Gasser HotRod Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
2,322 Posts
Discussion Starter · #1 ·
I've yet to finalize my front axle steering configuaration. I have the solid rear spring shackle set up. I still have the drag link '57 truck steering arm. Instead of a parallel cross steer, what are the pros and cons of the drag link or is it possibly dangerous? Mark L
 

·
Registered
Joined
·
374 Posts
Your setting yourself up for a LOT of bumpsteer due to the very short distance from the pitman arm to the steering arm on the spindle. With a raised front end, this creates a bad angle for the draglink to run at. It also limits you on steering box choices.
 

·
Administrator
Joined
·
13,197 Posts
I'd sure consider changing to cross steer. I'd also determine ride height prior to mounting the box and steering arm so you can try to keep them as close to level as possible. The steering box and steering in general gave me more headaches than any other part of my build. Mine worked out well, and steers beautifully, so it was worth the extra effort to me.
 

·
Registered
Joined
·
5 Posts
I went with a rear mounted manual Chrysler rack and pinion on my straight front axle. It's mounted on the axle and uses a Double D shaft for extension and compression as the front end moves up and down. Since I'm using a stout Chevy Van I-Beam axle, it is hidden fairly well behind. There is absolutely no "bump" steer at all. I have some extra caster added in with shims under the leafs, but this is a drag race car only. It is a little hard to turn, with a spool in the rear which complicates corners. I think without the extra caster and a differential rear end, it would corner nicely. Make sure that the Double D shaft can slide in and out without binding. Also, very important, the shaft can't bottom out with full compression, not to mention the importance of the shaft staying engaged when the front is in full lift. I limit my axle drop with safety chain between the frame and axle.
 

·
Registered
Joined
·
2,322 Posts
Discussion Starter · #5 ·
I almost went with a rack mounted on the beam as well. But It could be seen and I didn't like the looks of it. I'll probably end up with a cross sterring set up. Do the early GM trucks (49-59) have a problem with bump steer using the draglink type steering on this axle? Never heard of any complaints? But I never looked for those complaints before either. Mark L
 

·
Registered
Joined
·
374 Posts
Mark, even at stock height the early trucks have some bump steer, although very minimal. The problem really occurs when you raise or lower the axle in relation to the frame, causing a severe angle of the draglink from the pitman to the spindle. This holds true especially under a nose high car. You can remedy the issue with a z'd draglink, but this is a band-aid and does not eliminate the problem. You can get a second oppinion on this from any knowledgable 4x4 guy, as this is the same scenario as a solid axle
Chevy 4x4. Chevy's steered that way till '88 when they switched to independant front suspension.
 

·
Registered
Joined
·
2,322 Posts
Discussion Starter · #7 ·
Yea I noticed drag link on the GM trucks well into the later models. Always wondered how they performed. I just figured they were fine since GM stuck with it for so long. I would imagine that if I were to place the steering box lower (since it is a custom installation), so the drag link were more horizontal, it would work with less bump steer? As long as it was not too low or in the way of the suspension. You know. I built a wooden cart once s a kid and I just wrapped two opposing ropes around the end of the steering shaft and ran them to the spindles. Worked great then, I outer try dat now hey?? Wonder how If hook up a steering shock????---hummm---. Mark L ;^)
 

·
Administrator
Joined
·
13,197 Posts
I think that's the key Mark, and if you can get the steering box lower it will drastically help in eliminating or reducing bump steer. But one issue with that style of steering is the steering arm raises and lowers as it pushes the arm forward and back. So if the wheels are turned hard left or right and you hit a bump it will slightly increse bump steer as the angle changes.
With cross steer the steering arm stays on the same plane as it turns from lock to lock, so whatever bump steer it might have is not changed at any point of turning. If you can drop your box enough to get the arm perfectly level with the wheel centered, then it wont be barely noticeable.
I have cross steer, and I dropped the mounting plate on my Corvair box so that my steering arm is slightly higher than the other end of my drag link, so that as I hit a bump it levels out. I can't feel any bump steer at all with my setup.
 

·
Registered
Joined
·
29 Posts
One thing to keep in mind is that its impossible to eliminate all bumpsteer on a straight axle. Since caster and camber are fixed by your leaf springs in a parallel setup it is one of the easiest setuos for guys at home to make work correctly. I would not reccomend a rack mounted on the axle under any circumstance if it is to be a street vehicle, any type of accident and you are looking at being impaled by the steering column. Not to mention if it binds at any time the wheel will move in and out with the suspension movement. I have seen it done before, and it technically works but it is a potential problem. The key to making your cross steer setup work is: keep the the drag link as long as possible, as level as possible (it should remain slightly higher at the pitman arm end, than at the steering arm end) and try to mount the (typically Vega) box so the pitman arm is as close to level as possible---I try to keep them within 15 degrees or so. Dropped pitman arms are available to help with clearance and if you double taper the steering arms you can get a good variety of setups by possibly putting the tie rod on top of the steering arm and under the pitman arm to help getting it level.
 

·
Registered
Joined
·
2,322 Posts
Discussion Starter · #10 ·
All good thoughts guys. I'll probably go cross steering. I have a good situation in that my front end is so wide that I should end up with a really long cross shaft. That will help the whole situation. My axle is 53 1/2 inches at the king pins now and if I can find someone to make me a straight axle that will use all of my 55-59 chevy king pins and spindles but at another 4 inches wider it will come put even longer. So that is good having a big car for a gasser. Now--talking alot of weight ain't, heh! It otter ride nice tho. Mark L
 

·
Registered
Joined
·
29 Posts
I do straight axles all the time, generally I use the early ford spindles as they make life much easier (read MUCH) when trying to configure brakes, steering arms and easy to find parts. I know everyone is on a budget now a days but its kind of like trying to fix an antique hammer....if you replace the handle, then you have to replace the head is it really worth the effort? If I could see pics of the spindles I may be able to help, but I still think going with the new stuff is better than trying to save a few bucks on 55 yr old spindles. If the steering arm geometry is wrong from the start you will have problems all down the road, no pun intended. Send some pics, maybe I can help a bit.
 

·
Registered
Joined
·
198 Posts
I don`t know ,I`m using a drag link with an early Mustang steering box. And it steers great ,plus the drag link is only 12" long . It`s gone as fast as 110mph so far and no bump steer. But I`ve have used a Vega and cross steer on my Austin. But that is for header clearance. We have several guys I race with that uses both kinds of steering with no complaints. Gasserman
 

·
Administrator
Joined
·
13,197 Posts
Mark, you might check Speedway, as I think one of their axle will accept Chevy spindles. I know from a few Chevy 55-59 truck axles I've used for gassers that the 49-54 5 bolt drums fit perfectly. I got the Speedway axle that uses Mustang spindles and GM disc brakes. It's really clean and nice.
 

·
Registered
Joined
·
29 Posts
Axle

Speedway does have an axle that uses the earlier pass car spindles, I believe Mark has later model spindles. I'm not here to argue with anyone, in fact I like the different ideas, not a day goes by where I can't learn something new--although like the old Simpsons cartoon when Homer points to his head----something old has to leave to make room for something new LOL. But try finding a nice (reasonable priced, non custom) set of wheels with a 5 on 5 pattern and you will start seeing why I like to keep things simple. No matter what plan the whole thing out on paper and see where the costs are and time involved and build something you like. We all have opinons but it's your car.
 

·
Registered
Joined
·
2,322 Posts
Discussion Starter · #15 · (Edited)
I've had one of my thougthts (look out) about cross steering. It's probably over the top but. Instead of the single cross steering shaft from box to opposite side steering arm and the bump steer it invokes if there's too much angle. I thought of incorporating in an idler arm on the opposite side frame then another steering shaft back from the idler to the same side steering arm. What this does is allows you to have a steeper initial/primary steering shaft that does not move vertically, influencing bump steer. And places the idler down closer to the same level as the axle for minimun to zero bump steer. One additional shaft and an idler so still not complicated. Allows additional adjustments to get the steering good and straight as well. Tell me what you think? Mark L
 

·
Registered
Joined
·
374 Posts
Mark, it sounds like you're trying to re-invent the wheel here. Looking at your avatar pic, your car doesn't appear to be xtremely high in the front. Therefore, try locating your steering box as low as possible in the frame, run a single draglink bar to the top of the passenger spindle, and you should be fairly close to level with your link. With the link as close to parallel with the axle as possible, you'll have little to no bumpsteer as the suspension moves. You're not gonna completely eliminate it. It's just the nature of the beast. Keep it simple. Less is more.
 

·
Administrator
Joined
·
13,197 Posts
I think I'm sitting a fair amount higher than your Pontiac Mark, and I have zero bump steer. I dropped my Corvair box lower than the frame and welded the mounting plate below the frame, with braces and gussets to reinforce it to the bottom of the frame. My steering arm is slightly elevated about the attachment point to the axle, and gets level when I hit a bump, so no issues at all.
 

·
Registered
Joined
·
2,322 Posts
Discussion Starter · #18 ·
You guys are right. I'm over thinking things again. But I like to engineer things when I'm not actually chopping the car up, heh. Mark L
 
1 - 18 of 18 Posts
Top