Pitchblack Motorsports Rally e30 318i (now with M50) - and some Porsche 924S stuff.

[irish44j]

hey, honest to god, I botched that run and it wasn't intentional. I hit some rut/ditch that kicked me sideways, directly into a cone I hadn't hit all day, and was just out of sorts after that. Josh mentioned that he thinks that he's had random issues with the diff not unlocking and that that may have been what happened.

I had been planning on, and just drove as well as I could for every run until the last of the day. If I was between, or even potentially ahead of the two of you, I planned to trip the start and count out a few seconds or intentionally pick up a cone or two. I didn't want to do it till the last run so I'd know for myself how I stacked up against everyone over the course of the day and would have some idea where I might end up if I didn't purposely chunk the last run. Once it came time for the last run, I knew I wasn't going to catch Josh and that you hadn't caught Eric or Josh, but that I might be able to catch Eric. Since co-driving, I knew where you guys had ended up w/ your last runs finished before mine started.

Another run and I might have caught Josh, too. I was slightly careful to make sure to not cone away my last run with the chance to catch Eric and left a little on the table.

I can't thank Josh enough for letting me run his car, especially with some fresh(er) tires. It was awesome :)

Will take your word for it, lol. Wasn't trying to start a fight here or question motives.

But the diff issue is legitimate, and it's been doing it on and off all season. Sometimes if I come out of a slow corner or stomp the throttle through a loose section, it definitely feels like the diff is doing something funny and the rear of the car heavily "walks" to the side. I've tried different fluids which sometimes make a difference. I've added and taken out friction modifiers, etc. Just odd because it's fine for run after run after run, and then out of the blue I do the next run exactly the same and find the rear of the car stepping out on acceleration where it hadn't been doing it before. It's really a feeling of total lack of control over what the back of the car is doing, and I'm not sure if it's because it's holding lock too long, or if it's not locking at the right times....

I DEFINITELY had the issue last weekend the times I dropped into 1st on the horseshoe. Coming out of there both times I did it I damn near slid the car into the first gate (think I actually did hit it once). So it wouldn't surprise me that the same happened to you.

IDK, diff rebuilds are not my strong suit, but will definitely have to do something this winter I think.

[irish44j]

Edit: I assume way too much, and am bitter about losing to Eric.

Eric is starting to worry me. He's only going to get better, and with his low experience he'll do it faster than us old men will, lol.....

[spoth]

Diagnosing the diff is easy:

http://spece30.com/forum/48-drivetrain/53337-lsd-clutch-test

Rebuilding the limited slip isn't too bad, even Yoshi can do it (I've done several, would be happy to help):

http://e30performance.info/viewtopic.php?f=22&t=939

And here's the parts you'll need for your dinky 4 cylinder diff:

http://thayermotorsports.com/collections/168mm-standard-service-parts/products/bimmerdiffs-168mm-refresh-kit

[irish44j]

So back to car work.....

Let's get this stupid heater/HVAC stuff out of here. The eventual plan (i.e. before winter) is to pick up one of those aftermarket heater cores from Summit or Jegs and install with one vent to the windshield and one to the single dash vent. But that'll come later.

So after much cursing and working around my rat's nest of wiring, finally got all this crap out. This is, of course, both the heater core, fan, and A/C condenser stuff. It takes up a lot more space than it looks like, and all in all weighs in around 25lbs or so.





lot of space back there now



and a lot of messy wiring



I won't bore you with photos of me cleaning up wiring, but I did a ton of it. With that done, thinking about the empty HVAC sliders position and figured I'd just build a new switch panel for the center of the dash. Had some old Lexan scrap sitting around, so fabbed up a panel for the fuel gauge, power outlet, and some switches.



Not feeling especially creative, I just gutted the stock center console piece (which already has mounting points to the dash) to use it as a backing/stiffening plate for the Lexan piece



Painted the backside of the switch panel black (so I don't have to see my wiring) and then sanded the front of it, so it kind of just blends in with the flocked dash I guess. Wasn't really a real cosmetic effort, to be honest. I hate doing anything related to wiring and just wanted it back together.

So here's how it turned out:



Empty holes are either accesses for the upper mount screws or blanks for future switches. The bottom area is empty because I'll use that area for other stuff. Since the Jegs/Summit heaters appear to come with some pretty lame fan speed switches, I left the OEM one in the new piece and can hopefully just use it to control the new fan. TBD, but I have a lot of space on the panel in the event that I have to use the one that comes with the heater.

Last thing to do was to seal up the hole into the engine bay. For the time being I just used my favorite ghetto material: a cut-up Rubbermaid bin cover. Eventually I'll probably put an aluminum sheet there or something, but this should do fine for the time being. Also painted the areas that I couldn't get to with the old HVAC in there...

[ForcedFirebird]

And here's the parts you'll need for your dinky 4 cylinder diff:

http://thayermotorsports.com/collect...mm-refresh-kit

That's a fairly hefty mark up on those parts. The dog ear plates are available for ~$42/ea and the clutches are ~$35/ea if you shop around.

[irish44j]

That's a fairly hefty mark up on those parts. The dog ear plates are available for ~$42/ea and the clutches are ~$35/ea if you shop around.

Probably not worth it anyhow for me. Most likely will change to a medium-case next year so will probably just tough it out as-is for this year. But thanks.

[irish44j]

ugh, just did the test. Breaks loose at around 20lb/ft. Guess the LSD is definitely shot :/

[econti]

Go medium case! Mine was out of a 325i auto, 4.1 ratio.

[ForcedFirebird]

Medium cases in the z3's also came in a 4.27 ratio LSD, but am fairly certain they are all Torsen and not clutch type from the factory, though. I have one and put it in my car for a track day, the acceleration was awesome, but had to shift too many times for my liking.

[kts]

So that taken care of, it was time for some drinks at the rather pathetic local bar scene. It’s pretty sad for a “college town” (Frostburg State University) on a Saturday night, but did result in a nice semi-hangover the next morning for me. D’oh.

You were there a week too early, they don't start the semester until the end of the month so you were there in the quiet summer time. It's the same on my campus (dead until today when move-in starts and then 30k+ students all moving in over the weekend.)

[irish44j]

Medium cases in the z3's also came in a 4.27 ratio LSD, but am fairly certain they are all Torsen and not clutch type from the factory, though. I have one and put it in my car for a track day, the acceleration was awesome, but had to shift too many times for my liking.

Yeah, I plan to stick with the 3.91. It's perfect for rallycross with the G240 ratios. For stage work, where I will be doing more shifting anyhow, won't mind something different.

And yeah, I think y're right about them being Torsen - I'd prefer to stick with clutch-type for the loose surface.

[ForcedFirebird]

Well, as mentioned the 4.10 medium from an auto e30 would work, and the shift points wouldn't move too far from where they are now, but you would get a little extra grunt. They used to be very sought after when I started in e30's, but they seem cheaper then 3.73's these days.

[irish44j]

I'm working on a deal to get some new stuff for mine, and I"ll just rebuild it. It's already off of the car sitting on my workbench :) Less work than trying to track down a known-good LSD anyhow, and probably cheaper.

Thinking about whether to add a clutch pack (3rd one) in place of the spacer, but not sure if that can be done with the small-case without machining (I know it can be done on the medium case without machining). Most likely will just do stock 2-clutch setup. FIgure this one held up for 30 years and almost 40 rallycrosses, so pretty stout I'd say.

4.10 is close, but on our courses I literally just barely hit the limiter in 2nd on some fast sections. A 4.10 would require a shift or more bouncing off the limiter, both of which cost time. And since most of our events come down to 1-2 seconds difference between 1st and 2nd, even the split-second it takes for another shift can be a deciding factor on winning or losing :/

[irish44j]

So as mentioned the LSD is toast. While I wait for the rebuild stuff to get here, went ahead and disassembled - mostly because I wanted to see if there was an internal spacer that could be replaced by a third clutch pack for more lockup (which can be done on the medium-case diff). No dice though. The small case has no such spacer so it's limited to just the two clutch packs (supposedly good for 25% lockup). I suppose I could track down some Porsche clutches, which are 0.1mm thicker, but that's something I don't have time for so we'll just stick with the stock setup since it's worked fine for 30 years and over 40 rallycrosses...the plan will be to find a good medium-case over the winter and build it with 3 clutch packs (60% lockup).

So here's the diff when it came out. 4 years of clay, dirt, and mud caked on...



coming apart



All the parts (in order). Note that the small case has a few less washers (and no big spacer) than the medium case does.



So while I wait for the new clutches and seals and bolts to come in, on to another project while the car is "up high" (lol)





With the aforementioned heat shields removed, I remembered that the fuel tank crossover line is pretty vulnerable. So I cut the rear part off the heat shields to put back on along with the fuel line guard. Peace of mind



Today I went over to help Jason put the roll bar and door bars in his rallycross Miata. Turned out to be a lot more work than the e30 rollbar, but got it done....



parked the subie with the rest of his fleet, lol (the Mustang is his roommate's)

[TeXJ]

nice fleet he has :D