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Ask SPL if they offer rubber booties for the downlink ends to keep out the dirt/track grit out of the bearings. Also, corner balance with drivers weight in seat before the downlinks are installed.

Be very careful if using a pressure car washer not to blow soapy water on any of the suspension parts. You will get squeaks and other noises that are very unpleasant.
 
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Discussion Starter #102
Ask SPL if they offer rubber booties for the downlink ends to keep out the dirt/track grit out of the bearings. Also, corner balance with drivers weight in seat before the downlinks are installed.

Be very careful if using a pressure car washer not to blow soapy water on any of the suspension parts. You will get squeaks and other noises that are very unpleasant.
I spoke to them about it and they don't recommend them. It seems everyone on the internet is 50/50 on that.

Small update - I have done one new iteration of the front link with SPL now and we shortened it up a bit so we're good in that regard. We increased the spacing on the swaybar end of the link but it wasn't quite enough so I had to send out for longer bolts and more spacers to get it right. SPL has been great through all of this, couldn't be happier. I got the new pieces and will test fit them tomorrow. Now that I have been through this and understand the geometry happening here I see why that collar link is a much better solution than the stock location.

I received my OMP WRC-R seat and have been playing around with the mounting. I purchased Brey Krause R-9052 brackets to mount it to the stock sliders which seems to have worked out fairly well. At their narrowest mounting option, the WRC-R fits perfectly with no spacers needed. I got the seat bolted in centered to the steering wheel and there's clearance on both sides. I am going to continue using the stock 3 point belts unless I end up getting a cage someday, so, the only thing I am waiting on now is a new GT2 extended/kinked buckle (99780318311). The stock buckle is too short to fit through the hole in the seat. Because I am not driving much anyway, I placed an order with a British supplier for half the cost of what I could find it for in the US. Hopefully, it won't take too long to arrive, though!

I also received a pair of 18MM spacers to try out on the front when I get the car on the ground. If they end up being too wide for my setup (still using factory size wheels/tires and the NT-01s are WIDE) then I will throw those on the rear and order some thinner ones for the front. I went with ECS on these. They look nice and come with the appropriate size bolts for a great price.

The technobrace is here, too. That'll go in when I install the rear bar (maybe tomorrow?).

After sorting out the seat situation I am thinking about renting a Durametric Pro (saw it on eBay for $50) to take care of some coding. It seems like a decent deal because I have another tool to do my maintenance resets with and I should only really need it once. So far I have a list of the following I may do, if anyone has recommendations or ideas for other things that I can code while I have it I am all ears.
  • Overrev report
  • Remove seatbelt chime
  • Side marker turn signal (Don't know if mine does this already, just read about it)
  • Turn off TPMS
  • Comfort windows
  • Disable AWS
I guess that small update ended up being a lot bigger than I expected...
 

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Picture of your OMP seat installed?
 

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Discussion Starter #105
268066


Here's a photo for you with the OMP WRC-R installed on Brey Krause brackets and factory sliders. The GT2 buckle fits perfectly and is comfortable for me to use. Pricey but it gets the job done.
 

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looks comfy. I'm sure with belts, you are really snug. Do you need any additional bracing from you knees or will the seat provide all the bracing with big G forces?
 

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Discussion Starter #108 (Edited)
looks comfy. I'm sure with belts, you are really snug. Do you need any additional bracing from you knees or will the seat provide all the bracing with big G forces?
Even with the stock belts it seems pretty good. This seat has a high thigh bolster so I don't think I'll be doing much additional bracing.

It does make it annoying to get in and out but that's kinda expected... I'm just getting into the habit of rolling the seat back every time. Benefit of keeping the rails haha, but I do wish I could mount the seat a bit lower.

The seats and harnesses are plenty. I run Sparcos in my cayman and Sabelts in my STI. It's really nice since it lets you focus on driving rather than bracing for the turns.
I'm going without a harness for now over concerns about safety without a full cage and HANS. I know a lot of people do it. Maybe I will at some point. I did like some of the Sparco seats but they seemingly changed up their sizing and product line recently and I was unable to easily find the seat I needed. The WRC-R was at a great price and fit me pretty well so I went with it. Might pick up a lumbar bolster though since I'm not swapping it in and out.
 

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That's a good call, most track days require a Hans if you have harnesses now. Also equal protection for driver and passenger so you need 2 harnesses.

Roll bar with harness/hans are plenty safe for track days. The rollbar is fine for the street in terms of safety too. Really depends on what you're doing with the car and where you plan to go with it.

I'm going without a harness for now over concerns about safety without a full cage and HANS. I know a lot of people do it. Maybe I will at some point.
 

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Discussion Starter #110
I got my alignment done and received my rental Durametric Pro today. I played around with coding and was able to remove my airbag light for the driver's seat as well as disable TPMS. Woo! I also went ahead and turned on the side markers as turn signals, and got the "comfort windows" enabled because why not. It's pretty neat during the summer to roll down the windows with the fob I suppose.

I do have one thing I am confused about - the fog lights. My 987.2 has two round fog lights as well as an LED strip to the side The round fog lights seemingly only turn on when I've shut the ignition off (presumably so I can see in the dark when leaving the car). If I turn the lights to any other setting, I cannot get the round fog lights to turn on. Not even when I have the headlights on and pull the switch out. The rear driver's side fog does come on when I do that.

I can turn on the fogs manually using the durametric so I know they function. Are those round lights only used in that one instance? I swore I had them turned on at some point...
 

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Those fog lights can be modified with high intensity cred lights to give more of a ditch light, at least on a 987.1. I use them during the day and at night as running lights.
 

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Discussion Starter #112
Those fog lights can be modified with high intensity cred lights to give more of a ditch light, at least on a 987.1
The ones on my car are a powerful white color and pretty bright when they're on but I only saw them turn on during that one scenario. Seems like pulling the knob out to turn on the fog light should do it but seemingly not. Not sure if I broke that with my coding or that was already the behavior.
 

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Discussion Starter #114
see here for more details on 987.2 lights
987.2 LED Strip (Halogen v. Factory Bi-Xenon)
Awesome, thank you for the info!!

I had a great day out at Thunderhill East this weekend. Overall the car felt great. I have my swaybar set middle front full soft rear and the car felt like it rode the edge of understeer pretty well, I may try a little stiffer in the rear in the future. I also left PSM on all day just to feel out the car and get comfortable. I had some pretty decent laptimes when I could escape the traffic, I was pretty consistently in the 2:07-2:09 range. I know the car has at least a few more seconds in it, I just need to keep improving and carry more speed through the high-speed corners. It felt good that the only cars that passed me were a GT3 and a full-on stock car. I also struggled a bit with heel-toe and I think one of the Rennline spacers bring my gas pedal up would do wonders.

I am considering raising my ride height some, too. I think I have gone beyond the ideal range for roll center. Going to take some more measurements and talk to my new alignment pro to see what he thinks and what I can do to fix it without spending a boatload more money. My LCAs in the front are higher at the ball joint and the rears are parallel with the ground at best. I realized my RSS LCAs in the front have some ball joint height adjustment shims so I am going to move those down also.
 

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Hyrax- Are you talking about bump steer adjustments from your toe arms? Not sure there are adjustments to the LCA's except for shims to gain camber and track. Usually lower is better, as long as you have the spring to prevent bottoming your car. Ohlin's have 400 lbs/in f and 458 lbs/in r spring rates. This is enough until you add wings and aero to your car. The toe arms should be a parallelogram at rest with the LCA's . The toe arms adjustments with shims help to correct if its out of parallel alignment.

What are the symptoms that are pushing you to raise your car?
 

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Discussion Starter #116
Hyrax- Are you talking about bump steer adjustments from your toe arms? Not sure there are adjustments to the LCA's except for shims to gain camber and track. Usually lower is better, as long as you have the spring to prevent bottoming your car. Ohlin's have 400 lbs/in f and 458 lbs/in r spring rates. This is enough until you add wings and aero to your car. The toe arms should be a parallelogram at rest with the LCA's . The toe arms adjustments with shims help to correct if its out of parallel alignment.

What are the symptoms that are pushing you to raise your car?
No I'm not talking about bump steer, though that is one of the factors to consider when changing height. Lowering the car lowers CG, yes, but on a MacPherson setup like the Cayman has it also lowers roll center (faster than CG) which has its own effects. I am still reading and doing math on this so I am not certain exactly what I will do, yet. I don't have the knowledge to do a full writeup on the geometry involved with roll center, but one important factor for me is that when you put roll center below ground then you increase the effective load on the spring, thus increasing roll. You can combat this to some with stiffer springs and rollbars, however, there are also other considerations to look at in the suspension geometry, for example, the rate of decreasing negative camber under compression. I also don't want to shell out for stiffer springs at the moment, so raising my height back up to combat roll a bit is an option.

Unfortunately without some extremely good engineering tools and knowledge, it's hard to calculate what would be ideal because there are so many factors. Also real-world is usually different than theoretical, and it's hard to guess how much deflection there is in my bushings, etc. Instead, I am trying to read up on racer's personal experience as well as feeling out the changes for myself. Take a look at the spec cars and their ride height limitations, and then wonder why the fastest cars don't run the minimum height? There are a lot of factors that go into it.

At the moment I'm thinking I am going to raise the car enough so that my RC is at ground level or so (easy indicator for this is your LCA is parallel with the ground). And the RSS LCAs have some adjustability for RC by shimming up the ball joint effectively increasing its length. Putting more spacers on top of the LCA lowers the outside end.

268686
 

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Discussion Starter #117
Here's a picture of my front/rear LCA (phone said it was level when taking the photo, so it should be fairly accurate).

268687



268688
 

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No I'm not talking about bump steer, though that is one of the factors to consider when changing height. Lowering the car lowers CG, yes, but on a MacPherson setup like the Cayman has it also lowers roll center (faster than CG) which has its own effects. I am still reading and doing math on this so I am not certain exactly what I will do, yet. I don't have the knowledge to do a full writeup on the geometry involved with roll center, but one important factor for me is that when you put roll center below ground then you increase the effective load on the spring, thus increasing roll. You can combat this to some with stiffer springs and rollbars, however, there are also other considerations to look at in the suspension geometry, for example, the rate of decreasing negative camber under compression. I also don't want to shell out for stiffer springs at the moment, so raising my height back up to combat roll a bit is an option.

Unfortunately without some extremely good engineering tools and knowledge, it's hard to calculate what would be ideal because there are so many factors. Also real-world is usually different than theoretical, and it's hard to guess how much deflection there is in my bushings, etc. Instead, I am trying to read up on racer's personal experience as well as feeling out the changes for myself. Take a look at the spec cars and their ride height limitations, and then wonder why the fastest cars don't run the minimum height? There are a lot of factors that go into it.

At the moment I'm thinking I am going to raise the car enough so that my RC is at ground level or so (easy indicator for this is your LCA is parallel with the ground). And the RSS LCAs have some adjustability for RC by shimming up the ball joint effectively increasing its length. Putting more spacers on top of the LCA lowers the outside end.

View attachment 268686
This is something that many people who lower their car would miss out, how roll centre will affect the cars handling when it's too Low.

Good tip.


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Because of the taper on the ball joint stud, spacers would only work if the whole ball joint would be moved one way or the other. On my Tarett Cup LCA's it has an oversized ball joint and stud that is stationary, so that adjustment is not available to me. My shop just laughs at me because then specifying a certain ride height drop, other considerations become more important, like corner balancing. The ride height is changed on each corner to get the cross weight equal, so that was the overriding issue. The the rake of the car f to r. I wanted a lower than OEM rake by a few mm's to give more weight on the rear tires. OK, but the books say that I am introducing more understeer by doing this. Maybe, so I use wider front tires. In the end, my rake came out about OEM dimensions due to the position of the golden compression/rebound control knob and the half shaft boot space for finger movement. The shop was reluctant to change the ride height on the shock body barrel, which would cause another corner balance to occur. Currently, I use my thumb to change the rebound for daily use.

The point is that you can only lower to a certain level, then other issues happen. I am limited to -2.5 rear camber to get the toe to work out even with the Elephant adjustable toe links. I specified 12 minutes of toe in, which is less than OEM. I find -2.5 good enough and it does not wear out the inside shoulders of the tires as much as more rear toe in would. With the Wavetrac and PedrosTechno Bar, I do not have any rear threshold brake wobble, so all is good.

This photo shows the parallelogram of LCA's and rear toe link at rest. If you could blow up the photo, you would see the shock controller above the half shaft bellows with just enough space for my thumb.

Back to roll center, I find that as long as I get both roll centers about even, my car handles very well. Wheel spacers, wheel offsets, LCA's camber shims and other stuff , even tire sidewalls of 45,40,35,30 can change the roll center, it's just if you know about this issue, you can then detect the effects on the street or track and change the settings to make the two centers close to even.

Send us your synopsis of the roll centers as applied to the Cayman's front & rear suspension, that will be a good read. Diverdog changed his rear suspension to a 996 multilink to remove some of these roll center issues as well as allowing wider rear wheels, I think he wanted 13 in wide rear wheels.

DSC_0026.JPG
 

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Discussion Starter #120
Because of the taper, spacers would only work if the whole ball joint would be moved one way or the other.
Yes that is how the RSS ball joint works. The spacers sit underneath the seat of the taper so it does move it up. It's not a ton of adjustment but better than nothing.

268691


The point is that you can only lower to a certain level, then other issues happen. I am limited to -2.5 rear camber to get the toe to work out even with the Elephant adjustable toe links. I specified 12 minutes of toe in, which is less than OEM, so that is causing my limit on the amount of camber in the rear. I find =2.5 good enough and it does not wear out the inside shoulders of the tires as much as more rear toe. With the Wavetrac and PedroTechno Bar, I do not have any rear threshold brake wobble, so all is good.
It is definitely a balancing act, when you change one thing everything else is affected. Go too far one way and while you improve one metric you make another worse. Just have to find that "ideal" spot for you and your car. The guy who I am now going to for my alignments is very knowledgeable with this sort of thing so I will report back with what he recommends and the changes I make. I'm currently running -2.8F, -2.3R camber, and 9 degrees of caster up front. Based on my temp readings from this weekend that seems to be a pretty good point for my car in its current setup and my skills. Tire temps were pretty even on the passenger side (Thunderhill East CCW is heavy on left handers and thus the passenger side tires) and the drivers side had more heat towards the inside.

this photo shows the parallogram of LCA's and rear toe link at rest. If you could blow up the photo, you would see the shock controller above the half shaft bellows with just enough space for my thumb.
I'm surprised you can get your fingers in there at your height, haha. I suppose there could be some small changes between the .1 and .2 that make my clearance even less, but I struggle to get my fingers between the boot and the adjustment. I've got skinny hands, too.

Yep, your geometry there looks about right for the angle of that LCA from my understanding. However, with your LCA pointed upward at the hub at such a high angle you have moved your roll center pretty far away from your CG. You can bandaid this with stiffer springs and swaybars. If you leave everything the same but increase your ride height so the LCAs are level with the ground you will notice reduced roll (probably a pretty good amount). That is what I am probably going to test out for myself and see how it affects the dynamics of the car and my cornering speed/grip out on the track.
 
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