Shocks (dampers) and the AE86 (Part 2)

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Shocks (dampers) and the AE86 (Part 2)

Postby jondee86 » Thu Aug 28, 2014 1:47 am

As the factory front shocks are open oil filled type (similar to dirt bike front
shocks), replacing them means converting to sealed cartridge shocks.


Remove the strut from the car, undo the gland nut, pour out the oil, extract the
factory shock, and fit the replacement full length cartridge using the new gland
nut that came with the shock. Put the strut back in the car and job done. If you
need more information on how to remove and dismantle the strut, read this post…
(thanks to ZINCHOTRAN)

In the back it is even easier. Unbolt the old shock and bolt in the new full length
one, taking care to put all the rubber bushings and shaped washers back the way
they were before. You can use any shock listed in the manufacturer’s catalog as
a replacement for the factory shocks in the AE86 GTS Corolla. Congratulations,
you now have fresh new shocks that will work with your OEM springs or with mild
lowering springs. Perfect for a daily driver.

Don’t we all ;-)


And at this point things become a bit more difficult and a bit more serious.
Done the proper way, you can be slammed and still have a car that handles well
and is safe to drive. Done the wrong way, you can end up with an evil handling,
hard riding car that has you dodging manhole covers like they were landmines.

If you are into DIY you will shorten the front struts, get some TRD RACE springs
in your choice of rate, and install short stroke shocks that are matched to the
spring rate. You will also need to look at various other suspension mods to try
and correct the suspension geometry you just screwed up by slamming the car…
RCA’s, adjustable panhard, adjustable trailing links and modded bumpstops.

I’m going to break a few hearts here, but coilovers really only do two things,
and neither of them has anything much to do with performance. First, by using
a smaller diameter spring, they move the spring and perch away from the wheel.
This allows the fitting of REALLY wide wheels and tires on under-powered cars :roll:
And second, they allow the height of the car to be adjusted from low to stupidly
low. On the old style DIY coilover this was done by winding the spring perch up or
down. This would either preload the spring or allow it to become uncaptive, neither
of which is good. Coilovers also allow you to corner weight your car, which is
something serious autocross guys might find useful, but is kind of meaningless
if you have a couple of passengers in the car and a keg of beer in the trunk 8-)


Note how lowering the car with these coilovers will result in the spring becoming
uncaptive at full droop, which means that keeper springs will be required.

It’s not all bad news though. There is a huge range of small diameter coilover
springs available for your DIY coilovers, and by experimenting with spring length
and rate, it should be possible to get your car at a height you like without
preloading the spring. Because you now have much stiffer springs and reduced
suspension travel, your shock insert selection should include some provision for
rebound adjustment. This will allow you to adjust the damping to control the

Fortunately, most of the newer style store bought coilovers have a separate
adjustment for height which does not preload the spring… much better ;)


And decent store bought coilovers will have a thrust bearing at the top to avoid
winding up the spring when steering. They will also have external adjustment for
the shock, either at the top or bottom depending on the design.

… as the roads are crap where I live. Sorry dude, the Laws of Physics are against
you on this one. Soft springs require a decent amount of suspension movement
to stay off the bumpstops. Going low means you don’t have a lot of suspension
travel, and therefore you have to use stiff springs to stay off the bumpstops.
So you can have soft and long, short and stiff… but you can’t have short and soft.
That is why pretty much all store bought coilovers have 8/6kg/mm springs.

When your car hits a bump the suspension moves up and down. If the bump is
big enough, you will use up all the available travel, and the moving parts will try
and bend whatever it is that stops them moving. Steel on steel makes a lot of
noise and creates a big impact. To soften the blow, rubber or urethane blocks/
buffers/collars are installed at the critical points. In the AE86 they are inside the
top of the rear springs, and around the top of the spear (rod) on the front shocks.
They are there for a good reason, and you should think carefully before removing
or cutting them.

Dang... gonna have to have a Part 3....

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.