Superstrut Suspension, ST202 - ST205 suspention Options

[celi94]

In Europe we also have celica's with Superstrut Suspension.
Thats wy i'm sharing this information!


The ST205 GT-Four uses a system of front suspension design unique to Toyota. It moves away from the MacPherson strut used on all other Celicas and is much more complex. This system is used on the GT-Four, some Japanese spec Corollas and the higher spec Japanese fwd Celicas (SSII and SSIII). It was available in Europe on the Carina GTi and was an option on the ST202 (thanks Dirk for the info).

My understanding of the system is that the geometry does not give the same camber and castor changes during cornering that occur with MacPherson strut. Is it better? Well, it is different. There are reliability problems if maintenance isn't kept up, TTE had continual problems and I believe they swapped the rally cars back to MacPherson strut.

A brief description of MacPherson strut is in order. The Toyota system uses a lower A arm with rubber bushings front and rear. This has only one degree of motion (ie. it rotates on the bushings). At the outer point of the A arm is a balljoint which connects to the steering knuckle and allows for rotation (steering) and pivot (shock compression). The steering knuckle is rigidly bolted to the bottom of the strut. The whole strut turns when steering, twisting in the roller bearing in the top mount. Fairly simple and cheap, used by most manufacturers.

So what is Superstrut suspension? It is a hybrid between normal MacPherson strut and a multilink setup. One of the requirements of the design brief was that the system would fit existing suspension mount locations. Therefore the system can be fitted into export Celicas as well as the Japanese lower spec SSI! The late production cars even share the same subframe.

The photo below shows the lower part of the system. This consists of a front and rear lower arm, connected (by rodends) to a connector plate. The rear arm has a rubber bushing at the inner end (the only rubber bushing at the front except swaybar D-bushings), the front arm has a balljoint. This system allows the arms to pivot as the suspension turns.



The steering knuckle is quite different to that of the MacPherson strut cars. It bolts securely to the connector plate joining the lower arms (see photo below). The top end connects to the strut part way up using a balljoint (see red arrow in left picture and upper arrow in right picture below. The strut mounts to the body in the normal way, but the lower end is secured to the front lower arm using another pivoting arm visible at the right in the photo above. This arm is near vertical in the photos, it is actually about 150mm long and pivots at each end.



The photo of the assembled suspension below shows that the strut rotates minimally when steering ( the same amount as the front lower arm as it is rigidly connected). The steering knuckle moves instead. While the outboard strut moves rearwards slightly when the car turns in (turning left in the photo), it can be seen that the hub moves forward. But because of the strut movement the actual movement at the wheel is minimised.

The second photo shows the mounting points for the lower arms on the subframe.



All the info from: gtfour.supras.org.nz

[delusionz]

Very good illustration there, and a Celica with regular MacPherson would definitely not have been able to hold that apex as well as you have and be forced to decelerate and follow you on the outside.

On a side note, SS-III has different parts in the rear suspension setup to the regular SS-II, USDM GT, etc.

Btw Edophus aren't you from Australia? How did you get a real SS-III there? Since importing cars is a PITA there, wouldn't it be more logical to import a GT4 instead?? 98 SS-III holds a higher value than the 96 GT-Four.


EDIT: I just noticed someone said the SS-III has Helical LSD. It does NOT! No Celica comes factory with a Helical LSD, the closest is the ST205 GT4 which has a TORSEN rear diff.

All Superstrut equipped FWD Celica models also come equipped with Viscous LSD! And for that matter so does the Superstrut equipped GT-Apex, GT-Z, BZ-R Toyota Levin/Trueno models.

Unless equipped with the _AFTERMARKET_ TRD Helical LSD, you do not have it from factory.

Why is this? Because when a Helical LSD fails, the entire insides shatter and the car becomes undrivable either resulting in 1WD or a complete lockup of the wheels which cant rotate at all. Very dangerous to have happen to you while driving, and if you survive it's also very expensive to replace.

On the flipside, when a Viscous LSD fails, the diff simply acts like a regular open diff and the car can still be driven out the rest of it's lifetime.

The FWD Celica was never intended to be the flagship sports car for Toyota so the production cost and final showroom price could not be justified.

This post has been edited by delusionz: Mar 19, 2010 - 3:44 PM