Wobble?

[hardingfv32-1]

1) I'm sorry to burst your bubble, but there is very little difference between the two spring packs you describe. The normal spring pack is so soft at about 30 lb/in wheel rate, you would never notice the change you are talking about. A normal race car has a wheel rate 100 lb/in or greater.

2) How does moving the spring pack to the top beam improve braking/cornering? Is this just more FV mythology?

Brian

[Matt Clark]

Well, I do not know where the change came from then, but somehow the spring rate was a lot stiffer when I moved it from the bottom beam to the top. I put it in the same "ripple" on my adjuster, and it was a lot stiffer as soon as I put it together completely & felt it in the garage. On track, it was overly responsive and MAJOR loose. I can see how the solid outer leaves could be a bit stiffer, since you are trying to twist a larger piece of metal, but if you say it's not, then so be it. I'm just working off of what I did vs. what I felt. Perhaps the adjusters were welded on slight differently between top & bottom, but they looked the same to me.

The spring pack in the top was first explained to me by Steve Pastore. The theory behind it is the slight amount of twist the spring pack goes thru makes the length shorten a bit, therefore pulling the turkey leg in slightly and increaing camber slightly. Whether you believe it or not, or how much effect it actually has, is up to you. He hasn't steered me wrong yet, and I was willing to try anything to fix my car. There definitely looked like a slightly better camber result from a static height to car bottomed out after, as well. My outer front wheel does not appear to roll under as much this way, either. Perhaps this was my new spindle assembly showing better geometry instead. I would say this defintely isn't just mythology, but will admit the amount of change is arguable.

Either way, the problem seemed to be excessively stiff front springs, as all the new parts didn't do anything. Once I softened it, problem almost eliminated.

[smsazzy]

My theory is that the front end is stiffer because you overtightened the pinch bolts on the link pins or otherwise bound it up somehow. Unless the spring pack was more of a factor than you outline in the post.

The spring pack moving top to bottom should not have any appreciable difference in handling until you are getting 100% out of the car (see: http://www.racer.com/varacins-dominates ... le/149878/).

[jpetillo]

I agree with Steve and Brian that the spring pack will have the same rate no matter if you put it on the top or the bottom. The adjuster located in a different spot that could have you end up with the turkey legs on a much different angle will effectively give you a different rate though, but it should not be dramatic unless you had them on a steep angle either before or after. Did the turkey leg angles change much? John

[hardingfv32-1]

"The theory behind it is the slight amount of twist the spring pack goes thru makes the length shorten a bit, therefore pulling the turkey leg in slightly and increasing camber slightly"

That is not a bad theory. If you assume that the lower arm (sway bar beam) is riding against a thrust bearing and in a fixed position, then if the upper arm (spring beam) goes in them you will get camber change. Unfortunately not much....

I have tested a sway bay and got less than .010" shrinkage using the normal amount of service twist. If we assume the spring would have similar shrinkage and that it is anchored in the center, then that means .005" of arm travel or (est) .06 degrees. That is not very much camber change.

But still an interesting theory.

Brian

[Matt Clark]

Steve-
I don't think I overtightened anything, as it was nice & free before I put the pinning bolt in the center of the spring pack. I took my time to make sure there was no bind, in case I already had a bind that caused the problem in the first place. I actually thought it went together very smoothly for never completely tearing a beam apart on my own before. Also, I did not do any torque specs on them, either, just assembled them tight enough I was confident they wouldn't come loose. I didn't see anything that would make the spring pack more of a factor, as there was no visible damage or issues with them. The smaller split outer springs just made sense to me that they might have made a difference. I changed them more because I was out of ideas & things to try than anything else.

John-
The turkey leg angle did change before I bolted the shocks on. When the spring was on the bottom before, there was no limit as to how far they could rotate downward (obviously). Once on top, I could not get the legs to rotate down enough to match what I had. I had to take the nubs off the end of the beam horns. Major preloading going on. And as I said earlier in the thread, the shocks have an internal limiter that doesn't let the front raise way up. Without shocks on, the legs would angle downward pretty hard (both before I took it apart and after when I duplicated the setting) and gave it an offroad look. Once I softened it, it obviously did not preload it as hard, so the legs were flatter just under the cars own weight.

Brian-
Right. The theory makes sense, so I tried it. I thought I could see more than just a few thousands change, but it might have been just the rubber dust seal mushrooming out independently. Again, I had nothing to lose by giving it a go.


One thing I forgot to mention, was I added slightly longer eyelets to the end of my shock to allow more overall travel & let the front to raise up on it's own more. That doesn't matter under braking/cornering since the front is in compression, but it definitely changes how it handles under acceleration when it was pinned so low before. Thanks again for the input guys.

[problemchild]

Matt,

I would agree wuth the boys that the assembly and resultant friction/stiction/slop/freeness/etc had more to do with handling than changing spring rates or location.

However, now having more info, if you have interfering horns and preloaded dampers, that was surely the root of your problems. The dynamics of the entire suspension change by the millisecond with weight shifting all over the place. Your assumption that it was having no effect because it was in compression, would not be my conclusion from my experience.

Those were great-handling cars and I would work towards finding a ride-height in which the original shock lengthes (while fully extended) match up with static ride height (driver in). I expect the steering configuration will work better at that ride height. That is assuming you have the correct shocks as used on that car. I would avoid pre-load from static ride height unless testing it first to monitor the effects.

Cheers!

[Matt Clark]

The horns only interferred when I have the car jacked up trying to assemble it & set the spring preload (just the turkey legs on the spring, no spindles or anything). Based on feeling other peoples cars, mine was defintely stiffer. I could stand on my beam & bounce hard to get it to finally bottom the car out, and I didn't have to before. The shock limit only limited downward travel of the turkey legs. Once I was in the car & driving, it did settle slightly below where the limits were. There were no up or down stops working on the car when the shakes happened, hence my reasoning. And like I said, the only change I made when the shaking stopped, was softening the spring to what I felt other cars were. Made sense to me as I sat there afterwards, but I do see where you guys are going too.

I have black penskes on the car, but they are not the ones Masons used. Apparently those were borrowed from someone else, and did not come with the car (something I found out after I got it home). I have it setup now that the suspension works up & down almost all of it's needed range without using the shock limiter, but I will completely remove the limiters this winter since they are not needed.

It is very nice to have a drivable car again, I just need to get used to it without driving around issues now. I wish I could get one of the really experienced guys in the car to see what the feel/see, but finding someone overall small enough to fit is tricky. This is all defintelty a learning experience.