Sway bar question (NGC)

[rodekyll]

I am trying to install a sway bar.  I was not the one who removed it.  I'm asking about this because I don't want to break something.

This design is probably seen on a lot of IRS front and rear axles.  It's a simple piece of steel round bar tube about 4' along the front that has been bent to make trailing arms at right angles (soft cornered) left and right.  The two trailing ends connect under the A frames and the center section is held by bushed shackles.  When laid on a flat surface one of the trailing pieces is angled about 30º upward.

The problem is that the bar is taking a lot of preload to lever into position.  I started by assembling the semi-floating end mount points with the intention of simply pulling the center part up and slipping the bushing shackles into place.  Easy enough.  But with the two end points fixed, one side of the bar is in position for the shackle and the other side is low.

No problem -- slip the floor jack under it and pump, right?  Wrong.  The chassis leaves the ground while the bar is easily 2" low.  This seems like a LOT of preload.  More than I remember a sway bar should have when the chassis is on level ground.  I haven't done one in 20 years or so, but I don't remember it ever being such a hassle. 

So . . . .  What's up?  Should I have to coax it into place with levers and a cumalong or should it be more 'relaxed' when it's not working?  Thoughts?

[rocker59]

The sway bar is bent, and/or was used on a roundy-round racer! 

[Muzz]

I have seen them RK with the ends out of wind, and have had to jack them in to position.  Never have I seen them lift the chassis as much as you are describing.

[rodekyll]

Admittedly the chassis is bare and doesn't weigh much right now.

Rocker -- you think the bar is tweaked?  Should both ends be on the ground when it's laid flat?

[BMCMOTO]

Normally both ends mount in the same horizontal plane, so while the center of the bar may go allover the place the ends are mounted in the same plane. The mounts to the chassis are usually also in the same plane. I have seen one stabilizer/sway bar that mounted one end above the lower control arm and the other end below the control arm, was not a system that worked well.

Brian

[rocker59]

Yes. Sounds like it is tweaked. The ends  should be on the same plane.

[rodekyll]

Thanks.  :) Now I need to figure out how to jig it and straighten it.   Just when I thought I was done with that level of shyte.  :P

[56Pan]

Did this job a couple months ago. And I agree that the bar is bent.  Shouldn't have to be forced that way.

[charlie b]

Since they are basically big springs you will have a heck of a time trying to bend it back.  If you can, get a different one.

[dsrdave]

Yes, if you want to keep the bar it will need to be replaced.  On most vehicles a sway bar is not required.  If it has a link on each end the vehicle can be driven without it but you may not like the additional body lean.

[rocker59]

It will be a fun job straitening spring steel!

[cruzziguzzi]

Sounds like:

Been in a burnt car
Been in a crunchified car
Come from a wrecking yard from an abused carcass
Been pre-loaded to a task

Find a local blacksmith and donate it to him... damn good steel.

What's the application and what was the source of the bar?

Does this have anything to do with the trike? If so, you can "build-up" a custom sway bar.

Todd.

[Orange Guzzi]

The sway bar is bent, and/or was used on a roundy-round racer! 

I agree with this.  I have seen them bent for one way race cars. 

[rodekyll]

Sounds like:

Been in a burnt car
Been in a crunchified car
Come from a wrecking yard from an abused carcass
Been pre-loaded to a task

Find a local blacksmith and donate it to him... damn good steel.

What's the application and what was the source of the bar?

Does this have anything to do with the trike? If so, you can "build-up" a custom sway bar.

Todd.

All of the above.

Yes, it's the original bar from the trike.  It's the final bit of suspension/brake work to do.  I didn't think it was wadded up too, but I've been wrong about a lot of stuff with this project.

Getting the bushings for the bar was like pulling teeth.  I don't know about trying for the whole thing.  I'll look on ebay and see if there are universal, size-adjustable ones.  If not, I'll try bolting one trailing arm of the bar to a wood deck and do chin ups on the other one with a 12' cheater.

[rodekyll]

Ok, I'm not seeing any generic solution.  I've removed the bar and I'm headed off between snow squalls to borrow a wooden deck.  I'll let you know how it works out.

[Wayne Orwig]

It will be a fun job straitening spring steel!

Acetylene. Heat it up bright red. It will bend.


 :BEER:

[rodekyll]

Thanks for that tip, Wayne.   :P

After ripping up the deck planks at my friend's house (ok -- maybe I'm on his list now, but I did replace the planking) I took it to the collision center.  There was something big on the frame rack, so I anchored it in one of the main frame lugs, passed it under the ramp and supported it on one of the mobile 'puller' pillars.  There was a 16' boat trailer spine (3" square steel) lying about, so we used that as a cheater and unwound the bar to within a few degrees of on-plane.  There will be a slight preload, but I hope it's not significant.  Now it's off to reinstall it yet again.  I really hate assembling the trailing arm anchors.  They've got 10 parts each and assemble in situ, through a tunnel in the a-frames.  I always lose some skin on this job.   :(

[Mike Tashjian]

Depending on how your bar mounts you can make adjustments to the mounting height of the bar where the bushings mount.  I would not use preload if you don't have to.  All thread with tubing and washers should give you some flexibility with the mount if it is  typical.  You can also use different types of bushings for more or less initial lean in a turn.    Mike 

[rodekyll]

Those are good tips.   ;-T

I was wondering if I could 'fine tune' the action with those long hangy-bolts.

And Yes, I guessed that the bushings might come in different compositions, so I ordered a pair even though I only lacked one.  The ones I got are harder plastic and dimensionally slightly different, too.  I have to move the shackle holes a little to compensate for about a mm thickness difference that won't squeeze out.

Otherwise I think it's fitting up in a relaxed way until the last couple of winds on the long hangy-bolts.  It loads up a little, but with some effort, I can still turn the washers by hand.


ruined the paint.   >:(

[rodekyll]

Got it done.  It's hanging nicely.

[cruzziguzzi]

Got it done.  It's hanging nicely.

Nice. You may get some memory return through use and temperature variations but you can check that easily enough by jacking the rear and checking left-right variance. At this point it probably won't amount to much but had you been able to muscle it on without your re-bend it mighta got ugly down the road.

Having an extra-suspension pre-load can have benefits in countering heavy motive torque or contending with runnin' in circles but on a trike (IRS not withstanding) it would eventually find just the right turn/brake/camber... circumstance to shift your ass:teakettle relationship.

Todd.

[rodekyll]

The natural instability of a trike is one reason I want the sway bar.  Since it has skinny tires all around I'm hoping it will drift and warn me before it tumbles.

[cruzziguzzi]

The natural instability of a trike is one reason I want the sway bar.  Since it has skinny tires all around I'm hoping it will drift and warn me before it tumbles.

The tire choice is a great idea. I always marvel at folk going for the dragster look on trikes. Feedback'll be when the inside tire is higher than their hip. Thin tires and IRS and you'll have a sink and slide to note before things get outa hand.

Todd.

[rodekyll]

The donor came with fat (14") tires and steel rims.  One of them weighed about the same as the tire, rim and brake rotor/spacers/caliper that I've designed in.