BMW Compact Rally Car Build

[pdxmotorhead]

The subframe mods are very worked out. See a Pro-3 BMW E30.

It only changes the trailing arm angles, does not affect diff or the exhaust.

Dave T.

[DaveKern]

Originally Posted by pdxmotorhead

The subframe mods are very worked out. See a Pro-3 BMW E30.

It only changes the trailing arm angles, does not affect diff or the exhaust.

A bit confused here. I thought that there are two different things that folks were suggesting:

1) The subframe bushing kits physically change the location of the subframe in relation to the chassis (i.e. there's more or less bushing material on top of the subframe). This would not work with my setup, as the exhaust already sits low, and my new rear diff doesn't have any room to move in relation to the hole in the subframe based on where the input flange sits.

2) Weld-on bits that sit where the RTAs connect to the subframe. These are totally doable and just impact the adjustability range of the camber & toe for the arms.

Dave

[DaveKern]

Just in case you guys were wondering what I was up to for the 2 month break I took from the BMW:

Working/Fabbing stuff on the Evo:

http://racekern.com/Kernracing/2011/...lution-begins/
http://racekern.com/Kernracing/2011/...ding-the-buck/
http://racekern.com/Kernracing/2011/06/making-it-go/
http://racekern.com/Kernracing/2011/...ing-it-handle/

Race writeups from the 2011 PPIHC:

http://racekern.com/Kernracing/2011/...practice-week/
http://racekern.com/Kernracing/2011/...peak-race-day/

And of course what fun is reading...show me the video:

http://racekern.com/Kernracing/2011/...ne-pikes-peak/

Dave

[cooljess76]

Hay bails @ 2:30, tire coming off at 4:17 and you still took 4th!

[DaveKern]

Originally Posted by cooljess76

Hay bails @ 2:30, tire coming off at 4:17 and you still took 4th!

We ran just about 5.5 miles on a flat and 3/4 of a mile on just that rim out of the 12.4. Sucks, but what are you going to do?

Dave

[DaveKern]

Since I'm finally about done with the mechanical aspects of the car, . I'm looking at ordering the Harry Hockly parts in the next couple of weeks. I'm considering the kit mainly for two reasons:

1) with my E46 front arms, the front tires are barely covered by the OEM fenders, and have similar clearance issues in the back as the suspension nears full compression.
2) weight reduction - full kit weighs just 60 lbs.

Pics here:

http://www.hh-ms.com/projects-bmw-m3rhd.php

Individual parts here:

http://www.hh-ms.com/catalogue.php?S...=23&page=parts

If there's any interest, I'd be happy to ask these guys if we could fit a few extra parts onto the pallet for shipping. I know that there weren't too many fans of the full body kit, but I was thinking that something like the fiberglass hood & hatch might appeal to some of the track guys.

Dave

[DaveKern]

Another trip to CORE this weekend - have to say, damn we're lucky to have a place like this to really shake down a car hard.

Unloaded the car and set to work swapping in some new parts. We figured that there would be a bunch more swapping going on, as we had new springs and new bumpstops so all sorts of combinations would be possible.

First up:

-JVAB Bilsteins 260/90 valving with short eyelets
-Hypercoil 200# 14" springs (helper springs removed) tightened just enough not to rattle at full droop
-1" spring spacer (due to running out of threads on shock body)
-COT 75mm soft bumpstops
-14.5" fender/wheel center ride height (~0.75" taller than last time out)

Took a 75% lap and things seemed good. Took the next lap about the same but aimed for the spots that had given me trouble in the past. No issues. Then banged out a succession of 90%+ laps and hit the rough spots every which way possible, and no bottoming out!

I had been expecting to have to add another bumpstop, but I think the combination of a slightly higher ride height (i.e. more up travel available), slightly stiffer spring, and the longer more progressive bumpstop made it work.

On the whoops on the back straight, it flies pretty good. Only real issue I'm still seeing is that on the step-up style jump car likes to nose down on the landings, so much so that I've now got paint scrapes on the front of the front bumper. The good thing is that when the back sits back down, it just squats and goes, no crazy rebounds to deal with. I'm guessing the off kilter flying has something to do with that 6-cyl up front and no downforce on the back. That Compact Cup kit is looking better & better.

Going back to CORE being such an awesome place to shake a car...we did managed to find another weak link which cut our day short by about 30 minutes. I was cranking around the track and all of a sudden the throttle cable stuck. I fiddled with my feet through the pedals to see if something had gotten hung up. Nothing looked out of the ordinary so I killed the engine. Hopped out of the car and popped the hood. At first glance things looked ok, but I couldn't move the throttle linkage towards closing it at all. Looked closer and I could see something was up with one of the couplers on the intake, it was kinked. Weird!

Upon further inspection, the motor mount arm had completely removed itself from the motor mount and the mount was sitting ~1" too far forward. So, I look at the motor mount expecting to see that the nyloc nut and washer were missing....nope, they were still there, but had loosened almost all the way off. Turns out the engine had been moving around and it wallowed out a hole big enough in the motor mount arm so it was able to just slip off!

Also managed to find the limits of the stock cooling system. With the ability to rail on the car flat out, and with temps in the upper 90s, I was finally seeing the radiator temps moving past the half way point. Time to ditch the $100 Checker radiator for something with a bit more cooling capacity.

Dave

[pdxmotorhead]

I've run the stock one for over an hour at an indicated 100 in 95 degree weather. No issues..

No I wont tell where... The statute of limitations may not be worn off.

Dave

[DaveKern]

Originally Posted by pdxmotorhead

I've run the stock one for over an hour at an indicated 100 in 95 degree weather. No issues..

Big difference with the test track is that high RPMs come at lower speeds so there's not as much air moving through the core. Lots of wheelspin and only one spot on the track where I hit 5th. Also, I'm using a 4.3 rear diff, so that drops my speeds too.

Other thing working against me is that I've got a 14" pusher fan on the radiator right now. I've got a new radiator ready to drop in, but am waiting on a new fan shroud to make the swap. Don't want to run zip-ties thru the new shiny radiator.

Dave

[DaveKern]

Originally Posted by DaveKern

If there's any interest, I'd be happy to ask these guys if we could fit a few extra parts onto the pallet for shipping. I know that there weren't too many fans of the full body kit, but I was thinking that something like the fiberglass hood & hatch might appeal to some of the track guys.

Remember these are 'race parts' so they may not fit perfect, may require some extra love before painting, and may require the use of hood pins.

I'm going to be placing my order today and figure if anyone else wants in, you'd need to have your parts ordered by the end of the week.

Dave

[DaveKern]

Quick question for you guys:

My car's throwing a 1263 code which is related to the evap solenoid. The charcoal canister was removed and and the hard plastic line that comes from the tank terminates under the car. Whatever connections there were up in the engine bay have been capped and/or plugged so I've got no vacuum leaks.

I'm wondering if there's a workaround so I can get rid of the code. What sort of signal is the ECU looking for out of the sensor?

Can I place the sensor back in the engine bay not connected to anything?
How about applying a jumper wire?
Or...?

Thanks,

Dave

[DaveKern]

Hi All,

Looks like I may be in need of some internet diagnosis from the BMW experts. Took the car out to CORE again for some more shakedown.

Big test for the day was to see if the new Mishimoto radiator would lick the overheating issue. Radiator looks nicely made and it a bunch thicker than the cheap OEM replacement I'd been running. Last time out I was finally seeing full revs (7k) since the WAR chip allowed me to bypass the 'missing speed sensor' 6k cut. The car got warm, but didn't go more than one tick mark past half way while on course, and a quick half mile loop at lower revs would bring the temps back down to the half way point.

With the skidplate, I had a little gap under the radiator which wasn't sealed up, so figured this morning was as good a time as any to seal it up. Put a piece of plastic down there to cover up the entire gap and am happy to report it worked wonders. No movement of the temp needle. It comes up to half way and just stays there no matter how hard I drive it.

So after giving rides to a half dozen people and just running a lap or two (2-4 miles) at a time with plenty of cool-down, I ran into a big problem:

The car seemed to drop power all of a sudden and made a bit of a rattling noise from the head. Also noticed when we came to a stop that if I depressed the clutch pedal, I got lots of clutch rattle that I never had before. The engine also wanted to stall out when I did that, so I let it and we pushed it onto the trailer. When I tried cranking it again, it sounded like compression

Didn't seem to have any issues on the oil side of things, was still 1/2 quart over filled, and never saw the low oil pressure light come on. Car has already had the oil pump nut fix completed (fell off at some point in the past, but the car was idling when it lost oil pressure) and added a baffle to the oil pan.

In terms of revving the car, I don't think I had any mis-shifts during the day. There's a DSSR shift rod and AKG DTM style shifter so shifts are pretty crisp. Rev limit is set to 7000rpm using a WAR chip and with the slippery conditions out there, the rev-limiter did plenty of use. I've got a UUC M5 clutch and flywheel so the car revs up nice and quick. The surface is pretty loose and variable out there, so there's lots of wheel spin.

Curious to see how bad you guys think this might be and where I should go from here.

Thanks,

Dave

[cooljess76]

Sounds like it might have developed some sort of misfire maybe? IDK Dave, it doesn't sound good. I'd start by checking the coils and plugs, make sure one of the plugs didn't come untorqued. Check the brake/clutch fluid. Have you ever noticed flywheel chatter, I here it's common with these flywheels. Maybe the clutch got too hot and sustained some sort of damage. any oil on the bottom of the tranny bellhousing? If the rear crank seal blew, it could spray oil on the flywheel and possibly cause it to warp or something. Keeping my fingers crossed for you man, hope it's nothing serious.

[DaveKern]

Originally Posted by cooljess76

Sounds like it might have developed some sort of misfire maybe? IDK Dave, it doesn't sound good. I'd start by checking the coils and plugs, make sure one of the plugs didn't come untorqued. Check the brake/clutch fluid. Have you ever noticed flywheel chatter, I here it's common with these flywheels. Maybe the clutch got too hot and sustained some sort of damage. any oil on the bottom of the tranny bellhousing? If the rear crank seal blew, it could spray oil on the flywheel and possibly cause it to warp or something. Keeping my fingers crossed for you man, hope it's nothing serious.

From in the car that's what I though, but when I pulled my helmet off it was audible tick rather than a lack of pops.

The clutch/fw combo was used when I got it, so its got unknown mileage. I was expecting that it might not last that long, but so far its been taking the abuse like a champ.

Will pull plugs and depending on what I find, I may try to do a compression test, but don't want to do any more damage (if that even matters now).

My initial thought was a dropped valve, but after hearing the clutch noise, I'm now concerned that something might've happened with the crank too. Are BMWs succeptable to crankwalk issues? Thinking when clutch is in, it's allowing the crank to move around a little bit. IDK, but I'm really worried that if this is serious enough (i.e. costly), it may be the end of our racing for the year, even though we haven't even raced yet.

Dave

[DaveKern]

Time for the "broken stuff" post.

First up is the broken motor mount from a couple month's back. The mount on the left of the pic sheared off the top. I'm chalking it up to poor design. The mount has two metal pieces that 'float' in the urethane to isolate vibration better. While I'm sure that's fine for a street car, it doesn't seem remotely up to the task for a car that's catching air. The mount arm also was damaged, with the top of the other mount chewing a hole in the aluminum until the entire arm fell off the mount when I jumped it. Result of this mess was the throttle got pinned wide open after the motor shifted 2" forward.



Next up is the damage the car suffered its last time out. Not a good thing to see after all the clakety noises.



Valve cover & cams removed and we find the culprit:



Once the head was off the offending valve was confirmed to be not straight:



And the real kick in the gut:



I'm told 1995 M3 motors have notoriously failure prone valve retainers, so those all need to be replaced. The head looks like its ok, but probably safest to take it to a machine shop, have it decked and the valve mating surfaces cleaned up.

So, torn on what to do now. My instinct tells me I need to pull the pan off and replace a piston but that's such a pain in the ass I might as well just pull the motor. If I'm going to go that far, it sorta seems dumb to stick stock parts back in when they've failed me. I've got no $$ set aside for any sort of engine build since I was hoping that by leaving things stock, I'd end up with greater reliability.

Seems like a bunch of work and the lazy part of me wants to just dremel the piston damage away and hope for the best, its not like I'm running boost thru the thing...

Dave