AuthorTopic: front suspension  (Read 426 times)

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Offline sponge

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front suspension
« on: December 01, 2020, 10:09:16 AM »
Has anyone ever tried triangulated four bar on a straight front axle with air bags? Do you think I could keep the axle stable without hair pins ,radius rods, etc. Also thinking about mounting rack and pinion to axle. Am I way out of the box? any and all input would be appreciated!!!!

Offline Blackwater

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Re: front suspension
« Reply #1 on: December 02, 2020, 09:25:25 AM »
I see no reason that a triangulated four link wouldn't work, provided the geometric and mounting point requirements are met.  The old Ford "wishbone" suspension is a good example of triangulated suspension!  You should consider a track locator or panhard bar unless your angles can produce a sufficient lateral stabilization effect.

The airbags are just like any other "spring" apparatus.  A coil, a transverse leaf, a torsion bar, quarter elliptical, or regular longitudinal leaf setup do nothing more than hold up the vehicle, (the load).  The spring rate and the location of the spring device in your suspension will determine hight and rebound. The shock absorber controls the speed of the compression and rebound of the spring device.

As to the rack being mounted to the axle.  It can and has been done.  You'll have to allow for changes in position through all three planes of motion at the same time!! As the axle moves when traveling, it moves up and down AND forward and back!!  It also "yaws" when one wheel rises or drops in relationship to the wheel on the opposite side. Add to that the fact that the axle also rotates slightly as the vehicle rises and falls!!  The steering shaft will need to freely and safely telescope and NOT bind when these other motions are transmitted to the shaft. When one side or the other of the axle changes height, it will influence the steering as the rack pivots around the pinion, creating some level of "bump steer"!!  ALL steering systems have some amount of bump steer.  How much is acceptable and safe is the question to be answered!! Keep all these things in mind and remember that you'll have to provide for each of them 'cause it'll directly effect how the car drives!

Hope this helps!!  Ask any questions and show us pics!!  We're all glad to help!!

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Offline sponge

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Re: front suspension
« Reply #2 on: December 02, 2020, 06:24:35 PM »
Thanks Blackwater
I was thinking about all those things and more. It's nice to hear from another source that it can be done.I'll have to start taking pics and try to get them to the site. Sounds like you've bin down this road before.
Thanks again!!

Offline Blackwater

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Re: front suspension
« Reply #3 on: December 03, 2020, 08:39:40 AM »
Haven't tried it myself!!  I doubt that I would.  I've done many steering set ups for high speed and quick handling vehicles.  Seems to me that keeping it simple and solid is the best and usually easiest way to go.  REMEMBER!! If it can screw up, it probably will!!

Rack and pinion steering systems were developed to SIMPLIFY the steering process!!  UNLESS the axle is going to move a really long way, you're much better off mounting the rack to the frame. Allowing the tie rods to do all of the moving in the steering and suspension travel is just way more simple.  SIMPLE IS GOOD!!  EVERY extra piece that you put into a mechanism to make it work doubles the possibility and likelihood  that something will malfunction!!

If you're building something for extreme off road, I'd recommend using a steering box and a lateral or "cross link/drag link" steering setup!!

There's a steering and suspension page in the forum that folks look at and chime in on.  We should probably take this down there where more of us are likely add input.
« Last Edit: December 03, 2020, 08:43:31 AM by Blackwater »
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Offline sponge

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Re: front suspension
« Reply #4 on: December 19, 2020, 10:33:17 AM »
I want the frame on the ground when parked. It will have a ride hight of 5"-6" that's why I was mounting the rack on the axle. I'm still up in the air on 4 bar/panhard or triangulated. I want as much of this hidden by a grill/shroud/etc. I would love to make it work but if not I can go back to regular stuff. I want it safe !

Offline McLovin

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Re: front suspension
« Reply #5 on: December 19, 2020, 03:52:47 PM »
Laying it on the ground would have to do with the kick up's on the frame. I haven't done a front end on a build yet. I "cheated" by using a Ford Ranger frame on my build. I did do airbags. I , 2 linked my rear end but used a Watts set up on it. Not sure if it would be too easy to do it on the frontend , but I'm sure it could be done. About the photo posting I found mine were to big so I have to reduce them just slightly

Offline Blackwater

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Re: front suspension
« Reply #6 on: December 19, 2020, 10:48:56 PM »
I think I'd still mount the rack on the frame and have it set up so the the tie rods ran level when the car was raised to ride height.  You're getting into a lot of extra moving parts to make this work.

 Otherwise, you'd be better off to run a steering box mounted on the frame near the firewall and use a drag link running longitudinally next to the frame. Then the change from parked height to ride height would not create bump steer or alignment issues and there would be a MUCH simpler layout for the linkage.
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