Giulia Rear anti-roll bar

[Andrew]

Experienced GTV racers tell me to put on a big front bar, and leave off the rear bar altogether. I'm not sure if the Giulia sedan wheelbase and weight distribution is different enough to alter that advice.

Andrew Watry

[genericwood]

It is really difficult to talk about what type of sway bar to run without discussing spring rates. Both contribute to roll stiffness and the amount of weight transfer that occurs at each end of the car. If you are getting oversteer due to too much roll stiffness at the rear, you could leave the rear bar on and increase the front spring rate or bar size. Or you could soften the rear springs or take off the rear bar.

My GTV handled quite well with the rear bar installed. But I recently increase the front spring rate significantly and think I might have to increase the rears to keep it from being an understeering pig!

Erik

[yng]

I think the main characteristic of the sedan compared to the coupe is that with a shorter wheelbase and higher/more forward centre of gravity, it tends to be more stable (i.e. reacts less to the tail being unsettled) but also rolls more at the front, which promotes understeer to the extent the front end is not stiff enough to keep the desired tyre to tarmac angle.

Erik, interested to hear that a rear anti-roll bar worked for you. What were your spring ratings/front bar, and did you have an LSD?

There is possibly a difference between adding a rear bar versus increasing rear spring rates. A sway bar increases wheel stiffness both in bump and rebound, while an increased spring rate simply resists bump. In other words, I would have thought a sway bar would increase the tendency of the car to pick up its inside wheel, as the bar would act against the "droop" of the wheel.

[Shaun C]

Quote:

Originally Posted by yng Shaun, by the way, did you ever take off that rear anti-roll bar, and if so what are your thoughts on how the car behaved as a result? cheers Yushan

[yng]

Have a look here, that's with the 29mm bar and 650lb front springs

Sideways super

Below is another pic from the back immediately post-apex under full gas. You can seen the degree of roll at the back relative to the front. But also the slightly greater degree of front versus rear slip despite power application, so there is still some balancing to do.
however, I think camber is ok just looking at the front wheel angle.
(and yes i know what the number plate reads )



I'm actually going to reinstall my rear bar this weekend and see what happens!

Your description of how you car handles sounds like what I'm experiencing, though I get plenty of hairpin understeer if I go in too hot because my tyres are truly rubbish. Removing the anti-roll bar increases rear traction but also reduces front traction, because more weight transfer takes place up front. No such thing as free grip!

[Shaun C]

Hi guys

Thought I'd do a quick update on the recent changes I've made to my suspension set up and the results. A while back (see this thread and the following thread Link) I mentioned that since removing the rear anti roll bar I was experiencing serious shudder under hard braking. Well after asking around, we figured it was due to tired rear suspension bushes and I decided to go about replacing them. After hearing many different opinions on the types of bushes to go for, I decided to go for the harder rubber trailing arm bushes (not polyu), standard T bar end bushes, and polyu (Superflex) conical bushes.

The old bushes were so bad that I could actually twist the trailing arm with my hand, and the conical bushes were extremely perished. Anyway, it made a world of difference to the car - good or bad??? Probably a bit of both actually.

Now the only other changes to the car in the interim was moving the battery from the engine bay onto the floor inside the car and resetting carbs/checking fuel lines to stop splutter through left hand turns.

The short story - 1.5 secs off my best lap time (actually won my class on the day ) and consistently much quicker.

The long story - reduced understeer, more oversteer - a little scary at first but really fun and easy to induce and control when you get the hang of it. Also WAY more wheelspin when cornering. Now I was warned against this as the stiffer bushes will tend to lift the wheel more when cornering. The change was so drastic I thought my LS diff had packed up. I only have a standard LS and it could be quite tired so we may need to look at that and get a bit more lock there. Then again I was also going quicker than usual so maybe pushing the car just that much more. As for shuddering under hard braking? Haven't felt any yet, but I must admit I was braking a bit earlier than I have been in the past - still need to build up a bit more confidence in that respect after my total brake failure last time out.

So who knows if it's worked? There are just too many variables in this game (admittedly some under my control, but some aren't) but I'm happy with the change anyway. Now I need to decide what to do on my road going Giulia... decisions, decisions...