Adjustable Spring Seat/Perch onto G series Diff

[JustenGT8]

Can you explain yourself more fully then? What I see is a spring perch with height adjustment (although in image used it's at max low but that's not the way it HAS to be I'm sure). By having that, you can corner weight the car and you have readily available spring rate options. The stock setup isnt corner weight friendly, and spring rate changes, well they're even harder to achieve...

The lowest height is dictated by spring length with this setup...this isn't a restriction with your conventional coilover and means you have to start with a minimum length and can only adjust up from there. This would also limit the range of rates you could use not to mention having to use a short spring would probably result in a non captured spring under droop.

Far easier just to use a coilover design located to suitable mount.

[Soarer21]

custom springs can be made for $120 a pair in whatever size, length and rate you like. why not do this and save the dramas?

Not quite as easy as wandering in and asking for them off the shelf is it?

The lowest height is dictated by spring length with this setup...this isn't a restriction with your conventional coilover and means you have to start with a minimum length and can only adjust up from there. This would also limit the range of rates you could use not to mention having to use a short spring would probably result in a non captured spring under droop.

Far easier just to use a coilover design located to suitable mount.

Ok, I understand what you mean however refering to the below picture. Top one is a conventional HKS coilovers from a JZX90 (although its copped overspray in black) and the bottom is an S15 HD coilover.
The HKS unit is never going to go lower then the spring length will allow based upon the available threads on the sleeve fitted. If the sleeve is fitted with an appropriate length coil spring so its positioned around midway along its length then you can go either direction up or down. With the right installation using a tender spring the primary spring can remain trapped however damper stroke will be compromised. Its still better then a lowered spring though wouldn't you agree?
Optimally a setup using the lower pictured coilover with adjustable stroke that affects neighter spring entrapment nor damper position is the best but even that can be achieved.
I intend to use a coilover similar to the lower one, but seperate spring from body. The problem with mounting the coilover as a whole off the rear of the diff housing is it introduces a twisting to the housing against the trailing arms which isnt really desireable. An extremely short assembly "could" be mounted on top but you'd still need to remove the upper spring mount and bring the whole lot up into the boot to give it sufficient movement.
The best compromise especially for a registered car is to make it adjustable as per the picture, if possible use a tender spring and go from there.

[Stefan]

Why not use something like this? Dampers with threaded body. Apparently works fine on xA6x live axle...



http://www.paradiseracing.com/SCcoiloverkits.htm

[ill-minded]

i think the main reason is that the upper and lower mounts would need reinforcement to be able to use those. but otherwise, they'd work fine

[Stefan]

This is what a lot of people say, but they don't appear to be reinforced at all. You also have to beat the bodywork a little to fit these, no big deal.

[LeeRoy]

Im assuming this is for a celica (first gen) and if it is then coilovers wont fit in the standard shock position without some decent reshaping/strengthening of the area.

Heres some stuff i wrote after getting some measurements from my TA22 (initially posted in the thread ive linked below):

The TA22 shock (well the one in mine) has an OD of 60mm.
The place where it lives in the body or the hole for the shock if that makes sense is 80mm across.
There is 170mm between the top of this shock cavity and where the cavity opens up.
Finally, a coil over type spring like the one pictured runs an OD of 90mm.
In the pic of the TTT coil over it looks as though there is only about 100mm (being generous) between the top of the shock, and the upper spring perch.

In short, they will not be a bolt in straight out of the box and mods will be required for them to fit.

So, this leaves a few options.

Option 1: Since the shock mount on the diff and the upper shock mount on the body need mods anyways a solution is to do the following. Cut the shock upper mounting off and trim it down maybe 70-100mm or even less so that the upper part of that coilover is sitting lower in the cavity and will have clearance between the sides of this cavity. Then just weld a plate back in there, brace it so its strong, and then drill a hole for the coil over to mount in there.

Since the diff also needs mods for the shock mount, cut it off altogether, space it down the same distance as you have trimmed out of the top, reweld it back on, then brace it. I'd probably also ditch the standard extending bolt thingy though and go with a similar mount to what is used on the body for the trailing arms and use a bolt instead as i think that would be alot stronger. Depending on the coil over and the range of adjustment you desire you could probably move the mount down less than what was removed up top and just wind the spring down.

Its probably a good idea also to move the shock mount inwards as well to allow more wheel clearance.

Option 2 (and probably the shitter option): Cut the hole out bigger in the body to accomodate a 90mm OD spring and reweld it all together. Probably using just some round tube steel or even some 110? (or bigger) RHS.

Keep in mind that since the shocks are mounted on an angle, as the diff moves they pivot so although the shock is only 60mm it requires a larger hole to allow for this movement.

Another option may be modifying the coil over itself and moving the spring down furthur but this will mean you lose some travel at either max or min extention ie if it moves 200mm top to bottom it might only move 150mm now.

There is already a thread on putting coilovers into a 22. Will make for some good reading.
http://www.toymods.net/forums/showthread.php?t=28830

[Soarer21]

Why not use something like this? Dampers with threaded body. Apparently works fine on xA6x live axle...

The issue with that is the spring loads now on the rear part of the diff and through experience of others with this setup you need to change to spherical bearings on the trailing arms as the normal bushes flog out very fast from the extra loads placed on them. Even the spherical bearings dont last as long as would be desired.

[Stefan]

OK. Probably a fine solution for IRS though?

[Soarer21]

Yeah, can't see it being an issue with IRS
I'm yet to look inside the boot with a tape and a keen eye but I may yet hole-saw the spring mount area in the boot and add a pipe in there extending the length between diff and mounting surface to allow a damper to fit.
I'm doing that exact thing to a TA22 shortly but its a little more of an extreme build then my own car.

[grotty100]

Coming from a motorcycle background where suspension settings are critical, all I can see in all of the pictures in this thread is spring pre-load adjustments.

Whilst spring pre-load adjustment can 'sometimes' alter ride height, it cannot be classified as "ride height adjustment".

To adjust ride height you must adjust the mounts for the shock or diff housing.

[oldcorollas]

if you wind the adjustors, you change the ride height... you could say it is changing pre-load (if the springs are captive), but.. the load on the spring is fixed by the weight of the car... the amount of compression will still be the same (although droop length is changed.. but pre-load when at full droop means nothing as wheel is off ground anyway)???

[roadsailing]

yeah same thing for motorbikes, load on the springs = weight of car. I can state with absolute certainty that changing the "preload" does raise or lower the car. Ideally you should change the shock position to ensure correct bump/rebound but if you do you homework right forst with spacers etc you can have a pretty good range over the ride heights you will try out (in a 20mm or so range)

I was a bit worried about the rear of my car being too low as i was using TRD competition springs, if it was too low i was going to turn up some alloy spacers and chuck them on top of the springs, they would be as high as the amount i wanted to raise the car.

As it turned out the rear height was fine, and i just adjusted the front to match.

[grotty100]

spring pre-load

Whilst spring pre-load adjustment can 'sometimes' alter ride height, it cannot be classified as "ride height adjustment".

To adjust ride height you must adjust the mounts for the shock or diff housing.

The following is an excerpt from the tech section of http://www.sportrider.com
It explains how to use spring preload as a tool to adjust ride height:

PRELOAD AND GEOMETRY
Getting the right angle on things
Now for the fun stuff. We know changing the chassis angle by altering ride height will sharpen or slow steering, and there are many ways to accomplish this. Up front, you can raise or lower your fork tubes in the triple clamps. Most stock bikes are limited with rear ride-height adjustments, but you can slip a shim under the shock's clevis (see Ask the Geek, Feb. '03), swap the dog bones for a set of adjustable arms or obtain a shock with a length adjuster.

Thinking back to step two, you can make a front preload adjustment to effectively raise or lower the front end-remember that, for the most part, preload simply moves the suspension's working range up or down slightly. You can use that fact to experiment with ride height and get an idea of what effect a change has. Make a loop or lap on your test road or track after adjusting the preload by two lines or four turns in either direction from its current setting. Note the change in your bike-as long as your suspension is not bottoming or topping out, the difference in handling you feel is almost certainly due to the change in trail that altering the preload brought about, and not any change in the fork's stiffness. Ride again with the preload set two lines or four turns in the opposite direction from the original setting, and note the difference.

If you found a setting you felt improved your bike's handling, continue adjusting preload in that direction. If you run out of adjustment range or are worried about bottoming or topping out your suspension (check your sag each time and make sure you have enough), then you can change the fork tube height and restore the preload closer to the middle of its range. Return the preload adjuster to its original setting. Lower the tubes in the triple clamps by 1mm for every turn of preload if you had to back the adjuster out; raise the tubes if you had to crank it in. Note that the tube height adjustment offsets the change in preload, and your bike will sit at the same ride height. Be sure to take copious notes on what you're doing, and at each change check that you have enough sag.

[Soarer21]

In the first picture depicted in this thread, which some seem to consider pointless I can pretty much guarantee the springs are not captured therefore they cannot possibly be preloaded and the only affect on height to be had is with either adjusting the upper spring hat to raise or lower the car or to change the spring out for a softer or harder spring rate.
Motorcycle dampers are from my experience all trapped spring situations with twist adjustment on one of the seats to allow a variance in ride height by increasing the preload or decreasing. With a constant rate spring the actual manner of compression will not be affected, only the resulting height change will be noticed.

[grotty100]

In the first picture depicted in this thread, which some seem to consider pointless I can pretty much guarantee the springs are not captured therefore they cannot possibly be preloaded and the only affect on height to be had is with either adjusting the upper spring hat to raise or lower the car or to change the spring out for a softer or harder spring rate.

The springs are captured by the shocks.

Motorcycle dampers are from my experience all trapped spring situations with twist adjustment on one of the seats to allow a variance in ride height by increasing the preload or decreasing. With a constant rate spring the actual manner of compression will not be affected, only the resulting height change will be noticed.

Adjusting the preload is exactly that........adjusting the preload. Yes, it can result in changed ride height, but as explained in the article, the correct way to adjust ride height is to move the forks up or down in the clamps to keep the springs within their correct operating range.