looking for handling advice, castor, bushes etc etc

[hnygt4]

hi, so had my 3.0si roadster a year or so now, apart from a window reg, water pump and 3 coils dying (the coils the same day) its been a brilliant daily driver, done about 15k in it so far but looking to make some changes.
While the ride is really good and very stable at speed it just doesn't quite cut it in the corners, factory bias towards understeer and lack of front end feel ruin what could be a very good sportscar.
I've picked up some poly RTABs and lolipop bushes and was planning a csl geo setup, but the bushes I have aren't offset for castor.....do I swap these bushes for the offset ones?
the car will be going for an alignment once these are fitted, now I have searched but finding conflicting info so I'm after input from people that have used csl specs on a normal Z with factory M-sport suspension, or any other alignment settings that have improved handling.
I've read people saying 0 toe on the front made improvements and taking out allot of rear camber made it more neutral.
is the added cost of the castor offset bushes worth it?

also I've heard of people using M3 ARBs, anyone who's done this, has is helped reduce some of the front end body roll without inducing more understeer??
i'm hoping improving the handling will make up for what it lacks in the power department and keep me amused maybe even start doing track days in it.

 

[jpvd]

i personally wouldn't mess with the camber/alignment settings....all i would do is replace all the bushes for new - poly ones if you like (don;t think they make that much difference - other than they last longer - but does charging 4 times more than standard ones work for me???), but depends how much you want to spend. front and rear upper strut braces work well and an adjustable coil over kit.... thats my opinion...others may disagree!..

 

[brillomaster]

have you already punched the pins to add a bit more negative camber to the front? thats easy and free!

personally i run a slightly wider front tyre on trackdays for better front end grip - i run 245/35/18 front paired with the standard 255/35/18 rear - handles great IMO.

 

[Steve84N]

Do the following:

- Offset Z4M bushes, definite improvement in mid corner grip
- Max front camber by pulling the pins
- Min rear camber but not less than one degree if it'll go that far
- Parallel front toe or just 0.01 per side
- Not much rear toe, maybe 0.03 per side
- Front tower strut brace
- 10mm spacers all round (assuming standard wheels)
- Change to 245/40/18 rear tyre
- Replace other bushes as budget allows

 

[hnygt4]

i personally wouldn't mess with the camber/alignment settings....all i would do is replace all the bushes for new - poly ones if you like (don;t think they make that much difference - other than they last longer - but does charging 4 times more than standard ones work for me???), but depends how much you want to spend. front and rear upper strut braces work well and an adjustable coil over kit.... thats my opinion...others may disagree!..

thanks for the input, I'm not going to be stiffening the ride with coilovers as this is my daily, I just want it to feel more lively on the road, it just doesn't 'bite' into the road mid corner, my other car has 12kg/10kg F/R coilovers as well as upgraded roll bars, polybushes etc, so this car needs to stay comfy, but at the moment it's hilariously outclassed by a 21 year old fwd volvo estate
I've been under the car to check and all the bushes are in good condition, it feels like it needs a choice few replaced to sharpen it up and the geometry is set very safely and understeery. i'll look into strut braces for it though

have you already punched the pins to add a bit more negative camber to the front? thats easy and free!

personally i run a slightly wider front tyre on trackdays for better front end grip - i run 245/35/18 front paired with the standard 255/35/18 rear - handles great IMO.

nope the car is completey standard at the moment bar wheel spacers and good tyres, I'll be doing this when it gets aligned though!

Do the following:

- Offset Z4M bushes, definite improvement in mid corner grip
- Max front camber by pulling the pins
- Min rear camber but not less than one degree if it'll go that far
- Parallel front toe or just 0.01 per side
- Not much rear toe, maybe 0.03 per side
- Front tower strut brace
- 10mm spacers all round (assuming standard wheels)
- Change to 245/40/18 rear tyre
- Replace other bushes as budget allows

ok thanks for that, that's pretty much what I was thinking, although I think I got 10mm F/15mm R spacers, I know that'll help induce understeer but the rear arches just needed it!!
I run rainsport3 tyres on both my cars and love them
I'd love to chuck some coilovers and a LSD in it but proper mods like that are reserved for the other car, which desperately needs a LSD and 6 speed swap :evil:

 

[hnygt4]

Small update, returned the lollipop bushes and ordered castor offset bushes, just installed them and been for a quick spin but couldn't really open it up due to traffic but does feel better, using powerflex black bushes which are ally housings with a small poly sleeve over the arm, seemed to give more feedback and steering is a tad heavier maybe. Not a huge difference but a step in the right direction to making the zed feel like it always should have ☺
Have rear trailing arm bushes here to install too but tempted to order or make the tool to do it first, don't wanna get myself stranded.
Anyone made their own? Looks like an old socket, some threaded bar and a handful of washers should do the job?

 

[Steve84N]

Good stuff.

I bought a tool off eBay for not a lot although after the job I'm not sure it had enough strength left in it to do it again!

 

[hnygt4]

Good stuff.

I bought a tool off eBay for not a lot although after the job I'm not sure it had enough strength left in it to do it again!

well hopefully it'll only have to be used the once! Can I ask what difference you noticed from changing them?

 

[Steve84N]

To be honest I did them alongside other things at the same time so not as identifiable. However, the whole car was just tighter overall. You should feel more connection with what the rear axle is doing.