R34 Rear end Floating/steering at high speed

[R31/4 GTT/S]

Help my R34 GTT is suffering pretty bad Bump steer/Floating at high speed (100 k's)

I recently changed my right rear wheel bearing thinking it was my problem but the issue persists. 
Example. Around 80 km/hr car feels fine. But when I get on the monash and reach 100 k's /hr if I hit any sort of bump pot hole the rear end floats to the side for a second and seems to mainly favour the rear floating to the left. It really don't feel good. 
Can anyone tell me
What's going on??
The suspension only has very slightly lower springs otherwise all else is standard. 
All help is much appreciated. 
Thanks guys 
Ash

[thebe]

Hicas rod ends worn? On my r33 they were totally worn out and hitting a bump at 100kmh or so was terrifying

[Duncan]

+1. Wear there allows uncontrolled toe changes at the rear which can be really interesting

[niZmO_Man]

In addition to the above:

What condition are your dampers?
Alignment?

[R31/4 GTT/S]

Haven't checked alignment yet. 

But where ans how can I tell if the hicas bushes are worn?

[R31/4 GTT/S]

In saying that the rear wheels are wearing out slightly more on the inside than the rest of The tyre. 

[thebe]

Mine were so worn I could wiggle the hicas rods by hand. Guess you could lift the back wheel(s) up and try and move them to see if there's play somewhere

[GTSBoy]

9 hours ago, R31/4 GTT/S said:

In saying that the rear wheels are wearing out slightly more on the inside than the rest of The tyre. 

This is a reasonable sign that your rear toe is not in control and does point to HICAS joints.  But that's only so long as you don't have excessive camber at the rear.

[R31/4 GTT/S]

Ok so where would I look for replacement parts??

[mikel]

Many install a HICAS lock bar, but if your ends are worn you may need to replace them 1st (I did mine 10 years ago and don't remember how it all went together)
Having a computer decide where to point the rear wheels isn't great IMO
HICAS is short for the computer saying "Help I Can't Actually Steer"

Mike

[thebe]

I installed a Driftworks hicas Eliminator kit and im happy with it.

[Dale FZ1]

On ‎10‎/‎25‎/‎2017 at 3:36 AM, R31/4 GTT/S said:

 

The suspension only has very slightly lower springs otherwise all else is standard. 
 

How much lower is the ride height?  Post up a pic of the car.

And confirming no aftermarket suspension arms in the rear?

HICAS is still fitted, or removed?

[R31/4 GTT/S]

I'll try get a pic of the ride hight up. But it's not that much lower than other standard 34's. 

Im assuming this caused the pre mature wear on my wheel bearing which was completely destroyed when I pulled the hub apart. 

Does anyone know a part number for the hicas bits that I would need to change?

cheers

ash

[R31/4 GTT/S]

Here are some pics I took under the car

[R31/4 GTT/S]

This shows the ride hight. Not to low in my opinion.

[R31/4 GTT/S]

[R31/4 GTT/S]

[GTSBoy]

Subframe bushes could possibly do with some love. ARB end links are probably fine.  But can't tell anything about the condition of anything else from those photos.

[R31/4 GTT/S]

Sorry for the Heap of Pics people.
But the first one shows the ride hight.
The second/third one shows where the hicas meets the hub.
Can Anyone please see where I have the problem.
It's driving my crazy. Driving at 100kl/hr and
Suddenly hit a bump. MORE on the left the car steers off and it's frieking scary.
PLEASE HELP

[GeeDog]

Jack up the rear end, so the wheels are off the ground. Hold one rear wheel at the 3 & 9 o'clock positions, and try and move it. If there is free play (ie you can make the wheel "steer"), get someone to move the wheel while you look & feel for where the play is. It is likely in the outer ball joints (where the Hicas tie-rods / steering arms join the wheel hub), but may also be in the inner tie-rod end - the joint inside the rubber boot where the tie-rods come out of the Hicas rack. 

I've just fixed this on my R33 by replacing the Hicas lock bar & tie-rods / ball joints with a Hicas eliminator kit. You have the Hicas rack rather than the lock bar, but the same tie-rods & ball joints.

 

Old Hicas lock bar with tie-rods

 

The remains of the old ball joints

Eliminator kit installed

Edited November 7, 2017 by GeeDog