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Going Square, what is needed?

Norm, thanks the the info. When you cut the b/s flat part, did you then weld another flat piece back on? Even though the rears have clearance when loaded, thinking I should be concerned if they unload while at speed?!! Or if that happens, it's too late to save it anyway.
 
Is it common knowledge and practice to remove the bump stop bracket when running 18x11s with 305s? Driving on the back roads today, no issues. However the vehicle dynamics are completely different at the race track.
 

Norm Peterson

Corner Barstool Sitter
939
709
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
The main reason I trimmed mine was because I was (and still am) running the OE PHB. Its rubber bushings permit more lateral axle migration, which has at least the potential for wheel or tire to bracket contact when you're filling up the wheel well with wheel and tire. I'd also DIY-stiffened the PHB bushings.

1.25+g on the track is going to move things around a lot more than, say, 0.75g on the street.


Norm
 

APEXRaceParts

Race Proven, Street Approved
Supporting Vendor
641
911
Exp. Type
Time Attack
Exp. Level
5-10 Years
Bay Area, CA
Does anyone out there track 305s on 18x11 wheels that has not trimmed or removed the bump stop brackets from the rear fender well? Any issues?

You do not need to do any mods to the rear if you don't want to. Like mentioned earlier, having some load under the rear axle while installing the wheels is all that is needed. If you're ever out there and have zero load under the axle, I think you have bigger problems :)
 
The stock Boss has a 25 mm RSB and a 34.6 mm FSB, which is setup for the stock staggered wheel/tire fitment. I am now running a square fitment with NT01 305s with Boss T springs. I've tried a 22 mm RSB on the rear with good results, but a bit more body roll. Some suspension OEMs have suggested leaving the 25 mm RSB, but going with a larger FSB given the larger stickier tires. Note that I am moving to coilovers soon. Any comments regarding going to a larger FSB? Seems like most are in favor of a smaller RSB. Anyone have experience with the BMR 38 mm adjustable FSB?
 

Mad Hatter

Gotta go Faster
4,104
2,657
Santiago, Chile
Recently my setup has been square 320 tires on Apex 18x11 wheels. Tight corners do well with a 18mm rsb (or smaller). But presntly looking to get the car balanced without any rsb.

Sent from my SM-G900M using Tapatalk
 

Wingrider

'11 GT500, 99% Track Car. Lots of mods & I coach
I keep seeing the 25mm spacer suggested for these 18x11 wheels and it doesn't seem to matter if it's stock front struts or the CorteX offset struts. Seems like both cases are using them. What spacers are people running that have the CorteX offset struts and why would it be the same spacer if it's the 25mm one others are using with the stock struts?
 

Mad Hatter

Gotta go Faster
4,104
2,657
Santiago, Chile
I am fine with zero rubbing with 18x11, Cortex offset struts and 15mm front spacers... 25mm is for regular struts from the other threads on this subject.

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Norm Peterson

Corner Barstool Sitter
939
709
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
How much camber and where you're getting it. I've even heard of cases where camber was pushed in the positive direction at the strut to knuckle joint for tire clearance, and the whole business brought back to the desired negative value with camber plates and maybe a little strut tower work.


Norm
 

Grant 302

basic and well known psychic
How much camber and where you're getting it.
That too. Camber bolts or slots make a big difference in clearance to the strut. If using them for more negative camber, larger spacers will be required.

I've even heard of cases where camber was pushed in the positive direction at the strut to knuckle joint for tire clearance, and the whole business brought back to the desired negative value with camber plates and maybe a little strut tower work.
That was one way I was hoping to test 18x12 wheel fitment up front...one of these days. It also results in some interesting and beneficial suspension geometry, but that's off-topic for this thread.
 

ArizonaBOSS

Because racecar.
Moderator
8,574
2,445
Arizona, USA
All of this depends on what camber you have dialed in at the spindle, but I am running a 25mm spacer with the CorteX offset struts, with camber slugs. Some of this is to get a wider front track, vs. clearance to the strut. I'll look at my clearance when I'm setting my car up tonight, I'm sure you could do a 20mm spacer if needed.
 
147
60
In relation to the above posts, does anyone want to throw a discussion about "scrub radius" into the mix?
 

Mad Hatter

Gotta go Faster
4,104
2,657
Santiago, Chile
Thats often on my mind.... seen a pair of ZL1s that had slower lap times with 335 R7 up front then the same car on 295 R7.....

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