Hey Norval I meant to say that is a great idea to just attach the upper strut rod mount to the cross member . I am like you , it seems unneccesary to build a mount and attach it to the pumpkin. I am interested what kind of toe readings you get on your system.

 

I have a proper toe gage with dial indicators and the big aluminum plate that bolts to the hub.
Before I put the coil overs in I will run a curve, hopefully this weekend to finally see just how much toe change there is.
My coil overs are completely finished and other then installing the springs over the shocks the car is ready to be set back on the ground.
I will start the front end next week with the installation of the taller spindles and a spreader bar.

 

IF there is a toe in condition; then there will be oversteer right? Would a toe out / understeer be more desirable. Could that be obtained by mounting the arms in the other direction?

I know you won't be able to tell untill you measure it... just throwing out ideas in advance.

 

Both strut rods in the normal position are parallel to the ground so any movement of the wheel would cause the rods to shorten up due to the arc they travel in and get shorter so I would have a toe out conditon always. To create a toe in the rods would need to get longer and that can't happen.

 

the toe change can only be fixed by an arangement like a C4 with the dual links in front of the hub and the toe rod in back. Creating a system like that with the norvals upper link would be ideal!

A system like Guldstrands eliminates toesteer too

 

Got it ;)

 

Haven't participated in a 6 link thread in a long time. I've actually forgotten that I have a Corvette. It's still in pieces and the 700-R4 found a new home. It's so cold out right now that anything Corvette is at the very back of my mind.

Obviously i'm a 6 link supporter. It was probably the best thing I ever did for my car. Traction increased with the additional bars and this was at the same time that I switched from 3.08's to 4.11's. The only downfall is trying to get somebody to align your car. Luckily at the time I had a friend managing a Midas Muffler and I was able to get in lot's of trial and error testing on Sunday's. I have a picture somewhere showing how much camber change was going on with the stock IRS...lemme see if I can find it.

Here it is:

This was with a stock IRS with the exception of some small pieces to change the angle of the lower rods to match the half shaft angle. After numerous burnouts and all out craziness you can sure see how much camber change I had happening. Those tires never really did get fully planted, that is until the 6 link came in to play.





[Modified by Stingy74, 7:39 PM 11/21/2003]

 

It also eliminates any excess bills in your checking account.
The 6 link is all about BANG for the BUCK!


Hey Aaron (Stingy74),
Long time no speak.
been a while, thought you had quit the vette scene altogether.

Good to see you post again.
I'll have to admit though I haven't been reading/posting much here lately either.

later
dr

 

What's the difference between the pic below and a 6 link? I don't remember where I got this pic-I've had it saved for a few months.Also, what makes this a 5 link?


[Modified by 79VetteMike, 1:16 AM 11/22/2003]

 

Norval,

Thanks for answering. Those splined shafts are pretty beefy. I'm also just imagining all the time it took to drill all those holes... :crazy:
I also noticed that you lowered you inner mounting holes for the strut rods. By any chance have you compared the location you have on your setup to the VBP smart struts?
I am just starting my design for a new diff X-member to raise the diff and spring up about 3/4" to 1". I plan to incorporate an upper strut rod mount point into the X-member. I am looking at locations now. My first thought is to try and position the upper strut so that I get minimal yolk movement as the suspension moves up and down. Perhaps when I am done you would take a glance through it? :D
Out of curiousity, have you noticed any problems with the seals for the yolk with the movement in and out?

 

Well the one you show still uses the half shaft as a link. The 6 link adds another link above the half shaft :crazy:

BUt the one you show could remove all toe steer and possibly fix the camber change too

 

Here are two photos of "5-bar" rear suspensions:
Greenwood Design

This is a photo of the system whose sketch you posted. You can also look up an older thread by a forum member called Lohkay who worked on building his own version of this.

Guldstrand / Scott&Riley Design

This version can still be bought from Guldstrand, though expensive.

You asked what makes the first photo a "5-bar". The number of links is counted for each side of the car (passenger/driver). In the case of both of these suspensions, there are 2 trailing arms, and the half-shaft. That gives 3 links. In the case of the Greenwood suspension, there is also a strut-rod (below diff) and toe rod (behind half-shaft) for the total of 5. In the case of the Guldstrand, there are two strut-rods for controlling camber/toe together, bringing the total to 5.

In the case of the "6-link", the links are counted from both sides of the car to give a total of six. There is the single trailing arm (2 of them), 2 lower strut rods, and 2 upper strut rods. The half-shafts no longer count as a link.


[Modified by 75 BBC Stingray, 7:30 PM 11/22/2003]


[Modified by 75 BBC Stingray, 7:32 PM 11/22/2003]

 

75BBC Stingray I lowered the inner mount for the lower strut to make it parallel to the 1/2 shaft, I also did it the same is in a 6 link article. I blew up that article and put an accurate scale on it so I could measure the amount I should lower the inner mount.
It is find to raise the rearend but what about drive shaft angle. You screw up the angles between the transmission and rearend and you will get vibrations. The transmission tail stock points down and you must equal this angle with an up angle on the rearend so the 2 angles cancel each other. This is important and also alignment of the centerline of the motor , the transmission tail stock and the rearend.
This is a poor picture of my wheels but you will notice stings under the car and other strings with nuts to act as plumb bobs. I really worked on the alignment and ended up with zero vibration anywhere in the shifter handle.
The picture doesn't show much but you can see the strings hanging down

 

Norval, I've been following all of these threads lately, and I do believe you are a genius!! I wish I understood a tenth of what you know!!

I have a question though for you. I do not have any access to the specialized equipment, knowledge, or science that you have, but I do wish that my car handle as well as it can on the street. Not necessarily full street racer, and I don't think I need the 6 link that you have so artfully created. You have also made several comments on the things that GM did wrong in the design.

Is there anything I can modify or change easily to improve the geometry or handling of the car? In other words, without doing a major de-/reconstruction of the entire front and rear suspension system, can the car's handling be improved?

Last question, I could probably understand more about the workings of the various systems if I could see animations of the different types (I'm very visual!) Do you know of any online sites that have this?

I'd be interested in your response as an average layman trying to enjoy the car even more!

Thanks,
Paul

 

Norval,

I will have to give this some more thought. I had assumed that as long as I raised the front and rear of the differential the same amount, that I would be OK. Perhaps it is not this simple...
I could test this after installing everything as I plan right now. I could clamp a long round piece of wood or steel into the yolk of the transmission and another into the yolk of the differential. By orientating each of these pieces in the vertical direction, I can check that the angles are correct. In fact, I should be able to do this in the other direction (horizontal) as well... If I find any discrepency, I could shim to compensate. The longer I make these rods, the more accurate I would be...
As for your lower strut rod bracket, I assume it was a stock unit to begin with, so when I pull mine of later this week, I can compare it to my smart strut to see what they have as a drop and see if its similar to you picture.

 

73vert I am kinda new to the forum but have logged a few hundred thousand mile in a mid year (I love pain) , and I have tried many front and rear improvements. The best thing I ever did was to put a modern power steering box on the car. I wish we had the technology years ago. The other thing I have not driven but hear good things about is the rack and pinion kit by steeroids. Lets face it gm stopped putting slave assisted steering on cars in the early 60s but used it on our corvettes until 82.

Which ever steering improvement you try I feel confident it will be the single best change you can make to the c2-3 chassis, considering everything else is in good shape (no loose steering componets or rear bushings).

PS a set of 17 inch wheels and tires will do wonders also good luck

 

As long as we're talking about anything and everything. I guess I can add a rather specific 6link question to the mix...

Looking at Coleman Racing Products' website catalog, what exactly do I want for the 2 new links? I know I need 10". All of the trailing arm tubes seem to have 3/4" ends, is that right? Their tie-rod tubes have 5/8, but are they strong enough? Same question for the rod ends, I assume I should get the Heavy Duty type, but that would push the cost well over the $100 approximation for parts....

Thanks!
Chris

 

For the upper strut rods the 5/8th aluminum rods 10 inches long are fine, that is what I am using. For heim joints I bought the standard duty 5/8th fine. I have 3/4 inch is stock in the shop but deemed them too big and heavy for what I wanted.
Go 5/8th with everything, standard duty. Mine has been run for I think 2 years now and it is still tight, no heim joint problems with the standard set.
So that is 2 10 strut rods and 4 hiem joints 5/8th , 2 left, 2 right.

 

73sbvert What really got me started on the suspension is a near fatal accident. I went over a real bad section of road, running about 100 mph with 2 passengers. It was a bridge with a dip before and after the bridge. It is not really a bridge but a buryed culvert that frost has pushed up.
Anyway when I hit this the car's suspension compressed , then over the bridge where the car's suspension unloads and down the other side to full compression. You hit every extreme and the car just went nuts, I almost lost it, I did really have to fight to hold it on the road, Luckily the road was deserted and I didn't kill my self and my two passengers.
That started me hunting for the problem.
The problem is bump steer. Start with a tape measure hooked in one tread , pull it tight and measure to a tread on the other tire. Try to measure up as high as possible. Jack the car 1 inch, measure agian, 2 inches , 3 inches and you will see the front tires toeing in a couple of inches.
You can't compress the suspension but if you could the car toes out.
This combinations of input from the car with no input from you is what is called bump steer and you have to eliminate it. The grand national stockers can not have .050 maximum or they will be in the wall. We have INCHES.
I checked a new mustang and it had 3/4 inch toe in at 3 inches rise.
The best thing to help bump steer is dropping the outer tie rod about 3/4 inch just to start. This can be done with a 5/8th bolt, a 5/8th heim joint and a drill to open up the steering arm and of course washers of shims to set a lower outer tie rod.
When Mike tested my car this summer we flew over the same bridge, I never warned him about it nor mentioned that we were about to hit a bad section, he was comming down a hill passing a car and flying and we went over that same spot where a few years ago I almost crashed and I watch the wheel and nothing. He never moved his hands to correct anything, the car other then moving up and down stayed true. I never told him about that spot nor mentioned it afterwards but that is my test spot to check how the car reacts under harsh conditons.
I run soft springs so the wheels can follow the road, not bounce over it and at times I hear the 3 inch pipes lightly kiss the road as the suspension compresses but the ride is very good, the car is stable and I am not pounding the suspension.
If I was starting from scratch on another C3 I would lower the outer tie rod 3/4 inch, increase the length of the tie rods themselves to about 14 inch sleeves and weld new inner mounts on the drag link, on the top. I would run 280 pound springs , mill the upper A arm cross shafts about 3/8th inch for 5 degrees positive caster without a ton of shims and set camber at -.75.
Of course the steering box and all components must be is perfect shape, that includes the rag joint.
Good luck

 

Norval,

Do you have any plans of addressing the toe steer (rear) in the future? I know you are quite aware of the toe changes in the rear and that they case a rear steering that ives a total oversteering to the car, making it hard to control when you are really pushing the suspension into bump or jouce (like your bridge incident) ??

Marck