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Discussion Starter #81
This can also be caused by track conditions. A pavement change or even an imperceptibly small drop can lighten the car enough to throw the rear out far enough that it's difficult to recover from. Oil or gravel on the track could do the same. Could have been exacerbated by overheated tires, too. I haven't driven Thunderhill, but have had it happen to me on other tracks - there are turns where you have to modulate your cornering gees and open (or straighten) the wheel to keep the car stable.
It's certainly possible! I'm just going about it from the assumption that either I did something that exacerbated the problem, or maybe some component of my car did. In that regard, I've done a lot of reading on bump steer, roll center, and scrub radius to figure out how I can optimize that with my setup. I find it interesting. I now realize that you really shouldn't adjust ride height much without accounting for all of those other variables, meaning you need to be fully adjustable. It gets pricey quick.



I got the proper ducting and grille in for my center radiator! Unfortunately, in the process, I discovered that my front passenger side damper is leaking already. The other three look okay. I'll be reaching out to Ohlins, hopefully they'll take care of it. By the way Apex, I now see that clearance issue between the damper and the axle boot, mine is fairly close as well.

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Also got started on stripping my headliner. This stuff is sticky! But a wire brush and shop vac took a majority off fairly quickly.

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IMG_20190901_133324.jpg
 

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Looking at the Ohlin coilover, seems to be a rub mark just above the threads, opposite of the oil on the upper shock body. Just wondered if there was binding of some type that occured. Maybe a look at the backside of the spring in that rub area with a mirror. Or, this could have occured during your install. Maybe just wipe off the oil and see if it happens again.
 

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Hyrax- what happened to your Ohlin passenger side front shock? Has it leaked again, or was it just a setup issue? Also, have you figured out how to make your rear toe links parallel to the LCA's. Rear toe locker plates are necessary to keep the OEM twist adjustment from changing. The other thing is to add some teflon grease to the springs on top and bottom. I can rotate my front springs (most likely from spring sag), when on the jack with the tire off. I do have some grit on the bottom of the springs, so the teflon grease helps reduce any squeeks. I also noticed a rubber mark from the A7's on the front spring. Looks like I need the additional 3 mm front LCA spacer to get to -3.0 camber, which will push out the tire away from the spring when in the shop in the next couple of weeks.
 

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Discussion Starter #85 (Edited)
Apex1, that mark you saw on the seal is from my finger. Your idea of wiping it off and seeing if it returns is a good one... But I had already removed it and shipped to Ohlins a few days ago. Thanks for the info Joshua. I spoke to an Ohlins rep and he must have had some concern about it or I'd hope he'd have told me that himself. Maybe he didn't pay close enough attention. Either way they'll be taking a look at it soon and I'll have an answer haha.

Oh and for the toe links, technically you don't want them parallel with the LCA since they're different lengths. You probably know that. The best way to measure bump steer is to remove the spring, reassemble, then use a bump steer gauge or laser to measure changes in toe throughout the range. I will probably do a DIY measurement with a laser and see how much to shim it. I'm expecting results similar to what one of the posts I linked previously found. I think it's likely I'll need the max correction but we'll see. The front spring is pretty easy to remove, not sure about the rear... Hoping I don't have to pull the axle off again haha.

I took my car for a drive out to the Napa area the other weekend. A nice drive with some great food and scenery. The squeal from these DS 1.11 pads is HORRENDOUS though. I knew they'd be loud but it's almost unbearable. I picked up some Brembo pads to swap in for the street in the future haha.

On said trip I dropped by Wine Country Motorsports at Sonoma Raceway to try out some seats. The OMP WRC-R and the Sparco Evo fit the best. The OMP Champ also fit very well but I'm too tall for it without modifying the foam which is unfortunate. Definitely planning on installing a seat sometime. Soon enough this thing is going to end up being a dedicated track car...

Oh, and finally, I got a nice deal on some NT01s in the OEM sizes for labor day. Under $950 heat cycled and installed. I am surprised people say they run wider than 235/265 NT01s on OEM CS wheels. These things are already super fat. I cannot imagine gaining anything by going wider on this wheel width.

Some pictures from the track day and the tires below!
 

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Bumpsteer measurement is a time consuming tool to address the Cayman suspension shortcomings. 996/997's do not have this issue. But once done, forget about it and 4 wheel drift to your heart's content.

I would also look at pushing out the LCA's as much as possible to widen the track front as measured by camber (from -2.7 to maybe -3.0) and rear to -2.5. If you have reasons for not doing this, then use wheel spacers to fill the gap to your wheel arches on the corners. The additional track width will give you more leverage on the outside tires, meaning more grip. The spacers also change the balance slightly front to rear, so if you already have a slight understeer, then you would use more front spacers than the rear to reduce understeer.
 

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Oh, and finally, I got a nice deal on some NT01s in the OEM sizes for labor day. Under $950 heat cycled and installed. I am surprised people say they run wider than 235/265 NT01s on OEM CS wheels. These things are already super fat. I cannot imagine gaining anything by going wider on this wheel width.
Porsche oddly chooses wheel sizes that are slightly narrow for the tire sizes, at least for "lesser" Boxsters/Caymans. Nominal "measuring rim widths" for 235/40-18 and 265/40-18 are 8.5" and 9.5", this is what most manufacturers would go with to run those tire sizes even for non-performance-oriented cars. 1/2" to 1" wider than that would still be within tire spec and more appropriate for a serious sports car. But Porsche went 1/2" *narrower* than the conservative measuring width spec with 8" and 9" widths. These are the *minimum* wheel widths allowed for those tire sizes. WTF...

I'm running Yok A052 225/40-18 front and 245/40-18 rears on stock 18x8 18x9 rear wheels and it's arguably a "better" fitment as far as tire width vs. wheel width than stock. Did this to reduce points for time trial competition so I don't have to run as much ballast ;)

Trackworthy tires (which tend to run wide) in OEM 235/265 sizes are going to be somewhat pooched on OEM 8"/9" wheels, as seen in yer pics.
 

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Apex1, that mark you saw on the seal is from my finger. Your idea of wiping it off and seeing if it returns is a good one... But I had already removed it and shipped to Ohlins a few days ago. Thanks for the info Joshua. I spoke to an Ohlins rep and he must have had some concern about it or I'd hope he'd have told me that himself. Maybe he didn't pay close enough attention. Either way they'll be taking a look at it soon and I'll have an answer haha.

Oh and for the toe links, technically you don't want them parallel with the LCA since they're different lengths. You probably know that. The best way to measure bump steer is to remove the spring, reassemble, then use a bump steer gauge or laser to measure changes in toe throughout the range. I will probably do a DIY measurement with a laser and see how much to shim it. I'm expecting results similar to what one of the posts I linked previously found. I think it's likely I'll need the max correction but we'll see. The front spring is pretty easy to remove, not sure about the rear... Hoping I don't have to pull the axle off again haha.

I took my car for a drive out to the Napa area the other weekend. A nice drive with some great food and scenery. The squeal from these DS 1.11 pads is HORRENDOUS though. I knew they'd be loud but it's almost unbearable. I picked up some Brembo pads to swap in for the street in the future haha.

On said trip I dropped by Wine Country Motorsports at Sonoma Raceway to try out some seats. The OMP WRC-R and the Sparco Evo fit the best. The OMP Champ also fit very well but I'm too tall for it without modifying the foam which is unfortunate. Definitely planning on installing a seat sometime. Soon enough this thing is going to end up being a dedicated track car...

Oh, and finally, I got a nice deal on some NT01s in the OEM sizes for labor day. Under $950 heat cycled and installed. I am surprised people say they run wider than 235/265 NT01s on OEM CS wheels. These things are already super fat. I cannot imagine gaining anything by going wider on this wheel width.

Some pictures from the track day and the tires below!
So Hyrax, what's next over the winter?
 
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