D height is the differnce of heights from the ground to the tie rods. That's what it shows in the chevy pwoer manual.

 

oh..they just label the different specs so they can have a legend explaining what's what... without the manual "D" length makes no sense at all

 

All C3 owners should be required to own one.

 

The contact patch should be flat on the road. In cornering the suspension compressed and the car rolls causing only the outside edge of the tire to have proper contact. In road racing you need lots of negative camber because the suspension does not make enough correction. Not on any production car not event the c5 or c6. They are over in the roadracing section talking about adding camber plates and such to be able to dial in a bunch of negative camber when they get to the track.

if you look at the pict below the tire should be at a right angle (90degrees) from the track surface but its not. I need to dial in quite a bit of negative camber so the wheel tilts in at the top in turns. On the straights the tread would not be flat on the surface but who cares? You don't have enough power to break the back wheels loose anyway.

 

I don't have enough power? I beg to differ on that. I can't keep the tires planted in the the first 2 gears at any speed. 3rd is even tough at the upper RPMs.

I do see a lot of the road racers with a lot of negative camber when they are on the straight and I understand why. I do run a slight amount of negative myself. So the Smart Struts are not going to help. They won't fit anyways and I cancelled my order. This is good info.

 

I am at a 1 5/16s difference. I am pretty much right on spec.

 

I agree with both sides of this agument and here's why. Granted, in a racetrack environment with a (generally) very smooth surface and race suspension, TT's points are right on. You either have to have some camber change or you need a totally rigid (F-1 or gokart) suspension which doesn't work either on an old vette. My observation, mostly seat of the pants, is that a little less camber change in the rear works pretty well on the street. Certainly less bump steer under load on most of the less-than-perfect twisty roads around here (which can be scary) is nice and I can dial in a little more intial negative camber than I would normally.

The factory setup is biased toward daily driving by tourists, so the suspension reflects that. Many (if not all) of the changes we make are an attempt at a compromise track/street setup, with the key word being "compromise". just little stuff like a front brace, different tie-rod or rack/pinion setups in front, poly bushings all around, and yes, the lower strut mount makes a world of difference in a street car compared to stock. Heck, the mount is relatively inexpensive so I'd try it and go back to the stock one if you don't care for it.

Hans

 

smooth surface or not doesn't have a lot to do with it, camber change is only there to counteract the tire tilting due to body roll. It's not just for F1 or race cars, it's for every car and everyone who is enthousiastic about improving the handling on his car. The rear steering problem is caused by the poor toe control that a trailing arm setup has, it has nothing to do with the camber curve and/or bracket/smart struts.

If there was a car that would not need a lot of camber gain it would be a formula car, they have very little suspension travel and if you observe the wishbones they are - by eye- parallel.

Why would you want more initial camber? This is an indication you require a bit more camber during bump, which you would have if you had increased the camber curve (or in case you swapped to smart struts retained the stock bracket setup), dialing initial camber does nothing but accelerate tire wear and cause uneven temps. Ideally your curve will be such that initial camber is 0 and the curve such that it perfectly coutneracts all body roll. Now, some people see touring cars and similar sedan type race cars with a lot of camber, they have this for a reason....being McPherson & chapman struts that don't offer a camber active geometry.

If stock is a street setup and you want a compromise between street and track with suspension changes yet you retain the stock weight isplacement then you have to fit stiff springs and/or bars to reduce roll, this would make the stock camber curve suit the roll a little more, why reduce the camber curve towards a static setup if you want to go aroudn the twisties? It just doesn't make sense at all.

The shock tower brace is a fix for a flexing frame, a problem even more apparent when fitting stiffer springs because you load up the frame more.

Different steering setups don't matter either, if they are engineered properly they have an acceptable (at least) bump steer characteristic and thus have the components/pivots placed in the right position. Assuming they all are, there is no big individual difference between them (although, the bumspteer in the stock system is not good)

If you want a real world comparison, swap out JUST the bracket, leave the rest stock, comparing a stock system to an aftermarket system offering more roll resistance and what not can mask the difference and is not a fair comparison.

Fiven equal ride height, weight, roll characteristics, tires...and so on, a car with a camber active suspension will be able to corner faster than one with a static setup because it will have more tire on the ground in all cicrumstances.

 

Gordons unable to switch just the bracket because of his custom exhaust that's welded, we both have the same problem/exhaust or we would of done so and made a comparision like you suggested. He's lost his rear sway bar due to mounting larger tires/wheels 18" and stiffening up the rear with a higher composite spring weight. I don't know if just changing the bracket will help his wheel hop, I see how the smart struts and bracket would help camber wise, I still think he needs stiffer shocks to control the movement of the trailing arm/loading factor without flexing the frame...I see some have opted for the coil-overs but that involves some modifying ...jmo I think we'll strap a camera underneath and see exactly what's going on during acceleration....

 

Why does everyone think the bracket HELPS camber? Am I the only one that sees what's going on???

Gordon, use the stock bracket and install the smart struts on that, keep your camber curve..you'll love it.

 

That is what I have on the car and that looks like it will stay that way.

 

I had wheel hop after fiber spring. I had the sway bar link pretty tight. let up on it a few turns till it got under control. Or maybe it was in my head.....

 

The bracket by itself hurts nothing, only how you use it. I kind of like the freedom of adjustment it allows with an otherwise stock rear suspension. Also, a half a degree negative in the rear and a bit more in the front gives me pretty even temps across the rears and still a bit hot on the outside of the fronts, still using the stock steering. I've only been able to test it once @ Sears Point, and that wasn't full tilt by any means because of the roll bar (lack thereof). I can't (won't) slice up a '69 BB, so I'm just dancing around the far edges of optimum suspension design.

TT, I think your understanding of suspension engineering is far above most of our levels (certainly mine!), and I always appreciate your comments. I just think there are different outcome being sought.

Hans

 

Pretty sure he no longer has a rear bar...

 

TT,

He's trying to solve his wheel hop problem, do you have any suggestions?

 

This is where you and i always disagree. There is not nearly enough camber gain in either the front or rear of the C5 and C6 corvettes much less our cars. The guys who eat drink and sleep road courses dial in a ton of initial camber on their newer vettes. I have spent the last 7 years hangin out around road course junkies. Take a look at the pict i posted below on a banked turn at Lime Rock. I could use a lot lot more initial camber for the wheel to truely be parallel to the track surface.

Tire temps are going to depend on the track. The tire generates very little heat when driving in a straight line. It is possible to have 3 - 4 degrees negative camber and have even temps across the tire. You generate the heat on the outside tires in a turn not on the straights.

P.S. I like the new avatar better than the cartoon thingy.

 

It's the "wheel hop" that he's got the problem with....the stock strut bracket with the smart struts is there to stay like mine....We both have the identical exhaust and strut setup, he's not going to change the custom welded exhaust for a bracket, there's a clearance issue there.....Yes, he's removed the rear sway bar... great info as always there TT, any other suggestions for "wheel hop" control....

 

It's the "wheel hop" that he's got the problem with....the stock strut bracket with the smart struts is there to stay like mine....We both have the identical exhaust and strut setup, he's not going to change the custom welded exhaust for a bracket, there's a clearance issue there.....Yes, he's removed the rear sway bar... great info as always there TT, any other suggestions for "wheel hop" control....

BTW: He's got plenty of HP, can sit there and just burn the hides off.. makes me sick...

 

wheel hop is an instability issue. Put some stiffer shocks in. Maybe a torque/traction bar too. Let some air out of the tire.

 

What is the interaction between the Smart Strut and a 6 link setup?