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Stuff that hits when you modify for HPDE/Race

 
Old 01-06-2019, 02:08 PM
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Default Stuff that hits when you modify for HPDE/Race

RE: Potential hardware interference when prepping a 90-05 Miata for high performance. This thread is only about what hits what, not how to make your car faster

Thought it might be useful to start a list to refer newbs to. We'll update the OP as the community add their data points and photos.
Mostly suspension related. Focus is on kinematic incompatibilities and tolerance stacks.
Off the top of my head..

9" or wider wheels
Hit brake lines at full lock
- Clock (rotate at caliper) brake lines to clear
Hit front sway bar at full lock
- No fix
Hit LCA at full lock
- No fix but reducing caster sometimes helps
Hit OEM diameter springs
- Switch to any coilover or coilover sleeve

Aftermarket brake lines without locating pin
Hit wheels at full droop/lock.
- Re-clock brake line at caliper
Hit shocks
- Reclock
Bind at full droop
- Replace with longer lines

225/45/15 or wider tires
Hit fender at full bump, NA
- Roll fenders, add camberz
Hit tub at full bump
- No fix other than greatly reducing bump travel (bad idea)

245/40/15
Hit fenders at full bump, full lock
- NA needs flares are radical pull. NB, roll fenders.

275/35/15
Hit body seam,front, at full lock
- Grind body seam, reduce caster

NB2 FUCA (Front Upper Control Arms)
Gusset in NB2 FUCA can contact shock at full droop if camber eccentrics adjusted too far positive
- Increase camber
- Grind gusset in FUCA
- Swap to NA or NB1 FUCA

Extended Lower Ball Joints
If camber eccentric adjusted to reduce camber on NB2 FUCA, shocks might hit FUCA
-Adjust eccentrics to increase negative camber

Aftermarket sway bars
Allow bar to hit front shocks at full droop
- Grind end of sway bar
Allow bar to hit FUCA at full bump
- Shorter end links
- Grind end of sway bar
Bind rear end links at full droop with certain shocks
- Do not use adjustment hole in rear bar that causes binding

Aftermarket brake calipers / rotors
Allow brake lines to hit wheels
- Reclock lines at caliper
- Drill new 1/8 NPT port to relocate line
Allow calipers to hit wheel, but only under cornering load.
- This is wheel and/or spindle flex. Allow .120" min clearance to brake components from wheel.

Aftermarket header
Rear flange lower than OEM reduces ground clearance. Constant off track excursions eventually cracks header and breaks exhaust hangers.
- Cut/weld header to relocate flange upwards

NB engine in NA chassis with rubber motor mounts
Throttle body hits hood
- More rigid motor mounts
- Clearance hood

Offset FUCA bushings
May allow 9" or wider wheels to hit FUCA at full lock
- No fix
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Last edited by emilio700; 01-10-2019 at 12:36 PM.
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Old 01-06-2019, 02:42 PM
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Originally Posted by emilio700 View Post
Short body coilovers
Allow shock to hit NB2 FUCA at full droop
- Reduce camber
- Grind gusset in FUCA
- Swap to NA or NB1 FUCA
I believe this should be increase camber, not reduce camber. Less camber pull the shock in more toward the gusset. Or remove ELBJs and reset camber if applicable.

Great list!
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Old 01-06-2019, 09:14 PM
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OEM size springs hit wheels full lock, don't remember offhand what width/offset triggers that though.
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Old 01-07-2019, 11:34 AM
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Originally Posted by FatKao View Post
OEM size springs hit wheels full lock, don't remember offhand what width/offset triggers that though.
9" +36. I assumed folks reading this thread are no longer on OEM springs.
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Old 01-07-2019, 12:06 PM
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Repped. Perfect timing on this post, since I've run into NB2 FUCA issues and was working on getting data points for the need to roll fenders with my setup.
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Old 01-07-2019, 08:32 PM
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Originally Posted by emilio700 View Post
Aftermarket header
Rear flange lower than OEM reduces ground clearance. Constant off track excursions eventually cracks header and breaks exhaust hangers.
- Cut/weld header to relocate flange upwards
Does this occur with a RB header on an NB2? I picked one up and was about to install it.

Last edited by chp5; 01-07-2019 at 11:21 PM.
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Old 01-08-2019, 01:51 AM
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Originally Posted by chp5 View Post


Does this occur with a RB header on an NB2? I picked one up and was about to install it.
All
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Old 01-09-2019, 05:49 AM
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Don't seem to see anything about wheels rubbing FUCA's at full lock. Mine seem to rub around the upper ball joint at full lock. That's with offset FUCA bushings (which could be a culprit) at -3 of front camber and 6.5 degrees of caster.
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Old 01-10-2019, 07:28 AM
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Originally Posted by emilio700 View Post
9" or wider wheels
Hit brake lines at full lock
- Clock (rotate at caliper) brake lines to clear
Hit front sway bar at full lock
- No fix
Hit LCA at full lock
- No fix but reducing caster sometimes helps
Bullet and Vegas obviously are in this category and I imagine you do not drive around clenching near full lock so what do you do?
Are they a perfect storm of parts so nothings touches? Is it so extensively modified this doesn't matter? Do you have spacers to push the wheels out a little so it doesn't knock?
I've been lusting after some 6ULs in 15x9 (doesn't look like I can get tyres to fit them in the UK) but this does have me concerned.
I'm happy to hammer, pull and bend but no fix is present twice. The clock point would do well to have a photo example comparison too for others if possible.
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Old 01-10-2019, 12:45 PM
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Originally Posted by Lurch View Post
Don't seem to see anything about wheels rubbing FUCA's at full lock. Mine seem to rub around the upper ball joint at full lock. That's with offset FUCA bushings (which could be a culprit) at -3 of front camber and 6.5 degrees of caster.
Definitely your bushings. Thanks for the data point. Table updated.

Originally Posted by rrjwilson View Post
RE: wheel rub
Bullet and Vegas obviously are in this category and I imagine you do not drive around clenching near full lock so what do you do?
..The clock point would do well to have a photo example comparison too for others if possible.
Seriously over thinking it. If your 4" wider than OEM race wheels rub at full lock, don't use full lock. If you need things to not rub, don't racecar. WRT to photo example for brake line orientation, again you are over thinking it. You will figure out a good orientation once you are looking at the brake assembly by being patient and methodical.
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Old 01-10-2019, 02:37 PM
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I’ve found it helpful to throw a label on the steering wheel saying something like “180* turn max”. Sucks maneuvering in a parking lot, but that’s about twice as much as you need on the track
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Old 01-10-2019, 02:51 PM
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Originally Posted by curly View Post
Iíve found it helpful to throw a label on the steering wheel saying something like ď180* turn maxĒ. Sucks maneuvering in a parking lot, but thatís about twice as much as you need on the track
Good idea for an enduro car or rental.

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Old 01-10-2019, 04:48 PM
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Or if you're tired of fixing a customers splitter
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Old 01-11-2019, 06:25 AM
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Originally Posted by emilio700 View Post
Seriously over thinking it. If your 4" wider than OEM race wheels rub at full lock, don't use full lock. If you need things to not rub, don't racecar. WRT to photo example for brake line orientation, again you are over thinking it. You will figure out a good orientation once you are looking at the brake assembly by being patient and methodical.
Cool
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