heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Today I left my key in the pocket of my jeans and put them in the washing machine. Key still works lol

[heinzboehmer]

Was reading through the BlueBus thread and saw that some people were adding ground loop isolators to theirs. My throttle actuator seems to add a fair amount of interference, so I bought the necessary connectors + the isolator and made one real quick.

The isolator came with a 3.5mm male to male wire, so I cut that in half and crimped terminals to the cut ends. Ted mentioned that the car side connector needs both ground pins populated, so made sure to do that:







Fortunately all of Ted's stuff is open source, so no need to go probing with a multimeter to find out what is what. Instead, I just pulled up the schematics and based everything on that: https://cadlab.io/project/1479/maste...ZUJ1cy5zY2g%3D

Difference is huge. I was getting both a low frequency hum and a higher frequency noise (from the throttle actuator) as interference before. Pretty much dead silent now.

Here's the before. Creaking noise is me actuating the throttles to get the interference to come through:

And after:

I can hear some very slight high frequency pops with the isolator in, but I don't know for sure that those weren't there before. I have a feeling that the radio volume was set a lot higher during the test with the isolator and that's why those pops were audible. Either way, much happier with it now.

[heinzboehmer]

When I found both lower wishbone to subframe bolts loose, I torqued them back up, but was only able to get a torque wrench in on the passenger side. Driver's side I did using the double wrench thing. Wasn't too confident that it was torqued properly, so I bought a stubby socket. Surprisingly, it still wouldn't fit, so I had to cut the thing down:





Barely any socket left after that, but it worked! Still need to fix the subframe with the mending plates, but that will come later.

After that, I was pulling out of a parking spot and heard/felt a crunch when turning the steering wheel. It only did it once, so I figured it wasn't an issue. However, on the way back home, I noticed that none of my steering wheel controls were working. So I took things apart and found this:



Somehow one of the clock spring ribbon connectors failed. I didn't get an airbag light, but nothing else on the steering wheel worked. I guess the signal wires for the airbag are on the ribbon that didn't fail.

Was halfway through soldering the thing back on when I decided that I didn't want to risk driving around with a non-functional airbag:



Fine, I'll give BMW the stupid $200 that they want for a new one.

Also, the thing was surprisingly annoying to take apart. Here's how I did it for documentation purposes:

[heinzboehmer]

The spacers worked great as a quick, easy and cheap fix for the lower front ride height that I didn't want, but I realize they don't make sense for everyone.

The exhaust clamps are 100% worth it. Super cheap and took like 10 min to install.

[K-Dawg]

heinzboehmer I appreciate your ingenuity. You've come up with a number of unique and creative solutions that work for you.

I like those spring mount spacers. I'm going to have to do some pondering on whether they might be something I should try. Same with the exhaust clamps. 🤔

[Bry5on]

Glad it worked out! And it’s really a surprising difference! Makes the headers into a no compromise mod

[heinzboehmer]

I could, but it would probably make future installs harder if I ever fully remove the clamps. When installing, I had to dissasemble and bend them open quite a bit to get them around the pipes. The bolts were barely long enough to reach with the clamps bent open, so I think I'll just leave them for now.

And also, you reminded me of an update I forgot to include!

Slideways and I compression and leakdown tested my car the other day. 180 psi and 2% leakdown on all cylinders. Pretty happy with those results!

[Slideways]

Nice progress! Can't you cut down the bolts for the clamp?

[heinzboehmer]

And lastly, I installed some clamps with a plate to join them together onto my section 1, after Bry5on did the same thing on his car:



What a difference! No more rattles at idle or at random points in the rev range. I wasn't expecting such a change, but it definitely makes the interior of the car a much nicer place to be in.

I was slightly concerned about ground clearance with those long bolts on the clamps, but I used my precision instrument to measure and they just barely clear:




Piece of wood is butted up against the section 1 -> section 2 flanges in the rear and the plastic transmission shield up front. Should not have an issue with these things in that position and can always scooch them towards the cats a bit if I do find them catching on stuff.

[heinzboehmer]

Also got my front suspension spacers in the mail and installed them. Sendcutsend doesn't do filleting, so I had to do that myself. Was pretty easy to do with a 1/8" radius roundover bit since the things are made out of aluminum.

Here are the parts straight from sendcutsend (along with a couple different thickness of mending plates for the subframe):



Filleted:




Fits pretty well (and most importantly, flat):





Gave it a quick coat of paint to mitigate rubbing through the powder coat on the spring perch:





Install on the car was super straight forward. Street driving impressions are that it feels the same as before (which is good!) and there are no weird noises coming from the front (as expected). Also no more scraping when parking the car in my garage!

And here's the CAD for the spacer in case it's useful to anyone: https://cad.onshape.com/documents/44...9d6f3c638aa3a3

[heinzboehmer]

Over the past few months, a rattle/clunk started to develop in the rear of the car. It was only audible when there was significant and quick compression/decompression of the rear suspension. I took stuff apart and tried to replicate it, but was unable to.

I don't drive the car on the street too much, so I would kinda forget about it, but one day I got sick of it and decided to try and track it down. Had a friend drive the car while I rolled around in the trunk and tried to pinpoint it. It was super hard to do, as the noise sounded like it was coming from a bunch of different spots. Figured it was coming from something solidly mounted to the chassis and the sound would reverberate in the trunk. So instead, I got back under the car and started putting a wrench on everything. I do paint mark all the bolts that I torque, but after talking to another friend about having stuff rattle loose on track, I decided to do a torque check instead of just a visual one.

This is what I found:

That's the lower wishbone to subframe bolt. Both sides were like this and I have no idea how they got loose. When torquing them back up, I tried going up in small increments to see approximately how tight the things were. Started by setting the torque wrench to 25 ft-lbs and it didn't even click there. Sketch.

I'm thinking the bolts must have been loose for a while, but only recently did they get loose enough to start making noise. Unfortunately, it does look like they were moving around a good amount:



So far haven't heard them clunk again, but I'll probably need to add some mending plates to the subframe, as I'm expecting the bolt hole to be slotted now. Oh well, I'll do that whenever I stop being lazy and install some camber arms.

[heinzboehmer]

Well, he hasn't taken advantage of moving the shaft up yet with that 7mm thick tms spacer in there still right? I'll be interested to see what you do Heinz. I'm using a 2mm thick washer, though my setup is obv different (I have tms street plates too though). I saw Kdawg's thread, so even with that thick spacer in there, TMS plates are still considerably shorter than stock. Probably why I was so happy with TMS plates with NO spacer on my bilstein b6 converted into coilovers with GC, lot's of travel, free lowering, and stiffer rate (325lb). So maybe you don't plan to replace that 7mm tall tms spacer?

Turner street plates move the shaft up 5.5mm compared to the stock ones, with the spacer installed how it's shown in that diagram a couple comments up. So I've gained that at least. Spacer I'm going to make is going to be 5mm thick (to compensate for the loss in ride height), so a total of 10.5mm shock shaft travel gained.

I don't plan to replace the Turner spacer. Shock washer ended up being too close to the bottom of the camber plate for my liking. Don't want it to bind during driving so will leave it how it is in that diagram.

Did you contemplate getting a shorter but stiffer bumpstop ever? If so, why not? Seems cheaper than plates.

I thought about it, but decided I don't know enough about suspension tuning to make an accurate call about what to replace it with . Shorter + stiffer sounds like if I do contact the bump stop, the crash will be much harsher. Think I'd rather keep the longer, less stiff, more progressive ones for that reason. But once again, I'm no suspension engineer so no idea if my intuition is correct or not.

Also, sendcutsend quoted the two spacers (using rough measurements) at ~$15, so super cheap. This is with them made out of aluminum. They don't have 5mm thick delrin in stock, only 3.6mm, which was only a couple bucks more.

[Tbonem3]

Ya, I suppose it is dubious that the mild increase in rate is enough for the half inch+ drop on eibachs or Dinan, much less h&r or God forbid tein.

Well, he hasn't taken advantage of moving the shaft up yet with that 7mm thick tms spacer in there still right? I'll be interested to see what you do Heinz. I'm using a 2mm thick washer, though my setup is obv different (I have tms street plates too though). I saw Kdawg's thread, so even with that thick spacer in there, TMS plates are still considerably shorter than stock. Probably why I was so happy with TMS plates with NO spacer on my bilstein b6 converted into coilovers with GC, lot's of travel, free lowering, and stiffer rate (325lb). So maybe you don't plan to replace that 7mm tall tms spacer?

Did you contemplate getting a shorter but stiffer bumpstop ever? If so, why not? Seems cheaper than plates.

[Bry5on]

I personally don’t buy that the eibach setup is optimized correctly. I spaced my Dinan setup up 1/2” inch in front (similar rates and drop) and preferred the balance mid corner. It seems to be a balance of performance and aesthetics, where performance took a hit to manage aesthetics.

The strut moves up with the inner bearing/bushing, the spring mount moves with the outer bearing. Travel is dictated by the strut position, height is dictated by the spring position. Heinz is taking advantage of the fact that you can tune those locations/heights independently.

[heinzboehmer]

Tbonem3 I see what you're getting at. Worth noting that the relative positions of the surfaces that the shock shaft and spring sit against on a specific camber plate will dictate shock travel and ride height. So it's possible to get thinner camber plates (spring to body), lower ride height and also increase shock shaft travel, as is the case with the Turner street ones. Look at the measurements in this thread to compare against stock: https://nam3forum.com/forums/forum/m...ate-comparison

My car is modestly lowered (on eibach pro kit springs) and I was concerned by the measurements in this post: https://nam3forum.com/forums/forum/m...742#post181742. Admittedly, I haven't measured myself, but it looks like basically any modest bump would put me in the bump stops. Like Bry5on said, these camber plates give me more shock shaft travel, which results in me staying out of the bump stops more often and an improved ride. This effect will be even greater with the spacer I'm gonna have made.