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gearheadE30
gearheadE30 Dork
2/15/24 10:24 p.m.

The 924 let me down for the first time today. Driving down the highway at 75ish mph and the engine completely loses power. Oil pressure is fine, no alternator light or anything, just no power. Clutch in, 0 rpm, won't bump start or start on the key, so I put it in neutral, jump over 2 lanes, and coast as far as I can on the shoulder. Bumped the key, engine cranks fine, but no life. Of course you can't hear anything with the highway traffic, but I could just make out the fuel pump cycling.

Fortunately it's a narrow car, and I was able to get pretty well off the road surface. No weird noises or anything, and the timing belt looked good (it's new, anyway) plus good oil pressure meant I was pretty confident the engine was mechanically sound. Pulled a spark plug using the factory tool kit, and one of the leads was long enough to ground against the cowl while I reached inside to turn the key. Spark looks great.

You can see where I finally removed all the goop from the missing beltline trim, and where the paint has faded.

While cranking I caught a whiff of gas, so I checked around for a leak, but didn't find anything obvious. I thought I could hear the pump priming, but I wanted to be sure, so I wedged my house key across the terminals in the fuse box to trigger the fuel pump relay. Walk around to the back of the car where the pump is, and gas is pouring out. Found the problem! Hose clamp was loose and the line blew off. I tightened the other clamps while I was under there.

 

Unfortunately, the car still wouldn't start - it had siphoned all the fuel out of the distributor while I was checking spark, and the battery wasn't happy with all the cranking. I stuck the key back in the fuse block, pulled the airbox open, popped the air filter out, and reached inside to push up on the air flow meter panel. The injectors purging air was audible, and when that was done, it fired right up! Glad it was easy.

Unfortunately in general the car still doesn't start well. I probably need to check that cold start injector and make sure it's working, but I'm not quite sure what's up. It definitely seems like the AAV, which allows extra air on cold starts, isn't set up right. It could use a lot more airflow when cold, and a much slower ramp to warm idle. Of course, that valve is sealed, but I may try to mess with it anyway. Seems like it shouln't be that hard to improve.

gearheadE30
gearheadE30 Dork
2/17/24 11:51 a.m.

Videos of base timing testing a week or so ago. I'm surprised how little variation there was in time, though admittedly my stopwatch method isn't all that precise as the polling rate on the gps I had suctioned to the windshield is pretty slow. The difference was far more noticeable in terms of feel - lots of hesitation and surging below 4000 rpm until you got past 15-20 degrees of base timing.

This distributor is 2 stage mechanical advance - one weight bottoms out against a stop long before the other does. The second stage isn't working all that well, seemingly because there is a little wear on the advance arm. The weight falls into this little divot and it takes a big step in force to pull it past that point. I tried fixing it, but with only minimal improvement.

I also tried lighter advance springs, which made a HUGE difference. It's relatively close to spec now, but the advance comes off of base timing too early so it idles horribly as the advance moves around.

for now, fiddling with that is on hold both because we got 6 inches of snow last night, and because I discovered the pre-1980 924s have a single stage mechanical advance that is also a bit more aggressive. There was one on ebay for less than $50, so I'm going to try that before I try to cobble another solution together.

Video:

 

1979 is the "dark" lines, 1980 is the transparent overlay. X axis is distributor speed, Y axis is distributor advance. Multiply both by 2 to get the values relative to the crank.

 

gearheadE30
gearheadE30 Dork
2/18/24 3:17 p.m.

Older video from before the timing sweeps that I forgot to post. This is when I recorded the mid-10 second acceleration run.

 

gearheadE30
gearheadE30 Dork
2/20/24 10:37 p.m.

Parts distributor showed up and I was able to swap all the early bits over. Nearly everything between the two is identical, the only differences are the weights and the springs. Both weights are the same on the early distributor. The 1980 distributor uses one light weight with an early stop on it and one weight that is the same as an early weight, but with another chunk of metal riveted to it. Early uses one soft spring and one stiffer delayed action spring, 1980 uses one stiff spring.

Early weights are about 16 grams each. 1980 is one 15 gram and one 20 gram weight.

Performance below 4500 rpm is dramatically better. No more weird surging, or if there is, it's only very slight. The engine clearly likes the additional timing. I'll have to do another timed acceleration run for comparison.

One annoying quirk - mechanical advance starts to come in around 1100 rpm, and it comes in pretty aggressively. The result is an idle that kind of hangs at 1500 and slowly comes down to 900. Probably because I'm running the heavy weight along with one of the early 16 gram weights, and it's just too much for that spring setup. I probably should have just tried the correct weights, but I couldn't resist the prospect of trying to match the euro distributor curve, which ramps in much more quickly.

Performance above about 4500 rpm seems about the same, which isn't too surprising from my base timing testing. This engine just doesn't seem to be that sensitive to timing at the top end.

I did also fiddle with the hot start solenoid, which dumps control pressure when cranking. This car starts great when stone cold and if you've just shut it down, but after an hour and a half of sitting, it sucks. My theory is that it's cooled off enough that the hot start solenoid isn't being triggered anymore but it's really still needed. So I've jumpered the coolant temperature switch for it, and we will see what it does. The few starts I've done so far seem promising.

TED_fiestaHP
TED_fiestaHP HalfDork
2/21/24 9:15 a.m.

   Cold starts....

      My 1985 Honda CRX has a interesting start feature, there is a wire from the ECU that gets power from the starter, so while cranking it is in start mode, then it transitions to run mode over a few seconds.

     Maybe you could somehow activate the cold start injector or something with the start switch?  These older injection systems might not have been very good when new, but you might be able to improve it.  If the only weak part is cold start, I am sure there a way that can be improved.  

 

gearheadE30
gearheadE30 Dork
2/22/24 9:05 a.m.

In reply to TED_fiestaHP :

That's more or less how the starting system on this one works. There are 4 systems that govern starting/warm up behavior, and it's all fueling or air. No impact to ignition timing. 

  1. The AAV or auxiliary air valve. Literature is not consistent in naming convention. This is a thermally operated valve that allows air to bypass the throttle body. It has an internal heating element, and is mounted to the intake manifold where ambient engine bay temperature will also impact its operation. It is powered by the fuel pump relay. As the bimetallic strip is heated by the engine and the heating element, the AAV gradually closes, reducing bypass airflow until it is completely closed. This is completely open loop, and bench testing shows this fully closing in a matter of a few minutes operating only off of its internal heating element.
  2. The "5th injector". This is an injector that's in the main collector of the intake manifold, and it is powered by the key being in the crank position. It is grounded via a thermo time switch, which screws into a coolant manifold in the back of the head. The thermo switch allows for anywhere between 3 and 10 seconds of grounding time before heating from current flow + heating from ambient sources causes the switch to open. As soon as you stop cranking, power is removed and the cold start injector stops firing, regardless of thermo time switch activity. There is no ramp behavior between crank and run. 
  3. The hot start solenoid. This was added to the 924 in 1979, earlier cars won't have this. This is a solenoid that offers a fuel flow path parallel to the WUR. It also is powered by the key in the crank position. It is grounded through a thermal switch also mounted to that coolant manifold on the back of the head. When coolant temperature is over about 135F, the switch closes, so this feature only works on a warm engine. The solenoid allows fuel to freely flow to tank return rather than being pressure regulated by the WUR. The result is near-zero control pressure, so the metering valve can open easily. This means more fuel and, to some extent, more air because the flap isn't forcibly restricting airflow. This also does not have any ramp behavior between crank and run.
  4. The WUR. This only impacts initial startup if the hot start solenoid isn't bypassing it. This sets the control pressure, which = fuel mixture. It allows a lower control pressure when cold, and is mounted to the intake/head where it is heated by the engine and by an internal heating element. The heating element is powered whenever the fuel pump relay is on, and as it warms up, it increases control pressure to lean out the mixture. 

All of this stuff appears to be working the way it should, which is why I'm confused as to the starting issues. I bypassed the hot start solenoid thermal switch, so now it is active any time I am cranking, and this seems to have been a good improvement. It still likes to start on 2 cylinders if it is partially warm, and starts great if it's fully hot or completely cold, but it's okay enough now that I might just deal with it and move on with life for now. 

TED_fiestaHP
TED_fiestaHP HalfDork
2/23/24 9:48 a.m.

   The 5th injector is connected to a temp sensor, so it won't do anything if the engine is warm, that makes sense.  But wonder if that temp sensor is working as well as it should.  Also would it help if there was a fairly easy way to add a timer to the 5th injector to allow it to continue to work a few seconds after the starter stops, not sure how that could be done, but I bet there is a simple solution.

   My old Honda, the start mode seems to happen regardless of engine temp, a wire going to the ECU gets  power from the starter, then it seems to ramp to run mode over a few seconds.

    It's a older system with old sensors.   I adapted some sensors from the next generation of Honda, had to adapt and tune with a variable resistor to get things to work, have more confidence in the newer version of some of the sensors.  Once I had the right resistor correction, replaced the variable resistor with a regular resistor.

gearheadE30
gearheadE30 Dork
2/26/24 10:09 a.m.

You are right that the thermo time switch might not really be doing what it should - I probably need to hook my meter up to it and figure out what it's actually doing. 

That will come later though, since the car is now back in the garage for the next major round of repairs.

  • Steering wheel and dash are out so I can replace the odometer gear and replace the speedo drive cable. 
  • Oil pan gasket is being replaced. Might have to drop the cross member to do this.
  • Drain plug is way over tightened. The hex failed even with a 6 point socket. So I need to extract that and replace it so I can change the oil. 
  • While all that is apart, I may as well do the engine mounts since they will be a lot easier to get to
  • Exhaust has to come off to get to the passenger mount, so replacing the o2 sensor while it is off
  • Replacing the torsion tube with one with a rear anti roll bar, plus 26mm torsion bars and new Koni rear shocks
  • One of the rear wheel bearings is grumbly, so replacing that while the rear end is out

I also changed the trans fluid, which came out gross but free of metal. 

Cracked odo gear:

The other thing taking time right now is the engine for one of the E30s...too many project cars, not enough time. 

 

 

 

gearheadE30
gearheadE30 Dork
3/31/24 12:43 p.m.

Lots of updates to this one since it's been off the road for a while. Getting close to a condition where I'm happy with it.

Finally got the old drain plug out. Had to weld a socket to it to get it off. Also dropped the oil pan to replace the pan gasket, which was leaking aggressively.

This gave me a chance to do a lot of cleaning, and also get an idea of what the inside of the engine was like. It's sludged up a bit, but the oil looked good (had maybe 1000 miles on it according to the PO) with no metal or anything scary in the pan. I couldn't get many good pictures, but visibly the cylinder bores all look great. Visible cross hatching, no notable scoring or scuffing. Oil pump pickup didn't have any debris in it, either.

I also finished the engine mount project. Fixed some heat shields, engine is sitting back where it is supposed to and not touching things, got the clutch arm away from the trans tunnel, etc. The biggest difference somehow is shift quality, which is surprising since the shifter pivots on the torque tube. The shifter, torque tube, engine, and transmission are all part of the same substructure so there wasn't any relative motion anyway, but shifting feels massively more precise. Engine vibration is still noticeable. I'd say it's better than before below ~3500 rpm but there is a truly obnoxious resonance band that the engine passes through right above that. I don't think it's worse than it was with the stock mounts, or if it is, only slightly, but I was hoping this would be completely cured with the new mounts. Maybe this is what all the period reviews were talking about when they said the engine was buzzy and somewhat unrefined.

While it was apart, I found evidence that with the stock mount the manifold was hitting the frame, the clutch arm was hitting the trans tunnel, the cylinder head was hitting the battery tray wall, the clutch cable bracket was hitting an AC line, and the engine mount arm was sitting on the chassis heat shield around the exhaust. All of that is fixed now.

New speedo cable also went in, along with a new odometer gear. I removed the O2 sensor counter box and 2-piece cable because the box was clearly broken and rattling, and replacements don't exist.

The exhaust had to come off to do the rear suspension, so I replaced the O2 sensor while it was out. The sensor was not original, but it was old, and the threads got beat up pretty badly on the way out. Fortunately I have an M18x1.5 tap just for this purpose, which fixed it right up. I then proceeded to forget to tighten the new sensor, which resulted in a horrible rattle that took a while to find when I got the car running again.

Dog has been very helpful throughout this process.

gearheadE30
gearheadE30 Dork
4/3/24 8:41 a.m.

Continuing the previous update, here's a pic of one of the custom engine mounts installed. The mount with nothing attached to it is the bracket that the speedometer cable runs through. The previous owner installed those brake lines. They work so I haven't touched them, but depending on how long I keep this car, it's something I may go back and re do. I don't care for how they're routed, though I did improve things somewhat since taking this pic.

This car had a bit of wheel bearing play, so I figured I'd inspect and repack the fronts and replace the rears.

The fronts are tapered rollers, and are a lot like trailer bearings. They are also TINY. They looked great, just dirty old grease.

The rears were more of a surprise. They weren't making noise, but the passenger rear wheel had a lot of play. Parts are cheap for these cars because they're just Super Beetle parts in many cases, so I ordered bearings and seals before doing any real inspection. Turns out, the bearings were fine - the giant nut that holds the drum (and wheel) on was not tight! This is a 36mm nut that is supposed to be torqued to over 200 ft lbs. I tightened one up just to see and the play was basically gone, but I already had the parts, so a couple hours later I had new wheel bearings. It was still good that I did it, the seals were pretty dry and the grease was nasty. The tension spring on one seal had also somehow fallen off.

These cars are known for always having a little play, but it's a lot better than it was. There's one deep goove ball bearing and one cylindrical element bearing, so just not the same kind of side load support that the 1987+ aluminum suspension cars have with their more modern split dual roller bearing.

I also bought new rear brake shoes, they had life left in them but the linings were separating. I strongly suspect this is why I was having some noise and inconsistent braking in the rear.

That takes me to the rear suspension project, which is why all of this was coming apart in the first place. In the process of removing the rear subframe, I found a likely source of some vibration. One of the exhaust hangers had worn its way into the rear body cross member pretty darn aggressively.

Out with the old:

Comparing T bars. This car had 23.5mm rear bars in it - apparently all 924s got these rear bars starting in 1980 regardless of whether or not they had a rear anti roll bar. Prior years got smaller 22mm torsion bars and only got the larger bars with the rear anti roll bar.

I installed a pair of 26mm torsion bars. After some driving, I'm pretty happy with these on the 924. I think they'd still be softer than I would want on a 944, even as a street car. They balance decently well with the 250 lb front springs, but I definitely wouldn't go any softer with these front springs. Bright red is the new one.

Part of my reason for doing all of this is that my car has no provisions for rear anti roll bars, and I have the carrier from a 1987 944 on the floor in my garage. It also had 23.5mm torsion bars, along with the rear sway bar that all 944s got. I swapped over my spring plates (steel arm and aluminum arm spring plates are different and can't interchange), new torsion bars, and got everything clocked the way I thought it should be. The math paid off - I didn't want to change the rear ride height, and my spline selection got me only 1/4" lower than where I was, which I can adjust back to stock with the ride height adjuster cams. This is great, because if you do it wrong, you have to drop the whole thing again to reclock the bars.

Note the steel fingers on top of the new T bar carrier - these interlock with the torque tube to provide a solid fore-aft stop for the drivetrain relative to the body. The early cars, like this 924 and my 1984 944, use a different kind of stop that doesn't use these fingers, and doesn't have the mating tabs welded to the torque tube. So those got cut off after this pic because they interfere with the old-style torque tube.

Back in the car, now with 100% more rear anti roll bar, along with new Koni single adjustables. I set them on the middle position, which seems about right after my test drive.

gearheadE30
gearheadE30 Dork
4/5/24 1:38 p.m.

One last minor update to bring everything up to where things stand today. After getting the subframe in, the exhaust and such, went back on. Finding a new donut for the flare joint was a pain, but eventually I found an Audi/VW part the right size. The one that was in there was rust-pitted and had been sealed with carbon buildup.

I aligned everything, which took a few tries to get right. There are 3 eccentrics in the rear suspension: one for ride height, one for toe, and one for camber. They all, of course, have some impact on each other. If I remember this right, the camber adjustment is the eccentric on the bolt that also serves as the anti roll bar link mount, and the toe adjustment is the P221 alignment tool that you absolutely should buy if you're going to align one of these. I don't think it would be possible to align properly without it, and it's relatively cheap.

The rear alignment was way off before, so of course now I need to adjust the front to get the steering wheel straight again.

I took it for about a 30 mile back road drive, which happened to also be the warmest day I've driven the car on so far, and the most vigorously I've been able to drive it.

  • This is the suspension the car should have come with. Which Porsche eventually figured out - what I picked out is similar to the later M030 944s. Still fairly compliant on bumpy Indiana back roads, but reasonably well balanced.
  • No more horrible understeer - fairly neutral on throttle, and doesn't do the trail braking oversteer thing as badly as an E30 can be, but still rotates well. totally worth the effort.
  • No more pulling under braking - loose drums/wheel bearings and the delaminating shoes seemed to be the cause of that
  • On a 70 degree day, the temp gauge gets up to the middle or just above when driving aggressively
  • Oil pressure wasn't bad before, but is much higher when hot now with the 20W50 oil
  • Engine mounts made shifting dramatically better. Low RPM NVH is also better, but it's still buzzy around 3500 revs.
  • If I keep this car, I'll need to do something with the brakes. Maybe just pads. PO installed what are probably autozone pads on the front, and they are terrible combined with the small solid front rotors. My entire drive was spent managing brake fade - fluid is fresh and wasn't boiling, but more pedal wasn't getting me any real brake force, so the pads were just overheated.
  • when I got off the back roads, I noticed that the fuel pump had gotten much louder. It completely failed about 15 feet short of being back in the garage, so I've got a new Bosch pump on the way. This one is an autozone pump that the PO installed, and I don't think it liked the 70 psi CIS fuel pressure very much.

Where it died, which also shows the beltline trim I removed because it was falling off, and where the ride height ended up:

Annoyingly, the pump won't be here until next week. The good news is that someone converted this car to a single pump setup using 928 parts, and the in-tank filter looks great.

porschenut
porschenut Dork
4/5/24 5:39 p.m.

Great job on the suspension.  They can be one of the best handling cars when set up right.  Surprised the brakes didn't hold up to street driving.  The hot setup is 944 5 bolt and disc all around.  A weekend of track driving used to leave me with bruises on my shoulders from the harness.  

gearheadE30
gearheadE30 Dork
4/6/24 9:16 p.m.
porschenut said:

Great job on the suspension.  They can be one of the best handling cars when set up right.  Surprised the brakes didn't hold up to street driving.  The hot setup is 944 5 bolt and disc all around.  A weekend of track driving used to leave me with bruises on my shoulders from the harness.  

I was a little surprised too, but I think the Autozone pads just suck that much. I can do one hard stop from 70 mph and I'll smell pads pretty badly.

I've actually got the parts to do the 5 lug swap in the rear, but I don't have the front parts. If I end up keeping the car longer term, I'll do something, but for now I'm just going to drive it and be conscious of how much heat I'm putting into the brakes.

The new fuel pump showed up today, it's amazing how much better quality it is than the Autozone pump. I also bought the check valve for it, since there's no valve in the pump itself. That may be one of the problems I was having with the old pump too - you could hear it burping fuel back to the tank after shutdown, which this one doesn't do. This also gave me the chance to fix some stuff I didn't like with the fuel lines, so all the fittings are the right size now, and I've got a larger hose running between the tank and the pump inlet. I replaced the gasket for the fuel level sender while I was back there, because I had noticed with a completely full tank it would leak a bit.

I corrected the steering wheel angle, and finally the car felt done enough to install the underbody tray.

The antenna was broken off and isn't used with my stereo setup anyway, so that got removed and plugged.

I also found an actual copy of the 1980+ service manual, and it has different information for setting up timing than what the Haynes manual describes. For 1980 cars, the spec is 0 degrees BTDC with all hoses connected. With all hoses disconnected, spec is 10 degrees BTDC - the vacuum retard pulls 10 degrees from the base timing. The Haynes says 0 degrees with hoses disconnected, which is why it always felt so sluggish. It seems happy at 15 degrees with hoses disconnected. I'm keeping the vacuum retard - it helps a lot with idle and return to idle characteristics.

All seems well after another drive. She's ready for action, aside from a few interior rattles I need to track down.

I think what I need to do is list this car for sale soon at a price that's really looking for the "right" buyer, while I'm using it as a daily and finishing up the next E30 in line. That E30 will also go up for sale when it is done.  I am slowly coming to terms with the fact that 4 project cars is too many, and the car I really want to be working on is that white 318is, the car that started it all for me. So the 924 and 325is eventually get sold, the 318is gets rebuilt, and maybe I finally work on the LS1 944.

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
4/6/24 11:23 p.m.

Still following along, but nothing of note to say. I took my 924S out for a bit of a country/woodland road drive today and always remember why I love this car. That said, I'm thinking about whether it would be worth an upgrade in the suspension department (not sure, mine obviulsy has the later suspension compared to yours), so paying attention to what you're up to. keep it up!

gearheadE30
gearheadE30 Dork
4/8/24 9:49 a.m.
irish44j (Forum Supporter) said:

Still following along, but nothing of note to say. I took my 924S out for a bit of a country/woodland road drive today and always remember why I love this car. That said, I'm thinking about whether it would be worth an upgrade in the suspension department (not sure, mine obviulsy has the later suspension compared to yours), so paying attention to what you're up to. keep it up!

Thanks! Yes, this car is definitely happiest having fun on back roads. Even though on paper there are a lot of similarities, somehow it's a very different experience than my E30s. The seating position, shifter, and steering all make it feel much more sports car, and it probably helps that I didn't over-tire this car compared to the sticky rubber I have on the BMWs so that the 110 hp doesn't feel completely overburdened by the available grip.

If your 924S is all stock suspension, it's not all that different than my car. Yes, a bunch of stuff is aluminum and the wheel offset is different, but the overall geometry is fundamentally the same. Same front and rear anti roll bars, same or very similar factory spring rates, same torsion bars, and probably similar shock tuning. As far as I know, the biggest difference is that you have power steering and brakes that can actually tolerate some heat.

I went from ~160 lb/in front springs (or 140 depending on what reference material you believe) to 250 lb/in. I had to cut one of the dead coils to get the ride height where I wanted. The rear was the same 126 lb effective wheel rate 23.5mm torsion bars that your car has, and I put in 26mm bars that are 189 lb effective rate. If I did it again, I'd do 27mm bars for 220 lb effective rate. I erred on the soft side because I have no plans to ever track this car and wanted to keep the ride comfort, but it's still not harsh at all. Stock bushings probably help with the compliance.

So I went up around 50% in terms of spring rate with stiffer dampers and kept stock (or at least, matched where it was when I got it) ride height, which means it uses the available travel much more effectively. I find myself bracing for bumps all the time that it just soaks up with no issue at all now. Highly recommended if you have a weekend to play around with dropping the torsion bar carrier and playing with the clocking.

gearheadE30
gearheadE30 Dork
4/10/24 11:03 p.m.

Unfortunately the new fuel pump and check valve didn't solve the hot restart problem...but I might have finally found something that does. I've been running with the hot start solenoid jumpered (always active during cranking regardless of temperature, normally only active over 140F coolant temp) which ironically made cold starts nearly instantaneous, but didn't help the hot starts at all. The fundamental issue is that no fuel is getting to the cylinders until the lines between the distributor and the injectors are purged, so I figured I'd also bypass the thermo time switch for the cold start injector. Now, the 5th injector is always firing when the key is in the crank position.

So far, the car now always starts more or less like you want it to. At most, I've had a couple seconds of cranking before it lights off when hot.

The downside? It might be easy to flood the engine with fuel. But so far, I haven't done that, and it's never seemed like it was close to doing that, so for now I'm not going to worry about it.

Also, unfortunately I think my homemade engine mounts are too stiff. More to come.

porschenut
porschenut Dork
4/11/24 5:45 p.m.

I think a couple pages ago wiring the cold start injector to a momentary button was a good way to improve starting.  works with any CIS system

gearheadE30
gearheadE30 Dork
4/29/24 5:01 p.m.

Yep, there was a comment about the momentary button. I don't really want to have to deal with more buttons and switches if I can avoid it, but after a few weeks of driving, it seems like wiring the cold start injector so it's always on during cranking works fine. I did almost flood the car once, but I intentionally cranked for a while without giving it any throttle just to see what would happen.

It starts pretty well now, but still likes to hot restart on only a couple cylinders before clearing up. Replaced the system pressure regulator oring, added a check valve when I replaced the fuel pump, confirmed that the system holds pressure within specs after shutdown, hot start solenoid connected with factory temperature switch, and cold start valve grounded directly instead of grounding through the thermo time switch.

I did also unplug the AAV, which manages warmup airflow. It's got a thermal strip and resistive heater, and it always seemed to close off too early and leave me with a dying car until it was fully up to temp. Unplugging it means it just warms up based on engine bay temps, which so far has had no downsides. It always ends up between 850 and 950 rpm warm idle now, depending on electrical load.

 

Engine mounts - I went back to a stock mount on the driver's side of the engine. On the passenger side, which is the spring loaded OEM mount, I installed softer isolators of the same dimensions in my homemade mount. Mounts like this have a transmissibility peak at some frequency before then get to their attenuation region as frequency increases, and you can lower this peak by decreasing stiffness or increasing weight/preload. Previously, peak amplification was around 800 rpm, which was brutal. Now it's down in the 600 rpm range, and it is like driving a completely different car. There's still some resonance around 3100 rpm which unfortunately is about 75 mph, but this is just the nature of an unbalanced 4 cylinder with big, heavy pistons. The only way to make that better is to take things apart and start trying to blueprint the engine.

 

Otherwise, I've mostly just been driving it. I've switched back and forth between the 924 and the 325es a few times....the 924 feels so much more like a sportscar. The E30 feels very big and upright by comparison, though the E30 sport seats are much better, and of course it vibrates a lot less. You really notice the bus-like angle of the E30 steering column, and the manual steering in the 924 so, so much better than the E30 steering. I don't mind power steering, but the E30 rack ratio is painfully slow by comparison.

My girlfriend and I took a trip with our two dogs over the weekend, and she loves the car. Even sedately driving on twisty back roads was a lot of fun, and the dogs liked being able to see out the back hatch. The car is also knocking down 25+ mpg pretty consistently, and gets a lot of waves wherever it goes.

 

gearheadE30
gearheadE30 Dork
6/14/24 6:03 p.m.

Still knocking down the miles. Had some heavy rain lately that made me realize that the battery tray rust is leaking a bit. The hatch glass separation has also gotten a lot worse, so hopefully I'll be able to address those issues before too long.

There are no exhaust leaks, but somehow I'm still getting exhaust smell inside the car. I would really like to figure out what's going on there, since that can't be good for me to inhale all the time.

Went up to Reggie's Motorworks for the open house up there since I used to work there, great to see everyone again.

While the wheels aren't my favorite, these are among the best-proportioned cars out there in my opinion. This is a 4.7 car with the 6 speed manual. the owner let me sit in it....I do fit...

One of the most obsessively built S54 E46s I've ever seen. Odd build car to start with being a sport package, non-sunroof, non-OBC car.

Another beautifully built car, with a half cage in it, that actually does motorsporty things.

Reggie's beautiful Baur TC

And of course, the 924

gearheadE30
gearheadE30 Dork
7/31/24 8:35 a.m.

Still generally dailying the 924, it's generally been a great driver but I'm going to have to address a few things sooner rather than later 

  • If I park nose up, water collects in the battery tray area and makes it's way into the car. That is the only slightly rusty spot on the car, and there must be a hole under the sound deadening mat. 
  • The hatch as just about completely delaminated along the top edge. It's bad enough that as of yesterday after a drive on a bumpy back road, it will leak water on the rain. 
  • Hot start issues persist. It almost seems like the fuel pump isn't running consistently during cranking, but I need to hook a meter up and confirm this. Such an annoying issue 

I accidentally got wax on the trim, need to clean that up too since it looks like crap now. 

 

 

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