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  • Bob Andrews
    replied
    Your points are well taken, Gord. As you say, bump steer is of little concern at very low speed or in turns; the key area is reaction to bumps at speeds above, say, 15 MPH. For most street applications that's really the entire focus.

    For those unfamiliar, here is a good primer on bump steer:

    http://www.longacreracing.com/articles/art.asp?ARTID=13

    The general standard is .010-inch of bump per inch of vertical travel. That sounds like a lot, but it can be a challenge to get on a race car with much more adjustability than a street car. As the above article says: In order to accomplish zero bump the tie rod must fall between an imaginary line that runs from the upper ball joint through the lower ball joint and an imaginary line that runs through the upper a-arm pivot and the lower control arm pivot. In addition, the centerline of the tie rod must intersect with the instant center created by the upper a-arm and the lower control arm. This is where the problem with rack widths on Stude frames comes in.

    Another area I had forgotten about it turning radius. There have been problems stated with finding a rack that will allow enough room to fully turn the wheels. This is another challenge that needs to be considered. Check the below threads for more in these areas:

    http://forum.studebakerdriversclub.c...ht=rack+pinion

    Be sure to reread what Jack wrote in this thread, particularly post #25:

    http://forum.studebakerdriversclub.c...ht=rack+pinion

    Gord, pictures of the successful installs would be great. But the ultimate would be if you could get a chance to test drive it yourself, over uneven and bumpy roads, and give us your first-hand, unbiased impressions.

    I think few people really understand how tricky and complicated a prospect it is to produce a decent, quality suspension that does everything we want and need- caster, camber, toe, ackerman, ride height, and bump steer all have to not only meet their own spec for the given application, but that spec has to be compatible with all the other specs. With a race car you add roll steer, roll center, center of gravity, rear steer, brake bias, stagger, wheel offset, air pressure; and you get a feel for why it's so important to know you're really understanding all aspects and getting them all right. On a race track it means the difference between winning and losing. On the road it means comfort, but most of all- safety.

    Here's hoping truly proven solutions are forthcoming.

    Leave a comment:


  • gordr
    replied
    Yeah, I think so. Both intances I know of personally were the work of one guy, and he does fine work.

    You look at the books, and they will tell you that you will get bump steer whenever the length of the tie rod section between the chassis end and the steering rod is unequal to the effective length of the lower control arm. If you think about, you can really only have zero bump steer at straight ahead. Cramp the wheels over, and the effective length of the lower control arm changes. The steering arm is attached to the knuckle, and the knuckle moves more or less vertically along a line tangent to the arc described by the lower control arm, as the suspension moves through its range. When the wheels are turned, the end of the steering arm on the inside wheel moves closer to the pivot axis of the lower control arm, and the opposite occurs on the outside wheel.

    I think what you want to have is minimal bump steer at straight ahead and for gentle maneuvers, like lane changes, and allow to become progressively worse toward full lock, like in parking maneuvers, which are usually done slow enough tha bump steer doesn't present a problem. Center-pivot steering, as used by Studebaker and other makes, was a way of doing that by making the tie rods so long that the length ratio between tie rod and axis-length of the steering arm point didn't change much at moderate steering angles. Going to a center take-off steering rack would pretty much mimic that geometry for small steering angles. I could see that changing as you approach full lock, but aside from autocrossers, how many of us steer to full lock at any sort of speed where bump steer could be troublesome? As far as I can see, if bump steer is effectively zero going straight ahead, and nearly so so for gentle maneuvers like lane changing, you are fine. For a little tighter turn like going up a freeway on-ramp, zero bump-steer would be nice, but you can tolerate a little, because you are actiely involved in steering at this point, and paying a lot more attention. On the straight-away, you don't want to have to contantly make steering corrections.

    I will make an effort to learn a little more about the cars I mentioned above. Maybe I can talk one of the guys into cruising his car down to my place so we can put it on the hoist and take some pictures.

    Leave a comment:


  • sweetolbob
    replied
    Originally posted by gordr View Post
    Brian, PM me or e-mail me, and I will point you to a couple of folks here in Canada who have C/Ks with center-take off steering racks installed.

    I don't want to put peoples' names out here in public without their permission.
    Gord

    I'm just a lurker on these discussion but are these the same setup as Jerry's which I believe is also a center take-off rack? With your help and Brian's fabrication based on Jerry's experience, we may be getting close. Thanks guys.

    Good fabricating Brian, I'm following with great interest.

    Bob

    Leave a comment:


  • Jerry Forrester
    replied
    Originally posted by David View Post
    ^ +1.
    You people have no adventurous side to you. There's nothing more exciting than traveling down the interstate at 80 plus MPH and think about changing lanes and then realize that you just did by just thinking about it. .

    Leave a comment:


  • David
    replied
    Originally posted by Bob Andrews View Post
    Gord-
    I'm looking to build a car that I can drive well into the future, even if my RA progresses; and that means power steering. We need something better than the stock system, but don't want to create a whole new set of problems- and spend a lot of money and time doing it. That's how I got started on the Borgenson conversion deal. I'm not looking to build a road course racer, just make it easier to steer. I'm betting there's a lot of us non-teens who are thinking the same way.
    ^ +1.

    Leave a comment:


  • Bob Andrews
    replied
    Originally posted by gordr View Post
    a couple of folks here in Canada who have C/Ks with center-take off steering racks installed.
    Gord- are these on otherwise stock Studebaker clips? Can you tell us how they have worked out in actual use?

    And, any chance you could persuade them to post their experiences here? As I said, I'd like to conclusively determine how well this works, and if it truly does, how it was done? It would truly be a great service to the Studebaker world.

    I'm looking to build a car that I can drive well into the future, even if my RA progresses; and that means power steering. We need something better than the stock system, but don't want to create a whole new set of problems- and spend a lot of money and time doing it. That's how I got started on the Borgeson conversion deal. I'm not looking to build a roade course racer, just make it easier to steer. I'm betting there's a lot of us non-teens who are thinking the same way.

    Leave a comment:


  • gordr
    replied
    Brian, PM me or e-mail me, and I will point you to a couple of folks here in Canada who have C/Ks with center-take off steering racks installed.

    I don't want to put peoples' names out here in public without their permission.

    Leave a comment:


  • woodysrods
    replied
    Thanks Junior
    I was hoping that someone was excited about having done this with success already.
    I didn't think I was the first??? And I definitely do not have the steering geometry knowledge either.
    Brian

    Leave a comment:


  • junior
    replied
    Hey Brian, good luck with the r & p installation. FWIW, consider taking lots of detailed shots, and keep your measurements, and maybe even make templates of your mounts....there will be a line of people waiting to copy your work if you are successful, and I truly hope you are. I have to agree Bob Andrews that there has been so much discussion about such a swap, but to my knowledge no one has yet stepped up to the plate and proclaimed that they indeed have done a swap that exhibits no negative side effects...to date a lot of folks just throwin' around theory, or folks who have designed and installed, but have not done real world testing. I have been thinking about this swap for a number of years now, but am not prepared to fab a system myself because I don't believe my knowledge of steering geometry is at a level required to do the job correctly...but rest assured if you or anyone else nails the solution, I be one of the first to copy your design. Once again, I hope you find the solution. Keep us posted. Regards, Junior. oh ps, read your shawmail, I sent you a message the other day.

    Leave a comment:


  • woodysrods
    replied
    Thanks Rich
    I already knew what pertronixs were. Just thought you were selling them?/
    Brian

    Leave a comment:


  • Bob Andrews
    replied
    Originally posted by Jerry Forrester View Post
    Everybody is talking about 'bump steer'. I want to know who, besides me, has removed the springs and shocks from a stock Stude front suspension and checked the bump steer on a stock Stude. I think you'll be surprised with what you find and will not dis modified steering systems again because you think you heard someone say at some time, someone somewhere had bump steer in their system.
    Jerry-

    I have not done so. Before I seriously entertained the idea I naturally started to research it. To date I have only heard of two Studebakers that have actually completed and driven a R&P conversion with a Studebaker rear-steer setup. Both had bump-steer issues that could not be resolved. Both reported darty, unpredictable steering that made driving the car a constant white-knuckle experience. Both resolved it by tearing apart their fresh builds and converting to an aftermarket clip, like Fatman.

    I did not save the info on who they were; at least one and maybe both were discussed here on the Forum. Looking back I wish I had saved their information. At the time I was taking them with a grain of salt, thinking inexperience might have been the culprit. I kept them in mind and continued my research.

    As I look at the Stude suspension and visualize a R&P I haven't found one that looks possible to the naked eye. The problem is finding a rack with narrow enough take-off points; that is, the right tie-rod length. Yours looks great, and I have looked at it many times, but in the pictures I can't visualize the pivot point alignments; which of course is the key. The proof of the pudding is how it actually works on the road- and AFAIK you still have not tried it, correct?

    I don't yet have a dog in this hunt. My ultimate project is in the planning stages. Personally I'm rooting for a R&P to be the whole, correct solution. I don't want the stock Stude P/S system, and I don't want to do a clip. Thus far I have not seen one proven successful Stude R&P system. Ultimately that's what got me started on the Borgeson steering box conversion. That's a ways off, which is no problem for me; maybe in the meantime someone will take the risk on R&P and get one on the road, and prove out the solution. Until then, in my judgement I have not seen any encouraging results. Until somebody has proven it out in long-term use, I am not willing to roll those dice.

    I appreciate that you have checked bump steer on yours. But the real, final test will be when the car is assembled and running, and you get some miles on it. Make me a believer, I'll jump on the bandwagon with both feet! Until then, that cost and effort will be withheld.

    Leave a comment:


  • StudeRich
    replied
    Originally posted by woodysrods View Post
    Hi Rich
    Did you read my question to you re pertonixs for Sandi's Hawk?
    Brian
    Only if you PM'd me, I don't do emails (private conversations) on the Forum Posts, and I did not see it.

    UPDATE: I found this, see post #5, it could be your answer:

    http://forum.studebakerdriversclub.c...490#post579490
    Last edited by StudeRich; 09-28-2011, 04:55 PM.

    Leave a comment:


  • Jerry Forrester
    replied
    Originally posted by Bob Andrews View Post
    Everything I've seen seems to point to bump steer.
    Everybody is talking about 'bump steer'. I want to know who, besides me, has removed the springs and shocks from a stock Stude front suspension and checked the bump steer on a stock Stude. I think you'll be surprised with what you find and will not dis modified steering systems again because you think you heard someone say at some time, someone somewhere had bump steer in their system.

    Looking forward to your findings!
    Ditto

    Leave a comment:


  • Jerry Forrester
    replied
    Brian, once upon a time, a long, long time ago, you asked my why the driver's side tie rod ends are bent. Since you are this close to needing that information the answer is
    Last edited by Jerry Forrester; 09-28-2011, 06:42 PM.

    Leave a comment:


  • Jerry Forrester
    replied
    No, poor ole Leo hasn't been touched except for a wipe down in over a year.
    Yes, in my opinion, maybe, I think so. I think with the 2 to 1 reducer you wont even need power assist. I suppose without a power steering pump you may still need a fluid reservoir and hoses for lubricant for the R&P.

    Leave a comment:

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