What happens when you flip 3 out of 5 leaves, on an RT40Rona

[jfallen]

With the power upgrades occuring to the corona, something has to be done about the suspension, which was to say rubbish. Since I don't have a front subframe at the moment I started with the rear suspension. To my pleasent suprise RT40 coronas have 5 rear leaves (corolla's only have 4,) thus the the decision was quickley made to invert and clamp the bottom 3 leaves on top. This has the effect of flattening out the leaf stack (lowring the car) and making the stack much, much stiffer.

Results are as follows:

vs the new:


Installed the difference is obvious, it also became apparent that the diff has now moved backwards 2cm or so.



I'm yet to finish the second side, and I'll take some progress photos for the record.

Tips for First timers:

• -clean all threads with petrol, Turps or thinners, as they will all be gungy and this makes doing them up much easier.
  -Use plently of grease when re-assembling (I use Lanolin as it smells pleasent,) make it all slide together so much easier, and it also makes taking it out super easy if you need to. best bit it stops squeeks
  -Get a buddy to help, this is the first time I've done it solo, and in the clamping stage it's much more difficult. Also you can take both sides out at the same time, therein almost halving the total time.
  -If any through bolts are stuck when trying to dis-assemble, use the good old block of wood and hammer trick, this will prevent the thread from being damaged.
  -You'll need at least 2 jacks, I prefer vertical lift jacks like scissor jacks as the don't move around.

I'll also be installing some new gas dampers at the rear to make it the best it can be. Will be doing something to the front (not chopping springs) but will have to wait and see what is possible, since not much is made these days for the RT40.

Cheers
jordan

[stradlater]

I'm no king of suspension or anything, so I might be wrong, but isn't that a really bad thing to do to the vehicle dynamics?

[Cuzzo]

I thought adding more leafs will lower and stiffen it.

[jfallen]

it extended the wheel base, that a + on the stability side of things

it increases the rate, just the same as putting a stiffer spring in a more moderen car. You can add extra leaves, etc... but that cost $$, this is free and works great. If it's too low or too stiff you simpy dis-assemble and play musical leaves until you get a happy medium.

Cheers
Jordan

[JustenGT8]

works for me

[30psi 4agte]

I think you have gone tooo far. your leaf spring has no camber left in it and hence wont work correctly..

I have been here and done this about 10 years ago.

The best way to do it (Note: apart from doing it properly...I was young at the time and had no cash and only half a brain ) Is Turn your second leaf upside down and leave all the others the way they are. Keeping the springs in their original order. Ie longest at the top and working down too the shortest.
This will lower the spring quite considerably as the second leaf is a major one but still keep some form of useable camber in the spring.
You will have to use G clamps to get the spring into its shackles

Like i said i have been down this path and ended up changing the springs around as it was just shit.

This is a pic of my old springs before i went to the single leaf setup...... Notice the second leaf turned around.


This is one with the car on the ground...... Notice the is bugger all camber It is almost de-cambered which is bad..




I looked into leaf springs quite abit some time ago and was told im FAR better off using lowering blocks than resetting the spring once you start going that low..... You must have some form of camber in the spring for it to work.

If money is no option what they can do is ...... They turn the spring upside down and re-roll it so that the eyes are up the other way. This will set you approx 1-2 inches lower straight up with the same camber in the spring.
They can then reset the spring to go a bit lower... Unfortunatley you can only go till the spring is just off being straight though.

P.S i know money is almost always an option in most cases so id go the second leaf for now

[oldcorollas]

what you haev done is effectively pre-loaded the main spring.. but it might actualyl lower the total spring rate... since before you have say

A+B+C+D+E
now you have A+B-C-D-E... however, all are deflected more, but cancel out (otherwise the spring would be different shape).

i guess, in effect, what it does is to immobilise the part of the spring in contact with the reversed leaves, and only the free ends will flex to give any kind of suspension.
this might help with spring windup, but is similar to clamping coils together to increase rate in a coil spring system

[MWP]

Hmm, i wonder what effect that will have on spring wind-up during hard accel.
This would be my main concern...

[rms]

A leaf spring does not need camber to work 'correctly'
A flat rear leaf spring promotes 'roll understeer' as against 'roll oversteer' for a cambered spring.
With flipped leaves you introduce 'pre load' to the suspension with a falling spring rate once the pre load has been exceeded.

The major concern is the stress in the leaf/s carrying the pre load can exceed the yield point of the material and will fracture or sag.

Has been and is used on circuit cars with leaf rear suspension, is a major factor in chassis set up.

[jfallen]

I know I might have gone a bit too far, the best bit is it's a reversable modification, and as I've got 3 free leaves, there will be a happly medium in there somewhere. Cash was not the overriding factory in this, but mainly the point that I can change it back at any time in about an hour. If you get your leaves reset and you don't like them you're stuck.

We'll see how it goes, if it's crap, more tinkering will take place.
Jordan

[oldcorollas]

true..
can't be much worse than lockign the front half of spring solid against windup
it should be good against spring wind, as you are increasing the moment arm the wind up acts on.. instead of arm between axle and spring, it's now axle to the ends of locked centre part of spring...
if too low, you can start taking out the little springs to remove the reverse curve in the middle...
tinkering is good

[WDE_BDY]

Its an interesting area to experiment with. I actually had my leaves reset 2 inches lower on my KE70, wasn't really happy with the results and ended up removing one leaf (was too stiff as the rear of my ute is pretty light) and running lowering blocks. May still need to go lower but will just stack the leaves upside down (on top instead of below main leaf) so the leaves are not fighting each other.

Callum

[jfallen]

DisclamerI took this a little too far, but the process is the same when just flipping 1 or 2 leaves.

This is the 'How to" section:

After removing the leaf stack from the car it's bet to dis-assemble and give it a good clean to get rid of all the road grim.
it's also to give the retaining bolt and nut a clean with petrol, as it makes doing it up much easier.
to:
and

Now that everything is clean you need to chop down 2 of the slip pads in order for them to not slip out when you begin clamping.

after this is done smother them with grease.

Now it's time to begin the clamping process:
This is where it really helps to have a mate around, but it is possible to do it by yourself. In order to clamp the leaves together you either need a good vice, clamp or as I use vice grips. It'd be nice to have 4 sets, but I've only got 2. note 2 vise grips is a minimum
Without using a centering device (Screwdrivers work well) compress the stack and apply a vice grip to the end. If usng a vice or clamp you can simply wind them in. Once you've got the first 2 vice grips on place in the screw driver to centre the holes.

Continue to work your way in being very carful, as you're applying a great deal of preload to the leaf system.
Once youre done it should look something like this:

Now install the retention bolt and remove the clamping load:


Toss the leaf stacks back in the car using plently of grease to make it all slide together easily.

With the wheels on it became obvious that flipping 3/5 leaves was not such a bright idea, but at least it's a starting point (Tinkering to take place. It does however look hectic with about 35mm of travel before the bump stops. The rate has increased, but as has been noted the rate of the leaf stack will actually decreases as the stack compresses. This is not a desiable trate of a spring. This would be a great mod for a show pony that has leaf suspension.



Cheers
jordan

[30psi 4agte]

your right: it might not work too good but it does look tuff !

[oldcorollas]

i have a question....

what is the difference in deflection of the leaf when loaded by the car, with and without leaves flipped? does it deflect more or less with the flipped leaves (which would indicate an overall softening of rate?)