240z SCCA vintage race car, restoration

[AydinZ71]

Appreciate it @clarkspeed. I like the format here where folks can respond with their own volition based on interest, but I am entering a phase in the project where I might need to reach out directly. Greg has been a huge help as well, but his (well deserved) at-home-bodywork days are behind him so there are always questions being the novice I am. Between you, John, Jon, and the rest this has been a great resource for almost two years now. 
 

on to the updates:

 

I finally tackled the FRP hatch. If you are familiar, there are little steel stand-offs on the OEM hatch which mates with the hinge assembly near the roof of the car. I cut those tabs off my old rusty/damaged hatch and used them to correct the mating angle onto the hatch reinforcement channel. I test fit the hatch onto the car and drilled two 1/8” pilot holes through the fiberglass channel into the steel tab from OEM hood. After some finagling and repositioning the hinges, I was satisfied with the through holes. Mocked the whole thing up with through bolts and was ecstatic that the hatch went on with symmetrical gaps and nothing protruding too badly. I was anxious about the fiberglass being stressed and cracking, so I decided to put flanges on both sides of the channel to distribute the pressure. To maintain geometry, I used some spare 20-gauge stainless on the hinge side. On the opposite end of the channel, I used a small strip of 1/8” 6061AL. I chose these materials because they are light, quite resistant to inelastic deformation but still elastic enough to “hug” the fiberglass surface. Bolts are 1/4” X 2” SAE. Now on-to the single latch. 

[calZ]

On 5/10/2022 at 6:50 AM, AydinZ71 said:

Thanks @clarkspeed! Yep, 9” wide is the one! I confirmed with Greg after cross referencing with the Hoosier website. It’s the 245/560R15. Comes in MS and M compounds. Usedracingtire.com has them so il grab a set and get them mounted. Seemed silly to prep for paint without having the wheel clearance confirmed. 
 

my fenders are still OEM so il need some kind of a flare to fit those 9” meats. I know we can run FRP fenders front and back, but I just really want to get her on the road now. My street car has MSA flares the PO put on, so I could take and look and see how easy they would be to recreate in 20-gauge sheet metal. Otherwise il go with those Marugen ones.

 

 

There are lots of posts about people running 245s on stock sheet metal. You likely don't even need flares if that's as wide as you're going. 

[AydinZ71]

Ahh, yeah I should probably mentioned I also have wider track thanks to adjustable LCA’s etc. the rules allow for it and it does provide an improvement to handling. I haven’t purchased the flares yet and I’m gonna wait till I have the tire mounted. If it’s close, I might just make them out of sheet metal. It’s a race car afterall. Thanks for the heads up @calZ! 

[jhm]

Aydin, at the risk of stating the obvious, double-check the recommended max extension for those double-adjusters in your front LCAs....should be a combination of the number of threads engaged (on both ends) and length of exposed (unengaged) threads. 

 

The convenient thing about wheel spacers (and spacer adapters) is that they can be quickly added or removed without affecting front end alignment, and they can also be used to easily fine-tune your effective spring rate (both the strut springs, and the anti-roll bar if applicable).

[AydinZ71]

thanks John  @jhm! 
 

Ahhh I never thought about the broad utility of the spacers. I was just anxious about adding the rotational mass, but I do have a set that came with the car.

 

on the double adjusters, I fabricated them in a way such that at max thread engagement, it was already +1/2” track on both sides (totaling 1” hub-to-hub). This allowed me to use the S130 adjustable steering tie rod which is longer leaving max thread engagement on a starting basis. In hindsight I would have been more careful with my measurements and given a little more adjustability in the negative direction but se la vie. At least they are ready for even wider track (at least in the front, rear is limited) for non-EP events. 
 

while on the topic of suspension, I need some pretty hefty RC adjusters (2-3”) based on Greg’s specs but obviously no one makes them that big. Should I just stack 2-3 and have someone TIG them together? 

Edited May 12, 2022 by AydinZ71

[clarkspeed]

I think Greg stacks them and welds together. That is simple way and effective.  If following his formula, stick with it.

 

My tubular control arms have a spherical bearing with an adjustable tie rod bolt going into the steering arm. On the tube car I'm not sure where the RCs will be so I can adjust where I want. 

[AydinZ71]

Cool! sounds good, il go with welding 2X 1" ones and see where I land on my RC. 

 

I suppose once you get away from the OEM strut geometry, all bets are off. Are you still planning on a single control arm or considering double wishbone? 

[JMortensen]

You can also slot or redrill the inner pivot on the crossmember, move the LCA pivot up and this changes bumpsteer and RC.

Edited May 13, 2022 by JMortensen

[AydinZ71]

Oh 100% Jon. I’m a bit concerned about modifying the mounting hole position on the crossmember since we have this whole “stock attachment points” requirement in the GCR. I’m sure there is some wiggle room but it’s hard to test the waters without first-hand experience. We are specifically allowed to add-back adjustability in the suspension, but how the suspension attaches to the unibody needs to be OEM. For example, they gave a thumbs-down to weld-in camber plates. 

[clarkspeed]

For now you need to keep going with what you have. I posted a RC calculator in this forum somewhere. But you need to get everything on the ground first. 

When it's time to start doing alignments we have lots of helpful "hints". 

[AydinZ71]

@clarkspeed thanks Clark! Yeah I really don’t have any first hand experience so you and the communities tips will be much appreciated once the suspension is back on. 
 

Update: hatch mock-up and fastening is done! Used a single 1/4” quick latch in the OEM position. I sat there thinking about the geometry for a while until it dawned on me… I can just turn it upside-down and hit all the clearance and misalignment issues. The pin is now on the FRP hatch and the release button is upside-down. Accessible from right above the license plate holder. Works like a charm. 
i made a big 4” flange/washer out of 20-gauge 304SS to resist the downward force and prevent the fiberglass from cracking. It’s hidden in the hatch cavity. I’m happy with it. Going to tear this all down now and continue with bodywork.
 

245 slicks should be here next week so I can check fitment and noodle a flare. if it’s “close”, I might just modify the OEM fenders with some sheet metal. If I need more than 1” of augmentation, I might just buy a pair of flares. 

 

 

[AydinZ71]

Hello friends!!

 

Koenig Rewind wheels. What's the story? Why are they so cheap, and do they hold-up? Reviews online seem to be favorable but have not seen any on a race car yet. Listed at 13.4lbs

 

So I am striking out on the racing wheels... 

genuine panasports: US distributor out of stock

Ultralites: no longer available in 15X7

Ray's Volk: No longer available in 15X7. ones on ebay are all from FWD cars since they have massive offsets. 

Rota: heard they are not a good option for a race car

Jongbloed: left a VM... we will see if they call back

 

Turns out the diamond racing steelies the car came with were actually 14X7. Must have been drunk when I measured them, no idea how that happened. I just sold them for $200.

[clarkspeed]

Greg has an old set of Volks on the EP car and bought a set of Joengblods 3-4 years ago and really likes them.

I ran the 15x7 Konig rewinds on the Bob car I sold. No problems. The Mazda crowd runs them extensively.

I went a completely different direction, as usual. The olny small diameter development anymore is just for MX5. I bought 15x10 Konig dekagrams from Goodwin racing at 14.5lbs with 1.5" adapters to get the offset correct. The adapters and studs add a little weight back but I think still better than most other custom 15x10 options. Take a look at Goodwin Mazda wheels and that is the 15x7 weights you should be shooting for IMHO. A spec Miata weighs more than a EP Z car. So far, I am the only person I know that will try this. But most EP cars are running a 1" spacer anyway.

 

[AydinZ71]

Thanks @clarkspeed!

 

I went ahead and bought the Koenig Rewinds. $480 including insane CA sales tax and shipping from Summit. I really can't believe decent wheels have gotten this cheap! So far everyone I have interacted with is happy with them. 

 

This buys me some time (a few years) to save-up for and keep looking for a lightweight wheel. I will look-into the Goodwin Mazda wheels! 

 

Yeah Greg raves about the Volks, and even said he would be interested in buying another set if I could find them in our size. They apparently had an anniversary edition (15X7) that we just missed a few years ago. He also told me about the Jongbloed, otherwise I would have never run across them. 

 

That is pretty damn light for a 15X10! If you are going to add weight to a hub, the best place it can be is as close to the center of rotation as possible since the moment of inertia has an mass times r^2 relationship. This is why a lightweight tire is so critical. Hence, the few pounds added for a spacer isn't great, but its also not equal to the same weight added to the whole wheel. I am pontificating and you already know all this...

 

 

[clarkspeed]

Motorsport Auto buys the Konigs in bulk and puts them on sale often.

 

I am really concentrating on rotational weight with this build. I think it is the secret sauce for a Z car. I think about Greg's EP car with those tiny brakes, 15x7 wheels, and lightweight slick tires. I'm just trying to move that needle just a little more with my looser rules.

Edited May 22, 2022 by clarkspeed

[AydinZ71]

Most definitely. In the case of EP, it’s not the power that makes the Z shine 😂😂 Maybe against the Miata sure, but the Z3’s are putting out over 300hp from what Greg tells me. It does have quite a bit of torque comparatively though. I mean, what do I know… I have yet to see a track  
 

i still have not tackled the brakes… for now I was planning on running porterfield shoes with the AL rear drums, and the fronts are OEM calipers and cross drilled oem rotors (PO). I’m not sure if better shoes/pads alone will cut it. I have 2.5” ducts pre-made into the front air dam (PO did them), but I still need to fabricate a rotor backing plate to direct the ducts into the rotors. I also drilled a dozen or so 1/4” vent holes into the rear drum dust/backing plate to allow them to vent. 
 

tires are mounted and it’s time to work up a flare solution. The whole assembly is surprisingly light. Il throw them on the scale today. 

[AydinZ71]

Finished stitch welding the whole car and added a stiffening flange to the rear towers. They will be capped with a riveted sheet of aluminum. 
 

also got the 245 mounted and I do need the flares. I ordered the marugen delux from rhd-Japan. i could have fabricated a flare from sheet metal using the existing lip as a template but I decided to just spend the cash and save 10 hours of labor. 
 

 

[Dat73z]

Are you limited by rules on tire sizes and/or how wide you can go? Looks great. Almost looks like you could fit those tires by trimming your existing sheet metal without flares

[AydinZ71]

@Dat73z thanks! Yeah they are close but no cigar. Production racing rules say you can’t see the top of the tire when looking straight down from above. Max wheel we can go is 15X7” which is what this wheel is. These are cantilevered slicks meaning the tire is designed to be much wider than the wheel would normally support, without having to “stretch”. The whole assembly is remarkably light! No steel belt from what I can tell, although Hoosiers website does not provide much info beyond the word “radial”.
 

I really was super close to just modifying or adding sheet metal to make it work. Even more so since I can use the existing flare profile as a template (not much to add). Thinking about it though, each wheel well is going to be at least 4 hours of work (cutting, welding, hammer-dolly) and that doesn’t include filler, sanding, contour. The flares are like $350 so less than $100 per wheel well. Not many spots left on the car where a purchase can save me three or four weekends of work.
 

lastly, I’m doing the flares now because I’m on paint and body. It’s now or never, and going with a solution that is more versatile than just my current wheel/tire/track width makes sense vs. hoping every change in the future will work with something custom I make. Depending on the total surface coverage of the flare, it may even end up being a net negative in weight after I trim back the steel. We’ll see! 

Edited May 27, 2022 by AydinZ71

[AydinZ71]

Now that I am on to bodywork, it’s time to pick paint! The idea is something that will give a nod to the past (possibly even multiple nods), while still being unique. My current idea is a two-tone with the same profile as the BRE Morton Z, but with different colors. I thought the top color as metallic orange (Malibu Sunset by Eastwood) could be an image to Greg’s 13’ & 15’ winning car. The bottom color was thinking off-white (like a creamsicle) or silver (to match the metallic). Attached are some photos as guides/examples. Was also considering the top color as alpine green (sample attached, spruce green metallic).

 

would love to hear your thoughts!! 

6A9A569F-AE57-4D1D-9335-EDFA444C6090.jp2

Edited May 28, 2022 by AydinZ71