superstrut conversion

[chiksluvit]

Hi,
Has anybody done a superstrut conversion on their corolla before?
I'm currently in the process of swapping suspensions between two ae111, one has superstrut and one is standard mcpherson strut..
question is, does the steering rack need to be swapped over too? they are different steering racks, both with different tie rods.

reason for this question is that once i've completed the superstrut swap into the non-superstrut car, while still retaining the steering rack, we have found out that the steering does not re-centre when you turn, and in fact the steering keeps turning towards the direction you're turning to..
does the superstrut steering rack have some recentreing mechanism so i need to swap it over?
or is this just simply because the wheel allignment is out after the conversion? the front wheel of the superstrut recipient car is currently toed in quite badly... with like 4-5 degrees toe in

[oldcorollas]

what was the castor with the superstrut suspension?
castor usually gives self centreing

err.. did you adjust the tie rod ends to give normal toe?
as a minimum you shoudl set the toe in again, and at least check castor and camber

[chiksluvit]

yup, i found out during the conversion that caster of the superstrut is actually a lot less than the mcpherson strut...
which makes me wonder why my steering wheel used to self centre when i had superstrut, and now that the superstrut is moved to a different car it wouldn't self centre at all... well it only does when reversing, lack of positive caster of the superstrut explained it all..
toe wise... well i really couldn't be bothered with it in the end at 3am when i finished assemblying the superstrut... and we were still half way through the conversion to mcpherson strut for my car...

anyway, this is what i've found out
for the superstrut steering rack, it's variable ratio, and has angled tie rod ends
mcpherson strut rack is just a normal rack, its simple and works for mcpherson strut
but whether the rack makes any difference at all to the the self centring is beyond me, i dont understand why it would make such a huge difference from different racks..
or maybe there's something else? apart from the drive shaft, the rack is the only thing that's connected to the hub which was not changed

[oldcorollas]

the only function of the rack is to keep the steering arms a certain distance apart, and move them side to side.
the suspension design itself does the self centreing, either by the weight of the car, or by forces generated at speed due to ture angle...

are the frames of the cars identical? is it possible that there is some slight different resulting in different castor?
did the doner car have no castor either?
sorry, i'm not familiar with the systems but everyone else is asleep
massive toe may affect the natural tendencies of the suspension also.. might be worth giving the rack ends a few truns to set it.

what ydo you mean the SS rack sas angled tie rods? the racks are in different positions? did you swap over the cross-members/subframe also?

[chiksluvit]

the two cars were both ae111 levin/truenos... so yup same chassis
the sub frame and cross member of them were also identical so we didn't swap that either.

i had the superstrut suspension in my car before and it didn't really have much caster at all. the reason why i realised the difference in caster was when i put the mcpherson shocks into the shock tower of the previous superstrut car i realised how i had to lean the shocks a bit more to get it up.. so ya the original setup of the superstrut just simply didnt have much caster at all from the beginning compared to the mcpherson strut

the SS tie rods were kind of boomerang shaped, whereas the mcpherson strut just had straight tie rods... my guess for the boomerang shaped tie rods is to work with the variable rate rack, it's a bit shorter too so thats why the car had rediculous toe in when the mcpherson rack was used. the tie rod position on both hubs were at the same position when compared...

i guess i'll get the car alligned on monday to see if it'll improve it at all, the steering wheel is ridiculously off centre at the moment...

[TERRA Operative]

The superstrut suspension doesn't have any special self centering mechanism.
I don't think the steering rack is the problem, as when the conversion is done the other way, it isn't changed.
The massive toe in could be causing your problems, toe in increases straight line stability at the expense of steering response (opposite for toe out), that and the tendancy for FWD cars to try to pull the wheels towards toe in under acceleration could be compounding the effect.

It might also be worth checking your castor too. If you are running negative castor, that will tend to pull the wheels in the direction of the turn (like a trolley wheel going backwards). Running positive castor will pull the wheels straight after a turn.


Also be aware that the SS part numbers between AE101 and AE111 are different. Although you state that it's between two AE111's so that's not a problem. I think there was a difference between early AE111 SS and late AE111 SS, but I'm not sure what the difference actually is. Aparently the rear brakes were different in the late AE111 SS, where as the early AE111 SS rear brakes were the same as the AE111 macpherson strut.
Something vaguely like that.

[chiksluvit]

i see...
well i still dont know how the superstrut steering rack is going to affect the mcpherson strut yet since my car is still sitting on the hoist waiting for the new polyurethane control arm bushes to be put in...
the caster of the superstrut is about only about 1 degree positive when installed on either car, plus it's not adjustable anyway so i kind of doubt that was the problem.. so thats why i thought the thousand-dollar-superstrut steering rack would possibly be the cause by adapting the variable ratio design..
here's a picture of the rack gears from an ae101 superstrut equipped car, stole this from a jap website, you can see the variable ratio here

[TERRA Operative]

I wouldn't expect the rack to affect the suspension, just the feel of the steering action.
I know the SS setup has a slightly smaller turning circle, maybe due to the variable ratio or something.

I remember when I got my stock SS suspension aligned, about the only thing they could adjust was toe settings. I would say give the alignment a go and see what happens.

[chiksluvit]

hrm actually i thought the superstrut had a larger turning circle?
i'll give the alignment a try and report back...

[oldcorollas]

rack has no affect on self centring i'm pretty sure.... the different shape of tie rods is probably to do with having to kinda bend around th efunny moving superstrut bits... so in itself, no big deal.

if you use noormal rack with SS, then there might be issues.

the movement of the SS might also be non-liner, so the variable rack just makes overall linear steering?

[chiksluvit]

actually, that may be it... might be the none linear movement of the superstrut, that's how i felt anyway

the normal straigh type tie rod doesn't actually interfere with any parts of the superstrut, it has plenty of clearance so i'm not 100% sure why it needs to be boomerang shaped, maybe to assist with the variable rack and further compensate the none linear movement..

[oldcorollas]

nope, the bent tie rod acts like a straight one.. the end points are fixed.. it could be S or W shaped and still do the same thing...

the rack can have non-linear movement. the geometry of the SS joints can be non-linear, but the rack end and tie rod end are just dead drag links effectively.. the don7t contribute to anything, just connect the rack to the steering arm...

[TERRA Operative]

You cave checked clearance to the tie rod with the tyre on? Could be for clearance at full lock?

You're right re. turning circle. Damn late night.....

[JP]

I've put an AE111 superstrut steering rack into an AE92 before with mcpherson struts, was an excellent upgrade IMO.

[chiksluvit]

You cave checked clearance to the tie rod with the tyre on? Could be for clearance at full lock?

You're right re. turning circle. Damn late night.....

ya the clearance is fine... checked with wheel on/off and it doesn't hit at all...
might be extra rigidity? or possibly steering angle as superstrut's got different geometry