steering

[Francis Blake]

Speedway has a similar setup on page60 of cat#260.

 

[T4TWO]

Ok... I have played with racks on drop axle cars several times. And here is what I have learned. First, they do work, and work fine. The first T I built, had a rack mounted to the chassis, and it did not have any bump steer. Everyone said it wouldn't work, couldn't work... Well after completing it, and seeing how well it did work, I went looking for answers. Answers as to how I got it right, when everyone else got it so wrong. And the guy I turned to was a friend of a friend, that happened to be an engineer at visteon (visteon is, or at least was at the time, a tier one oem supplier). But not just any ol' engineer. An engineer in the steering department. He had 7 us patents on steering gear design and had written sae tech papers. He was a for real steering expert. So I sent him photos and asked lots of questions, and what I got back was interesting... at least to me . The first thing he shot down was the theory that the axle moves straight up and down, and the rack ends move in an arc, causing toe change and bump steer. While that is true, in reality, you are not going to have both front wheels hit the same bump, at the same time, to make the axle go straight up. In the real world, you are more likely to have one wheel hit a bump, or drop in a pot hole. In which case, the axle moves up and down in an arc, because it pivots on the spring that is center mounted. Where people are having problems with the frame mounted rack, and the transverse spring, is the spring shackles. As the rack pulls on one side, and pushes on the other, the shackles and the spring deflect, shifting the whole front axle. A simple panhard bar is the answer there. I never had this problem, as the car I built had a torsion bar front end. The 3/8" thick chrome moly arms held the axle in place. In wasn't until later that I discovered this.

The next thing I found interesting, is that there is no set number of toe change, that will cause bumpsteer. You can't say " if you get over 3/32 of toe change it will bumpsteer". Right from someone that designs the parts in the cars we drive... He said they have no firm numbers. It depends on many variables. With all the sophisticated computers, and programing, and all the education, blah, blah.... At the end, they make thier best guess, and build it, and drive it. I was also told that rack placement can be very critical. Sometimes moving the rack as little as 1/8" can make a big difference. This is where I think the swap isn't for everyone. If you do not want to take the time to make sure it is 100% the best it can be, move on to something simpler.

The next time I did a rack on a straight axle, I mounted it to the axle. This I did NOT like. This was on a Model A with air ride. Because of the large amount of suspension movement, mounting the rack on the frame would not work. So on the axle it went. The thing I didn't like about it was that The steering shaft has to move as the axle goes up and down. Everyone I spoke with suggested a slip joint. I did not like that because it introduced play. It can't be set up tight, or it won't slide freely. And I was afraid if it didn't slide freely, that it would bind the steering or possibly causing bump steer. The other option was to put in a u-joint and have it pivot to match the suspension. This might be OK on a car with headers out side the frame, like a T, but on a model a with a full hood, not so easy to do. I can't find a picture of this set up. I found the air ride pics, but none showing the rack.

And the last one... I didn't do much on this, outside of maching a few parts and a little tig welding. My father did all the fitting etc on this (it's his latest car). It is a rack mounted thru the frame, and only one side is used to push the drag link. Works pretty good. He's got one cruise season on it, and is happy.

You may be wondering why all the work with the racks ? Well 2 reasons, one... they have better leverage ratio's than the typically used boxes. Which means easy steering. All the ones I've done have steered very nice. As close to power steering as you will get without the pump and all the hoses. And two, they are cheap, light, and compact. We have been using geo metro racks. They are $40 at my local pick n pull.
Is it for everyone, NO. If you are not willing to put in the time to make sure it is installed properly, and willing to do some testing, I would walk away. And it is not a simple install, machining, fabricating, and welding (sometimes on delicate parts) are all part of the deal. But, If you are willing to do the work, and it can be some work. You can end up with a nice system. My father wouldn't own a T without one. Me? My car has a vega box :razz:

LKE, Thats some nice custom fab work there. I copied the pix's that you posted so I can study them at a later time. Lots of ideas here on the forum! :welxome:

 

[der Spieler]

I kind of like this idea. It's ironic that Whitney sells it for $392, they claim down from $545, and you can buy it direct from Unisteer for $385 and Speedway sells it for even less. Makes me wonder even more about J C Whitney

Unisteer would be the way to go with a rack and pinion.

Sets up like a cross steer on Vega box mounts
Unisteer Performance Products Cross Steer Rack and Pinion : JC Whitney: Auto Parts & Accessories

 

[Youngster]

LKE, that was awesome! great write up, super pics! anyone who studies then is going to learn many, many things.

let me say the r&p set up is a good one. looks good set up properly and functions well too. now in the real world, we aren't all expert fabricators. the words that are used most buy new members are simple, lo buck and small budget. for those people i would say, there are tried and proven systems out there that will function well and are much simpler to set up. especially for those of you that are beginers here, keep it simple and functional. you can always step up to more exotic stuff on the next build.

this is not, i repeat, not to belittle the offerings in this thread. there is so much wisdom here for all to absorb, and thanks to those who took the time to post it. JMHO!

Ron

 

[der Spieler]

I agree with Ron. It is easy to overload your a$$ sometimes trying to tackle a project that in hindsight you should have realized was beyond your skills. I'm speaking from experience here and I've learned some valuable lessons. The Unisteer rack, however, looks pretty straight forward. Most kits can be had with Vega steering box mounts as an option so it should, in theory, be a bolt on. Having never done this I'm speculating. I did look at the photos at Unisteer's web site and they show the rack mounted much closer to the front crossmember than it is mounted on T-bucket chassis for the conventional box. I don't know if this is because the rack shown is on a deuce chassis and the normal T-bucket mounting position would work or if it is mounted forward because the rack needs a more forward mount to relieve stress on the rack. Maybe RPM can answer that one. I want to use this rack on my build. The price is comparable with the Vega box and I like doing things that are different from the norm.



It dawned me after I posted this that the rack has to either be mounted forward or the standard mount has to be placed at an angle for the rack to work without putting it in a bind. Sometimes thinking things through helps things become more clear.

 

[EX JUNK]

I installed a Vega box in my build. I have had absolutely NO problems in almost 10K miles. There has been NO bump steer what so ever. Another thing that I like with my installation is the angle of the steering column and wheel. As you can see in the picture, it is at a very good ergonomic angle which makes for very comfortable long cruises.

 

[LKE]

LKE does not post that often but when he does, he speaks volumes. His posts are always VERY informative and to the point. His knowledge comes from designing and building suspensions and vehicles for many years. We are indeed, very fortunate to have him participating on this board.

Thanks for the kind words. I don't post much on any forums any more. I mostly just read the threads, and look at the pictures. I like seeing what other people are doing.

Youngster and der Spieler, I agree with you 100%. Installing a rack is not a mod for a first timer. But is do-able for someone with moderate fab skills, and some patience and common sense. And if some one wants to try it, I think I put out all the info I could. And I am always available by email or phone to answer any questions.

I also use the vega boxes. I just am not a fan of the original corvair boxes. I used them for a while, and always thought they were flimsey. That and so many of them, that I bought off ebay, were junk. I was turned on the the vega box, and mounting it under the frame by the guys at Kenny's rod shop many years ago. This was how they built thier track T's. And it has served me well. Attached is a picture of one in the car I am building now. I think it makes for a clean install, hidden under the frame and partially by the lower four bar mount. And being mounted further forward than the covair's typical location, it makes for a better column angle (with makes for a more comfortable steering wheel angle). Also, you can get a new vega box for less than buying a rebuilt, and reversed corvair box.

 

[Wild Mango]

What a great reading thread. What its all about for me. I only ever built cross steer, two basic rules;
1/ The longer the drag link the better.
2/ At ride height, the tie rod and drag link should be paralell in both planes, or at very least the horizontal plane as most important.

Down here we don't have many straight freeway type roads. So as well as bump steer we can be stricken by roll steer, which can feel like loose or push and has the same effect of having to make wheel corrections all the time.
This spoils the cruzin' image of rumbling along, devil-may-care grin, one hand casually on the wheel and the other affectionately clutching a brew or your sweeties knee.

 

[Keeper]

Ex Junk - would you have any more pics of the mounts of your box? That looks like an excellent setup.

 

[EX JUNK]

Keeper, I hope that these pictures will help you.

 

[Keeper]

yup they will, thanks. That is a pretty nice looking setup.

 

[oldtman]

The first rack I saw on a t bucket was about 40 years ago. the column was mounted almost straight up and only one side of the rack was used to push pull like you do with a corvair box. to a steering arm on the spindle.