moog cc247 spring for rear lift?

[dlb]

i've been looking for a replacement for the rear springs in my ae95 and tried out moog cc247's. they wound up being way too tall for me but i looked into them more and it turns out they are commonly used as replacements for first gen pathfinders, which are of course the donor vehicle for a lot of our rear lift springs. i also compared the cc247's to a rear 4wd terc spring i had and it was the same height but slightly smaller inner diameter, and with 2 mm thicker wire. they might work really well for a t4 rear lift so i thought i'd post it here.

here's the specs on the cc247's. scroll down to page 10, it's the 11th one down.

http://www.moogproblemsolver.com/moog/w ... s_Spec.pdf

[c_j]

What about giving them the heat treatment like they used to do to lower front ends? Or chop off a coil?

[dlb]

i've never heard of heat treatments for springs. what is that?

i could have chopped some coils but i decided not to for a few reasons. the final coils on each end were closer together (the same as on t4 and ae95 springs) so if i cut one off, the final coil would be spaced farther out and might not sit properly in the mounts on the car. also, the springs cost me $224 and i would not be able to return them if i cut them, and i'm too cheap to risk that on something i might not be happy with. i've considered getting some used pathfinder springs (much cheaper) and cutting those but would have the same problem of the final spring being spaced too far out and not sitting in the mounts very well.

so i'm still unsure what i am going to do. for now, i have the rubber donuts in the springs to prevent bottoming out the shocks when i have a car full of people but i intend to move them up between the spring and the upper mount when i get a chance and see how i like that.

[c_j]

What I meant by the heat treatment is where you heat them up with a welding torch while installed in the vehicle, and the weight pulls them down as you heat them. Don't heat too much or you'll end up fully slammed. There has got to be a video out there on that. I seem to remember it was all the rage in the '80s and probably earlier than that.

[ccmt]

Has anyone tried moog cc217? It looks like it has the same dimensions as the cc247 but is 0.5" shorter and a little less stiff. It is still taller and stiffer than the moog 211, which appears to be their equivalent of the t4 stock rear spring, so you should get some lift but not as much as the "full Barto."

[Petros]

there is an extensive thread where I list a lot of different spring rates, easy to determine with the correct formula.

unless you want to alter the front to rear "understeer/oversteer" behavior, or alter the anti-sway bar sizes, you want to keep the ratio between the front and rear spring rate about the same. calcuating the stock front and rear spring rates will allow you to do this on what ever springs you choose.

also note, that cutting a coil off the spring will give it a shorter length, and increase the spring rate (make it stiffer), since you are shortening the total length of the wire coil.

You can change this front to rear weight biase if you want to change the understeer/oversteer behavior of the car, or are willing to change the front to rear weight bias by moving installed equipment around (moving the battery to the back of the car is a typical way to do this), or change the front and/or rear sway bars. you will eithe have to alter the stock anti-sway bars to do this, or find the smaller rear sway bars from the rwd corolla or ceilca which will swap into the Tercel4wd, or adapt a costly adjustable aftermarket rear sway bar for the RWD Corrolla GTS. You can also adjust the understeer/oversteer of the car a little by adjust the tire pressrue front and rear.

Stiffer springs will increase the tire side slip, lower tire pressure will increase tire side slip, more weight over the that wheel with increase side slip, stiffer anti-sway bar will increase tire side slip. You use these different means to balance the oversteer or understeer of the car in a turn. so if you put in stiffer rear springs, as compared to the front springs, you will increase overseer (more rear tire side slip means rear wants to make a slightly larger curve than the front of the car), or if you increase the tire side slip in the front, you get understeer.

too much of each is annoying, too much oversteer can be dangerous. I have noticed the stock suspension is neutral, slight understeer on dry roads, but becomes heavy understeer on loose gravel roads. more weight in the back helps this, but too much weight in the back it becomes oversteer, particularly on loose gravel roads where you can actually swap ends if you take a turn too fast.

I hope this makes sense, if you go swamping out springs you will make it behave differently. Knowing how you affect this will allow you to be aware of what could change, and how to correct it. Test the corning behavior of the car after you change the springs on a large flat parking lot or a safe cure and see how it behaves, with tire pressue all the same. Adjust weight bias and/or tire pressure to try and get neutral steer. If you have to, you can make changes to the anti-sway bars to get more adjustment.

Usually car makers will try and get understeer in the car, except in the performance or sporty type cars, where they want neutral steer. On a vehicle designed for both hwy and off hwy use it becomes more difficult (tires can not develope as much side force). As one guy I used to work with at the Nissan racing program once told me; when some goes around a corner too fast and spins out and crashes (too much oversteer), they blame the manufacturer. But if someone goes around a corner too fast and goes straight off the road and crashed (too much understeer), they blame the driver. Hence the tendency for most car makers to have their cars come with heavy understeer.