I have my spreader bar installed, and was just thinking about what is the proper method to adjust it?

Should the bar be 'pulling in' or 'pushing out'?

Also, how tight should it be once the alignment is set?

 

I installed mine with a slight bit of outward preload. The idea is the upper mounts tend to bow inward, but it should help all movement. A turn or two should be plenty - done with wheels on the ground.

 

I did mine with wheels on the ground and just hand tight without a wrench. Then tightened lock nuts.

 

I agree.

 

This' spreader bar' is just to aid in preventing the upper control arm points getting any closer to each other. It really does not have the integrity to provide any serious stretching or pulling together capability. It merely triangulates the front upper suspension area and makes it super stout.

DUB

 

And I would do the alignment AFTER installing the spreader bar

 

I agree with the others. I put a very little amount of preload once the wheels were on the ground.

 

They had to remove the spreader bar to do the alignment. The shims needed to be added to the upper control arms, so the brackets for the spreader arm needed to be loosened.

I also just have it hand tight + about an 1/8 of a turn, but seems like it should be pushing out. Mine is tightened in such a way that pulling them together now.

I realize it won't make THAT big of a difference either way if the tolerances are tight, but just wanted to check the theory on what it SHOULD be doing.

 

Sorry...but I feel I must...please do not take offense....just trying to help you and other that may read this.

Actually if you stop and think about the physics and motion dynamics of the front suspension....and HOW MUCH side to side play the bolts that hold the spherical ends have in the brackets they pass through....logic would dictate that you want the rod the longest it can be...and not the shortest. And by writing LONGEST...does not mean to crank it out with a wrench and chip your teeth because you are biting down so hard while cranking it to make it the longest it can be. This is because the first good bump you hit....can cause the space outside the diameter of the bolt ( due to its free play..allow the A-arm shafts to actually come closer. YEAH...I know I am 'splitting hairs'....but sometimes small tolerances like this can cause for an issue.

Kinda much like when you are tightening up the three bolts for your torque converter....and knowing that when the three bolts are installed and loose...you can rotate your torque converter in both directions. Well that is when you rotate your converter opposite of the direction that the engine turns so the bolts are against the wall of the hole in the 'flywheel'...and thus....when the engine is started...these bolts can not move from side to side....and....if it were the other way....the torque over time could cause these bolts to move...beacsue they have a place to move to... and make a noise when starting or shutting down the engine.

I find the relaxed point...so when the bolt that holds the spherical end to the bracket can be pulled out and slide in with no effort. This rod is not rocket science. All it is doing is trying to reinforce what you have as a setting for the front alignment and frame....and keep these components from moving when under loads. AND your adjustment of this rod is also determined by how much play the holes in the brackets allow when the bolts are installed for the rods. Just extend it out until it stops. That's it. And spinning the rod can be done by hand...or by hand tool...just don't crank on it to extend it out.....that is not needed.

DUB

 

Hey dub,

No offense taken. That was precisely the reason for the post, and I agree 100% with the logic. In fact, it was because of this suspicion that i started thinking about it. The spreader bar should be 'longer'. Not tight, since that would create more stress on the frame, but snug in the 'pushing outward' direction. I have readjusted mine to make sure that's how it is. Thanks for the help and comments everyone.

 

Have you driven it much since?
Can you feel the difference?

I LOVE mine.....

 

Not sure if I feel a difference directly related to the spreader or not. I did a TON of stuff to the car at the same time (big ol' crack in the frame welded, new springs, new shocks, rebuilt the upper and lower control arms with new poly bushings, new ball joints, new tie rod ends, tie rods, Borgeson steering box, etc.). Car feels totally different, but not sure what percentage the spreader plays in the improvement.

Im still not in love with how the car drives, even after all of that work. I did have the alignment done, but I think its still not quite right, so the car still doesnt drive how I would like it to. But I have no frame of reference. This is my first C3, so I have nothing to compare to. Never even drove another one besides my own. Not sure if its just how they are or if something is still out of whack.

 

I put my speedirect speeder bar on my car a few years ago now as a stand alone modifications (I almost always do 1 modification at a time to gauge the result) and the results were/are VERY noticeable. Just to put the change in perspective, the front suspension already had:

Poly Upper and Lower Control arm bushings
Poly mounting and endlink bushings on the OEM 1 1/8 inch front sway bar
550 springs-1 inch shorter than stock
Bilstein HD shocks with poly upper bushings
Custom Blueprinted/rebuilt OEM steering box
255/45/17 ZR Ultra High Performance tires

AND the spreader bar made a big difference in the tightness of the chassis and suspension.

If after installing a spreader bar on any C3 (the stock frame flexes a lot), the installer does not notice a noticeable improvement in chassis/suspension response, something else is not right with the suspension.

 

PLEASE answer all questions...they matter a lot!

PLEASE describe what is happening when you drive it
.
Sluggish or spongy steering???
Tracking/wandering wherever it wants to when driving at higher speeds???

Did the alignment shop use a laser alignment machine???? and if so...did they give you a print out on your specs????

Did you do a four wheel alignment????

I know you wrote you did the front suspension...have you done anything to the rear suspension??? THIS IS IMPORTANT...and has a lot to do with how you respond to how it handles and drives. VERY IMPORTANT!!!!

The spreader bar when being normally driven is not the HOLY GRAIL of a prefect driving experience. It does provide a major improvement in how the suspension react to forces when driven hard or 'spirited'.

DUB

 

Agree that "something is still out of whack" gives very little information to go on. So, in addition to making sure we know the specs and what other work was done (or omitted), please to include clear feedback as to what it's doing wrong.


In any event, adding a spreader bar is one of the higher priority improvements I'd suggest that any C3 owner should consider making. My $.02

 

 

I understand them loosing the brakets to install shims; however I would question the removal. Did they reinstall it or was it left to you? If left unintalled I would find another shop next alignment.

I have always adjusted the bar snug without a preload.

 

When I installed mine, I lifted the front up about a half of a crank on the floor jack. I would say it raised the car about 1/4-1/2 an inch. Just letting a tiny bit of weight off. I tightened the bar by hand then lowered it. I then used a couple wrenches on the lock nuts.

Vette feels alot better around the curves.

 

Taken me a while to reply. Here are the answers:

Compared to before the frontend rebuild and subsequent alignment, it felt like I was standing on a basketball when driving the car. It felt unsafe. It took a lot of concentration and focus to keep the car tracking down the road. Any grooves or unevenness in the road would be unnerving.

AFTER the rebuild and alignment, MUCH better. No longer feels unsafe, just doesnt feel as nice I would have hoped.

Road unevenness still causes more bump steer than I would like.

Now the car tracks fairly straight on the freeway on even smooth roads. When not perfectly straight, as in just past center in either direction, the steering is a little sensitive. Not nearly 'darty' as before the rebuild, but still darty compared to rack and pinion steering cars.

I feel everything in the wheel. The smallest bumps and groves are very noticeable in the steering wheel. I can feel everything.

Weird thing. When driving in a parking lot, every time I drive over a painted line, the tires squeak. Always. This is normally at slow speed, but I would assume its the same regardless of speed.

Lots of tire dust on the fenders. Clearly something not right about that. I dont remember this problem before the frontend rebuild, but I wasnt really paying that much attention back then.

When doing a tight u-turn, when I turn the wheel to the stop, I can feel one tire sliding and squealing fairly aggressively. Something definitely not right there.

As mentioned, if I am tracking perfectly straight at highway speeds, on an even road, its tracking nicely. Uneven road, its wandering a bit.

Its a weird thing. I feel like is both sluggish and spongy as well as sensitive. Its only sensitive at certain points, and spongy at others.


I think it was a laser machine, and attached is the printout. There is another thread I posted on here talking about the tire dust, and someone else commented this is a crappy alignment, but not to redo it until the rear rebuild has been completed. Not quite ready to tackle that just yet for time reasons.

I specifically asked for a front end alignment only since I knew the rear still needed to be built, but he made a small adjustment on the rear anyway. However, I dont think he did a complete rear end alignment.

I havent touched the rear yet. I spent forever on the front, and finally got the car back on the road, so wanted to drive it for a bit before I started on the rear. I THINK the front was the bigger issue, but I am really not sure about the condition of the rear. The main reason for taking on so much at one time on the front end was that I had a cracked frame that was getting worse, so 'while I was at it' I ended up redoing everything.

 

I am concerned about the black rubber dust you mentioned is getting on your fenders.

You replaced the idler arm...correct????

You still are using the factory power steering system...correct????

IF SO...have you done anything to it????? Because you can have worn out bushings at the end of the power steering cylinder...OR the bracket mounted to the underside of the frame his loose or may have cracks in the frame where it is mounted....which I have seen MANY times before. The power steering control valve can have play in it along with the taper stud in the power steering cylinder where it is attached to your center link.

I would be curious to see what the alignment specs would show if you put your car back up on the alignment machine and get the readings now. AND I would have to stand there and watch...like I do when I am getting one aligned for a customer....mainly because...even though I trust the alignment shop...I HAVE TO SEE IT for myself. So when I look my customer in the eye and let them KNOW for a FACT that the car needed to be aligned...because I KNOW how the alignment machine can be 'fudged' to get the numbers to be in the green in some areas. NOT WRITING that is what happened...but black rubber dust IS NOT RIGHT!!!!

DUB