heinzboehmer's 2002 Topaz 6MT Coupe

[Tbonem3]

Yes, I should have clarified that it depends on the setup - is top perch above or below the point where you're removing stack?

So in your example, you'll gain a little bump travel (shaft travel) without affecting ride height. Or, they way I looked at it always wanteing to lower the car: maintain the same travel, but still get to lower the car for "free."

But replacing the stock mounts for thinner camber plates will lower the car rather than simply give you more travel because you've change the top spring perch's location relative to the strut housing. If you had adjustable coilovers, you could then scoot up the bottom perch or put in taller springs.

So pairing thinner camber plates, and not using a spacer like TMS', with stock style spring and strut, is something to do if you wish to get the car a little lower (good for B12 which is gas pressurized) without compromising travel.

[Tbonem3]

Here's another thought - If you don't want to lower the car (at all or much at all), why bother wanting more travel? Travel is sufficient (barely) at stock ride height with soft (143lb) front springs.

Generally, you'd want more bump travel because you want to lower the car (for looks, for lower COG) without severly ramping up the spring rate. So if you keep the 143lb front spring rate or similar comfortable amount (like158lb eibach springs, for example), but you also want to lower the car a full 1" like people usually do, you'll run into problems. If you're moving up to a stiff spring like 400lb, travel doesn't matter so much because that stiff of a spring won't be that compressed (without aero and very high speeds) so you can lower the car significantly and not worry about travel. Your worry will be finding dampers that can adequetly control rebound from 400lb springs (FCM, ohlins, jrz, mcs).

[Bry5on]

Heinz you’ve got it right. Keeping the ride height (effective upper spring perch) fixed and moving the strut top upward will increase travel as long as there is no coil bind, which in your case there is not. Your calcs are right and you’re gaining about a half inch of travel, which should improve your ride quality by keeping you off the bump stops in more situations.

The rubber spring perch is on the bottom of the little grooves and would not aid/hinder drainage there, and at least in my car, there was dirt around the upper strut bearing that was able to get there between that small gap from the upper strut bearing aluminum and the rubber splash shield. It’s worth noting that spacing the spring perch down opens up this gap and makes drainage a more relevant topic.

[Tbonem3]

How will he move the strut top upwards other than not include the TMS spacer? Unless he finds a smaller spacer like I had suggested.

Also bump stops are part of suspension tuning. Eibach increased spring rate by 8%, and only lowered the spring height by .6". They would have taken all of this into consideration. You're only "on the bumpstops" too much when you lower the car, but don't increase spring rate, comensurately. The eibach springs have a slight increase to match the slight drop.

Increasing bump travel to stay farther away from the bumpstops will only mean his wheel will come closer into contact with the wheel well before bump stop is engaged and spring rate is exponentially increased. Might make the car more confortable up front (since spring rate won't increase as much), but he could also slow the rebound on the konis to match increased rate from slight contact with bumpstops.

[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.

[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.

[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.

[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.

[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]

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]

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.

[Slideways]

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

[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!

[Bry5on]

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

[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. 🤔