Scott78

Since I have to rebuild the front end due to an a-arm bushing thats gone missing. I was looking at getting the heavy duty tie rods to replace the split ones with clamps that are original. From Vette brakes you can get either just the tubes with jam nuts or the anti bump steer kit that has those and some blocks. What do the blocks due and where do they mount? Would getting the kit over just the tie rods be overkill or is there some good that comes from installing the kit? Thanks for any information.
Scott

Brutus

Scott...Here's what Guldstrand has to say about their kits. I have the blocks only on order.
This kit was developed to remove most of the bump steer designed into the front end geometry on all 1963-1982 Corvette's. The kit eliminates all but just a few thousands of toe change generated through normal suspension travel. Helps stabilize the car and maximize the tire foot print. A more simpler way to understand how this kit works is: imagine driving down a road, and you run over a pot hole or a bump or a dip in the road, inherently your Corvette will want to shoot off in one direction or another... This kit is the cure for that problem.

Scott78

ok makes sense,not to much in cost so I'll probably get the kit. But where do the blocks mount? Some drilling required? not a bg deal just wondering the install procedure. Thanks Brutus
Scott

ddecart

Scott,
Where that kit mounts is to your steer arm on the steering knuckle. You have two holes in the steer arm that allow your ateer ratio to be adjusted to "fast" or "slow". The two bolts you see in the photo above mount into those two holes.

What the kit essentially does is reloacte the outer point of the tie rod. Tis changed the orientation and length of the tie rod, affecting it's position during wheel travel. I'm not sure if this kit moves the outer tie rod end up or down at all, and I haven't seen any data with and without the kit to give you any educated info on specifically what it does to the ride steer curves. If and when I think of it I'll try to dig for some old test data to see what kind of shape these cars are in to start with.

Dave

Scott78

Thanks Dave,
That explains alot. I'll order it after x-mas. Might as well do everything once while I've got it all torn down.
Scott

ddecart

Scott. Here are a few pics I put together a year or so ago to give a SIMPLE explanation of bump steer and what's going on.

This plot shows a suspension without bump steer. Very simplified, it's a parallel, equal length suspension, but it shows what the basic relationship between the suspension arms and the tir rod/steer arm is for no bump steer.



This one shows the basic mechanism for bump steer. Again simplified with parallel/equal arms. As the suspension goes into jounce, the tie rod is pivoting about a different center and it "shortens" faster than the suspension arms do. So when you go into jounce, it "pulls in" and causes the wheel to steer (in this particular example, steering out is possible, too).



This is what might be a typical bump steer curve. The vehicle's suspension is designed around the point shown, so that small suspension changes up/down don't change the toe very much.

When you lower the car, you change your position on that curve, and you probably move to a spot where the curve is more aggressive (smaller bumps cause more steer). There are basically two things that can happen by altering the suspension/steering linkage. You can either flatten this entire curve, makingit more vertical and less sensitive to suspension travel, or you can relocate the components to bring your 'lowered' suspension closer to the ideal zero point.

I have no idea exactly what the bump steer kit is designed to accomplish.



Hope this helps.
Dave

Scott78

Thanks Dave for going thru the trouble of drawing out the geometry.
It does seem to make sense to keep the geometry of the tie rod on the same plane. If it does keep the front end from "jumping" as you hit bumps then it well worth it.
Have a Merry Christmas and New Years. I just arrived in Dallas after skating thru southern Minnesota and Northern Iowa. Too bad the weather was to bad to consider driving the vette here. Weather here is perfect.
Scott