I have a 2004 tdi and it really runs well. I have gotten as much as 65 mpg on the hwy and average around 45 mpg. I will be watching your progress. I will be in So Cal in January and would like to see it if that could work out. This thread is about your car and should be kept that way. Keep up the good work!

Thanks Ken...for sure contact me before you come down to LA. Hopefully, we can drive around in it by then:)...BTW, I used to spend many weekends in Hood River and Bend when I lived up there in Portland. I miss it dearly....Black Butte Porter straight from the tap, hard to beat that!

1973 3.0 CS sahara

2000 VW Golf TDI

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(nt)

Edited by manimal

New M20 swap mounts when I get around to welding them up. I should make this font smaller because it may never happen...🙃

'71 2002 Restomod under the knife, 2012,...2018, 2019 it will run again! 2024? IDK

'74 260z K24 swap

 

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I can appreciate the time and work that both of you, couttsdesign and manimal are investing in your projects and I nor anyone else should say that your approach is right or wrong, unless of course you ask.

When we, Rob (2002 Haus) and I first started contemplating producing an e30 differential swap that would be a bolt in kit we made a list of what we thought was important. 1- improvement over stock for high HP/Torque applications, 2- maintain stock mounting locations, 3- ease of installation, and 4- keep the price as low as possible on a quality product.

We started by building a jig using a stock rear sub frame with the stock differential bolted in place and made centering pins to locate the center of the differential output shafts as well as the other mounting points for the sway bar, trailing arms and the rear carrier mounts. A new sub frame was built on the jig using the centering pins to locate the center of the output shafts on the medium case e30 differential. I checked the measurements under the car with the original sub frame and differential mounted and then mounted the new sub frame with the e30 differential to confirm the measurements and they are the same to the center points. It is a tight fit but the e30 differential output shafts are in the original location. I have had it installed in my car so I know it is possible. I am supplying this information for others who may be reading this thread. You can chose to believe it or not but it is true.

This kit comes with a new sub frame with built in adjustments for toe and camber, rebuilt CV joints assembled onto new half shafts made with heat treated 4340 steel. We wanted to use new parts where ever possible to avoid any possible metal fatigue problems.

I built a 1 off version but we felt the cost would be too much for most customers. This is a picture of that half shaft assembly.

Conversionhalfshaftassembly.jpg

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