My '75 2002 Sleeper

[SkiFree]

Glad to see you got the parts.....

Quick question, what is the i.d. on the mouth of the itbs?

[JoeMadoo]

These last 22 pages just blew my mind. Amazing things going on here.

[e30_neverstock]

those itb's are looking great. i need to do the same thing for my 2002, but i need a little more practice with my tig welder.

[325ix]

I can't wait until I have the time/space/money to do something like this. The car looks awesome, I can't wait to see it rolling down the road.

I also really want to learn to tig weld. I learned most of the other types but, never got to learn that one.

[evandael]

very inventive work with the ITB adaptation, i always admire how simple you make it seem!

[tinkwithanr]

Thanks for the tip. I have been using my MAP torch to Preheat for now. Ideally I'd love to be able to find an old oven or something like that, it would be a lot more precise. But for now the torch is getting the job done. It definitely makes a difference.

[maniacmatt]

I find when you weld cast aluminum like that manifold, a good preheat works wonders.

I used to have a hell of a time with cast aluminum and then I was talking to a friend who does powdercoating who was telling me about how he has to pre-bake all his cast aluminum parts to keep them from "out gassing" while the powder is curing.

Basically the principle behind it is that cast aluminum is very porous. So air, containing oxygen, is trapped in those pores and then when you heat it during welding the air escapes or "out gases" right through your weld puddle. If you preheat it most of the air will escape during the preheating not while you are welding.

PS: I love your project and am super jealous of your work space.

[Zreberlcoe]

This is sooo freaking cool. I'm 16 and I really want to just dive into a project like this.

[tinkwithanr]

Picked up some more parts for her over the past week.

Euro Turn signals. These sit flush with the fender as opposed to the stock US-spec bits, which stick out pretty far to the side. They aren't brand new, but they will fit the patina of the rest of the trim nicely.






5-Lug Rear hubs and new rear brake rotors. These will round out the rest of the 5-lug swap (pared with the e12 front struts) and the rotors match the vented front ones that came on my struts.






Then I got a box of goodies from IE, including: Front and rear sway bars (2002 front, e30 rear), Posi-lock Camber and toe adjusters, New poly bushings for the front and rear suspension/subframes, and a lower oil pan baffle. These (plus the coilovers) will let me mock up all the suspension parts and make sure everything fits and works together.







I also got some work done on the itb manifold. In this first picture you can see the adapters I turned on the lathe to mate the stock 'i' manifold runners to the throttle bodies. They started as aluminum tubing 1.5" i.d. (~38mm) and 2.0" o.d. This will leave me plenty of material to help merge the ovalish shape of the runners to the circular shape of the throttle bodies. With all 6 made I tacked them in place on the manifold, 91mm apart.









If you look at the above picture, you can see how the 2" o.d. of the adapter is wider than the sides of the runners. In the picture below, you'll see that the inside of the runners are narrower than the i.d. of the adapter. In order to help these transition from one shape to the next I'll weld extra material to the outside of the runners. Then the inside can be ported out to the adapter diameter without worrying about making the walls to thin.






Here you can see the opposite runner with the adapter fully welded on. You can see all of the extra material welded on the sides to help build up the wall thickness. Also don't mind how ugly the welds look. The intake casting is full of contaminants, so no matter how clean the surface is as soon as I start my arc it just bring more crap to the surface. Aggravating to say the least.





Here is a close up of the adapters and the throttle bodies. You can see how the lip on the adapter mirrors the lip on the throttle body. This will let me use the stock rubber boots that BMW used on the bike to seal the intake tubes.





And here is the boot. I ordered 2 new boots (only 1 set of throttle bodies included them) and 6 more hose clamps that fit on each side of the rubber for a complete set. The rubbers have a step on the i.d. that grabs the lip on the throttle bodies and adapters that will help to seal and hold them in place.






Lastly, here you can see how the linkage works. The middle throttle bodies have the standard cable operated rotary linkage, but only one of them will need to be operated in that manner. To 'link' the rest of the throttle bodies to the cable operated one, the 'tabs' on the left sit in between the two adjusters on the right. Because the throttle bodies are 18mm further apart now, I just need to weld gusseted extensions onto the tabs (304 stainless) so that they will function as they used to. This will let me adjust the plate position of each throttle individually with respect to the others, and dial them in properly.






Thanks for looking.

[tinkwithanr]

To each his own. I do like the look of the rabbit flares, but they just don't really give enough extra room for wide rubber. I wanna run at least 245's, and maybe even wider in a racing slick for track days, so that was a big concern for me. I definitely want some meat on the tires.

The fact that they are fiberglass doesn't really both me. I mean the entire body of corvettes are made from the stuff. Plus it's the OEM way BMW did it, I like to think they knew what they were doing back then lol.

[CubbyChowder]

With all this insane metal fab work going on, it bums me out that you're not welding in fender flares. I understand if you're going for a certain look with those flares, there's just something about fiberglass/plastic that doesn't settle well with me.

Regardless, I love the progress on this. You are really going hard at it as frequently as you can, and I really respect that. I've been having some lack of motivation to work on my '02 lately as every day solely consists of tedious filling/sanding/grinding/etc. and results come VERY slowly. Keep it up dude, you're a boss.

[tinkwithanr]

There's really nothing to complex about making them. The hardest part is having the tools to properly machine the manifold and then weld the tubes back together. Once that's done it pretty much just connecting them to an intake and making the throttle linkage.

[knuklehead92]

if you get the itbs working properly please do a diy lol

thanks for the fuel pump!

[tinkwithanr]

Sorry, not really looking to make any kits or anything like that. Don't have the time or energy to put towards it.

As far as build plans:

1. Buy two sets of throttle bodies
2. Cut stock manifold
3. ???
4. Profit

[TrentW]

Great work on those ITBs!

Agreed. I've been contemplating ITB's for awhile and now you've got me started again dammit.

How bout possibly offering these as a kit or at least build plans?

This thread delivers!