Adjustable Spring Seat/Perch onto G series Diff

[wilbo666]

The springs are captured by the shocks.

That assumption prbly ins't correct in the above system.

My assumption is that you would choose shocks that have enough length so that they aren't preloading the spring at the highest ride height that you want to run.

As a result you will live with the fact that at lower ride heights the spring will no be 'fully' captive (but it should be due to the design of the threaded sleeve extending down into the spring). Or you could install tender springs...

My thoughts...

Cheers
Wilbo

[grotty100]

That assumption prbly ins't correct in the above system.

My assumption is that you would choose shocks that have enough length so that they aren't preloading the spring at the highest ride height that you want to run.

As a result you will live with the fact that at lower ride heights the spring will no be 'fully' captive (but it should be due to the design of the threaded sleeve extending down into the spring).

Fair call Wilbo. I think we are all making assumptions here and perhaps getting a little bit off topic. I notice that Esteban never mentioned ride height in the thread starter. Perhaps he only wants to adjust spring preload.

In your colour diagram in post #7, are both the top and bottom mounts adjustable? I think if you adapted this idea to incorporate a coil over shock it would be a brilliant addition.

Grotty.

[wilbo666]

I think estebane will be looking for height adj only, with adjustability for corner weighting etc. I think he would like to avoid spring preload, but indeed we can wait and see what he has to say for himself!

In your colour diagram in post #7, are both the top and bottom mounts adjustable? I think if you adapted this idea to incorporate a coil over shock it would be a brilliant addition.

Grotty.

Adj at the bottom only...

What isn't shown in that pic I put up is that there is a guide internally to hold it all together.

I was simply going to use a cut down oil shock with the valving removed for my ap, but I don't see any reason that you couldn't leave the valving in place

Cheers
Wilbo

[Stefan]

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)

Bingo (unless you have coilovers with separate ride height and spring pre-load adjustments, a luxury most of us don't have).

[Esteban]

Yikes, thread got outta hand fast :-) Good discussion here though!

Yes I'm only after some height adjustability, not the ability to preload a spring, but thanks for the info grotty1000

UZA28 isn't a race car but I thought it'd be prudent to have some ability to change the spring rates/corner weights/ride height. I also wanted to modify the chassis as little as possible (The current shell is quite fubar and the plan would be to re-shell it eventually)

I don't need a great deal of adjustment, but I'd rather avoid compromising my front setup to match my rear setup iykwim. Doesn't feel right.

I'm quite happy to modify the diff mounts as I have to do that anyway. I realise the upper spring mount will need mods but shouldnt require strengthening as the shock top mount would as the cars weight is already taken at the upper spring mount.

Leeroy did you ever find Linden's AE71 pics? I'm keeeeeen to see them!

Thanks fellahs!

[takai]

Fair call Wilbo. I think we are all making assumptions here and perhaps getting a little bit off topic. I notice that Esteban never mentioned ride height in the thread starter. Perhaps he only wants to adjust spring preload.

In your colour diagram in post #7, are both the top and bottom mounts adjustable? I think if you adapted this idea to incorporate a coil over shock it would be a brilliant addition.

Grotty.

The theory is the same, but remember in bike shocks the forks are linked, and travel along the same plane. Therefore you can adjust dampening in one leg and preload in the other. Plus the air assisted shocks are vastly different to oil transferrance shocks.

The biggest thing in this case though is that the shock is not moving in the same arc as the deflection of the suspension (its angled inwards), which causes more issues than just preloading springs.

[oldcorollas]

i see what grotty is getting at, but i think in car situation, it is better to think of it as "shock length ajustment" as opposed to "pre-load".... since what you are really doing is changing where the shocks will be extended when loaded with car weight.

i guess you could also call "preload" "spring length limiting", since you are really just reducing the inital length, and thus reducing your rebound distance, and "length car will sink when car weight is put onto springs"

the fact that there is a preload on the springs when shock is fully extended has no effect on the actual properties of the spring or shock when loaded with car weight? ie, it is just changing extension of shock, and the point when your springs and shocks no longer do anything ..

ie, it is all just semantics

[Munki]

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?

Where do you get custom springs for that price?

cheers

Daniel.

[EVOSTi]

i have gotten mine from All Springs in Liverpool in the past, havent had the need for a few years tho. i know they sell 'jumboz' springs off the shelf but make their own too. i went in with two springs and said i wanted the bottom like the corona one and the top like the sprinter one for when i did my hilux brake conversion years ago, i think there is an atricle on the old forums.

but im sure if you try the yellow pages or something there are plenty of places that make springs, ive heard of other people gettin them made in vic and qld.

[PULSE]

Whats the big problem with getting the mounts reinforced? The bottom one certainly wouldn't be too difficult, the top one might be a pain to get to but if you remove the fuel tank and back seat there should be plenty of access?

EDIT: woops i didnt read the second page, so im replying to what someone else said a while ago.

[takai]

i see what grotty is getting at, but i think in car situation, it is better to think of it as "shock length ajustment" as opposed to "pre-load".... since what you are really doing is changing where the shocks will be extended when loaded with car weight.

i guess you could also call "preload" "spring length limiting", since you are really just reducing the inital length, and thus reducing your rebound distance, and "length car will sink when car weight is put onto springs"

the fact that there is a preload on the springs when shock is fully extended has no effect on the actual properties of the spring or shock when loaded with car weight? ie, it is just changing extension of shock, and the point when your springs and shocks no longer do anything ..

ie, it is all just semantics

The thing to note is that most car shocks have a stroke longer than the exposed length of the shock. I.e. their stroke is longer than the amount of suspension travel you have. I know for my Tokicos in the AE86 they have a 140mm travel range with only 100mm of that being usable before the chassis hits the ground.

Bike shocks on the other hand (because there is nothing to foul, and normally no or minimal bumpstops) can bottom out over rough terrain (and since Grotty is talking about adjusting the triple clamps im assuming either DH or MX), and when you change preload to adjust height then you are changing the shock's ability to dampen as it compresses. BIG issue for DH and MX shocks (and trust me, popping Boxxers was not a fun experience), but not such a big issue for cars, as there are other factors to limit suspension travel outside of the range.

Caveat Emptor: Im assuming here that the OP and anyone modifying suspension to this degree will have reasonably thought about stroke length of shocks, and so will be using short stroke shocks. All those VP commys you see bumping along the ground bouncing away, well thats the end of their stroke range....

[Munki]

Cheers for the spring info EVOSTi

I think the adjustable perch would be a good idea if your trying to setup the ideal corner weights. The coilovers would be great if you want to change springrates all the time or you want to put your previously useless rear strutbrace to use But otherwise why bother?

[brett_celicacoupe]

i reckon pushrods and bellcranks would be sweet.

probably a bit of work though

[Esteban]

i reckon pushrods and bellcranks would be sweet.

probably a bit of work though

I don't want pushrods in any of my cars

[wilbo666]

I'd have an LS2

Cheers
Wilbo