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Thank you all for the education regarding the proper setup and ways of for ways of dealing with "Bump Steer". Thanks to your explanations and pictures I know have a better idea "What" Bump Steer is and "how it" affects the Corvette. This is the kind of material I love reading as I feel I have learned something and it answers a nagging question regarding Bump Steerr. I really appreciate being able to just read and learn from people who have the ability to explain it well, again, Thank You.
That parts from Van Steel are sometimes a bit more expensive but having the ability to speak with a warm blooded person who has an awesome knowledge regarding Corvette Suspension? I have purchased a lot of parts from Van Steel starting back in the 1990's and I have been nothing but happy with their staff support or their Quality of their Parts. The Support alone makes it worth buying from them. On my 1968 C3 and 1988 C4 Corvettes I replaced the ALL the bushings and many of the rear suspension parts from Van Steel. Every question I had was answered and they helped me along the way even when I was a "Newbie" and had a lot of silly questions and a pair of dry Rear wheel bearings/Trailing Arms.
GREAT DISCUSSION - I have been working through most ALL of the handling issues in this link.
Regarding the obsolete Vette-Brakes “BUMP-STEER KIT” shown in Jason Staley post #35.
Photos in this link show both Jason & Ignaz have the bump-steer blocks installed.
These blocks require shorter steering tie-rod tubes. The STOCK tie-rod tubes are Approx. 10-1/2”.
Requesting “Ignaz or Jason” to measure /verify their shorter tie-rod length, I’m guessing Approx 9” ?
Again Thanks to everyone adding to this discussion.
GREAT DISCUSSION - I have been working through most ALL of the handling issues in this link.
Regarding the obsolete Vette-Brakes “BUMP-STEER KIT” shown in Jason Staley post #35.
Photos in this link show both Jason & Ignaz have the bump-steer blocks installed.
These blocks require shorter steering tie-rod tubes. The STOCK tie-rod tubes are Approx. 10-1/2”.
Requesting “Ignaz or Jason” to measure /verify their shorter tie-rod length, I’m guessing Approx 9” ?
Again Thanks to everyone adding to this discussion.
Thanks for the kind words Larry. My markings have disappeared but likely it is the VBP kit. In any event my tie rod on the driver's side measures 9-1/4"
Thanks for keeping the thread alive, and for all of the real-world measurements! My 79's front left suspension is ready to come apart. Gotta order that long upper ball joint...
Been researching ZL-1, so didn't join this one. Bottomline is if you plan to keep all kinds of suspension travel, you shouldn't worry about bump. I run zero toe, eliminate deflection, I run wide tires, so less camber, I run heavy springs 800+ to limit suspension travel about 2 inches jounce and 1 inch over on rebound, I have the SPC arms, longer ball joints, and I connect the tie rod with the Van Steel or Howe type pins, so not a street set up. That is why the Bump Steer blocks are off!
HeLLo ALL - - First Off, THANK YOU Cliff ( Ignatz ) for posting the tie-rod arm length information above.
Next question is directed to Joe ( Bikespace ) If I may please, You stated that You were ordering LONGER length upper ball-joints.
What length and how did You determine the length would work for You? I have in my possession 1/2” longer (middle spec.) guessing this would be a good place to start testing by plotting the movement as shown in Ignatz post ( #4 ) using the TOE Measure TOOL shown in Leigh’s (Leigh1322) post #44. Again, THANK YOU to ALL of the “First-Rate Knowledge” offered on this post from People with backgrounds in Chemistry, Physics and Engineering, proving that the “Corvette Forum” sure is a GREAT Place !
Yes a taller upper ball joint would increase the negative camber gain of the suspension.
Jason Staley runs a 1" upper B/J and I modeled that earlier in the Suspension Analyzer program.
At 1" suspension bump, an initial -0.5 Neg Camber setting changes to as much as 0.2 Pos on a stock corvette.
A 1" BJ along with lowering the car, and 5* caster, you can drop that change to only 0.2 Neg in bump. Barely any camber change, which is a good thing.
There are downsides that I have not explored yet, and will not until I can measure all this directly.
The longer BJ raises the front RCH significantly, changing the balance of the car.
And it "may" likely affect the bump steer as well. But this one I would like to measure.
Actually, it should affect the bump steer, and it may increase the toe-in on bump, which could be a good thing because it could counteract the vettes natural toe-out. And Jason's bump-steer curve was almost Zero or straight up, so maybe this is one of the things that helped that.
Jason's zero-bump curve is the one to emulate!
Last edited by leigh1322; Jan 19, 2024 at 08:33 PM.
How would you measure this? I have most of a new front suspension to put on my 79. As soon as the longer ball joints arrive, I can redo the front left suspension. Is a laser pointer sufficient for tracing the lines? I'm not equipped for carpentry, but I can 3D print something.
If you have no springs in it is easy.
Just measure the camber angle with one of these little digital levels from Amazon. (Magnetic carpenter's level)
Stick it on the hub, it's magnetic.
Move the suspension up & down.
It is interesting to see the way the spindle moves, in & out, camber tilting, caster changes, etc.
Ride height is about 3.0-3.5" below the bump stop.
Or you can get accurate and measure the Z height. 2.5" is OEM.
I even figured out how to stick it on the spindle and measure caster directly.
......
Move the suspension up & down.
It is interesting to see the way the spindle moves, in & out, camber tilting, caster changes, etc.
Agreed. Bikespace - words of encouragement here from me - keep at it, I was reminded by leigh what I wrote years ago
This is kind of neat to play with by hand. The laser is stuck near the lower ball joint pointing straight ahead as it is swept through the range of the arm. Naively you would expect that the trace should describe a small arc on the cardboard box because that is what the control arm is doing. That's not what really happens, as the up and down straight line trace proves. It's doing what it is supposed to. As the tie rod moves with the control arm it steers the spindle as well and the resultant of both motions is zero change in toe.
Not being that mechanically inclined, it looked like magic.
Not much progress this weekend, but I did check to see if I have all the parts.
The Global West LCA's came with lower ball joints, which is nice.Looks like I'm missing one of the two SPC UCAs, so I need to track that down, not that I can do both sides of my car without turning it around...
Last edited by Bikespace; Jan 21, 2024 at 09:39 PM.
If all of the new parts don't work well together on my 79, I may send the Borgeson box out to be modified by Turn One (or, more likely, send them a new one to modify, so I have one to swap).
Both sets of steering arms I have available have the single hole for power steering. They do not have plugs. Has anyone tried to drill a hole for the outer, manual-steering ratio? Do you happen to know what tapered bit I'd need to fit a stock rod end, and an exact dimension on the hole spacing? Two holes seem to be required for any off the shelf bump steer solutions, and would give two ratio options for solutions that simply lengthen the tie rod shaft, like the VanSteel solution.
I ordered the Van Steel bump kit.
I have yet to install and measure, but basically I would expect lowering the end roughly ~1/2" should really help cut out a lot of the bump steer.
Dont be mislead, Bump steer is very noticeable and if everything in your supension is in good order you will notice your car darting left and/or right when it hits a bump.
I have just carried out a bump steer analysis on my C3 and the inner ties rods need to move in about 2-3/8 (60mm) and up about (1 inch 25mm)
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Slideshow: A Jaguar designer's personal project imagines what a modern front-engined Corvette might look like if Chevrolet revisited the golden age of the Stingray.
