Rear passenger rubbing - fuel line risk?

[kyippee]

I think this is a laguna seca issue with the corkscrew. Noticed deeper rubbing after Sunday. How panicked should I be about what I imagine is a fuel line?

Replace and put a thin metal shield there?

Video for extra fun.. that load on the rear passenger side

[SYT_Shadow]

When you rub that it means it's time to raise the ride height a little bit

[kyippee]

Yikes.. will have to see how much it can be raised... I know the front height is hard to increase because of the short springs needed to clear 18x10.5 and 295/30/18 tires. Don't know about the rear...

A friend says I should just upgrade to Ohlins TTX and tune it out stiffer.. hmm that's very expensive.

[RickyBobby]

Originally Posted by kyippee

Yikes.. will have to see how much it can be raised... I know the front height is hard to increase because of the short springs needed to clear 18x10.5 and 295/30/18 tires. Don't know about the rear...

A friend says I should just upgrade to Ohlins TTX and tune it out stiffer.. hmm that's very expensive.

My problem went away after I added the ohlins ttx.
They have better compression control.
Or you can add longer bumpstops, but this will cause a rise in force at the end of the shock stroke.

[tsk94]

Like SYT_Shadow said, you need to raise your ride height.

The other option is a stiffer rear spring.

What size tire is this happening with?

Also raising the front wouldn't cause issues, lowering it would. Unless you're running into preloading issues by raising it beyond where you currently are? Raising the car will move the perch up which should result in more clearance to the wheel/tire. If you end up raising the rear you can also raise the front to maintain your rake if you're happy with it.

[kyippee]

Thanks all - thinking through options.

Setup is:
18x10.5 ET22 wheels
Nankang AR-1 295/30/18
JRZ RS One dampers at 18 out of 21 clicks
Hyperco 550/800 springs, 5" front and 7" rear
Ground Control Race Camber Plates in front and GC weight jacks in the rear

[tsk94]

Originally Posted by kyippee

Thanks all - thinking through options.

Setup is:
18x10.5 ET22 wheels
Nankang AR-1 295/30/18
JRZ RS One dampers at 18 out of 21 clicks
Hyperco 550/800 springs, 5" front and 7" rear
Ground Control Race Camber Plates in front and GC weight jacks in the rear

So a smaller diameter tire isn't an option unfortunately.

Leaves you with either raising the ride height or a stiffer rear spring.

[SYT_Shadow]

Originally Posted by kyippee

Thanks all - thinking through options.

Setup is:
18x10.5 ET22 wheels
Nankang AR-1 295/30/18
JRZ RS One dampers at 18 out of 21 clicks
Hyperco 550/800 springs, 5" front and 7" rear
Ground Control Race Camber Plates in front and GC weight jacks in the rear

Pretty soft springs, although you are running a sticky street tire so they're probably well matched

In the E9X I understand you want to run the lowest rear height possible until that happens, so then you either raise it or increase spring stiffness like Trevor says

[kyippee]

Originally Posted by SYT_Shadow

Pretty soft springs, although you are running a sticky street tire so they're probably well matched

Hmm what would you recommend? Car is full interior still, no front lip, front hood vents and GTS replica wing. So light aero.

Maybe swapping springs is a good medium point? I did get setup feedback saying it needs to be stiffer.. next tire is Toyo RR, does that change the assessment?

[SYT_Shadow]

Originally Posted by kyippee

Hmm what would you recommend? Car is full interior still, no front lip, front hood vents and GTS replica wing. So light aero.

Maybe swapping springs is a good medium point? I did get setup feedback saying it needs to be stiffer.. next tire is Toyo RR, does that change the assessment?

You're using a JRZ damper. Ask whoever specced the valving whether it can take 1000 rear and then swap the front to 700 as part of the package.

The stickier the tire the harder the spring. I use a BFG R1/R1S and run 700/1000 in the E9X platform and 800/1100 in the F8X platform. With a true slick I'd probably run higher, but I'm not there yet.

I can daily drive the 700/1000 car without any issues suspension-wise. I also have a full interior.

[dogbone]

The Corkscrew is not the problem. That turn loads up the driver side. Turn 6, however, CAN be a problem for the passenger side where the fuel filler tube is.

Check this pic out of my car in Turn 6------

[Kelse92]

Originally Posted by kyippee

Thanks all - thinking through options.

Setup is:
18x10.5 ET22 wheels
Nankang AR-1 295/30/18
JRZ RS One dampers at 18 out of 21 clicks
Hyperco 550/800 springs, 5" front and 7" rear
Ground Control Race Camber Plates in front and GC weight jacks in the rear

I have a similar setup but with KW's instead of JRZ's and have squeezed on a much taller tire with no rubbing like this. I would still lean towards the ride height first (free, just your labor) and then maybe spending money on springs after that.

[kyippee]

Thanks guys, this is all super super helpful. Going to see how much more height adjustment is available. I'm a noob mechanically and didn't do the height myself. Checking with shop that did the install, and may get a visual on it at next visit. I think I recall it being at max height already.. but we'll see.

If I go the springs route, what about running 550/1000? Just increase spring rate in rear. My friend ran 600/1000 and reported heavy understeer, and being more balanced with 550/1000. Setup feedback from several fast friends driving my car has consistently been that my suspension feels far too soft and squishy. I was thinking 700/1000, but now I'm thinking 550/1000. JRZ RS One dampers were running at 19 out of 21 clicks all around already, so I think it's spring rate now.

Checking with APEX about the dampers I bought via them, to see if the valving can handle it.

[dparm]

Originally Posted by dogbone

The Corkscrew is not the problem. That turn loads up the driver side. Turn 6, however, CAN be a problem for the passenger side where the fuel filler tube is.

Check this pic out of my car in Turn 6------

STANCE BOI

[dogbone]

Originally Posted by dparm

STANCE BOI

hehe yeah I was pretty shocked when I saw that photo. That particular turn has a way of sucking the car down. It has a dip on the inside. The turn is quick---80+mph. And it's uphill, so you sort of jam the passenger side into the hill as you turn left. And you see the result. This was several years ago. I believe I have a bit stiffer springs in the rear now (900 vs. 800).

In that photo, I'm running a super fat 300 Yoko slick. (it's a full inch wider than 305 Pirelli DH) My fuel filler tube has been rubbed and I believe it's that turn that did it. Ran a new personal best that day, so I'm not too sad about it.

[fsmtnbiker]

Originally Posted by kyippee

Thanks guys, this is all super super helpful. Going to see how much more height adjustment is available. I'm a noob mechanically and didn't do the height myself. Checking with shop that did the install, and may get a visual on it at next visit. I think I recall it being at max height already.. but we'll see.

If I go the springs route, what about running 550/1000? Just increase spring rate in rear. My friend ran 600/1000 and reported heavy understeer, and being more balanced with 550/1000. Setup feedback from several fast friends driving my car has consistently been that my suspension feels far too soft and squishy. I was thinking 700/1000, but now I'm thinking 550/1000. JRZ RS One dampers were running at 19 out of 21 clicks all around already, so I think it's spring rate now.

Checking with APEX about the dampers I bought via them, to see if the valving can handle it.

550/1000 will be good as long as you have a larger than stock front bar. I'm 560/1100 with the eibach front bar and it is pretty balanced.

Buying TTXs to solve this would be like buying a big brake kit to get shorter stopping distances.

[kyippee]

Thanks fsmtnbiker Thanks! I do have a Dinan front bar, currently on the softest setting. Maybe I just switch it to stiffest setting.

1000 wouldn't be too twitchy?

[tsk94]

Originally Posted by kyippee

Thanks fsmtnbiker Thanks! I do have a Dinan front bar, currently on the softest setting. Maybe I just switch it to stiffest setting.

1000 wouldn't be too twitchy?

Not if you're willing/able to adjust other elements of your setup accordingly. If the car becomes too oversteer biased on the stiffer rear springs you have a few options - it also depends on what phase of the corner the oversteer is occurring. You can stiffen the front sway bar as discussed previously - this will primarily influence mid corner balance. Do you have an adjustable rear sway bar? If so you can soften it if it's not on the softest setting already. You can lower the rear for more rear end grip. You can increase rear toe in to help corner exit/power-on stability and decrease rear rotation in the beginning-middle phase of the corner.

Then you also have your dampers to play with. Do the single adjustable JRZ's only adjust rebound or do they simultaneously adjust both rebound and compression? I'd assume they just do rebound but I'm not 100% sure. Assuming they adjust only rebound, you could stiffen the front and/or soften the rears to help any oversteer issues that might come up.

[kyippee]

It has pre-determined compression for each rebound setting; so effectively adjusts both at the same time.

Thanks for all the comments and feedback - have a couple things underway now:
- Getting 700/1000 springs to try out
- When we swap them out, will try to see if we can raise it more; previously tried raising ride height elsewhere but it was supposedly maxed out already!
- Verified the 700/100 should work with my existing dampers, APEX will check in with JRZ for advice on how many clicks to run at. Already been running at 18-19 out of 21, not sure if higher makes sense.
- Had already planned and got parts to do solid rear subframe mount, poly diff/trans bushings, and powerflex purple bushings for a lot of the rear parts (currently stock for nearly all of it there, aside from SPL rear toe lock-out kit + the ECS rear trailing arm)

On the rubbed fuel filler... yikes. Going to have the shop check out what we can do and how bad it is.

[RickyBobby]

Originally Posted by dogbone

The Corkscrew is not the problem. That turn loads up the driver side. Turn 6, however, CAN be a problem for the passenger side where the fuel filler tube is.

Check this pic out of my car in Turn 6------

Agreed, T6 is the culprit. I have a similar picture of my car from 2009.

The good news about upping your spring rates is that it will also raise your ride height.

[fsmtnbiker]

Originally Posted by kyippee

Thanks fsmtnbiker Thanks! I do have a Dinan front bar, currently on the softest setting. Maybe I just switch it to stiffest setting.

1000 wouldn't be too twitchy?

It really depends on your comfort with a balanced car. I ran 515F/1000R w/ Eibach front bar on middle setting for a long time on my car, its very neutral and drives really well. Same with the current 560/1100 but I backed the front bar down to soft to get it back to neutral.

I strongly suspect your car will be pushy with the 700/1000 setup unless you go back to a stock swaybar up front (assuming the rear is also stock.) If you have larger bars on both ends, this will probably be fine. It will definitely help to reduce the rubbing you're seeing, even if you set the ride heights the same. I haven't gotten bad rub there yet on my car, but I'll keep an eye on it next weekend at Laguna and raise it a bit if it's digging in. The extra downforce from running a wing only makes that worse.

[kyippee]

Does anybody know what the part number is for the fender liner I've rubbed? I think I found the fuel filler line, if we need to replace: https://www.ecstuning.com/b-genuine-...e/16117203752/

But the liner.. realOEM is confusing the heck out of me!