Homologated simply means allowing new body types into compete that have some resemblance to the real production car. They are trying to not have "funny cars".

The second link does not work.

FYI,
1 N/mm = 5.7 lbs/in.

Sounds like a good idea...

Where did you get those spring rate numbers? The Hyperco and VBP rates are advertised, but I am especially curious about the OE numbers.

Well, yes and no. With a Penske 7500 or similar non adjustable shock, you can basically replicate any curve that a 8300 or 8700 could do, but dyno's do not tell the whole story. The 2 and 3 speed shocks are analogous to having a carburetor with idle, main jets and power valves, in that they have a wider bandwidth. For a single condition, single track situation, a non adjustable can be optimized for those conditions, just as a carburetor on a single speed generator engine does not need any more than a single carb jet. This is what most F1 and Cup teams do. They can characterize the track with dozens of springs and adjustable shocks, get it correct in testing and then go with the single point solution for the race. For those that have broader circumstances, there is only so much that that can be done with a non-adjustable, albeit with the 7500 it is a very good solution for a large % of the people out there.

They are 8700 3 speed Penske's, and as you mentioned the high speed bump circuit allows the rumble strips to disappear while the low speed bump is nicely controlling the body roll. The more I dyno other brands (name any, foreign or domestic) the more I respect Penske shocks.
BTW, when I did a spell check on this thread, my Mac had a very funny suggestion for "Penske's"!

When you get it right, the rumble stips really are not there anymore. For years I maintained that a spring is a spring and defended the leaf springs. I now have to say after having them back to back with the same shocks, with a coil in the front and the leaf in the rear, the coil definitely works better. This was just for testing purposes and now I run a dual rate coil over on our Hardbar/Penske 8700's with our clevis mounts. Here is the way the car acts over rumple strips at NHMS. Note the lack of upset the car sees over the rumble strips at 3:10 and at 2:48 in the video.

http://s67.photobucket.com/albums/h28 ... =view¤t=NHIS3-1.flv

What do Smith, Penske, Gordon Murray (McLaren) know anyway? All they have ever done is win NASCAR, ALMS, F1 and Indy car races!
A guide to damper tuning can be found on pages 15-17 in the Penske manual on my website:
http://hardbarusa.com/PenskeManual.pdf

Lets really make this the best forum on the net! We have all experienced the rise and fall of some of the others so we can learn from past mistakes.

The unloaded side is always the hardest to control.

Quote:

You are always welcome to come to NE and be my guest in the Hardbar C6Z.

Tom is correct, the motion ratios (shock travel/wheel travel) need to be equated. The leaf spring forces are reacted on the lower a-arm in the middle of the web(s) and the coil overs have both the ratio of lever ration and the angle of the coil-overs as well. This is not necessarily linear, and in the case of the C5 and C6 the rear motion ratios for a coil overs are not only not linear/constant but have a falling rate that makes a linear spring a bad idea. The rear shock is at a severe angle and that angle gets less with bump travel. This means that a linear spring that is appropriate at ride height is too soft at full bump and vice-versa. That is why we use a dual rate setup on our Hardbar/Penske coil over package and also use a very significant bump "rubber" (really a polyurethane foam) that makes it a triple rate to compensate for this non-linear motion ratio.

Wow Glen, can we combine all of these threads? Your bump travel is limited to the point where the tires hit the fender and the droop is limited (maximum) by the upper a-arm hitting the spring. If your shocks are topped out at static ride height, then you cannot keep the tires in contact with the road when going off of a drop off or on an off camber turn. Here are a couple of pics at NHMS where a Noble has (pick one or more) a) too much sway bar stiffness, b) not enough droop travel, c) too much rebound damping, d) not enough bump damping, e) all of the above. Compare to my C6Z with almost 6 inches of total travel.

[IMG]http://i67.photobucket.com/albums/h287/gshoffman/20080527_NHIS_INS_5949.jpg[/IMG]

[IMG]http://i67.photobucket.com/albums/h287/gshoffman/20080527_SCDA_NHIS_INS_5914_HiRes.jpg[/IMG]

I really want to thank the owner of Corvette Guru for this forum. It is nice to have a place where opinions can be discussed. Thank you!

Gee, I kind of liked the old rough surface, it really separated the rock stars from the groupies. Since I am very fortunate to have a first class suspension, the rough surface gave me a competitive advantage. Any type of shocks will work on a billiard table! Now if they can actually make a decent bathroom facility....

Alyssa is a New England Patriots Cheerleader and graduated Suma Cum Laude with a B.S. in Mechanical Engineering!
[IMG]http://i67.photobucket.com/albums/h287/gshoffman/ImgDyncfm.jpg[/IMG]

deleted (by me!) I will be a complete gentleman from here on out. No comments about any other vendors from me! On the other hand, I welcome any and all questions, comments, even sarcastic remarks about my company or products. I feel discussion is a good thing and that is what forums are for.

Please post pics!

The boots are great! Here is what they look like for the lower front shock eyelet. This is a Hardbar Penske 7500 for the C4/C5/C6.
[IMG]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/DSC_5908.jpg[/IMG]

Well Bill, I wish I could race Laguna Seca!

I know it is silly, but it is a fun promotion! go to:
http://ampenergy.com/ampenergy500/

and enter ghoffman@hardbarusa.com and see where it is on his car!

I agree! I am considering eliminating my entire C4 product line for that very reason. It actually costs more to make C4 stuff because of that reason and the fact that C5 and C6 and C6Z have many common parts, but alot of C4 stuff is unique, so economies of scale ar harder to achieve.

Realistically, even if you have extensive machine shop capabilities, you could not buy the raw materials and parts in onesey-twosey quantities for less than what Tom is charging for the entire kit. For example, a typical anodize shop charges $80 to$100 as a minimum charge if you have 1 part or 30.

Go to page 5 of the downloadable PDF. If you need more specificity, I will ask Kurt.

From Curt Tucker, owner and designer of Teamtech:
The Jet Pilot Pac is listed with SFI as a 6 or 7 point providing that it has two anti-submarine straps the addition of a middle anti-submarine strap constitutes a 7 point harness. Anti-submarine straps are designed to prevent the forward excursion of the pelvic region under the lap belt, the original design theory was that if the pelvic region is tied directly into the lap belt then the possibility of excursion is thus eliminated, this theory has been for years tested and proven correct and effective by hundreds of racers world wide, SFI test laboratories and dynamic sled testing as well. Many people make the mistake of noting the number of straps anchoring to the vehicle in which the harness is used, the number of straps anchored can either be a benefit or if incorrectly positioned prior or after mounting can be a detriment.
Counter comments in defense of the sternum are it keeps the shoulder belts targeted on the HANS Device in both lateral high g-turns and roll overs, stabilizes the shoulder belts with out HANS Devices as well, helps to properly position the shoulder adjusters and prevents or eliminates the possibility of bruised or broken sternum and/or thorax region when used with TEAMTECH's impact dispersion padding. SCCA Pro Racing approved (see rules appendage J).

The Jet Pilot as you know has performed incredibly since I designed it in late 1991, it continues to be the favorite of many monster truck drivers, off road racers, boat and automobile racers very where do to its comfort, ability to pull the user tightly and securely back into the seat and provides incredible impact resistance as well as survivability as well. Many consider it to be a performance item as well, that is interesting because its not bolted to the engine. Many racers state that they reduce as much as 1 to 1.5 seconds off their road race course times just by using the Jet Pilot Pac, lets do the math reduce your track time by 1 to 2 seconds for $400 and change or spend $4,000 on engine performance parts to reduce the same amount of track time. By the way, this story was not fiction but first noted and proven by Randy Popst and his Porsche car owner Bob Raub (80's Tran Am Champ) of 3 R Automotive Englewood Colorado.

She definitely talks too much. RP is an ex-F1 driver for crying out loud, and is very smooth and he is driving a foo-foo car anyway. A Civic Type R, big deal! Imagine if he was in an NSX or similar. Maybe she needs her own Type R:
[IMG]http://i67.photobucket.com/albums/h287/gshoffman/segway-r.jpg[/IMG]

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Ah, no, but it can be re-webbed if you soil it or when it becomes out of date. Brian and Tom have driven with me at Loudon and Lime Rock, and with an LS-7, I am always a little loose! When it doubt, gas it!

The Teamtech JetPilot is the best and most advanced harness, period. It is however, very different and very hard to explain. The lower part is like a parachute harness in that your thighs and pelvis are totally constrained. You would not want to jump out of a plane at 150MPH with your nads reacting the load like you have with a 6 point or a 5 point. The lap belt goes around your thighs below and above and gives you not only fore and aft support but left and right as well. It has some downsides as well. It is made for each person and has limited (3-4 inch) adjustment and is not for 2 people of very different size. As far as the upper part goes, it is fully padded (think business suit vest) not just 2, 3 inch straps, and has a NASCAR approved sternum strap that is very different from the dangerous latch type common on Simpson, Impact harnesses. It is a Velcro strap that goes through a loop and keeps the harness on your shoulders and HANS. It has no sub belt per se, but qualifies as a "6 point". I use it personally and everyone that has one loves it. One twist of the cam lock, either way, releases it all (plus the Velcro sternum strap which just rips off). The cool thing is it only has 4 attachment points to the car, no need to fish a sub belt somewhere.

And we are trying as well!
[IMG]http://i67.photobucket.com/albums/h287/gshoffman/DSC_0007-1.jpg[/IMG]

I'll see you there!

Here are my Guru Cut Vinyl Decals on my trailer:

[IMG]http://i67.photobucket.com/albums/h287/gshoffman/DSC_0007-1.jpg[/IMG]

The F-22 is simply the best. Kelly Johnson is unknown to most people outside of the aviation community but he is up there with Edison, Einstein, Oppenheimer in the 20h century. People now use the term "Skunk Works" as a general term that means a small no BS shop that makes trick stuff, but he started THE Skunk Works. The great aircraft that he was part of, P-38, P-80, F-104, U-2, SR-71, F-117, and the F-22 is an amazing career. He is a great american hero.

Quote:

Wow Bill, is the Raptor going to do a few laps of the race course? You have to take some really good videos and/or pics!

We have faced the same issue and made a really easy tool to use for toe, thrust angle easily. This was one of those made by popular demand things. I was using it for years and guys that saw it made me put it into production! The tool is now made with a slotted wheel interface plate for all 5 lug cars. Share it with your BMW and Rustang friends!




Here are the instructions:
http://hardbarusa.com/uploads/image/A ... ool%20instructions%20rev1(1).pdf

I got a ticket in Spain from photo radar that I had no idea I got until I went to turn in my rental car and there was this bill. There was no discussion unless I wanted to hang out for a few more weeks. I was at a cocktail party here later and bitching about it and saying that I thought the photo radar and photo stop light thing was unconstitutional in the US and should be banned. This woman said that she thought it was fine because after all, they have it in Spain and Germany. I said, great they have it the home of Franco and Hitler, just what we want to emulate! That ended that...

We must have some Police Officers here that can enlighten us to "the other side" of this. It is the photo crap that really gets me, since I thought you had the right to face your accuser (albeit for profit for the accuser). Did anyone ever notice the most good law abiding people love firefighters and Military and feel the opposite of Police? I wonder why...?
I guess I have never had a USAF, USA, USN, USMC Officer pull me over and ask for money (sorry, my license).

Wow Tom, 2 seconds, congrats! And I thought it was due to swapping engines with me....

If I may ask a potentially sacrilegious question, why not just use an LS-7? It is already dry (well, perhaps damp) sumped, has similar or more HP and torque and probably weighs less (about 435 pounds). The price is about $12k new in the crate, or get one from a wreck, which alot of C6Z's get into because some people have more money than driving skills.

Brian can tell you, what is immediately noticable is the stiffness added by the Hardbar harness bar. Even if you have no need for it from a racing standpoint, the stiffness added is like the difference between the top on or off.

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OK, I will do it, but we publish it, OK?

I suck out the old fluid from the M/C with a thing I got at Tractor Supply company:
http://www.tractorsupply.com/webapp/w ... ______?rFlag=true&cFlag=1

Then refill it and just crack the bleeder screws and let gravity do it. The tool above is also great for sucking out trans and diff fluid as well.

The C6 shock was broken, it was cavatating very bad, that is why it has so much hysteresis (not coming back along the same path it went out). With that much hysteresis, it is sloppy and not really controlling the wheel very well and would chatter over bumps. The C and D shocks can be adjusted so that either could do the rebound values of the other. Note that they both have alot more compression (top half of the curve) than the other 2, and is velocity sensitive, which is what you want. The sample A shock is fairly new, had no outward signs of leaks, but has such stiff urethane upper mounts that is prematurely wears it out internally.

The first is a new GM T1 C6 shock as labeled.

The ones labeled are

A=Renamed brand made in Asia (Japan or China) coil-over on full soft. The adjuster only effects rebound, but there is some bleeding over. It only added a little to full hard to 225 pounds.

B- Bilstein aluminum body after re-pressurizing it. It would leak down in an hour to 75 PSI. We kept it up at 150+ for the test. The fronts leaked too, and they were about a year old. At least it had a Schrader valve so it could be recharged, otherwise you would only know when it is on the dyno because you can hear the cavitations. It sounds like a kid sucking at the bottom of a soda with a straw.

C- My old Penske 8100’s (that I bought used and rebuilt like 2 years ago, now sold) with the bump on full soft, rebound on ½ hard, after 6000 miles or so and 20+ track days. I did these plots when I sold them as a QA check before I shipped them to him.

D- Moton T1 shock on moderate bump, max rebound.

Dyno's don't tell the whole story but clearly they can find issues like the T1 shock that was broken and I really don't know what was going on with sample "A". Sample A made audible clunking when cycled as did the fronts from the same manufacturer. I presume it had some kind of a floater gizmo inside it, which we have seen (or heard) on KYB's.

Can you believe that ZO6vette.com denied this post? No names, no brands, identical to this and they denied it!

Ok, here are 5 force-velocity and Force-displacement plots we ran on our dyno. These are all Corvette C5/C6 rear shocks, 5 different brands, which do you think is the best, and which one actually works the best on the street and/or track? What curve do you think is the worst? What do you think causes the hysteresis in some of these curves?

Without a dyno, you are only guessing, and real world (road race and steet) has lots of greater than 3 in/sec velocities. Body roll, squat, dive, etc is the less than 3 in/sec stuff, but bumps, curbs, ripples are much greater than that and 8-10 in/sec is very common. An interesting thing is when I was at Penske last summer, it was mentioned to me that a tolerance variation of .0005 inch (yes, 1/2 a thousand) could cause 20-30 pounds (depending on the valving) on the dyno, and that is why each shock has to be tested and if not within spec, it is made to be correct. If the super quality CNC parts in a Penske can cause that kind variation, what do you think you get in a mass produced cheap imported shock? The first plot is Force-Velocity, the second is Force-displacement. There were many details that we have not discussed, but I will later (things like not holding gas pressure, leaky seals etc)

We have seen new GM T1 shocks that flat were not working (shown here):

[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shockT1bad.jpg[/IMG]
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shockT1badFD.jpg[/IMG]

The rest are shown here, brand names deleted.

Brand A
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shockbad.jpg[/IMG]
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shockbadFD.jpg[/IMG]

Brand B
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shocksoso.jpg[/IMG]
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shocksosoFD.jpg[/IMG]

Brand C
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shockgood.jpg[/IMG]
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shockgoodFD.jpg[/IMG]

Brand D
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shockMfullhard.jpg[/IMG]
[IMG width=640]http://i67.photobucket.com/albums/h287/gshoffman/Corvette%20shocks/shockMfullhardFD.jpg[/IMG]

I don't remember where I got it, but it dates back to 2002. What cracks me up mostly on these cars is stickers. Most of them are really crappy parts like Tein shocks and Takada harnesses.

[IMG]http://i67.photobucket.com/albums/h287/gshoffman/garfield.jpg[/IMG]

Instead of that, you can use saaft mounted rockers from Crower, Jesel, etc. They are more rigid, more reliable and do not require the tall valve covers.

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Yes, some do, and alot of guys have fun drag racing their Vettes, but it is a Sports car and that implies turning right and left. Nos only lasts a few seconds and that is not something that is very usefull for a 30 minute session at that local road race track day event.