Thread: How to guarantee bump steer.

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This was part of an article in "American Rodder" concerning installing "Nostalgic" steering.

I see more and more magazine articles teaching what most of us have always considered bad practice.

yep, that'll do it.

Yeah Jack, there's a lot of that going around. Here's a '29 hiboy I looked at last week that's a project near completion.

Now that hotrodding has gained a new popularity due to television, there are a lot of magazines trying to cash in on the "how to build traditional hotrod" stories. Sadly, a lot of the people who edit these magazines wouldn't know a traditional hotrod if one rolled up behind them and bit them on the ass. As a result of this, anybody who claims to be an "authority" on the subject can get ink in the magazines. I see things like this in magazines, I see absolutely horrible advice given on the internet hotrod websites---things that will affect the ways cars will handle, and even things that if taken seriously by new-wave rodders, will endager their lives.

Okay, I'll buy what you're saying, but would like to learn from these pics, as there is no explanation...... Is the problem that the draglink is not level and 90 degrees to the pittman arm? The reason this would seem wrong to me is that it wouldn't turn as far to the right, but I was unaware that bumpsteer was a problem on straight axles with straight tie rods unless they are cross steered. Obviously R&P bolted to the chassis would also change toe as the suspension worked.

The "ideal" is to have the drag link parallel to the radus rod, and have the rear pivot points as close to the same vertical plain as well so that when the suspension moves they travel in similar arcs. Differences cause a push me - pull me = bumpsteer. Most cross steers avoid this.

Use the oil pan for a skid plate in case of a flat. That pan can't be more than an inch or so off the deck. Besides, it totally spoils the clean lines of a pretty nice rod.

Well guys, if the pics you posted of the new stuff is the right way, I guess I'll just keep doing it wrong.......

Originally Posted by Henry Rifle

Use the oil pan for a skid plate ......

A few years back a guy up here in Olympia Wa. developed oil pan and trans pan w/skid plates with a little style. He called his products Road Surfer. He sold out to Transdapt and they now market under the name Slamguard.

BTW Jack, aren't you glad your grille slants back more in line with the rear cowl and windshield lines?

maybe its time to reconsider

The sad part is these cars are on the road with the rest of us and our children. I don't care how bitchen it looks, if it has nasty tendencies to change lanes on bumby roads or entering my lane because of a flat tire that's bull****! These Mags have a job to do. Selling mags in one thing but , they shoud also be promoting safe rodding. I recall an article about 6 months ago in a rodding mag that was featuring a car that they were calling grouldbreaking. I think the suspension was mounted on top of the chassis. The whole time I was reading the article all I could think about was don't get a flat, cause it would be all over with! My car has no bump steer and passes the scrub check with ease, and it's low. It can be done, I'm no pro builder just an every day guy! Oh yeah it's not a groundbreaking rod, oh well. OK, I'm done.

Keith...

BTW Jack, aren't you glad your grille slants back more in line with the rear cowl and windshield lines?

Bob,

At least Kyle got that right - that's one in a row.

I spent the whole day unbleeping another Gibbon goat rope. I had to completely redo the power windows. It's a little hard to explain, but the carrier that lifts the glass and the window channels were not in line. When the glass got to the top, the center of the carrier was 3/4" outside the channel. The glass was actually bowing somewhat in order to get it to the top - and needless to say, it was in a total bind. The motor sounded like it was going to have a hernia. I had to cut into the wood bracing in the door, chop a piece off of the upper mount of the regulator and re-mount the motor. Kyle had the motor hung from an 8" long piece of 1/8" aluminum, and it flopped around like a beached carp. He also left in a couple of capscrews that are supposed to be taken out so the carrier can float.

Seems to me it's a pretty simple concept that the carrier needs to travel in a the same plane as the window channels. I have no idea why I didn't catch this during mockup - but I didn't.

By the way, the reason I keep posting the Gibbon bleepups is so that anyone searching the forum for the word "Gibbon" finds some interesting information.

Originally Posted by Henry Rifle

At least Kyle got that right - that's one in a row.

Knowing how "fond" you are of the little twerp, you just might be giving him too much credit there.

I suspect Slover had more to do with the design part of it than Kyle, since P&J had a marketing exclusive on the Viper at first..........if I remember correctly.

K.. I'll bite. Looks like a suicide front end, which is the way I want to go with my 36 master sedan. I think I know which part is the drag link, I definietly can identify the pitman arm, but what is the radius rod, what is a cross steer, and how do I visualize the various pivot points?

This is a cross-steer package. The most popular steering box for cross-steer is a Vega or Vega clone. Note that the drag link moves parallel to the front axle, as does the tie rod. It's possible to induce bump steer in a cross-steer chassis if the drag link and front axle are not parallel.

The so-called "radius rod" in this picture is the 4-bar linkage that locates the front axle. In the first photo on this thread, it's the reddish-colored split wishbone.

In a suspension like the first photo, it's important that the drag link and the radius rod be as close to parallel as possible, and as close to the the same length as possible. Those shown are neither.