so i'm re-doing my suspension and seriously considering going the way of weight jacks.

Couple questions, first of all anyone know what the solution is to the fact that the rear springs come unseated over the last couple inches of suspension travel? Seems like a pretty dangerous thing to me.

here's a pic of z28evans car


any ideas on this? would it be possible to find a shock that just has 2" less travel?

also i dont know a damn thing about spring rates, seems people are running between 1000-1100 on the fronts and 200-250 on the rear.

car is going to be used for road racing/autocross and as a weekend warrior so i dont really care how uncomfortable it is on the road, just how it handles on the track.

suggestions? i'm probably going to be ordering in the next day

 

you could use limiting straps on the rear.

I dont know about springs rates, it has a lot to do with the cars weight as well.

I actually just ordered mine last night, im unsure of the rates, so i had GC figure it out for me. It will be a start. If i dont like them, i can swap to a different rate later.

Im not using the rear setup though, my wheels wont allow for it. Im using coil-overs in the rear.

 

Those are good rates for a track car. For Street/some Tack, 850-ish seems to be a good rate, lower if your "sensitive" to harsh rides.


See how much your compresses at ride height. Subtract the compressed height for the Free height....Add 1"-2" to that number & that will tell you how far the suspension will hafta drop, before the spring can come loose.

Limiting straps, like what the 4x4s use, are the way to go. But short of jacking the car up or LAUNCHING across a curb in a wreck, the rears aren't gonna just pop loose. And are cheap piece of mind & make jacking the car up by the body/SFCs, much easier, since the rear springs can't fall out & hafta be reset when lowering the car back down.

 

hmm i hadnt thought of jacks in the front and coils in the back. Isn't that going to mess with the overall geometry for how the car handles front to back?

how much does jacks in the rear limit wheel sizing? and what spring rate did you go with for the fronts.

also are you running the qa1's from spohn? if i do go coils i wouldnt want to use those shocks, wonder if they'd sell just the mounting plate

 

yea, im using spohn rear coil-over kit. I dont see how they will affect anything, the rate is the same, just a smaller diameter spring. When the jacks show up i can you what they picked for me as far as springs.

I mini-tubbed the car, and have 12" rims in the back, the spring pockets are cut almost in half, and the wheel is where the coil spring would be.

whats wrong with the qa1 shocks? the are china crap, adjustable and all, but i have no issues with them. Could always swap them for something else.

You could make the plate, its quite simple. As for the mounts for the axle, i have them sitting on the shelf in the garage, i made different ones. So i could send them to you if you need them

 

how thick is the plate? my access to equipment to fab stuff is very limited, so thats the part im worried about. I've heard a couple of complaints about the qa1 shocks being garbage on this board. I'm not getting koni's or anything but not sure how the qa1's would compare with something like AGX's.

what are you going to run in the front for shocks? got any pics of the mounts you fabbed? Coil overs for the back is sounding good as im going to need all the tire i can get for competing in street modified classes.

 

the plate is 1/4" think.

you have to cut out the entire side of the frame rail before your tire will get intot the spring, its very common for people to use the 17x11 zr1 wheels and 315/40/17 tires without issues with the spring. That should be more than enough.

If you are going to use weight jacks, just use them front and rear, you cant buy them separately, so you will have the rear set anyway, and im only using the coil overs in the rear because i need them for tire clearance

the rear coilover shocks have threaded bodies for the adjuster nuts for the springs. You cant use koni's or agx or whatever shocks. you need coil-over shocks.

Front i have koni yellows

the axle mounts i fabbed are just like what spohn supplies with the kit, just wider so i could gain some clearance with my swap bar. It's a U shaped piece of steel, 3/16 think, 2"x3". With a bolt through the back into the axle shock mount, and then i welded them on as well.

 

ya if i can run a 17x11 thats plenty of tire.

i'll just order the weight jacks with some stiff springs and go from there.

any input on what would be a better combo, 1100/225 or 1100/250 springs?

car is relatively stock weight, minor lightening but not much, gutted interior.

 

The spring rates you choose will be affected by the ride heights you choose as well as the chassis rake. These will affect the roll centers front and rear as well as the overall roll couple (imaginary line the chassis rolls about on).

you need to figure a desired ride height both front and rear, then scale the car getting your cross weights 50%. Then its simply driving the car and adjusting the track bar up and down nuetralizing the cornering state if you can with those rates and not cantering the roll couple too much to do so. If so, then you need to make rate changes accordingly and re center the track bar setting ands try again. so many other things affect handling like shock damper rates on rebound and compression values, tire quality and widths, alignment specs, TQarm lengths and mount height and the rear squat and lift presented by it in dynamic chassis loading, the same with rear trailing arm angles, roll induced oversteer or understeer, etc. - chassis weights alone and option weights will be major affects car to car.

Dean

 

i was hoping you would pop in here dean, though my head is hurting after reading that

 

whats do you mean by cross weights?

plan is to set it up for the track about as low as i can get it without my long tubes hitting off the pavement, which isnt really that low.

i dont have a good understanding of suspension in general really. as far as rake i cant imagine a third gen would handle well with a positive rake being a solid axel car. So i would go as far as to guess somewhere around neutral.

Car is more or less stock weight, riding on stock rims for the next month or two but am planning on running 17x as big as i can fit, so either 9.5-10 front and 11 rear come beginning of next season so would rather setup for that.

it will be raised two inches or so and driven on the street but i'm not perticularly concerned with how it handles the odd time it gets taken out on city streets.

Going to be running kyb agx's for the next little while.

So given those spec's and what i want out of it (racing being the most important) do you have any suggestions for a ballpark figure as to where i should start with spring wise.

i dont see how i can get all of those measurements on the sagged junk i have on there now, or can i?

this is all very new to me, unfortunately i'm doing this last minute. Motors out and getting some work today, engine k-member is damaged and getting pulled on sat. I know ill be waiting a week or two but i need to get some stuff ordered so i can put the car back together.

 

If you really want "as wide as i can fit".......Put 11"s up front too.

Requires careful selection of backspacing & some fender trimming, but there is a 3rd gen here on TGO that is currently doing that & you can barely tell from the side a what little fender trimming was needed.

 

wish it was easier to detect sarcasm on the internet.

not sure what you mean by that, am i misguided in the general concensus that the more tire you have the more grip? I dont know anything about setting up a car, so i have a ton to learn.

oh and im ordering the weight jacks today, going to get ground control to suggest a spring for me and go from there.

 

It wasn't sarcasm. I use emoticons to show sarcasm.

I was serious. If you want as wise as possible & are willing work for it....You can put 315s up front.

 

good stuff

ya i dont mind having to roll back a little bit of the inside of the fender. That will be a future plan and a future post tho.

Going to call and order these weight jacks now and go out later today and pick up some kyb agx shocks.

 

yes, i have seen cars here with 11 and 10.5's on the fronts, BIGMODS mas 10.5

they will fit, but at full lock, they will rub really bad, unless you have them sitting a decent way outside the wheel well. I would think they would work fine on a road course, not so much autocross, they are a lot more super sharp turns in autox than a real road course.
something to chew on, maybe grab a tape measure, pull of a wheel and see what you find out.

I know for a fact, that at full lock, i have 1.25" of space from the inside of my tire to the a-arm. So i can run a 18x9 with 5" of BS with no issues and still keep the wheel tucked under the car a bit.

I could probably push the wheel out another inch and stay flush with the fender. so thats a 18x10, and I would probably have to roll the fender and remove the liner, maybe trim a little of the fender lip.

After that, im unsure how to fit an 11 without it sticking way far out, or rubbing really bad.

 

I found the thread I was looking for......
315s up front

 

yeah, but those are sutihomos or whatever, they are narrower than most 315's. They fit, and have 315 on the sidewall, but are a good inch narrower than most every other 315 on the market