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    Originally posted by The Dark Side of Will View Post

    This is how EVERY bolted joint works.
    Uh, no it isn't. Only a slip-critical joint works by the friction of the materials clamped together (and the bolts usually have to be fully tensioned, instead of the usual snug tight). Other connections might only be in tension, but no shear at all, and some rely on the shear between the two planes (plates) acting on the bolt cross section. It all depends on many things, such as materials, cost, available space, constructibility (or manufacturing), and of course engineering/codes. I've worked in structural engineering a loooong time - I've seen every bolted connection you can imagine. :)
    Build thread



      Originally posted by NC325iC View Post
      RE: M7 x 60mm studs
      would something like these M7 to M8 studs work? May need to increase the hole size in the manifold
      Those may work, but... The manifold is plastic with metallic inserts to provide strength and something solid to torque the bolts against. Six of the 7 holes are about 8mm in diameter, but the center hole is 7.1mm. I believe BMW made the 6 holes oversize to allow for ease of assembly and possibly for expansion of the head? The center hole aligns everything from end to end.

      Not sure how much could be drilled out in order to make things fit and still retain the strength needed.

      7mm bolts/studs are an odd size in my experience. Pun intended.

      I guess HomeDepot has the bolts.
      Last edited by LukeJ; 07-08-2020, 12:40 PM.


        Originally posted by nando View Post

        Other connections might only be in tension, but no shear at all, and some rely on the shear between the two planes (plates) acting on the bolt cross section.
        Point to one on a car.

        EDIT: yeah, holding a brake tube against vibration might not be a serious stressor for a bolt in shear, but those are typically sheet metal fasteners rather than machine threads.


          Dude, I'm not going to argue with you, you always seem to "know everything". But I just finished a million dollar walkway replacement at a dock that had all three types of bolted connections in one bracket (it was a pain in the ass, but when you're stuck with existing conditions, you gotta do what you gotta do). Bolt engineering isn't any different because it's on a car or on a building - the same principles of load paths, tension, shear, pinned/flixed/sliding, etc. apply. Different bolted connections are designed in different ways, they're not all "slip critical" on a car either.
          Build thread



            Not like shit I built is in orbit or anything...

            ETA: aaaaand I have to specify automotive applications on a car forum? ok, I'll get right on that.

            ETA2: yes, there are other types of bolted joints in the world. They might as well not exist in automotive engineering.
            Last edited by The Dark Side of Will; 07-09-2020, 06:50 AM.


              Well, if you want to go there - head bolts, are not in shear at all, they are completely in tension. The trailing arm bolts on an E30 are in shear, but they are not slip critical, same with the lower bolts on the rear shocks (this would be a pinned connection). The control arm bracket bolts are in tension only, because they have a shear key built into the frame so the bolts don't have to take it. I could go on and on, but I won't bother.
              Build thread



                Not sure how you're misinterpreting what I said, but I never said bolts were only loaded in shear.

                The RTA pivot bolts clamp the faying surfaces at the ends of the steel tubes inside the bushings against the mounting ears on the subframe. Those bolts are loaded in tension and suspension loads handled by the friction between the tubes in the bushings and the mounting ears.
                Last edited by The Dark Side of Will; 07-09-2020, 11:13 AM.


                  Just stop dude. It's off topic, and you're just arguing for the sake of arguing.

                  BTW, I actually taught a class about this stuff for several years, if you want to talk about dick swinging contests.
                  Build thread



                    Nando’s just trying to help you understand why you were wrong in this post. Not much to misinterpret, but I agree that we’re getting off topic and appreciate the effort to move on.


                      It looks like my last real update was some vague rambling about driveshafts. I'm still slightly worried about driveshafts, but I've scratched my head enough to decide that it's a solvable problem down the line. I came very close to having a driveshaft built *now* to make sure my geometry for the engine and trans worked, but after some concern that my silver car might have a different CSB arrangement (it's an 87, and thus fully early model) than the red car (an 88, the transition year which I thought was an early with late bumpers but I'm finding out has a lot of late tweaks) I abandoned that effort. Here's a useful diagram for the e30 driveline so you don't have to crawl underneath and pull your heat shields:

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                      Hilarious, right? it's an ix and completely useless to me... but I need as many Nando points as I can get. Anyway... using the front half of the e30 auto driveshaft installed backwards (which offsets it to one side, but ignore that for now) I was able to just barely hold the front half of the Z4 driveshaft in place and check vertical alignment of the flex disc. The spline direction is reversed between the two shafts, and on opposite sides of the CSB, allowing this unusual install. To get the flex disk suitably centered I needed "four washers" spacing the CSB down. There's references in the e36 driveshaft alignment TIS allowing up to 2 mm of "shims." I'm twice the tolerance... or in other words "only 2mm off"

                      Realistically, this means I have the ability to move the CSB up and down, and the ability to move the trans down, when making the final driveline adjustments (either a straight driveline or parallel pinions either side of the U joints). That's enough for now. This is probably all going to be different in the other car... As long as I don't have to move the CSB up into the rear seat to make it work it's solvable.

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                      While I was rolling around frustrated with the driveline, I took delivery of a very cool puzzle:

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                      I've designed hospitals and walked onto a jobsite and seen steel pieces that I detailed magically appearing in reality, but for some reason this was more immensely and immediately rewarding. Something about how many people are involved in that process so you're able to assume it works because of the group makes it feel easier, but even if I push this whole thing into a lake next week it was cool to prototype, draw, and tack up a bracket like this:

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                      I should have made the slot on the upper side longer, and the diagonal plate/brace shorter (I had to trim the mount to clear . I have two more gussets but don't want to add them until I can finish weld on the inside. Other than that I think all the clearances are ok, and it certainly leaves more room to work on the flex disc:
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                        I'm just going to post some images of the pan flange too... I'm not sure I know enough to make any improvements to this at the moment... it came out exactly like I'd hoped:
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                        1/4" is obviously too thick. I need to research the part numbers for the bolts for the aluminum pan and figure out what actual thickness is too much. As long as I can get bolts... I'm fine with 1/4 because I'm not going to warp it between bolts when I marry the pan pieces up, I think the engine-side plates made an appearance earlier during the bolting discussion, but here's one of the other pieces. All four of these fit perfectly, but be aware that bosses in the block that weren't used for your factory install probably have fouling in the threads from corrosion. On both of the blocks I have I can't get the bolts all the way in and will need to chase the threads if I want to use those locations (but they do appear to be fully threaded and deep enough)

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                          After honestly a full week of wiggling, shimming, jacking, levering, measuring, and angle-finding... I decided that the engine was in the right spot. I tightened the trans mount bolts, and fitted the worlds most rigid motor mounts:

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                          Not a lot of pride in these... they were UGLY. Cleaning the inside of the framerail to get something to tack to... not wanting to make too much heat right next to my plastic and magnesium engine. On top of that I managed to lose the shroud to my mig welder on the one day I had to work put real time into this and get everything out, so I made one out of a piece of radiator hose. It was kind of a day, but the fixtures seemed like they would work. I then executed the procedure that I've described poorly to everyone who's shown any interest in this project. The engine and trans package came out again:

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                          and the not-a-pan fixture went back in by itself:

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                          That is, within a mm or two, where the pan gasket mates to the bottom of the engine block when it's oriented correctly in the chassis. I briefly load tested it with a nervous 6 year old, and dropped the bare block on:

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                          This... is... so... cool...

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                            you know what? I'm not done. This is so cool.

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                            "I wonder what it looks like with the head!" oh, it looks like this:

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                            "what about with the valve cover?" gotcha covered:

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                            "it was hard to see what the clearance at the firewall was with the engine dressed" ok here:

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                            "that looks like it's too far forward! why didn't you move it back!" well... the trans was hitting the tunnel after this, and so going back further meant going down. Going down meant clearance problems with the steering rack... so this is pretty much it. This is also what my pre-first-post guess was, which was "I bet if I line up the shifter with the hole in the tunnel it'll kinda work"

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                            There's miles of clearance at the front for a radiator... but probably not the radiator and Z4 fan package unfortunately. I have a Z4 fan here, and I'll try it again now that I don't have to push it against the engine on the way in. That lower radiator support at the top of the frame (visible on starboard side above) also isn't on my early model and I couldn't cut it out with the full engine in place.

                            I have some progress on the engine arms and motor mounts, but I couldn't find one of my pieces while I was doing it so the photos aren't great. I've found them now, so the next update will show engine plate location options (I've picked the location on each side) and how the e46 hydraulic motor mounts are going to adapt and locate on the e30 subframe.


                              ix questions for Nando... Does the ix not have a front swaybar?!? I clicked through to this from a google images search:


                              Is the reason no one considers an ix subframe and leaving the rear sump intact because the ride height comes from the ball joints being lower (relative to the frame rail?) What's the ground clearance of the aluminum crossmember vs the 2wd m20 pan?

                              Edit: Search indicates Nando has been answering this question periodically for 15 years.
                              Last edited by hubcapboy; 07-14-2020, 03:01 PM.


                                So I've been staying busy with all the 'extra downtime'.

                                I started out trying to model the factory E85 driver's side engine mount. I quickly decided that was a waste of time since my mount will look nothing like it anyways.

                                So the main thing is the relationship between the 3-4 holes on the engine side to the one hole one subframe side. I measured to the best of my abilities with a small surface plate and several different measurement tools. Then once I had something digitized, I printed a side view to scale and compared it to actual parts/hole patterns. At this point it's close enough and I can 'massage' the parts or adjust the models in the future. The other aspect is the 'implied' one inch dimension change moving the engine toward the firewall 1". My engine mount had the rubber mount hole lined up with the flange hole on the lower rear corner. (looking from the driver's side) That was the dimensional change and everything else was 'filling in the blanks'.

                                So the first assembly I made was a collection of 6 machined aluminum parts that would be welded together. Second row, upper right corner. "Extra" holes were added to ease in fixturing for cutting the angles.

                                The second assembly is the evolution of the first. It's three machined parts to be welded together. Third row.

                                Then I decided to go along the mixed metal route. I modified the parts to be an aluminum piece that bolts to the block and then flange bolts come through the backside for the steel flange fastening. The other parts could be water jet or laser cut. Top row.
                                Lastly, I made probably the strongest version that utilizes 2.5" square .188" wall tubing and a smaller piece of 2" square .188" wall. This assembly also uses the aluminum part bolted to the steel weldments. Bottom row.

                                I can't get into the machine shop so all I can do is 'draw' in the computer. Other than printing things to scale and relying on my years of experience, I can't guarantee fitments. My car is still functional with the M20 in the engine bay. The subframe I ordered is 'hung up' with the seller not responding to my messages.

                                I was originally just going to see if I could modify the factory mount in a reproduceable way. But all I can do is stare at it ATM. So I did all this other stuff in the meantime. lol

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