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clarkspeed

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Posts posted by clarkspeed

  1. Exhaust blasted and coated. Decided to go with Cerakote in titanium. My first time using it. It's not a TBC coating but hopefully looks good for a long time. Its an air dry ceramic coating that hardens out once you run the engine. Easy to spray, and 5 day for full cure. Just wasn't in the budget to do a true TBC. Getting closer to first fire.

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  2. All the Z iterations can look good with minimal modifications. I personally think the z32 had perfect proportions not surpassed since. So simple but so exact.

     

    For this build as all of my builds, I am sticking with stock half shafts and Spicer U-joints. Never had a fail road racing yet. Cheap and effective only if you limit the angles generated and minimal power loss.  I currently plan to raise/lower the diff as required to keep them in their sweet spot. They even withstand high power drag racing if you can keep them close to straight when launching. If it looks like I will struggle with this when I final assemble the rear, I will be scrambling for some CVs. 

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  3. I suppose it is time for some updates. Lots of work accomplished since holidays but not much to photograph. Finished all the strut builds and got them bolted up. Completed the clutch build and mated the tranny. Dropped engine back in and found if I raise the engine mounts 1/8" on each side it will clear my steering rack. Yeah.

     

    Finally caught up from my last minute changes and medical setbacks. I feel 10 years younger now and kicking ass in the shop. Getting closer to first fire. Have a 2nd Z car in the shop now and a 3rd coming. More on that later. 

     

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  4. To fit the struts I had to get creative. I already had camber plates welded and did not want to modify those. The BC setup is nice but not a large amount of camber adjustment. 

     

    Not much problem for the front. I only needed a 1mm thick bushing to fill the gap between the shaft and camber bearing. After I tried to drill something several times I ended up just 3d printing one.

     

    The rear required some fabrication. I had slotted the towers and built my own camber plate/spring perches.  To retify I duplicated the plate in aluminum and bolted the BC bearing holder from the bottom.

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  5. You got it! 

     

    My timing plate is marked with a range for typical Datsun cams for the 4 timing events. Makes it a little easier wrap my brain around it.

     

    i like to look at it like this. Intake valve opening is the most important timing sequence. In the end you are really just trying to get that point to match what you engine needs. Not to early and not too late to maximize power. I set the cam to the CL like you described and then adjust the gear a little on the dyno to max out power and torque.If you plan to adjust at the dyno with a high compression engine, I always check valve to piston clearance with the cam gear in min and max settings.²

  6. Nope. But I could probably come up with something if financially motivated. Of course it would not pass at a concours show. Not even close. It would need to be printed in multiple parts. 

     

    I am currently working on a fairly large airbox using a big rectangular Audi filter element and a 4" hose inlet. Could easy adopt it to a SU's if I ever finish it. 

  7. 6 hours ago, calZ said:

    6. I don't know if I agree with calling airdams a crutch, but an airdam without a flat floor is leaving a lot on the table. The less air you let under the car, the easier it is to manage and the easier it will be to make your diffuser effective. That's true with or without a flat floor. If you put a flat floor on but leave your front end the same, you're still going to generate a bunch of lift on the bottom of your front bumper for anything shaped like a Z. Modern cars are pretty good at not having much upward-facing area, but old cars with the diving board bumpers really need airdams. 

     

    Thanks for your comments!  Cool job. 

    I know virtually nothing about vehicle aero but i am a mech engineer so I can grasp the concepts. Even with my meager knowledge, Edgar's book seems to have some funky conclusions.

     

    I just reread the flat floor section again last night.  What he recommends is a slightly rounded panel roughly starting at bottom of the front bumper to a smooth rounded transition knee point in front of front axle.  Then totally flat section back to where the diffuser starts.  And the diffuser being the minimum of another flat panel angled upward at 10 degrees or more to the rear bumper.  The start of the diffuser section seems to like being as far forward as possible.  With this arrangement, you want as much air as possible flowing under the car and no airdam.  So no extra drag and net downforce like a reverse wing.  I am still struggling with this.  It seems like what interference you do have with suspension arms and maybe wide wheels would screw this up.  Also it seems ride height would be a critical factor. For an S30Z I assume this would look like a short full width airdam, with the curved floor section attached at the bottom lip.

  8. Well I am about 40% through this book now and it does not necessarily match what I have read in magazines, Internet, or anywhere for that matter.  Many of these concepts are not intuitive.  I will try to list out some of the salient points I am tracking.  I don’t think Mr. Edgar would mind since I am only scratching the surface and promoting his book. In my own words.....

     

    1. Cd, coefficient of drag, is not an exact measurement.  Almost impossible to measure without only the best wind tunnels.  Most manufacturers quote a number from less accurate wind tunnels and no one can prove or disprove what they post in their marketing material.  Coast down testing is a disaster at best, not repeatable.  Way too many variables come into effect at speeds below 60mph and a perfect consistent environment is impossible to achieve.  Edgar proposes just measuring the change in drag rather than trying to quantify it.
    2. Vehicle aero is complicated.  More complicated than CFD analysis can fully cover.  Even if you can simulate the flows over a car, the flows under the car and side winds (yaw) cause unplanned effects.  Even the best OEM aero specialists have to experiment, measure, and rent wind tunnels.  And for OEM’s, style often takes precedence over aero.
    3. Every standard vehicle shape creates lift.  Air speeds up when it is required to change directions quickly so the transition from grill to hood and window to roof speeds up the air and creates low pressure.  The amount of lift depends on the area of these surfaces.  Some lift is created in the rear transition from roof to rear window.  So most all cars without any major aero features create lift. The lift/downforce can be different at any point location front to rear on the top and bottom surfaces of a car. The overall lift is the sum of all the points. Really the only exceptions are supercars with splitters, flat bottoms, and diffusers. Not Camry’s.
    4. Since most all cars create more lift the faster you go, then obviously it is not such a bad thing as long as it is not excessive.  Counterintuitive, more lift in the front than rear gives a feeling of stability.  Yes, you read that right. 
    5. Drag and lift are related but totally different.  Decreasing lift usually comes at the expense of increasing drag and visa-versa.  Race cars obviously want as little lift as possible or even downforce.  The performance gains usually outweigh the increase in drag when done correctly but you have to be aware of both.
    6. I will not go into all the aero tricks available to reduce drag and increase lift.  Edgar goes into pretty much any mod you can think of with pictures and suggestions to make more effective. However he emphasizes, modification to the underfloor, adding a flat bottom, is the best place to start and gives the most benefits. He has plenty of examples on how this should be done. Air dams are basically a crutch to prevent as much air as possible from going under the car and hitting all the "stuff" hanging down there. A flat bottom is more effective and can make negative lift. Most newer OEM designs exploit this. 
    7. Even small splitters can make large downforce but it is in front of front axle, which creates lift in rear.  Same problem for rear diffusers and spoilers.  They create lift in front because they are behind rear axle.  You have to be careful with these mods to get a balanced car.
  9. Thanks for the kind words.

     

    Basically Redshift purchases a full coilover package from BC.   I tried to pick and choose some components since I already have camber plates and springs, but was not successful.  It comes as a kit. They then take the strut cartridge and revalve to your specifications, in most cases is based on unsprung weight, sprung weight, and motion ratios or your own recipe if you prefer.  They dyno at multiple settings and ship the kit to you.  

     

    The struts are 32 click adjustable and the adjustment combines both rebound and compression.  The nominal setting is at the bottom 1/3 of the click scale or around 10 clicks.  A sample dyno is below (not mine).   I also ask if they were racer rebuildable.  He said they were theoretically, but the parts they use were not available to be purchased retail anywhere.  As I said before, Chris was very patient and helpful.  He offers a full rebuild service and his reputation seems very solid.

     

    As far as spring rates, I plan to start with 250F/225R springs which I already have.  I also have a pair of 275 and 300's.  So I ordered the Redshift's with 6k/7k (336/392lb) to have another heavier set.  Springs are cheap.

     

     

     

     

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  10. Well, I had some major setbacks the last couple months. A triple heart bypass put a little delay in the build progress. I thought I was a little young for this but such is life with family history. Feeling much better now 6 weeks later but still on the recovery. Not really ready for heavy lifting yet so trying to complete some of my easier projects.  Anyway, here is a pic of the new Redshift dampers that arrived just before my hospital visit and a pic of the front struts I am prepping for the dampers. Sorry for the crusty bed sheet they are staged on. I am motivated to get stuff done, so hope to be back on the car in another week or 2. 

     

    The dampers are essentially custom valved BC coilovers to my specs. The single adjustment controls both compression and rebound combined. They came with full dyno graphs. I have to say the BC hardware looks to be of very high quality in the adjusters, hats, and camber plates. Chris at Redshift was incredibly patient and answered my 20 or so questions with detailed explanation and honesty. He seems to like emails to communicate but is very responsive. Can't wait to try these.

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  11. On 10/30/2023 at 3:28 PM, JMortensen said:

    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.

    Thanks Jon,

    This book seems to be everything he has done for 25 years all rolled up and adjusted to the latest technology of the last year or so. I'm about 1/2 way through but I can't find any aero mod you can do to a production car he doesn't cover in depth somewhere in the book. 

     

    Yes, he emphasizes no aero modifications should be made unless you measure the effect. It may not be what you expect and may upset the aero somewhere else. I am trying to wrap my head around how much lift a car, any car, produces. So for a production body style, you are basically trying to reduce lift, not create downforce. Exception being major mods like splitters combined with diffusers and wings. And as expected, lift and drag are 2 completely different things. Air dams reduce drag, splitters increase downforce forward of front axle only which can really lighten up the rear axle due to the lever arm.

     

    One example on an air dam he tested a 4" deep and a 9" deep. The 4" reduced drag almost as much as the 9" and left greater ground clearance. He tests plenty of bolt on parts in the book and proves they work as intented. So obviously there are bolt on parts designed for specific cars that benefit lift or drag. But if you have to make choices or optimize the part, better be ready to test. Obviously a rear spoiler works on an early Z. But how tall and what angle is best to optimize? 

     

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  12. Well I am going down quite a rabbit hole now. I recently ordered Julian Edgar's newly released book. Very down to earth and all practical solutions to testing and tuning production car aero on a tight budget without CFD or wind tunnels. For example he uses a throttle stop to measure changes that affect drag. Stop the throttle at 10 or 15% and measure top speed at roughly 50 or 60 mph.  Make an aero change, then check top speed again.

     

    Not cheap, but 500 pages packed full of info and lots of pictures. Highly recommended if you are looking to reduce drag and lift on your car.

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  13. 6 hours ago, AydinZ71 said:

    @clarkspeed thanks Clark. Because the brake lines and masters were all newly installed, I struggled getting enough “throw” without having the front bleed with the rear. I bled the front first so they had little travel. The front would lock up quick and the balance bar would give me another 3/8” throw on the rear as it pivots. I bet it would be fine if my rear drum cylinder was not clogged, but I seemed to be just compressing air in the rear line. 
     

    going to get going on the rear drum-rotor conversion w/ the dynalite calipers. Thanks again for all the files you sent a few months ago! Il try to pick a reasonable rotor diameter so balancing with the fronts aren’t a challenge, and I’ll use your calc. 

    Yea, I could see that happening. A lot depends on the volume of the slaves. Luckily there is more than one way to skin the horse. 

  14. Bleed F and R simultaneously? Don't understand. Usually the balance bar self adjusts and allows you to bleed each wheel as normal. Feels wierd, but works fine. I don't do anything different with dual master as I would with a single. 

     

    Let me know what you are thinking. Usually a non issue getting rear too strong. I tend to experiment with rear pad materials if things are too outa-whack. I have run street pads in rear before. 

  15. Couple pics. I had to fab my own pilot bearing. Bought something close from MacMaster Carr. Drilled it and honed the last .003" out to fit the tranny input shaft. 

     

    Also got a very large blast cabinet into the shop on a trade. Next job is to blast another set of strut housings for paint and then the exhaust system.

     

    Many more pics coming.

     

     

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