ghoffman

We have a couple of cool things ready for Spring! The first is a new upper shock mount that allows you to use spherical bearing ends instead of the "pin" tops on your shocks. This is a CNC machined aluminum billet mount. This has several features and is common for C4, C6, C6, C6Z and can be used with any brand of shock with spherical upper mounts. Please note the shoulder bolt that has no threads in shear, is threaded in the mount with a jam nut on the end and has almost zero clearance for quiet operation. In addition, the upper M14 stud is located with an offset custom flange washer for up to .200 inches of location adjustment. It also has a very large base to react the loads and spread the force into the shock towers as opposed to a small circle like the pin mount. This is made for .875 wide large angular 1/2 inch spherical bearings, but can obviously accept spacers for narrower bearings. In the rear, you use the OE upper 3 hole plate.






The next is a Penske shock unique item, and is a new lower rear C5/C6/C6Z shock clevis that incorporates a "clicker" rebound adjuster and quick change pin. All you do is insert a 3/16 ball driver or Allen wrench in the small hole and you have 8 clicks per turn, 5 turns total. Also, note the new quick change pin with the push pin locker. It will have a small stainless steel lanyard for track safety. It will be available as an option on new Penskes or as a retrofit kit for existing Penske shocks.



I am due to get my new Penske 8760 triples next week, and I will add some more pics later!
Thanks!
Gary Hoffman
Hardbarusa.com
603-682-8073

AU N EGL

Very Cool.

Any sway bars coming ?

ghoffman

Thanks, but we have no sway bar plans anytime soon. Actually, I am in the Gordon Murray school of thought about that, meaning smaller bars have more total grip. The cornering loads need to be reacted in the springs and damped appropriately. What is the point of having an independent suspension, if you are going to tie them together with massive bars?Perhaps we might make correct sway bar end links though, since there is a market opportunity there, and none currently on the market are what we think are ideal.

Wicked Weasel

Gary nice work again and I have been waiting for this.....

When ever you are ready I want to Penskes.


thanks

Bob

fatbillybob

Gary,

Wow those are awesome new products! Can you take this comment about sways to a new thread and start a discussion about springs and sways? I am confused by all the theory about roll stiffness, rollcouple etc... and what you say about independent suspension makes sence. How does one determine the tradeoff between bars and springs without infinate $ and time spent testing?

Zee916

I think that you have to take into account that what he has shown is a very very sophisticated shock..... not something everyone is gonna throw on a street car.

When we are talking about normal "street line" shocks as in not a pure race shock, that most of us run, puting a bigger bar on the car is just the easiest way of reducing roll w/o getting into highly adjustable shocks.

I agree bars are somewhat of a bandaid mod for the stock suspension, but most of us are not buying triple adjustables....

Z

ghoffman

Thanks for the kudo's!
True, the Penske 8760 is superb, but the whole idea of the new little upper clevis was started so that the $399 non adjustable, non-Corvette specific, Penskes, or Koni's, Bilsteins, QA-1's, etc can be used on C4's. For the C5 and C6, you still have the big lower clevis, but that is available in simpler forms than shown here and the upper mounts are common. The entire upper kit as shown (well, they might be black instead) will retail for $70 a corner and then you can use any shock you want with Heim style upper mounts, thereby eliminating the pin mounts.
Carrol Smith has written alot about springs versus bars as well as slew of others. Basically you need to react the roll energy of xx Ft-lbs of roll moment (i.e. "torque"). You do that with springs, (F=KX) and the bar adds to the roll rate up to the point where it is trying to lift the inside wheels, but is working against the springs trying to extend the wheels to contact the road. If you had soft springs and big bars, the initial turn in would feel good, but the cornering limit would be less than optimum because you are trying to lift the inside tires. The loaded side of the car is much easier to get correct than the unloaded side. You are right, another thread would be appropriate, this can get long! I get back on Wednesday night so if you guys start it, I won't be able to discuss this much after Sunday until Thursday.

John Shiels

Nice stuff Gary! Since you are not making any sways someone else will be soon so I think it will be worth the wait.

BrianCunningham

Nice!

I'm looking forward to bolting a set up to my car

ghoffman

Another way to think of how the bars are related to the springs is that if you had no bars at all and got the springs correct for +/- pitch moments (i.e. dive under braking and squat under acceleration), it would be too soft in roll. And since the car's track width is narrower than the length, even if the roll centers were the same, this would be true. The "sway bars" are in reality "helper springs" for roll whose rate should be as small as percentage as necessary or in other words, a tuning aid, not a primary roll resistor. If the bars are too stiff, your compliance over irregular surfaces is compromised as well and the net result is poor grip for a 2nd reason (unless the bumps are perfectly parallel to the car). And another thing, since the damping needs to proportional to the spring rate for a given mass (Fn= (K/M)**.5) any damping that you pick for the springs is less than optimum when the bars are adding to the rate and vice-versa. Now you can see why the new VDP (Velocity Dependant Piston) that Penske has introduced is very nice indeed. It can control the damping correctly for bump situation in a straight line, in roll where the spring and bars are working or in pitch/squat when the bars are not working. It is available as an option in even the non-adjustable Penskes.
Does this help?

C6400hp

Tell us more about the VDP Penskes, specifically the non adjustables.
Wish I had asked about that when I had you on the phone the other day.

NoOne

I must have misread, I swear it said 3 New Innovations

Nice pieces.

Wicked Weasel

was on the phone with Gary today and looking forward to putting in the Penske 8300 2 way shocks and the dual rate coilovers.

I personally feel that everything Gary sells is top notch. Gary's knowledge helps make it easier to decide what is needed and why it is needed. Many others fail to tell you the entire story which in the long run may end up harming your car or yourself.

and yes I have heard it before that Gary is not the cheapest, but if you step back and look at his parts compared to others you will see that you invested your money wisely with his equipment because it is throughly thought out, tested (most likely in his car or another corvette which means alot to me), is top quality and made in the USA.

Bob

db2xpert

Really cool stuff Gary.
You need to get this onto your website too!!

Joel

ghoffman

Yes, there are 3! Here is the new front lower "T" bar mount. It looks fairly normal and plain, but this is made from a SS super alloy that has a yield strength of 150,000 PSI (double the normal Penske part). It is made to very tight tolerances by the same company that makes Starrett micrometer threaded pieces, and is setup for 3 widths of spherical bearings, 1/2 inch width, 5/8, and 7/8. We use the Aurora bearings in 7/8 width shown.




My personal Penske 8760's with VDP (Velocity dependant pistons) will be here this week. The VDP's are, as the name says velocity dependant because if you think about it, the spring force, even with a linear spring is not constant. Let's say for example that you have 5 inches of shock travel and 500 lb/in springs. This means that at full bump, there is 2500 pounds of force to be damped by the shock but at 1/2 inch of travel there is only 250 pounds. The shock dyno does not really represent reality here because the dyno "pulls" the shock at some test velocity, typically 1-10 in/sec, but that is not how a spring works. You want the wheel to rebound as fast as possible without being underdamped and "pogo-ing" because every brand of tire works best when actually in contact with the road! This is an option on the non-adjustables, 8300 doubles or of course on the 8760 triples, so you can have the best without breaking the bank too much. You should also consider that the resale on used Penskes is very high (as John Shiels has noted on a few occasions!) because in reality they will last longer than the car with periodic maintenance, so if you sell your car you can recover much of the initial cost. The 8300 doubles with the VDP's would be an ultra hot setup for track and street. When I get them full assembled and on the car I will post some more pics and data. Thanks!

ghoffman

Here are some pics of testing the "T" bar, or front lower mount. We have seen them bend from various brands and wanted to make sure that did not happen on this part. We actually went to 3600 pounds, but the cylinder was leaking slightly and would bleed down slowly. We used a Intercomp spring tester and figured that the entire weight+ of the car on 1 wheel was a reasonable test. It passed with flying colors, no yield at all (which was expected to be 4400 pounds according to the FEA model). I will be actually using this test piece on my car.
Test setup:




And here is a quick sneak peak of the internals with Penske VDP piston:



And the rebound adjuster in the front:

FRC#44

Will you sell just the "T" bar mounts? Need a pair for a set of penske shocks that I have.

ghoffman

Yes, absolutely, all of these new mounts are available separately or as part of a new Penske shock purchase! It is setup for the wide, 1/2 inch Aurora bearing shown below and you will need that as well to use it, but you probably need new ones anyway.

C6400hp

Very cool stuff!

vettedan

Gary,
Very nice engineering!!! I need to change my QA1 junk over to Penske.