speed.chad

Has anyone made a set of solid replacements for the shocks and struts to use for chassis setup. By this I mean set the ride height, remove springs, install solid replacements adjusted to ride height and then set caster/camber/toe, bumpsteer, adjust wheelbase, square rearend,etc. This the way most round track and road race cars are set up, however since we have a much different suspension than a coil-over round track car its not near as easy.

The rears I think I can do with no problems, the fronts will require a little more effort.

Guest

Who sets up cars that way? I never have. Someone sold you a bill of good on that idea.

Are you sure you are not mistaking "transport shocks" for when the car is stored and trailered?

skinny z

Probably not what you're talking about (which reads like a live chassis setup on a nearly finished car) but when we're building a vehicle in the shop (mostly dragsters/gassers) we always build a set of solid bars so as to simulate the ultimate ride height. The bars replace the coilovers or shocks. When the frame (or bits of it) are on the jig, we can't have any movement in the suspension as everything is plumb and square.
As we add weight to the car either with roll cage material, suspension or drive train parts, our frame to floor measurement is consistant. It's also how we achieve the proper look with respect to how the tires sits in the wheel house regarding both fit and appearence.

speed.chad

Let me try and give you a little more explanation of the purpose and reasoning behind doing this.

First, what you are doing is this. With the car as you would normally run it, you would get it up on blocks (car is resting on all 4 tires, but with enough clearance for someone to slide under it. Next you would get fuel and driver in the car, wheels straight ahead. You would then send someone under the car and take measurements of the shock lengths. A car with 4 coil overs would give you an "eye to eye" measurement but on a 3rd gen you will have to use some other reference points (bottom of upper strut mount to top bolt hole on spindle for example). This measurement is for your static ride height. You fabricate a fixed length "shock" to go in place of the shocks and struts ( the front will need to be extendable and collapsable, with a way to lock it since we cannot remove the strut and maintain our geometry. I will explain more on this in a bit). Next you would replace the shocks/struts with the "fixed length" shocks and struts you built. I suggested removing the springs, that will make more sense in a few ( if it were coil over tehy get removed with the shock anyway). Now you can jack the car up, add or subtract weigh, etc. and the car stays at ride height.

Now for the method behind the madness. We know that a suspension system is dynamic, and always moving when the car is in motion, so why are we locking the suspension in one place? Well, you need a reference point to take measurements at, and to reference against when certain measurements change as the suspension moves, it also allows you to hang the car in the air by the frame and the car is still at "ride height". Now we can take baseline measurements and "string the car". If you want to know more about stringing the car, i will go into detail in another post, but suffice it to say its a method to be sure that the car is "square", and that you know where the suspension is in relation to the car, not where one wheel is in relation to another, or an angle vs the ground, etc. Once you have taken your "ride height" measurements on all of the suspension, you can remove the "fixed shocks", and release the "fixed strut so that you can move the suspension through its range of motion. It would also be helpful to disconnect the sway bars for this. you can now check for things such as bump steer, camber change, caster change, rear steer, housing offset, etc. The purpose of unhooking the sway bars and taking the springs out is so that you can articulate each corner of the car through its full range of motion without trying to pick it up off the jack stands. When you do this, and learn what the suspension is really doing as it moves, it can clue you in to some of the behavior of your car ( especially if you autocross or roadrace).

Guest

Chad, you are making yourself alot of needless and pointless work. You can string a chassis with what ever suspension you like on it just get the drivers weight (bumbbells, weights etc) in the drivers seat to mock the driver and do not touch the rest of the chassis- it ain't gonna move unless you move it. But hey, suit yourself if you want to go through all that trouble for nothing. You might want to check my resume so you have an idea who you are talking to.

Now if you are initially building a chassis and adding comnponants into it and proportioning weighjt bias then yes I can see a fixed location of suspension movement until the chassis weight is set and then the desired spring weights are determined after that for each corner of the car- but again, this is chassis building not suspension setup.

speed.chad

well I don't see a resume posted,so I don't have any idea who you are unless you tell me, but I get my info from VERY good sources. I've never been afraid of doing extra work to assure I get a better result. You say its needless and pointless, however i have 1st hand seen the benefits of doing this.

Guest

A few pictures in my profile page will show enough of a resume. In a 24 race history in NASCAR where I came directly into tcircle track ranks as a crewcheif (on a major leaning curve in non symetrical setups) I have 2 wins, 1 second, 7 thirds, and only 2 of those 24 races were out of top 10 finishes. I am in the history book at Toyota Speedway with a 3rd place championship of 41 entries my rookie year and only full season I was able to run due to this poor economy, lack of sponsorship money, and politics. I've retired early because I made my mark & proven my abilities-and do not need the BS headaches- racing is suppose to be fun and this was not. I would say this qualifies my opinion I have given you.

https://www.thirdgen.org/forums/album.php?albumid=992

blyth18md

Here we go again...

radical82

I've got a set for a third gen, use them for the initial scaling more then anything. (As Vetruck mentioned.) Also have some for the different length coilovers I use on Hot Rods and Drag cars. I use them when doing mock ups and tacking things on the chassis table so the welding and grinding sparks don't mess up my new shiny stuff!!!!

Guest

Get your popcorn.

What I do not get is why he is refering to chasis building on a car that is already built. He is talking about building an entire new geometry from ground up and this is not the case becasue no mention of this was placed other than replaing the factory strut with a fixed lenth rod.

So... I will have to access that he is refering to "setup" rather than "build" since he has stated "setup" in his post title and has also talked in the format of setting up camber, caster, toe, bump etc without the shocks in place.

Bump needs to be set without shocks, but it also need to be set without a solid rod in there either- So I question his question and say that someone sold him a bill of goods. Things are not done that way.

Now granted, chassis squareness canb be set either way- with shocks, or with solid rod- so why take the time to build a solid rod? just square it on the shocks and springs- we do not have front A-arm adjustments on a 3rd gen (yes a few aftermarket guys are now making them but generaly on coilover setups which can easily be adjusted without coilover removal, just jack the car and shoren or lengthen the ear mounts and reattach. I do the same on the racecars with coilovers in tack- just jack and relieve spring tension, then set in back down loading the chassis...
,,,, so now we get to the real problem I have with what he said in setting camber and caster and toe without the shocks and springs in there- Why on earth would you want to set this and then jack the car and remove parts & replace parts and trust that the car is sitting ride height and strut to spindle mount angle exact to what the rod was- YOU CAN"T and someone is selling a bill of goods saying you can. Your alignment spec WILL be off- I GAURANTEE.

I rest my case.

speed.chad

First off I did say that the front one would have to be able to "unlocked". If you can't see the advantages of being able to let the car hang in the air with everything locked in place, I can talk till I am blue in the face and you still won't get it. Skinny Z and radical 82 so far understands what I'm talking about. I will agree that on a strut car you will have to reset the caster/camber at least as a double check, but the rest of what I am talking about there is an advantage here(i'd actually like to have a set of struts that i could drain, then put a lock collar on the shaft). If you don't have a reference point (that doesnt change, is static), then you can't knwo what you're doing from zero.

I asked a specific question, if anyone had fabricated these before, trying to save myself the time of engineering it. I never asked if anyone thought it was a good idea, or whether you thought I was wasting my time.

speed.chad

radical 82, could you snap some pics of what you have, I'd like to get an idea of what works before design/build them myself. I have some ideas in my head but haven't sat down in front of the computer and drawn it out in solidworks yet. If you have something that works, no need to reinvent the wheel.

JamesC

iTrader: (5)

To avoid innuendo, honoring the OP's request, I think, is the best bet.

JamesC

Guest

I happen to have a telescopic shaft that has a fixed upper mount like factory but with a lower extended shaft to a strut bellcrank and an inboard coilover.One of my top secret designs I will hint at that will be fabricated on my next third gen.

Guest

Then we are in agreeance because I stated the same thing they did about building the car, not setting the car.

Now as for setting the car and pertaining to your last sentance above, please explain to me why you would need to hang the car in the air and move what from Zero and why?

speed.chad

Excuse the fact that I'm buch better at doing this than explaining it, I guess its a good thing I never decided to be a teacer. Can we agree that to examine the suspension through its full range of motion, it would be easiest to do without the springs in the car? Can we also agree that having a static "ride height" to reference off of is a good idea? The purpose of having the car in the air at "ride height" is so you can take measurements of everyting and crawl under the car easily, and with no tires/wheels on the car and no weight on the suspension its just much easier than having the car on blocks. As long as you have your "ride height" struts/shocks, you can put them on the car to see if anything has moved ( wheel to wheel or wall contact, rough track, big wheelstands for drag cars). Its all about having a static reference point. Just like building a house, if you don't have a true "zero" then you are lost. you can do a traditional 4 wheel alignment and the car may go down the straightway sideways ( not to say that itsn't desired at times). The 4 wheels are aligned with each other, but not with the car as a whole. I know you grasp that, because you obviously have strung a car before.

Yes what I'm talking about doing is a lot of work, but if it gives me a true zero, that is repeatable that I can go back to, then it is worth it to me. You obviously disagree. As for having to reset the caster/camber, its the easiest of all the suspension geometry to set, so its no big deal.

Guest

I can see in bumping a car the need for true zero hence why I do such a measurement of the upper control arm to the tube chassis near the top shock mount via a peice of tape as a reference mark(in the case of the NASCAR Supertruck) or you could do a measurement of the strut body to the strut mount distance on a third gen.

Having that measurement as welll as chassis ride height, you then take two floor jacks- one under the chassis to suport that corner of the car at ride height under the frame, and the other to jack the unloaded (spring out) suspension by the ball joint parallel to lateral vertical movement to that zero'ed ride height measurement- then take the bumpsteer plates and micrometer and run the jack up and down on each side of the car individually to check tierod motion compared to A-arm motion and shim accordingly.

This is the only real measurement I see for having a zero'ed baseline with the wheel off the ground- other than in actually chassis building design when changing suspension frame mount points to change geometry.

Maybe a limiting strap would be better suited to your needs top hang a suspension and still be able to move the assembly upward? but I still see a lack of use due to no downward ability of movement. I just do not see any other reason for the use of a soild static rod other than weight placement on a vehicle build sitting on scales.

Please understand it is not nor was it ever my intention to bash this idea, I simply was stating my opinion that I for one think it is pointless and am just trying to give you a positive debate to see your needs and find out maybe there is another wway I could maybe assit with advice. I still stad my ground on my opinion and RESPECTFULLY TO YOU just have my opinion that this soild static rod would be pointless for anything other than a chassis build and conponant placement until spring rates are later calculated based on corner weights and bias.

For ideas on a simple shaft rod that can be "Locked in place". You could use a typical double D telescophic sateering shft with a a threaded rod welded to the top (same thread as the strut shaft) and brackets weled tot the bottom simulating the strut body. You then simply drill a hole through the shaft about an inch from where they meet and use a press pin (like that on a bench press machine changing weights- or a larger hoodpin type unit, something that will hold the weight of the car).

speed.chad

thanks, that's a good idea