240z SCCA vintage race car, restoration

[tube80z]

5 hours ago, AydinZ71 said:

@clarkspeed thanks Clark!

 

lesson learned… if you buy “bolt on” parts, even if the reason is to meet class rules, it’s safer to assume they were designed for the street crowd. I no longer believe any of these companies, T3, Apex, Ground Control, have designed or tested their parts for anything other than a street car. I’m sure there are exceptions, and recognize im frustrated. I will only de adapting universal parts designed for Motorsport in the future. 

To be fair to GC the plates aren't intended to be used with that much track increase.  You may need to back that off to stay legal in EP rules.  I don't have a GCR so I'm not sure what you can or can't do with the shock tower and camber plates.  When I widened the front track in my car, I moved the camber plate to almost under the fender mount.  I've also used a porta power to add some positive crash damage but that needs to be done before you tie into the roll cage.

 

Cary

[AydinZ71]

@tube80z true. In hindsight, the shock adjustment nib was always going to interfere with the tower opening, given how much positive camber I need to add back. Thats not GC’s fault. What was frustrating is (see attached picture), this is considered max positive camber. Sooooo… in the neutral position is as far to the outside of the car the camber plate can adjust. I just wish that was more clear when I got them. 
 

we are allowed to add adjustability within the existing unibody. I called a few years ago and asked tech what the limits of that definition are. Drilling new holes or slotting the towers is OK. Welding-in a camber plate to replace the strut landing in the tower was NOT considered OK. 

Edited March 23 by AydinZ71

[tube80z]

On 3/23/2024 at 2:49 PM, AydinZ71 said:

Drilling new holes or slotting the towers is OK. Welding-in a camber plate to replace the strut landing in the tower was NOT considered OK. 

 

It's funny how certain rules are set in stone and others are ignored.  You could make a custom camber plate that is mounted to the top of the strut using the tower edges.  There would be no more center hole in this design as it would all be covered.  If they challenge it you could argue that you wanted to be able to swap springs more quickly out the top.  Take a look at rally car service videos and many of those cars come out the top.

 

My personal choice for camber plates would be a square/rectangle design where you can shim for camber or caster/strut angle (rear).  Ford has a really cool design I meant to steal but couldn't find it again on their GT4 Mustang.

 

Hope that helps, or inspires some rule bending.

[AydinZ71]

@tube80z thanks as always Cary. I think you are right about that. Even if it’s a rule, the enforcement of such is often non-existent. For example, the rules say you need a catch can for your diff and trans lube, and in practice no one enforced this on Greg’s car throughout all his years at the runoffs. 
 

One more option is I seperate the shock tube from the wheel hub, change the angle, and weld it back-on. That would give me the track and ride height I need and still center the strut in the tower. Despite my whining about the camber plate, it does have a well functioning uniball shock attachment that can make-up quite a bit of shock angle without applying lateral force in the shock.

 

just for simplicity, I think I’m going to turn the camber plate 180 deg, drill new mounting holes, make a new center hole for the shock nib, and see if that gets me where I need to be. I’ll also make a 3/8”tk retaining ring to distribute the force of the mounting bolts on top of the shock, since changing the angle is applying forces in the tower in areas that were not as heavily reinforced by OEM. That should “sandwhich”  shock tower when the mounting bolts are torqued. 
 

My next event will be with NASA in May and I still have a ton of work between now and then, including a radiator front-end cowl/shroud. I have pushed my cooling system to the limit without one, and had overheating issues (even at an 85mph avg spd) on my last session. 
 

appreciate the help sir!

Edited March 25 by AydinZ71

[JMortensen]

9 hours ago, AydinZ71 said:

One more option is I seperate the shock tube from the wheel hub, change the angle, and weld it back-on. That would give me the track and ride height I need and still center the strut in the tower. Despite my whining about the camber plate, it does have a well functioning uniball shock attachment that can make-up quite a bit of shock angle without applying lateral force in the shock.

 

just for simplicity, I think I’m going to turn the camber plate 180 deg, drill new mounting holes, make a new center hole for the shock nib, and see if that gets me where I need to be. I’ll also make a 3/8”tk retaining ring to distribute the force of the mounting bolts on top of the shock, since changing the angle is applying forces in the tower in areas that were not as heavily reinforced by OEM. That should “sandwhich”  shock tower when the mounting bolts are torqued. 

I'm in this same boat. I widened the LCAs an inch to prevent CV bottoming and the rear ended up at something like -3.5 with the camber plates flipped and maxxed out positive.

I had the same idea about removing the tubes from the uprights. I actually have Mustang 36mm Bilsteins I am going to run. They are the same length as my sectioned front struts that I run now, so I'll need to run a spacer in the back. My thought was to make a mount and bolt the uprights to it to measure the strut angle, then bend the strut tube in say 4 degrees. The camber plate should handle about 2 degrees of adjustment (guesstimate) and so if I could get somewhere in the 0 to -2 or -1 to -3 range I think it would work.

My other thoughts were to cut the top of the tower out, plate it and recut the hole for the camber plate (sounds like a lot of hassle), or to make a 1" thick offset plate to mount between the bottom and top of the camber plate and move everything outboard, but seems like that might be a lot of extra stress on the camber plate and strut tower.

[AydinZ71]

@JMortensen I am glad its not just me Jon! After-all, I don't have the years of track-going experience you, Cary, and John have, and I humbly admit "camber" could have been a cheese to me as little as five years ago (ok maybe a slight exaggeration) . 

 

The more I think about it, I don't see an appropriate way around this without changing the angle of the strut tube relative to the hub. The further the strut gets away from the OEM mounting position, the less the chassis is prepared to accept the loads. My towers are all braced more-or-less at the centerline of the towers, not towards the fenders which is where the mounting is migrating towards. 

 

My concern about "bending" the tube: My Koni's are already a "tight" fit as it is. I'm concerned any bending on the tube will just mean the shock will bind when I reinsert it, somewhere along its length. One option is to cut the tube with a cutoff wheel right where it meets the cast strut assembly, locate the new angle, and use MIG welding wire to fill-in the "wedge" created by setting a new angle to the tube. 

 

I think your idea of cutting the top of the tower will definitely work (to a limit), as long as you reinforce the surrounding unibody to accommodate shift in load. Its not an option for me (race class), and changing the strut angle may end-up being easier and provide better adjustability in the end. 

 

I have not done the math yet, but I actually think one of the misconceptions I had was that the added track is driving the majority of the negative camber. I really think its the significant change in ride-height that's the significant driver in my case. It occurs to me that most street Z's that have been lowered significantly are unlikely to have checked their camber before/after. I know I certainly didn't with my own street car back in the day. 

 

PS: Anyone else doing their own string alignment? I have done so twice now, and starting to get a little faster. 

[JMortensen]

Yeah, lowered otherwise stock Z will have something like -3 in back and -.5 in front. Terrible.
 

[tube80z]

@AydinZ71 I'm not sure that bending the strut will work for Konis as they are generally tight.  I've heard rumors but never seen them in person about a certain BMW team that had a jig that mounted in a hydraulic press to bend in some extra camber. 

 

Getting the tube out of the is going to be some work but I think that might be the best way to go.  Another option would be to build a custom strut and use Nascar hubs 5x5s I think are called.  That will help with pad knockback.  Another option if you haven't used them is 280Z struts.  They are thicker and should flex less. Or you can show up with some DTM inspiration

 

Cary

[tube80z]

Here's the Mustang GT-4 camber plate I mentioned

 

 

Here's a slightly better picture.

 

You can see they moved the center a bit.  You could make something like this but has a square shape or even just a flat edge and easy shim adjustment awaits.  I was looking at this for being able to make faster adjustments between runs when testing for autocrossing.  Having to jack up the car wasn't going to help make it faster.  In some of the events I run, we may get 10 minutes between turns.  You need to add in looking at the data to see if it helped if the lap time doesn't seem to show an improvement.

 

I have a long list of items I want in my next car.  At the top is a lever adjustable brake bias with presets.  So while driving I can change between slow corners and fast corners.  Drive adjustable ARBs, and externally adjustable ride height.

[AydinZ71]

@JMortensen well that explains why I have even more negative camber in the back. That’s actually not as bad as I thought! Gosh, I have not had a stock S30 in so long, I couldn’t even tell you how much lower the race car is 😂. Low enough that the roll center is all screwed up, even with the largest hub/knuckle spacer I could find. The rear too, where the LCA’s are horizontal, and put the roll center underground at times.

 

@tube80z man those hubs and camber plates are pretty neat! Unfortunately, I do believe they are radical enough that they would be spotted and protested. We have to use our OEM struts and are only allowed to add “adjustability”. To be fair, I’m not going to be racing competitively until at least next January, when SCCA novice school opens up again. Private school is waaaaaay too expensive ($6k+). At least I have time to continue learning the tracks. My next opportunity will be NASA HPDE on May 18th. I need to get my camber figured out before then. Also have to finish my radiator cowl, as overheating was an issue last time. Last mod, which would be gravy, is to fabricate the 280zx front rotors and calipers. I was hoping I was overweight and could therefore afford the 2% penalty to use willwood calipers and a different rotor, but alas she is 1900lb W/O fuel. 
 

are you considering dropping-in a Tilton pedal assembly with an adjustable mechanical bias knob? That’s what I have on the car now. I take notes on how many turns either direction will lock-up the front or the back.  Would you be adjusting the brake bias mid course or just at the beginning of each session? I only have two tracks I plan on participating-in. Big Willow is really fast, but I have yet to try Buttonwillow. 
 

 

[JMortensen]

I ran Buttonwillow and Streets of Willow but never Big Willow. I signed up but something came up and didn't go. Buttonwillow speeds are lower, there isn't shit out there to figure out braking markers so you end up looking for cracks in the pavement and stuff like that. Track is very hard on brakes especially if you run the hairpin, good place to stress test your build. Used to be pretty bumpy in the braking zones 20 years ago.

I can't remember if you play Assetto Corsa or not, but you can download Buttonwillow and it comes with a bunch of configurations. Well worth the $6 or $7.  https://www.simtraxx.net/shop/product/buttonwillow-raceway-usa-aerial-laserscanned-ac-ultimate-edition/

[tube80z]

4 hours ago, AydinZ71 said:

@tube80z

are you considering dropping-in a Tilton pedal assembly with an adjustable mechanical bias knob? That’s what I have on the car now. I take notes on how many turns either direction will lock-up the front or the back.  

 

If you have a logger/dash and front and rear brake pressure sensors you can set it by pressure in the pits.  Instead of turns.  Turns are also hard to keep track of when you come running up to a corner.  I have a Tilton pedal set and their bias adjuster already.  I'm looking at changing from turns to a linear system of steps to easily change from max front to max rear. I've seen two systems I like.  During the Schumacher era at Ferrari they created a stepped system so Michael could change brake bias between corners.  Triple Eight racing (V8 Supercars) created a system like an ARB adjuster for their drivers and that's another option.  I have had too many runs that rain started falling and I would have loved to be able to change bias and ARBs quickly.  I'd like a Bosch motorsports ABS but it's too expensive to justify for me.

[calZ]

22 hours ago, tube80z said:

 

If you have a logger/dash and front and rear brake pressure sensors you can set it by pressure in the pits.  Instead of turns.  Turns are also hard to keep track of when you come running up to a corner.  I have a Tilton pedal set and their bias adjuster already.  I'm looking at changing from turns to a linear system of steps to easily change from max front to max rear. I've seen two systems I like.  During the Schumacher era at Ferrari they created a stepped system so Michael could change brake bias between corners.  Triple Eight racing (V8 Supercars) created a system like an ARB adjuster for their drivers and that's another option.  I have had too many runs that rain started falling and I would have loved to be able to change bias and ARBs quickly.  I'd like a Bosch motorsports ABS but it's too expensive to justify for me.

 

Have you read any about the Mk60 standalone systems? I'm in the process of putting one in my Z. They aren't quite on the level of a Bosch Motorsports system, but tons of people are using them effectively in racing. 

[clarkspeed]

Maxing out traxk width is way to go, but I have always had wide tires with relatively narrow body panels. I have never had the excess camber problem. If you are in a bind, just narrow the track until you figure it out.

The brake bias knob obviously adjust f & r  pressure. I typically set mine a little front heavy on the first day and forget about it for the weekend. Too many other things to worry about. But if you are looking for more linear adjustment it is possible to add a lever or screw style valve to the rear line. It adjusts the "knee" point along with pressure. Much easier to change if you are only taking out some rear if the tank is getting empty.

[clarkspeed]

And engine oil......

I don't recommend additives. Best solution is buy an oil with everything in there to match your intended use. Synthetic has the additional benefits of not braking down over time and is unaffected by moisture. And get an oil with plenty of zinc. That should narrow your search down.

 

I attended a seminar by Gibbs Racing oils and really like their stuff. I use the synthetic  Hot Rod  oil vs. their race oil to save a little $. Redline 40W is also excellent. Brad Penn is good synthetic blend that's a little cheaper. Sam Neive used to recommend it. Purple, Amsoil, and others out there.