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Everything posted by JMortensen
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Sounds like a good time, and with all of the suspension figured out might not be that much of a time suck getting it up and running. Some of us took a decade or more to get our shit together. For a Ford powered car, look up username 74_5.0L_Z Dan is a good guy, runs a 347 stroker IIRC.
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Looks like I'm late to the party. From Richard Holdener's videos I learned that any cam is a turbo cam. Since the stock Z cams are PUNY, I'd suggest you go with a healthy cam and get some benefit from it. I ran a .490/280 with SUs and Mikunis, that worked great and didn't lose low end power. I'd suggest something around there, and skip all this A and C cam stuff. ALL of the stock cams are way too small. Go bigger. Ditch stock springs and retainers, get lash pads and shorter stem seals. You won't be sorry.
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IMSA GTU vintage racer build
JMortensen replied to clarkspeed's topic in S30 Series - 240z, 260z, 280z
I don't remember the source, but I was pretty convinced by it that the goal is to get the front wheels equal. More important than getting cross weights perfect. -
What struts to use in 2024?
JMortensen replied to 74_5.0L_Z's topic in Brakes, Wheels, Suspension and Chassis
What Dan is describing is a known issue with Zs that are raced. The forces on the stub axle stretch out the bearing pocket in the strut housing. Had a guy on FB DM me about the same thing just a couple days ago. Now that has me thinking about putting a reinforcement ring around where the bearing is located. I bet that would be pretty easy to do, too... -
What struts to use in 2024?
JMortensen replied to 74_5.0L_Z's topic in Brakes, Wheels, Suspension and Chassis
One avenue I thought seemed promising but haven't pursued is to use the adapters that people sell to screw in a cheap Chinese coilover (AZC, T3, Apex) and find a really high quality strut that fits, like a Penske or Ohlins or something. I think this is essentially the route the Coffey went to get those 46mm Bilsteins in that rally car that went across Asia, but John had the adapters machined because he was way ahead of the curve on that idea, IIRC. FWIW, that guy ended up swapping those Bilsteins out for something he thought was better. Bilsteins are supposed to be pretty tunable, but you have to have someone who can do it, which is a whole nuther can of worms... I think the easy button is to fork out big bucks for the KW or similar high quality stuff. -
ZX rack is mounted behind the crossmember.
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cant figure out steering clunk/pop
JMortensen replied to kaibiagi's topic in Brakes, Wheels, Suspension and Chassis
Yeah, that needs replacing for sure. Think you probably found it! If you don't mind the vibrations, get a poly or plastic one. People have also drilled hockey pucks and used them, if you happen to have one. -
cant figure out steering clunk/pop
JMortensen replied to kaibiagi's topic in Brakes, Wheels, Suspension and Chassis
I just remembered a clunk I had, and turned out it was the big bolts that go through the steer knuckles and into the strut. Might check those and make sure they're tight while you're under there. -
cant figure out steering clunk/pop
JMortensen replied to kaibiagi's topic in Brakes, Wheels, Suspension and Chassis
You can just remove one sway bar end link and then it will flop along and not be doing anything and shouldn't make any noise outside of maybe bushings squeaking. Easier than removing the whole thing. If it stops and you think it's around the bar/frame mount, pull it all the way off and inspect the frame rails where it bolts on. Aftermarket bars tended to rip up the frame rails when these things were new and not rusty. How about the rag joint in the steering column? OG rubber, or did you upgrade that one too? Sorry, can't help with wiring part. -
240z SCCA vintage race car, restoration
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
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/ -
240z SCCA vintage race car, restoration
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
Yeah, lowered otherwise stock Z will have something like -3 in back and -.5 in front. Terrible. -
240z SCCA vintage race car, restoration
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
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. -
Should I fuel inject my 3L stroker?
JMortensen replied to zev's topic in S30 Series - 240z, 260z, 280z
I was under the impression that since you don't need airflow to atomize the fuel, you should go bigger on ITBs. -
They had a problem where their fabbed upright was flexing. Wasn't the arm. Maybe this one didn't get the update, or maybe the update wasn't good enough. I have similar arms (Apex modeled theirs on mine) and I don't have issues. Regardless, that doesn't look good at all.
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Make sure that the suspension moves freely through the full range. Can remove springs and compress the strut with ratchet straps and make sure you don't feel any solid resistance.
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The factory mounts are pretty tall. I think you're going to have to remove them with any seat you choose at that height. If you want to race might need to go 1x1 square frame and screw directly into the tubes. BTW, removing the mounts is a PITA too. 487 spot welds holding those bastards in.
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I think tube80z shared that with me a few years ago. Made me regret that I had installed my fuel cell at a 7* angle because when I did it 7* was considered the max angle you could run without separation. He's talking 20* in there though. That's way outside of what I would have thought would work. I think when I do build one the focus will be on making it as long as possible and I may try to change the angle along the length. Been looking at AJ's gigantic one, and it appears that maximizing the angle in that particular space is the focus, rather than sticking to a particular angle. You can see it kinda steps up past the axle, then flattens out a bit under the gas tank, then steps up again at the end. https://ajhartmanaero.com/modular-diffusor/
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4. This doesn't seem counter-intuitive, as more lift on the front end will tend to make the car understeer, and that's the more inherently stable tendency. 5. I'm sure I read in a book somewhere that lift or drag translates directly to work. If the airflow is doing work it will show up as force on the car. So as calz says, if you clean up the airflow under the car so that it isn't turbulent, you can reduce drag and lift, as it has to do less work to get under the car - acting less like a parachute. If you have a lot of lift, that's a sign the the air is doing more work. Closing the huge hole in the front and ducting to the radiator prevents all that air from packing into the front and pushing up on the hood. This will reduce lift and drag. A spoiler on a Z reduces lift and drag as well (to a point, after which it will reduce lift and increase drag). 7. The further away from the axle the more leverage you have too. So a rear wing can be mounted lower and further back and make more downforce than the same wing mounted in cleaner air and higher in some circumstances. Thinking back to what might be the same video about splitters, I think his view on the shape of a proper splitter is a little simplistic. Most of the time on a race car you're rule limited, or you have practical constraints that limit the shape, but in the more unlimited classes you see the upturned nose of a splitter or a raised tunnel entrance in the front. There are also interesting front wings on open wheel cars that we can learn a little bit from where they have unusual profiles: relatively high in front, flat and close to the ground for a bit, then sloping up at the back. Not unlike McBeath's drawings of what an undertray should look like, but with a more wing-y looking top side. Most low level race cars use flat splitters, but diffuser on the splitter kind of aim for the same sort of shape in the back as the wing. If you're going to design a splitter I'd suggest a close look at what AJ Hartman is doing. He's working with high level aerodynamicists, does lots of CFD and wind tunnel testing, and makes good stuff. Then he makes youtube videos telling you how to DIY it. Pretty amazing, really. Note the front lip shape. Sharp on top, rounded on bottom.
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I've watched a bunch of his videos on youtube and ended up buying a bunch of pressure pucks and five 1" manometers to do some track testing. Of course I bought all that shit and then put the car down and spent the next year doing other stuff. Still need to make a temporary dashboard to hold the gauges. The one thing that he really bugged me with was his refrain that "you can't just slap a splitter, diffuser, and a wing on and make downforce" which he said quite a bit IIRC. I ended up linking in the youtube comments to AJ Hartmann's company, because that's exactly what he sells, and it obviously works. I haven't watched anything in a few months, but I did finally find one where he added I think it was a splitter and wing and was like: "HEY! That really worked!" As you mentioned though, he has a ton of good info and practical techniques in his videos, I can imagine the book will be better. Did a lot of coast downs for drag measurement too as I recall. Anyway, thanks for the heads up. Will purchase.
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240z SCCA vintage race car, restoration
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
Read your previous post, if it's plugged at the wheel cyl probably just need to rebuild/replace. -
240z SCCA vintage race car, restoration
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
What worked for me with an entirely new brake system was pushing fluid backwards. Open the bleeder, use a tube feeding syringe to force fluid to the master. I tried everything; pump/hold/open bleeder, gravity bleed, repeated pumps with hose submerged, vacuum bleed, couldn't get a pedal until I reverse bled. Good luck. It was frustrating as hell for me. https://www.amazon.com/Syringe-Adapter-Feeding-Refilling-Drawing/dp/B07SQC95DT/ -
This doesn't look like the more aggressive NISMO one, looks like a Z31T LSD. That's probably a good thing. They're plenty aggressive as it is. You might open it up and see if it has the big washers on the sides. If so, that's a pretty big weakness. You can get some clutches from Gary Savage if he's still making them: https://www.facebook.com/garysavage42 or pull the clutches and have 4 more of the ones with the tabs on the inside laser or water cut. Here is a write up on installing it.