Camber Set-Up—Hoosiers to Driverz Cup/Challenge Cup Tires

[housejoe]

Hi Everyone,
I hope you all had a safe and Happy Holiday. I am starting to prep for next season as I am sure most of you are. In 2023 I will run a mixture of SCCA and Driverz Cup events. Currently my front camber setting is at -1.5 deg with offset link pin bushings (Currently on Hoosier FVS). I know I need to remove some camber for the wider DC tire (target is -.9 deg). Can this be done while still using the offset bushings and just messing with the shims? Or is it better to get a second set of knuckle/spindle assemblies that have the stock bushings and shim them to -.9 (assuming they can achieve that amount of camber)? The thought would be then to just swap the spindle assemblies (having labeled the shim positions for each) for whichever series I happen to be running on a particular weekend. I’ll be doing this usually for 2 cars (2 drivers) so I’m looking for the most efficient way.

Thanks in advance for the “education”. Joe

[Steve Davis]

Joe,
I'm pretty sure that NO ONE has ever made a spindle change to accommodate the DC tires compared to the Hoosiers. Just swap the wheels/tires and go for it. You MIGHT have to tweak the brake bias a tad, but that should be it... at least until you learn differently .

Steve, FV80

[Matt Clark]

Hi Everyone,
I hope you all had a safe and Happy Holiday. I am starting to prep for next season as I am sure most of you are. In 2023 I will run a mixture of SCCA and Driverz Cup events. Currently my front camber setting is at -1.5 deg with offset link pin bushings (Currently on Hoosier FVS). I know I need to remove some camber for the wider DC tire (target is -.9 deg). Can this be done while still using the offset bushings and just messing with the shims? Or is it better to get a second set of knuckle/spindle assemblies that have the stock bushings and shim them to -.9 (assuming they can achieve that amount of camber)? The thought would be then to just swap the spindle assemblies (having labeled the shim positions for each) for whichever series I happen to be running on a particular weekend. I’ll be doing this usually for 2 cars (2 drivers) so I’m looking for the most efficient way.

Thanks in advance for the “education”. Joe

As Steve mentions... no one is changing front camber for the radials. We always want as much as we can get in a FV because things will flex & tuck the front tire anyway.

Rear camber is another story. There are some different theories about more or less being better, but even that is not a massive change. Don't overthink it all, as any changes can be figured out in a session or 2.

[housejoe]

Thanks for the replies fellas. I’m glad it’s as simple as that, that allows me to focus on some other stuff!

[housejoe]

While we’re on the subject of camber changes, could any of you give me a recommendation for the correct spring perch wrench to use on the rear coil over? My cars are both citations with the penske 8100. I see a bunch of “universal” sets on Amazon, anybody had luck with those? Just trying to avoid a bunch of trial and error purchases. Thanks! JOE

[BLS]

While we’re on the subject of camber changes, could any of you give me a recommendation for the correct spring perch wrench to use on the rear coil over? My cars are both citations with the penske 8100. I see a bunch of “universal” sets on Amazon, anybody had luck with those? Just trying to avoid a bunch of trial and error purchases. Thanks! JOE

Years ago I bought this one and it works, not perfect, but good enough. They tell you a little bench grinder work might be needed...

https://www.pegasusautoracing.com/pr....asp?RecID=842

[housejoe]

Thanks for the reply! At least at that price I won’t feel bad if mess it up on the grinder. Meanwhile, If anyone has a “perfect” solution, please let me know.

[jpetillo]

Thanks for the reply! At least at that price I won’t feel bad if mess it up on the grinder. Meanwhile, If anyone has a “perfect” solution, please let me know.

Joe, on my SpeedSport, which has a similar setup to the Citation, I used to detach the droop rod then jack the rear up and let the shock fully extend. The spring would unload enough that I could then turn the spring adjuster nut easily by hand. Wear gloves. Depending on how much spring preload you have this might work for you. John

[Steve Davis]

My adjustment 'tool' is roughly the same as the picture above.. except that it will fold - the 'grabber end' folds in sorta like a pocket knife. I also have been able to make adjustments by releasing the limiter, jacking the car high and forcing the rear suspension all the way to (in my case) the LEFT side. It is still ALMOST impossible due to interference with other 'parts' in the way of getting the correct angle. I have seen a LONGER version of that same tool, but it would be useless with the shock installed.. you'd HAVE to remove it.
I do also have a different shock that has HOLES in the perch instead of those 'notches'. It's a bit easier, but still pretty tough to do on the car... but not as tough as having to remove the shock completely to make a change. I use different size 'blunt end punches' to turn it - mostly to remove the spring for rebuild. I HATE having to screw that perch under full spring load for long distances, so built myself a spring compressor to unload it in the shop after taking it off the car.

Steve, FV80

[sabre1fv]

McMaster Carr has an assortment of these wrenches and you choose the correct one based on the diameter of the adjuster (ring); both pin and hook type are available, as well as the pivoting head type that Steve mentioned.

https://www.mcmaster.com/products/wrenches/ and click on spanner wrenches

-Jim

[problemchild]

The "perfect solution" is to upgrade your spring perch to a better Penske spring perch with six 1/4" holes drilled radially around the ring. To adjust, you just use a punch or phillips screwdriver (with point ground off). I suppose you could also modify your exiting perch by drilling radial holes in it. I have not seen those hook style perches on any race car but a FV for 20 years,

If you look in my pics in https://www.apexspeed.com/forums/sho...ion-Discussion you will see the perches in every shock in those pics. Also visible on the Frankenstein Penskes in https://www.apexspeed.com/forums/sho...-F-Garage-Sale

Regarding adjusting rear camber and droop for different tires, it is my experience that once you find the "sweet spot" between the spring placement on the shock body and the droop setting, that "sweet spot" is common for different tracks, tires, etc. Once I find that "sweet spot", I just adjust my pushrods to get my desired static camber settings. I would go years without moving the spring adjuster (which also makes the adjuster tool less significant)..