I would never advise running toe out or even zero toe in the rear of these cars. Unless you've eliminated rear toe change during suspension travel in the rear, (5-link or some other way) the rears will tend to toe out during hard braking as the nose dives and the rear unloads. This makes hard braking from high speed very scary, as the car tends to dart around because of the geometry change.

Also it seems to me that under hard acceleration the rear would tend to toe out, but I can't say for sure that this is true.

 

Haha...... There is nothing like seeing a 30 year old car blow by at 130+

 

TT - You get that thing running and I will fly over and help you sort it out.

I was just bringing up the fact that "0" toe on the rear of a C-3 isn't that easy to accomplish. I had to keep adding and deleting stainless shim washers on the trailing arm pivot point. It was well worth the effort.

If your C-4 rear has readily adjustable toe that would be great to just try the different settings.

TurtleVette - Tail happy is also a function of the rear tires. I had a set of 315's tires on for the whole driving season - spring to fall. Lots of heat cycles. Just to put on a show I could pull up in the middle turn lane on 4 lane road. I could just start to move forward at the green light. Then turn the front tires and floor it and it would do an instant 180 turn. Then ease back into it and then go for the smoke show in a straight line to opposite way while all the other lanes were waiting for their light.

Then I bought a new set of 315's and tried the same thing. The rear only came around about 2/3rds of the turn and I was headed for the curb and had to lock up my tires and back up. When tires are just brand new they really make your car hold

 

150

 

69autoXr - what rear suspension set up are you running?

 

Better yet, ship the whole thing over there. There's no action here when it comes to track days and stuff, there's only 1 major track (well 2 but 1 for auto racing) and it's on the other side of the country, it's not open to the public and there are no trackdays and even if you get to arrange it it's very expensive. In typical Dutch fashion they hav "noise days" and only so many so they use them on large events, no room for joe schmoe to go racing so why get a license, it's completely useless unless you want to compete in some lame 1.3 liter *** crap racing class... no thanks.

The C4 diff has a mount for a toe control rod, but I won't use it because the mount is geometrically wrong. I have a toe control setup already done for the older diff and will redo it for the D44. My way the rods are equal length and parallel to the halfshafts, making it a trapezoid giving absolutely no toe change over susp,. travel. The stock C4 toe rods are long and mount at the center, they do give toe control but it's a much cheaper way of doing it, the longer rods reduce angular effect and that way GM could mount it there and not worry about setting it up perfectly for the halfshafts. Everything on my setup is easily adjustable. I am only using the D44 differential, nothing else..well maybe the alu halfshafts, they're longer than the C3 ones but the C4 hubs are "deeper" also, with the C3 hubs there would be even more increase in the track width.. will see if they work and if I can tuck it all under the flares.

George, I don't get why you haven't changed to an adjustable johhny joint type front trailing arm bushing where you jsut turn the bolt to change the setting, like a jackscrew.

 

Stock, with VBP "420" lb composite rear spring and adjustable camber rods. If you meant alignment settings, 1/8" toe in and 2 deg negative camber.

Possibly going to waaay stiffer springs all around soon, especially in front. Stiffer front springs will reduce nose dive during hard braking, which should help reduce the rear geometry change.

 

 

Life begains at 150.

 

Yep,

I noticed both you and 72Ray have huge wide tires on the rear that stick out way way past the stock fenders. This is an absolute no no in the club i run in. Putting fender flares on puts me in the Prepared class. All tread must fit under the fender. You guys get away with a lot of stuff out west. No wheel adapters here either.

 

Turtle, get creative... remodel the rear quarters so they are wider, you could use some of that modelling clay and mould a completely stock appearing new contour..it'd be hard to spot..jsut an awful lot of work.

As for the toe control stuff, it's not that hard to add toe control to the 80-82 differentials, there are 4 "bosses" cast into the diff, they are just perfect for drilling and tapping, I used M12 allen heads





Then all it takes is a wide metal plate w/ the holes in the right position for the toe control rods.

 

I'm not getting away with anything. Back in the 80's I would drive to the track. but because of my mods I was always placed in the "SCCA BSP class" The majority of those cars were all stripped down trailor queens on slicks or R-compound radials.

Just the other day I saw a guy with a fancy jacket that said 2005 SCCA BSP divisional champion. So I walked over and ask him what kind of car does he drive. He told me a 79 Vette and they had just finished up a days classes on auto-X. I got invited over to his house to check out his ride. He told me that it has a 600 hp 358 ci Southwest tour car motor. 8000 rpm and 4.88 rear gears with a 5 speed.

 

What kind of suspension dynamics did you design for? camber change, anti/pro dive, etc.?

-Chris

 

it's all adjustable, I can adjust the camber curves and all. Just the anti dive setting of the front susp. is nto adjustable and similar to stock as it's in the angle of the upper cross shaft. For the rear I set the rods to a certain setting w/ a virtual swing arm that is a compromise between anti squat and tilting of the hib. W/ the IRS we can't get 100% (or more) anti squat anyway, 50% is already pretty much.

The stock cross shafts are setup for a giood bit of anti dive already so there's no use in tinkering with that.

The settings I mentioned will be my baseline, from that all adjustments will have to be made. It's a pretty conservative setting IMO, and mainly aimed towards the street. Look at the static camber some of the racers here are using, they are using more than full degrees of neg. camber

 

The needle quit counting after 85!!

 

one of the first things I installed on my car was...

 

TT - both of our 140 and 160 mph is kind of wimpy. Monty or one of those guys had either a 200 or 220 mph speedo.

I didn't feel comfortable taking a picture when i was really moving so I had to wait till this canyon area on the freeway to take these. The freeway turns actually felt like your doing some lateral "G's"

4200 rpm and just a touch over 120 mph. Just into the power band with a 7500 red line.

 

I don't have that anymore (it was a 165mph speedo, don't think they're available anymore)...I now have:

 

I've had my 68 up into the 110 range, but that was pre-alignment and it was getting scary.

I've had my Lincoln up to 152.

 

I've hit 145 in the '72 and 185 in the back stretch in a real NASCAR at Dale Jarrett's Talladega racing adventure.