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I am really interested in this so I am going to follow along and drop questions if you do not mind.

What do 2" drop spindles actually do and how do they differ from the factory spindles? I am gone to complete aftermarket suspension parts - Spohn and UMI. I have been looking into the drop spindles but do you know if they will work with my Spohn tubular A-arms and coil-overs for a 1992 z28?

I will be reading this when I don't have a headache from these newly discovered allergies lol. Subscribing.

2" drop spindles do the drop at the spindle, which means the angle of the front control arms is kept as parallel to the ground in a stock resting position. Simply dropping the car via springs will cause the control arm chassis mounting point to be lower than the ball joint.

Imagine holding your arms out level, this is the neutral position from which suspension movement should start. Drop springs cause your hands to be higher than your shoulders, where as 2" drop spindles will maintain your arms parallel to the ground while making YOU 2" shorter.

In radio controlled world the neutral position is usually called "Bones level" because when the dog bones are parallel to the ground the power is transmitted to the wheels with optimum efficiency.

ahhh got it. Thanks, now maybe you can chime in on my other post on which spindles to order for my setup

Thanks!

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I'm curious about some of your ideas along the same lines for the v6! I was looking back at some of your old posts the other day. I've done some stock car racing now and understand a lot more about suspension than I used to but still have to go back and reread a lot of stuff you say to try to understand it!! (simply put, I know I can still learn a lot, knowing how much you know.)
Would you mind posting some baseline spring rates for the v6? I've got bigger plans for my car now (for suspension) than I ever used to but unfortunately it'll be a slow process getting it there.

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your Spohn link isn't working BTW could be just me. thats true what you were saying about suspension qualities. same goes for the rear. when a 3rd gen is lowered, many extensive suspension mods need to occur, not just the simple coil fix. After a coil drop, the rear, in my opinion, needs to modify to keep up with some positive tractions and positive results. For example, new adjustable Rear lower control arms need to be adjustable, and also include drop brackets for both sides, the pan-hard bar would need the drop bracket and the adjustable threads. the torque would need to be adjustable with the right angle. the front struts would need the special offset camber kit to correct some minor difference and reduce tire tread wear on one side of the tire. . again with your analogy about neutral, thats great example. little confusing but understandable. i can see that idea about the coil-overs and second the spring figures. With cars, Ive seen some that are so light, practically all sheet metal. and nobody wants a bouncing Cadillac type touring suspension and others don't like the railroad track feel. Lower profile tire help some sway. Its great you have posted some good info. I think think there should be just a forum about third gens and ones experience.

Spohn A Arm Link

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It sounds like what your specing out, is for an all-out, pure race 3rd gen, not a street car.

In other words...It only applies to a VERY small audience, here on TGO.

How about some real-world, real budget, street car advice, that most can use.

I'm working on mine, but virtually nothing in the thread applies to my STREET (like most cars on TGO) car.

Stephen, the thread is called "ultimate" 3rd gen suspension, not "how to build a fun daily driver". I do think a majority of the information can also be applied to a street car. But, I'm no expert.

Edit: I think it is obvious that this is "real world, real budget, street car advice". There are a lot of people that have more money invested in their street cars than what it would cost to do what is described in this thread, most likely including you.

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this is a really great thread.
i will be making sure that i follow this more or less in my planned mods.
one question though:


are weight jacks necessary?
seems like they add a lot of excess weight when you could simply use urethane spacers or make your own spacers (i cant but some people have the ability)
any input?


another thing that you alluded to but did not actually say outright is that proper racing bucket seats and a harness (worn correctly) will improve anybody's driving even in a Cadillac Deville.
recently i had a chance to drive a friends 2004 Z06. the suspension was amazing and i found myself much more in control of what i was doing. later i realized that my knees and elbows were not all tired out from bracing myself while i was cornering. good seats can make a huge difference.

Install ones like this. They only add a few pounds, and they don't add any unsprung weight. There is a nut welded to the bottom side of the subframe, and usually the rod you see sticking up through the center of the hole there would be threaded, and the weight jacks would be adjustable from above. What you see now is unadjustable, since the threaded ones were often removed to comply with rules at a certain track.
Can't get pic to upload...

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Vetruck,
Nice to see you back posting on here... Haven't spoke with you in a while.
Your insight was very helpful in the past & hopefully this will spark some research by anyone wanting to maximize their suspension.

As for your mods listed, everything here can be useful in a street car. One thing you mentioned was roll center, which is very important. Most get lost in lowering the car without respect to the roll center effect.

The key here is to make changes & test your car out. The setup has to match your driving style, & what works for one person may not work for another. If you are trying to achieve the perfect handling car, some trial & error is required & you may have to swap springs or swaybars to get it where you want it. Remember it has to work or you, not what someone else says is the "setup" to have.

Some conessions will have to be made to ride quality, but you cannot expect to outhandle a Vette & ride like a Cadillac at the same time. The interesting part is you will start to notice flaws in other cars when you drive/ride in them as you make your car better. Today I drove a 17,000 mile original 88 Formula WS6 to work. It is original in every respect & literally like a new car. It was a good benchmark comparison to my 91 Formula (that I normally drive) which I have done a lot of work to. The difference is night & day, & now I fully realize how much I improved the handling.

It's good to see a large in depth tech post from you. I know I learned some stuff.

I know what you mean when you say people shouldn't buy parts solely on what others say is best. I bought my Eibach Pro-kit springs this way and I regret it. It feels like the front spring rate is too soft but the back is alright. I plan on going with weight-jacks when I build up the motor and tranny.

Since you keep referring to chassis bracing, would you mind making another thread about that? I think I have a pretty good idea of what kind of bracing you would recommend, but it would be good for everyone to see.

Also, you mention you were generating 1.07 lateral g-forces on street tires in your camaro... What kind of "street tires" are you talking about? There are a lot of DOT approved tires that are pretty much just a step below real race rubber. Another thing I was wondering is if your camaro was gutted or if it still had a full interior and what not.

Thanks again for the great thread.
Mike

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Thanks for the great info. I have some questions pertaining to my 1986 Camaro. This was my first car back in the day of highschool. Back then I did Bilstein shocks and struts with Hotchkis springs. Well, the shocks (blue and yellow ones) are worn out, so I am shopping around for replacements. I want to redo the shocks and struts and prob the springs all over and do it the right way. Do you know what you would consider to be the best ones out for my '86 Camaro? I want to have a perfect stance and harder corner features, I HATE BODY ROLL! Interested what you think, thanks!

PS: Do they make a strut tower brace that works with our cars that are carb'ed? Would the TBI strut tower brace work with a carb'ed car?

suscribed

DIY TBI/CARB STB http://www.austinthirdgen.org/galler.../Randy/TBI_STB

so.. quick question... an upper panhard bar, panhard bar relocator and adjustable panhard bar (with what kind of bushings) would be a great imporvement for a street car that is driven hard..... when compared to stock rusting stamped steel... would it not? kinda dumb question, but im wondering if i need the adjustable panhard bar .. and if i need the upper panhard bar part too? my car is lowered 2" up front with 2" drop spindles, and i cut 3/4 of a coil out of some brand new moog 5665 spings for a 1 1/4" drop in the rear.. so yes the rear is lowered.. is it worth doing the upper ph bar, ph bar relocator, and adj ph bar?

yest you should change ph bar to adjustable as now your drivetrain is not centered (after lowering). as for upper ph bar part there is no need to replace it if it is not damged, as for ph relocator you use it only if you have problem with fitting exhaust

best regards

Just tripped over this thread.

Questions: are these true progressive springs or "bilinear" springs that have two different coil spacings (and suddenly jump up to the high rate once the close coils all close up at about the same time)? What happens when the inside rear gets back into the "soft" rate?


Norm

But it's amazing how much having only a cheapie chest strap helps you actually use the potential that you're building into the car. Tires are Falken Azenis RT615, although they do have quite a lot of runs on them. I'm guessing I'm at worst only a little shy of 1.0 lateral g.

This car is 100% street legal and is fully daily driveable with full interior (and everything remains functional, even the A/C). Some of Dean's tips I am not easily able to add to this car, but there isn't anything in his list that I wouldn't consider 100% streetable.


Norm

At stock height, with the stock PHB & with good bushings, my rear end was already off by a good 3/4"!

Just my opinion, but once you've got your tire treads as flat against the pavement as you can, body roll becomes rather meaningless. And if you've got enough shock/strut damping, it happens a little slower. I know my 85EP car rolls a lot more than Dean's 3rd Gen does. But quite honestly I hardly notice it during a run, and if anybody told me to forget all about what I know about that car's amount of roll per lateral g and then forced me to estimate how much it was rolling, I'd likely guess it to be about half of what it really was. With only a few of the tweaks, once you stop looking at the hood line and focus down-course, you really don't pay much attention to the roll.

I notice the pitch under braking (nose dive/tail rise) in my '08 Mustang GT to a much greater extent.

I know I'm introducing a bit of "driver" into a suspension discussion, but the whole picture is "car" + "driver" + "road" and I don't think you can fully separate them.


Norm

There isn't much need to replace the PHB brace, with a couple of exceptions.

If it's been damaged. (duh)

If you've lowered the chassis-side PHB attachment. Then you'd perhaps want the brace to attach a little closer to the relocated PHB attachment point for structural reasons, and the OE brace might not fit right (needs to be a tiny bit longer).


Norm

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Thanks. Exactly what I was looking for, as sometimes the term 'progressive' is used inappropriately. I suspect that many of the mass-market "lowering springs" that are advertised as being "progressive" are really "bilinear" with a "knee" in the load vs compression plot.


OK, I see what's going on here. We're actually looking at the point that the sprung mass actually rotates about (or at least an indication of its lateral position), which certainly would affect spring compression on one side and extension on the other. Not necessarily the same "roll center" that is used to determine lateral load transfer in a corner with no banking, though.


Gotta run, something just came up.


Norm

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Subscribing... I need to read this sometime when I don't have a massive headache Makes comprehension a lil' difficult sometimes.

Dean - thanks for adding that picture.

It illustrates quite nicely what I keep telling people who want to lower a strut suspension with springs - that the roll center will drop about double the amount of ride height lowering. I cringe at the word 'Sportline'.

So anyway, a 2" body drop via springs ==> 4" loss of front RC height, which probably buries it an inch or two in the dirt. As bad as it sounds, if not worse (been there, done that on the 85EP, could hardly fix it fast enough).


Norm

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Where do you suggest purchasing the custom springs?

so is it bad for the ball joints if I only put lowering springs in my 90 IROC for now?

no

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