just confirmed via the corroded metal tag on the diff
S391 = 3.91 gears with limited-slip 
so that is the medium-sized LSD from the mid-80s 325is, instead of the stock small-case open unit that would have come with the 318i in '85
woo!
unfortunately, I think that by itself kicks me out of stock-class rallycross unless there is some kind of update-backdate rule.
Yeah, that intake hose before the filter box is not factory. The original parts are probably still available.
Coming from the much simpler 2002 world, it's hard for me to believe there's an M10 hiding under all that.
I know it kicks you out of stock. I am not sure about PR. Does it meet these requirements?
RXR said: Differentials must be contained in a stock unmodified housing/thirdmember with stock or optional ring and pinion ratios available for the specific model, body, and year of the vehicle only.
If not welcome to M2 (maybe MR next year)
In reply to moxnix:
I'll have to do some reasearch. What class I"m in isn't of much concern to me, honestly. I'm in it for fun with no expectation of winning with a 100hp car, lol.
My info about that diff being from a 325is is from wikipedia, so it very easily could be wrong. Considering how stock the rest of the car appears to be, I find it interesting that someone would have done a full diff swap to one with a different case (requiring a different crossmember, I think).....
We'll see....but M2/MR is probably fine anyways. I can't leave things near-stock for very long anyhow, based on past experience. That's why I had a freaking E-Prepared Maxima for autcross, and the WRX is going to be up into SM next season, lol....
Also, looking at WDCR RallyCross results, it looks like the SR, PR, and M2 classes have pretty similar times anyhow, so whatever.
SR and PR maybe because it is mostly those 3 guys running the E30 BMW. You can't have more than 2 people running the same car in the same class so the third guy runs PR. But my times in M2 have been a decent amount ahead of them this year. If you are planning on pulling the carpet anyway you will end up in M2/MR with it.
When looking at results the one thing you don't see is what run group they are in. Different run groups may have very different conditions thruout the day depending on when they send out the water truck and how much water it puts out that time thru.
You coming out to the one on the 16th?
What size are those copper nuts? I kindof want them. They look cool. 
Damn you ran up on a deal. Great find. Keep us updated
I very much approve of this thread.
This has the makings of a great build thread. It would be cool if you keep us up to date. Love the e30s!
Should we expect to see this at the next DC Region RallyX?
my '85 318i had an open 3.91 in a small case. I've never personally seen that ratio in a medium case.
turn the ignition timing ahead, that really wakes them up.
4th pic from top is a maf sensor. if its good that can be worth a bit of dough.
Nice deal!
I've got a complete M42 with harness sitting in my shed...I need to get rid of it!
Those copper (exhaust manifold m6?) nuts are $$$ from the dealer for what they are.
i suspect that diff is stock. the 325i had either a 3.73 or 4.10
+1 for boost! 
2002maniac wrote: i suspect that diff is stock. the 325i had either a 3.73 or 4.10
Interesting.....I can't find anything suggesting that the '85 318 came with a LSD (or had one available), but this is definitely an LSD.
The info. I found says that pre-1986 325is were available with a 3.91 LSD (and the other two ratios).
CLynn85 wrote: Should we expect to see this at the next DC Region RallyX?
Expect to see it at the first one of next season. As of right now I don't even have tires to get the car to Summit, much less run. I don't plan to register or insure it until the spring....not going to pay for that stuff while it's sitting in the garage!
I work pretty fast though, so the plan is to have it ready to run by March or so. Thankfully the heater still works fine!
familytruckster wrote: Nice deal! I've got a complete M42 with harness sitting in my shed...I need to get rid of it!
don't tempt me.....
I want to sort the suspension and rest of the car before messing with engine!
I'll post a pic of the diff up tonight. I dont' know visually what the difference between the small and medium case is.
Other odd thing is that the diff fluid fill and drain plugs are offset diagonally - all e30 diffs I've ever seen have them oriented one directly above the other.
so here is the diff that is in my car
note the offset fill/drain plugs, which are vertical in pretty much all other BMW diffs that I know of.
is this the "small case"?
I don't know what I'm talking about, but I believe the E21 320is (unofficial designation, but the sport model of the 320i that added stuff like a rear sway bar and some sweet factory Recaros that I put in my non-sport 320i) came with a 3.91 LSD. Your 318i has the heart of the E21 320i under the hood, so maybe that's the diff you've got. I haven't had the car in years so I can't tell you if the diff looks like the one you posted or not.
interesting...didn't think to look back at older non-e30 models..
one nugget I did find is that Canadian-market early 318s were available with an LSD 3.91
At this point it's moot though - I'm going to build to prepared spec, since that will allow me to put the 325's vented rotors and bigger brakes up front, which I think this car sorely needs for rallycross and all the braking it will be doing, as well as using poly bushings.
prepared allows an LSD as long as it's in the factory casing, and the diff casing on mine is same as factory.
Since I just ordered the first parts, I'm going to start a seperate build thread on here tonight. Will post up a link
That sensor isn't for engine management, it's for the little display unit that came optional on the 318i. (OBC, on board computer)
It's supposed to read outside temp.
here's the build thread
http://grassrootsmotorsports.com/forum/grm/mein-e30-mein-sammlungkreuz-baugewinde-my-318i-ral/40440/page1/
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