Ultraracing rear arb

[GrumpyTwig]

Has anyone fitted one?

Interested to hear if it actually made a perceivable difference as I've been thinking for a while that it might correct the bias towards understeer I've always felt running R888s.

 

[Yiannis197]

I have mate, very good mod indeed, you can feel the rear more planted and it also gives a noticeably better turn in. I had that fitted before fitting coilovers so it couldnt have been a coilover effect. Cheap but very effective mod, go for it.

 

[GrumpyTwig]

I have mate, very good mod indeed, you can feel the rear more planted and it also gives a noticeably better turn in. I had that fitted before fitting coilovers so it couldnt have been a coilover effect. Cheap but very effective mod, go for it.

Mmmm i was hoping to make the rear less planted! :w00t:

 

[Yiannis197]

More planted rear, less understeer though

 

[Seventh Seal]

Where can you buy one?

 

[A2ON]

When I have fitted RARB to cars in past it stiffens up rear makes it more stiff this "looser" and in turn reduces understeer.

 

[RalphyBMW]

Stiffer front ARB made the understeer much worse, so stiffer rear should help.

Stiffening the rear will usually reduce understeer in favour of oversteer, when it gets too much you start stiffening the front to counterbalance.

 

[930Tech]

When i was sorting the anti roll bars on my alfa i was told by the guys at balance motorsport to stiffen the rear if only buying one roll bar (i was buying one at a time) on a FWD car.

I fitted the ultra rear upper bar but can't honestly say i felt a difference, it does not fit to any of the suspension components just the boot floor and upper seat mounts.

The only real difference i could tell was that i could no longer get my spare wheel in the boot

 

[Yiannis197]

Stiffer front ARB made the understeer much worse

I agree to some extend, I wouldn't say that as a general rule though. You notice understeer if you go really stiff at the front and keeping everything else intact, Renault fitted a slightly (1mm more) thicker ARB bar to the 200 cup, I don't think they would if that caused understeer.

Back to subject, I did notice a difference after fitting RARB. But that is just me

 

[GrumpyTwig]

Thanks for the replies will have to take a look if i can get one. Just to clarify I'm only interested in the rear arb as fitting a front one would have the opposite effect I just wondered if it actually worked as expected.

For anyone interested this is aimed at the sim racer but applies the same to real life car setup http://www3.sympatico.ca/cbarnett/SetupMatrix.html .

 

[Andreas187]

When I stiffened the rear ARB on my Mini JCW it increased lift-off oversteer which was magic in slower corners. When the front started to push the slightest lift off would loosen the back end slightly, the understeer would stop and you could really play with the throttle to get the car round the corner.

BUT at higher speeds (over 70/80mph) you'd better not lift off or the car would snap sideways and was pretty dangerous so you have to realise there is a compromise.

I took my Renault on those same mountain roads with hairpin bends and once it starts understeering I can't lift-off the throttle to hang the back out to get it to turn in tighter as easily as the Mini but it is more stable at high speed.

 

[Andreas187]

Also, people tend to forget that you can dial in/dial out some understeer or oversteer simply with tyre pressures. Especially for track days, you need to find out what the hot pressures should be and not the cold pressures.

 

[GrumpyTwig]

Also, people tend to forget that you can dial in/dial out some understeer or oversteer simply with tyre pressures. Especially for track days, you need to find out what the hot pressures should be and not the cold pressures.

Already done this as much is practical. If you go too far either way you risk damaging tyres or causing unusual wear.

 

[A2ON]

Already done this as much is practical. If you go too far either way you risk damaging tyres or causing unusual wear.

What pressures are you running ( hot )

 

[GrumpyTwig]

What pressures are you running ( hot )

Depends on the weather a bit but usually set them to be 30ish hot at the front and a few psi more at the rear, then adjust slightly as I go depending on how it feels.

 

[A2ON]

FYI later half of this year and at the ring I've been running 36rear and 35 front hot - not seen any tyre degradation in over 6 days

Might be worth a shot

 

[GrumpyTwig]

FYI later half of this year and at the ring I've been running 36rear and 35 front hot - not seen any tyre degradation in over 6 days

Might be worth a shot

Will make a note, the tyres have worn well though so far but anythings worth a punt.