Coil over shocks convo

[itawolf]

I'm looking to take my bug to Italy
Where I org got it from

And run a mtn race event

FYI
I'm an dual citizen

[Ol'fogasaurus]

I think your roads are similar to ours; we have good, bad and rugged roads also.

Good to have you here. I got to work around some Italians many years ago when they were here for "industry assist". Nice guys for sure.

Lee

[itawolf]

I've been in the US since 89 when I joined the Marines
But I go back every year or so

Props to an Italian mother
And American Father

I bleed red white n blue
Always

Semper FI

I'm hoping to run Barbers in my bug within a year

FYI

Italian roads are needless to say very very bad
If not on the autostrada (autobahn)
Or in a big city

Hey my first car was a 67 fiat 500!!

[jhoefer]

Getting back on to subject, the more preload you put in the stiffer the ride and conversely so. By using less preload and a stiffer/bigger dia. bar you may get better suspension action w/o too stiff of a ride at non off-road settings.

You are conflating preload and spring rate.

Preload means you have pre-compressed the spring with a certain amount of force. But it also means that it takes more than the preload force to even begin to move the spring. It's there to counteract the weight of the vehicle, passengers, and cargo (and in our case) so the ride height is correct when the car is loaded. So, for example, lets say we have a 200 lbs/in spring, and we have 800 lbs of weight over that spring, and we want 2 inches of droop travel to get the right ride height. If we had no preload, the spring would compress 4 inches with the weight and the car would be sitting 2 inches too low. If we add 400 lbs of preload to the spring, the 800lbs will compress the spring only 2 inches (400 lbs absorbed by the preload, 400 lbs left to move the spring) and we get the correct ride height. Now lets say you preload the spring with 1000 lbs of force. Our 800 lbs of weight isn't enough to even move the spring. The suspension is stuck at full droop and the car sits 2 inches too high. And it will stay rock-solid at full droop until at least another 200 lbs of force is sent into the suspension from road bumps. That is why your ride got bone-jarring when you put far too much preload into the springs, you locked the suspension solid and the only thing absorbing bumps is your tires.

The proper way to do what you want is to increase the spring rate of the torsion bars and reduce the preload to compensate. If you swapped our example to a 400 lb/in spring, our 800 lb weight would have the car sit at the proper ride height with no preload. That 200 lb-f bump impact from before that didn't even make the suspension move now causes the suspension to compress 0.5 inches. Half the compression of what you would have gotten with our 200 lb/in spring with normal preload, so the ride will feel stiffer, but it doesn't make the car feel like you've welded the suspension solid.

[Ol'fogasaurus]

... By using less preload and a stiffer/bigger dia. bar you may get better suspension action w/o too stiff of a ride at non off-road settings.

You are conflating preload and spring rate.

The proper way to do what you want is to increase the spring rate of the torsion bars and reduce the preload to compensate. If you swapped our example to a 400 lb/in spring, our 800 lb weight would have the car sit at the proper ride height with no preload. That 200 lb-f bump impact from before that didn't even make the suspension move now causes the suspension to compress 0.5 inches. Half the compression of what you would have gotten with our 200 lb/in spring with normal preload, so the ride will feel stiffer, but it doesn't make the car feel like you've welded the suspension solid.

Hmmm... I thought that was my point!

[jhoefer]

What I'm saying is that preload in and of itself doesn't affect ride stiffness. You could run a wide range of preload, assuming adequate suspension travel, and you'd never notice a change in the ride feel because if your preload is ok, ride stiffness is dependent on spring rate and damping rate. For example, if you dumped enough bricks into your back seat to overcome your excessive preload, the car would ride just like it did before you messed with things. (Actually probably a bit more comfortable because you've increased your sprung/unsprung mass ratio.) It's only when you take preload to extremes and run out of suspension travel that you notice anything.

If preload has made your ride stiff, you've either got springs that are too soft or inadequate suspension travel.

[Ol'fogasaurus]

Mr. H, I have set the preload, in increments', all the way from ~20° (stock) to 30° and not only does the ride definitely does get stiffer as the preload gets greater but things on the floor fly around more also (we are required to carry some additional potential missiles when out on the dunes). As I said before: ~ 26° to 28° is in my opinion max for any kind of sensible rid.

I used the same White KYBs during all the preload changes that is until I got hurt while running the White KYBs (several times they let me down... hard but this time it was so hard when I hit the compression stops that I jammed my back bad enough that it took most of the summer to get over the pain). I then I changed to Bilstein 6100 series (7100 series is now available and supposedly a good change to use off-road) of shock which, when the same situation happened, they did not let me down (pun not intended) hard; as a matter of fact I did not hit the stops on the same drop when the crown of the same dune collapsed on me a second time.

I am running a short wheel base VW pan with a glass body: after talking to Sway-away they said I could go to either a 26mm set of bars compared to using the stock bars but with the rest of the equipment I have and how and where I ride they thought re-setting the preload might be enough. My buggy came with cheap, helper air-shocks which almost sent me pitching ass-over-tea-kettle when I hit a series of rhythm whoops at the bottom of a dune.

I am running notched spring plates and bus CVs. My buggy probably will not safely handle much more travel because of the short wheel base. I have badly cut up my paddles when the suspension collapses and the tires hit the body which was cured by a body lift (stiffened up the pan) and the new shocks.

One of the guys in our group (one of my stepsons) was running the coil over shocks then put my old white KYBs on his (two pivot rear suspension) rail. He felt the ride was better but still may go back to the coil overs.... his debate with his self continues on even though he knows it is not really the correct thing to do.

I don't remember what the travel I have but I think it is in the 10" range in the rear and probably 6" in front because of the use of a BJ beam. In my case, it was the shocks that made the difference not double springing which I also have tried (disappointing test).

I have played with cars since the late 50s and have been around all types of racing (I couldn't afford to do it myself); even back then it was felt that you do it right the first time and using a second set of 'helper shocks' did not work as many people think it does. Some people do seem to get by with it but doing the right thing the first time is so much cheaper and less irritating to you or your (metaphoric you/your) friends that have to listen to you complain about your suspension.

Granted this is not on the street but the suspension works about the same and the effect of proper shocks and proper torsion bar settings or replacing it with good coil overs is similar enough to think about.

Lee

[PhillipM]

That's why even though the rest of my car is built out of scrapyard parts and junk welded together, the dampers are fox all around with a mixing of Bilstein and Penkse parts to improve 'em. Don't matter what suspension you have if the dampers are junk!

[Ol'fogasaurus]

That's why even though the rest of my car is built out of scrapyard parts and junk welded together, the dampers are fox all around with a mixing of Bilstein and Penkse parts to improve 'em. Don't matter what suspension you have if the dampers are junk!

Very true! The value of good dampeners (a more proper name for what they do than the term 'shocks') always seems to be underrated. My experience with lever style of shocks is limited but I do remember the different ways people used to upgrade them... up to and including filling them with "STP"; the same thing as solid mounting the suspension even after things got hot.

Sorry for butting into the 'suspension and handling' forum but I thought I had something of value to add. I have picked up info from reading you guys posts also.

Lee