Group A 23 Rear Arb

[blackscooby 0]

Video from my 1st timed run when the pressure plate fails.

 

Unfortuately its very washed out as I had the zoom far too wide so the white balance tried to make the inside OK whilst whiting out everything else

 

Still you can see a bit ....

 

http://www.btinternet.com/~blackscooby/vid...clutch_goes.wmv

 

Right click and save as.

[C_W 3 1 Cars]

I have a 23mm rear anti roll bar too. It makes it turn it/react much quicker, though at first it seems to make it feel more nervous you get used to and it just seems more responsive.

 

At first I thought it might have affected the balance of the car as it seemed to be less fluid(?), I think you just need to get used to it but round some corners it just feels a lot more stable.

 

Mark; does your anti roll bar use the original 205 end plates?

[blackscooby 0]

Mark; does your anti roll bar use the original 205 end plates?

Yes

[Wurzel 16]

Blackscooby,

I heard you start the car in the paddock, you looked busy so I didn't interupt. It sounded like you had either a different engine other than the 8v. At first I thought it might be the 16v as I haven't heard that either. On reading your website though I find it was an 8V, very nice.

 

Good to hear C_W backs up the handling claims of the thicker ARB. I should imagine it would make the car feel different. When I renewed my sus it felt really different and took a while to get used to.

 

Cheers

[saveloy 8]

Glad you are very happy with your purchase blackscooby. I have been using a 24mm item for almost a decade now. It is fantastic & certainly complements the usual suspension upgrades. In fact,it was fitted to mine as a cake & eat it mod. Since,in a straight line,the ride is not compromised.

[jackherer 543]

What we did find when we took the old ARB bar out was that the bloody thing was 17mm... not even 19mm.  I won't comment on this further until I have taken some action myself.  Needless to say it was a new beam not that long ago so I'm not best pleased.

(cough)ssp(cough)

 

from what I understand a lot of their beams are supplied at excessive ride heights too, I imagine they have resorted to using parts from base models now there is a shortage of 1.6/19 beams.

 

I imagine trading standards would be in a position to take action in a situation like this. If you were running a standard road car then the wrong arb would technically count as a modification and would invalidate your insurance.

[fiji bob 0]

Glad you are very happy with your purchase blackscooby. I have been using a 24mm item for almost a decade now. It is fantastic & certainly complements the usual suspension upgrades. In fact,it was fitted to mine as a cake & eat it mod. Since,in a straight line,the ride is not compromised.

does it make the car more nervous in the wet or isnt it affected too much?

[saveloy 8]

fiji bob,no not at all. Increasing the ARB size doesn't increase the stiffness of the suspension. So,there are no adverse wet weather reactions.

[Adi 0]

Increasing the ARB size doesn't increase the stiffness of the suspension. So,there are no adverse wet weather reactions

 

Eh????

 

The increase of the ARB increases the roll stiffness.....which in other terms is uprating the suspension.

Also anything that is going to increase lateral movement....as the ARB does.....is going to make the tyre work harder. As such...in the wet....the tyre will not grip as much. Thay is why no matter what level of motorsport.....wet whether settings will always be softer than dry whether settings. That is so there will be more roll which helps the tyre in the wet.

 

The main thing the ARB will make worse in the wet is lift off oversteer. Again that depends on how far anyone is going to push the car in the wet. That is easily reduced with the uprating of the rear axle bushes.

[fiji bob 0]

im not really familiar with the rear beam whereabouts are the bushes that could be uprated?

[Adi 0]

whereabouts are the bushes that could be uprated?

 

They are the axle bushes that basically hold the axle in place.

 

I wouldn't be suprised if there are a few replies disagreeing with the axle bushes and lift off oversteer theory. I've had it b4 (NR )

 

But like I mentioned before......you will have to be pushing the car in the wet for there to be any adverse effects.

 

Get the bar and try it first. Hopefully you won't have any probs.

[fiji bob 0]

wll im going to be buying a rear beam from a scrappy to rebuild so i would be replacing the mounts do you think grp n mounts would be much of an improvement?

[Adi 0]

do you think grp n mounts would be much of an improvement

 

It would certainly help reduce the rear axle twist to a minimum and make the handling more predictable.

[fiji bob 0]

anyone want to buy a couple of brand new standard rear mounts?

[Adi 0]

anyone want to buy a couple of brand new standard rear mounts?

 

You want to try them you know

 

I have heard of a few people that have sworn by the standard rear mounts. It's really down to personal opinion. But if I were you....I would try the new standard rear mounts......and if you experience any extra lift off oversteer with the uprated rear roll bar.......then try some Grp N mounts.

[fiji bob 0]

your probably right

[saveloy 8]

OK,badly worded. What I meant,was that the rear spring rate is unaltered. Since,this is governed by the torsion bars.

fiji,I wouldn't go for an uprated rear set up,without the Gp N bushes. However,given that the beam bushes are kept standard,but the rear bushes uprated.on most road set ups,it does mean a change in fundamental mounting set up. Many engineers would say the beam bushes need to be uprated along the same lines to keep a consistent phase. Regardless,the questionable approach works very well & I cannot fault it.

[red 0]

I think a lot of problems encountered with lift off oversteer are down to how you drive the car and the way the throttle is applied, with respect to the above I agree with Savaloy in that you would be better fitting the Group N mounts along with the ARB, I use this set up and it transformed the handleing of the car running standard torsion bars with Bilstein rear tarmac shocks it seems a lot more predictable and my times at the sprints have tumbled as I've got use to driving the car, but in the wet at Anglesey last month the car was nearly undrivable any lift off and the back would begin to drift out, it was a particularly bad surface but again it can catch you out if your not aware of it.

 

Regards Russ.....

[GtiMad 1]

I think a lot of problems encountered with lift off oversteer are down to how you drive the car and the way the throttle is applied

 

Agreed.

 

I never get a problem with it, apart from occationaly on a wet track when you make a mistake or miss an apex or whatever. Nothing quite like the crainer curves, sideways, in the pissing wet to open your eyes that extra few mm

 

On the road though I never get it (unless it's invited ) it has to be one of the things about the 205 is the way you can steer/balance the car on the throttle.

 

Sod it, I am going for a drive.

[C_W 3 1 Cars]

OK,badly worded. What I meant,was that the rear spring rate is unaltered. Since,this is governed by the torsion bars.

fiji,I wouldn't go for an uprated rear set up,without the Gp N bushes. However,given that the beam bushes are kept standard,but the rear bushes uprated.on most road set ups,it does mean a change in fundamental mounting set up. Many engineers would say the beam bushes need to be uprated along the same lines to keep a consistent phase. Regardless,the questionable approach works very well & I cannot fault it.

The rear spring rate is unaltered by the fact that the "springs" are left the same BUT in theory with a fatter roll bar you are joining the springs together more meaning they a less independent, so a bump on one side will make the other side react too, this making it a bit more skittish and why it will make it trickier in the wet. So it basically restricts how well the suspension can work which is obviously more noticeable on a bumpy road than a smooth one.

 

I bet in the world of suspension design, anti-roll bars are thought of as a cop-out, but hey they are cheap!!!

[Adi 0]

I bet in the world of suspension design, anti-roll bars are thought of as a cop-out, but hey they are cheap!!!

 

Not at all!!

 

The anti roll bars do a job all on its own.......but does combine with the springs, whether they are coil or torsion.....to provide roll stiffness.

 

If the springs did all the work to provide the roll stiffness......the rate would be that high........the tyre would be bouncing at every little bump. There must be complaince with the spring to allow the tyre to follow the surface of the road/track.

 

The roll bars then take the slack up......so to speak......and then provide the rest of the roll stiffness. But they must be balanced in rate.

 

BUT in theory with a fatter roll bar you are joining the springs together more meaning they a less independent, so a bump on one side will make the other side react too, this making it a bit more skittish and why it will make it trickier in the wet.

 

 

Whick is the exact reason why the roll bars and springs have to be balanced. If the roll bar provides too much roll resistance.....it can start doing the job of the spring. Then the symtoms will be as described above.....with the rear hopping over bumps etc.

[red 0]

ADI you obviously know your stuff mate ,it would be good if you got time you could do an article on suspension set up, I know Dave with the TT 205 would like to pick your brains as would I, I'm of the thought that if it's adjustable then you'll mess around with it to much and never find a setting that works, and the big factor of if I do this what should happen, with my current set up the car is flying with the streetline kit at the front and the rear set up as above, I've got SBC phase 1/2 for next year but I'm thinking do I want to change somthing thats working for me! a few lads in the paddock reckon leave it alone, I wonder how much set up is reliant on how you drive or vise versa.

Some questions I would like to know is you find time are the following.

 

How does neg camber, Toe in, castor angles, affect things. Would it be possible to make the front ARB on the 205 adjustable, i.e from standard to softer for the wet.

 

I know there are a lot of questions but some brief ideas on what these changes do would be very helpful, I hope you don't mind me asking the questions.

 

Any chance of pinning the topic if ADI doesn't mind answering a few questions etc.

 

Regards Russ....

[Adi 0]

I don't mind answering them.....but don't want to hijack someone elses thread.

 

So if can be sorted????

[jackherer 543]

you can always start a new thread if you like...

[NickR 10]

FYI.

 

Skip Brown left my std rear bushes in as they were new (rebuilt the beam a few months before), std bushes are stiff enough for the road, main thing about the group N beam bushes is that they dont split like the OE ones will, stiffness is an extra bonus, but not needed on a road car.

 

My car handles so well balanced in the wet, infact its more predictable in the wet with the phase 2 than without.

 

I think that one problem is people put stiffer dampers on the rear then a stiff roll bar, when stiffer torsion arms are also needed.