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  #441  
Old 01-14-2014, 08:59 PM
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Very nice. New covers look great. Sorry about the heads. I keep a torque chart in my shop that I'm constantly refering too.
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  #442  
Old 01-18-2014, 08:02 PM
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Thanks guys!

After I was sure the valve covers would fit, I took them to the local powdercoater, Applied Powdercoat in Oxnard. This place does a lot of work for Haas Automation (CNC machines) and I've used them in the past to coat my own automation equipment (the type of engineering I did before I got into medical devices). They do great work. I selected Cardinal BK59 textured black for the finish. It is a little shinier and more black than what the Proform covers came with and it makes a great match for the plastic intake cover. I thought about doing VHT wrinkle black paint at home, which would have been much less expensive, but I was worried I wouldn't get a consistent finish. I'm glad I went this route.





I did a lot of research before deciding how to finish the lettering. This is a common task for the Honda tuner people, so if you search "painting raised letter valve covers" you can find some videos and info, but hardly anything that actually shows the process of finishing the letters. From what I've read there are three common techniques: mask, vasoline (or variant), and sand. The masking method is tedious and can actually leave a bad edge. With vasoline, you coat the faces of the letters prior to painting, then wipe the paint off afterwards. Both of those methods seemed iffy to me, so I went with the sanding method. I used painters tape to protect from accidentally sanding the wrong part and loaded 220 grit into a 5" random orbital sander. It took about 5 minutes per cover to remove the powdercoat and leave a swirly-brushed finish. I would definitely recommend this method; as long as you are careful with the sander and let it do the work, it does a very nice job. The edges of the letters look very crisp.













Before



After



I'm extremely happy with the results. Now I better get back to making the car go.
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Last edited by TheBandit; 01-19-2014 at 04:46 PM.
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  #443  
Old 01-18-2014, 08:48 PM
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Man! That looks sharp!

I didnt notice you were in Oxnard.My sister and bro-in-law lived out there while he was in the Navy. And I think my dad stayed there when RCA used to launch satellites from Lompoc.

Hmmm...medical devices? Are you looking for any machinists? LOL! I gotta get out of NJ!
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  #444  
Old 01-19-2014, 05:02 PM
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Thanks bullnerd. Yeah there is a Naval base in Puert Hueneme which is basically attached to Oxnard. I don't know anyone looking for a machinist but I'll PM you if something comes up. Most of the stuff I work on is injection molded.
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  #445  
Old 01-19-2014, 05:13 PM
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Also if you use a belt sander you get a brushed aluminum finish :)
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  #446  
Old 03-10-2014, 02:26 PM
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Originally Posted by TheBandit View Post
I chose a 600lb/in spring which is significantly stiffer than the stock ~325lb/in rate, but still a little bit softer than what the "hardcore" autocrossers like to run (650-750lb/in seems common). A good ride is one of my considerations and I don't want to go overboard with this. I calculated a ride frequency of about 1.9hz with these springs vs. about 1.4hz with the stock springs. I'll be using a 1-1/8" OD hollow tube swaybar. The stock bar was a tiny 11/16" solid bar. This should be about 5 to 6 times the roll stiffness. Shocks will be Bilstein with valving selected by Hotchkis specifically for this spring rate and application.
Since I was thinking on this subject today, I wanted to update this thread to correct a mistake I made in my ride frequency calculation. I did not properly square the motion ratio of the suspension when i was doing my original calc.

I have 600lb/in AFCO springs for the front (same rate as Hotchkis) and Hotchkis 1.5" drop leafs for the rear. I've read the Hotchkis leafs have a rate of about 175lb/in. I don't know the exact weights on the car, but according to this the curb weights for a stock V8 Nova are 1,703lb front and 1,440lb rear. I realize these are a combination of sprung & unsprung weight, but for a rough calculation I will assume all the weight is sprung.

Front corner weight = 850lb
Front corner rate = 600 * (9/16)^2 = 189.8 lb/in (motion ratio of 9/16 for LCA per this measurement)
Rear corner weight = 720lb
Rear corner rate = 175lb/in (motion ratio of 1:1 for leafs)

Using the formula
ride frequency = 188*sqrt(k/W)

Front ride frequency = 188*sqrt(189.8/850) = 89cpm or 1.48hz *CORRECTED*
Rear ride frequency = 188*sqrt(175/720) = 93cpm or 1.54hz
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Last edited by TheBandit; 03-10-2014 at 02:31 PM.
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  #447  
Old 03-10-2014, 06:16 PM
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Wink

As has been often said... frequency is for Radios
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  #448  
Old 03-10-2014, 06:29 PM
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Just trying to get a rough order of magnitude here Mr. E. I'm an engineer but I recognize the following theorem as often holding true:

In theory, practice and theory agree. In practice, they don't.
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  #449  
Old 03-10-2014, 06:45 PM
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Don't get me wrong and I'm laughing as much at myself as the freqz.
I once calculated all the math to design a specific header it took me a week to figure out the calculus and stuff. I had my math checked and then I then built it and learned that the mathematically correct unit cause a rather sharp drop in power over the previous unit that I had just built by eyeball...
I can clearly remember not understanding a engineering friend who explained the whole freqz thing to me about springs (many years ago) and I just went with the unit of force and got there... I still don't fully get it. On one hand I can see the theory but I'm likely to hands on to really understand the purpose of the Freqz part because in the end it comes down to the spring rate the available... Just me
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  #450  
Old 03-10-2014, 07:14 PM
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I guess it depends if you are chasing 10 thousands of a second around a track or not!

Clint, I saw one of these in the identical colour to yours, last weekend! They are horn!
It is the first on I have spotted here in Oz, and I cannot stop thinking about acquiring one!
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  #451  
Old 03-10-2014, 07:28 PM
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Springs (like headers) are just one component of a complex dynamic system, so it's misleading to handle them in isolation. There really is no such thing as optimized when you consider the range of potential use. In my case I want a dual purpose street and occasional track car; I can't expect to be best at both. I have to compromise ride comfort for handling, cost for quality, etc. And even if I were building a dedicated racecar, who knows what would fit best with my driving style and track conditions.

Geometry, shocks, swaybars, and tires are just a few other items in the system that make selecting the perfect spring a tough matter, which is why I said this is for order of magnitude only. I went with a rate consistent with a tested/commercially available system from Hotchkis, which includes shocks, swaybars and springs. I trust their real world testing because I know a lot of successful autocrossers and happy cruisers that have used the same system. I am going to use their shocks, rear springs, and swaybars of equivalent stiffness so my system should be very close to theirs. I am going to make my rear swaybar adjustable so I can make adjustments since I'm sure my tire combo will produce different results in terms of over/understeer.

The point on spring selection ("it comes down to the spring rate available") is kind of interesting to me because coil springs of this size are available in 25lb/in increments. If you go through the calcs above, a 25lb/in change in spring is only going to change my front ride frequency by about 1CPM - hardly a noticeable difference. However it may have a more noticeable effect on roll stiffness; I'll have to run the calcs on that and see where I stand.
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  #452  
Old 03-10-2014, 08:01 PM
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Clint, I saw one of these in the identical colour to yours, last weekend! They are horn!
It is the first on I have spotted here in Oz, and I cannot stop thinking about acquiring one!
I didn't know they had Novas down there. They were sold in Canada ("Acadian") and Argentina ("SS"). Maybe it was imported? If not, any idea what the make/model was in Australia? Holden perhaps? I see the HT Monaro looks very similar to a Nova up front, but I don't think they are related (the back looks entirely different).

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  #453  
Old 03-10-2014, 10:29 PM
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The Nova was LHD so it would have been imported.
Cars over 15 years old can be brought in and driven here as LHD (even though we drive on the left)
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  #454  
Old 03-12-2014, 12:32 PM
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A couple thoughts on your calcs:

1. I wouldn't get real spun out about the frequency of the system. There are so many different theories on this one that it's hard to put too much stock in any one of them. My prof for chassis design in college was real fond of Olley's flat ride theory, which calls for the rear frequency to be about 10% higher than the front...but there aren't many cars out there that actually have rates/ride frequencies that follow this.

I think the best application of the ride frequency calculations is if you have a vehicle that has favorable ride characteristics that you're trying to duplicate in another vehicle that's significantly heavier or lighter. It's just a good way to normalize the relationship between the wheel rates and the mass.

2. I would ballpark the unsprung weight for your car at 150 lb for each front corner and about 350 lb for the rear. It will definitely make a difference in the end calculated values, but I don't think it's going to matter much because you're not trying to match ride frequencies with another vehicle.

IMO, I think your wheel rates sound within reason. I would look at getting a front anti-roll bar that's pretty easily adjustable (multiple holes on the arms) so you can tune the balance for autocrossing. Maybe look at adding a rear bar if the car really understeers.
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  #455  
Old 03-12-2014, 02:12 PM
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My understanding from others running similar suspension is that this setup will still tend to understeer without a rear bar. I plan to put an adjustable bar out back to help dial things in, but there isn't much room to package an adjustable bar up front.

I will rerun the calcs later considering unsprung mass, but like I said this is more for ballparking and understanding what I have than it is for actual design since I am relying on a commercialized, real-world tested system to establish my suspension parameters. This will give me a baseline for future changes. My frequencies seem to be inline with a baseline C6 Corvette, so that gives me a rough idea of what the ride quality will be like.

As always, I really value your input since this is what you do for a living. I would be interested in your take on the spring rate discussion is thread: http://www.offroadfabnet.com/forums/...ad.php?t=10738
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Last edited by TheBandit; 03-12-2014 at 02:15 PM.
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  #456  
Old 03-12-2014, 02:20 PM
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That all makes sense. After taking a little closer look at your pictures, I see why getting an adjustable bar in the front would be a problem, especially if you're still running stock type end links.

On edit: Leaf springs...ugh. I'll have to do a little digging. I can tell you they're a pain to model. In the simulation world we model them as a combination of rigid links and springs to get the model to match the wheel paths and rates.

Last edited by Graham08; 03-12-2014 at 02:25 PM.
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  #457  
Old 03-12-2014, 02:43 PM
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Reaching back to my Street Machine/Road Racing days, the rule of thumb was soft springs and big bars, how does that simplistic statement hold up in today's world?

On our last "muscle car" a 68 Buick Skylark GS built before so much of this hardware was available, choices were limited. I swapped the front springs to a big block station wagon and adapted late 70's Trans Am bars F&R (1.25"F) and the car handled really well. I don't remember the configuration of the springs(rate) but I did cut them by a couple coils to get the ride height. The car still under-steered but your could get OS with throttle; easily!
Full weight 1968 Buick GS, 350-Buick (+/- 400HP), M22, 2.73 gears posi 12-bolt, 235-60ZR14 ft & 245-60Rx14 R, full interior and mid 12 second ET, it was built to prowl the highways not the Strip, top-end was about 135-MPH or so. It looked like an old Buick and suprised many when the tail lights faded in to the night

E
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  #458  
Old 03-12-2014, 03:05 PM
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Reaching back to my Street Machine/Road Racing days, the rule of thumb was soft springs and big bars, how does that simplistic statement hold up in today's world?
Depending on the application, it's not really out to lunch. That was really in vogue in the stock car roundy-round world for the past few years, but it had a bunch to do with getting the car down from mandated height at technical inspection to where the front splitter almost touches the racetrack.
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  #459  
Old 03-12-2014, 07:56 PM
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Another consideration for the soft spring / big bar concept is you will get more suspension travel when you pitch the car (i.e. upon acceleration and deceleration), so this could introduce more geometry changes (to or against benefit). For example, coming hard into a corner, if the front compresses more you may gain more camber which will help coming into the corner, but on the way out of the corner the front would lose more camber and tend to understeer more on acceleration. It's all a very interesting balancing act with no right answers and plenty of wrong ones!
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  #460  
Old 03-13-2014, 08:41 AM
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It's all a very interesting balancing act with no right answers and plenty of wrong ones!
Exactly. If everyone was doing the same thing, this stuff wouldn't be very interesting.
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