Snake oil??!!

Tell that to the identical fabia that was following me around a curve a couple of years ago - my only handling upgrade at that time was a rear ARB. He followed me exactly matched in speed and line and lost control (rear end came out). Must've been a shock for him, very nearly going off the road...

Bas

But that could have been down to technique or tyres or suspension. I must say the majority of the 'testimonials' I read prior to starting this thread talked about improving the handling in low-speed sharp bends like roundabouts and junction, and now people seem to be extolling their virtues as high-speed racing mods... :confused:

@ZS, the RARB on your Astra pivots around mountings on the chassis, so I can see how that works, based on...

@ Kaiser_b, my point about the FARB is that it creates a link between the chassis and the suspension which means that it needs to pivot in order to make the outside suspension compress relative to the chassis in a bend. If it wasn't attached to the chassis, it wouldn't have a pivot point independent of the suspension so would give you something resembling a live front axle (which is a parallel that Ken drew much earlier in this thread...)

I am prepared to believe their efficacy as a brace based on other people's experiences; I'm now more questioning whether it's necessary to give the cosmetic appearance of a drop-linked ARB, when a hefty piece of girder will do. Maybe it's my Bauhaus sensitivities that make me mistrustful of unnecessary garnishing of functional kit... :ne_nau:

Based on suggestions I made in a previous post about developing a simple brace, maybe the way is open for pikey mod #4!

The ARB has to be attached to the trailing arms to get a differential movement one side to the other in roll with a trailing arm (pure trail, semi-trail, torsion beam...). You could attach it to the trailing arms at 2 points each side with the same effect, or get a better decoupling of the roll and bump moments by fixing the pivots to the chassis.

The droplinks are there primarily to prevent mechanical binding of the mechanism as the rear suspension moves.

In practice, minor differences in the centres of the ARB fixings and the axle fixings means they'll tend to rotate in slightly different arcs. This is before one takes a twisting beam into account.

Also, as the suspension moves in cornering, one rear arm moves up, the other moves down, effectively increasing the distance between the wheels. The bushes on either end of the droplink flex and allow a smoother movement.

Main drawback with any droplink is that which afflicts the Fabia front ARB. i.e. they wear out and start knocking.

You can play with droplink lengths and with the Whiteline bars, the effective bar stiffness, by plugging them into different holes in the bar ends.

J.

I am prepared to believe their efficacy as a brace based on other people's experiences; I'm now more questioning whether it's necessary to give the cosmetic appearance of a drop-linked ARB, when a hefty piece of girder will do. Maybe it's my Bauhaus sensitivities that make me mistrustful of unnecessary garnishing of functional kit... :ne_nau:

Based on suggestions I made in a previous post about developing a simple brace, maybe the way is open for pikey mod #4!

Different manufacturers have approached the design in different ways. In my experiance of both Whiteline and Jabba I have found both to work quite well with the Jabba having the edge on the track for the more discerning driver and the Whiteline having a little more flexibility for road. I don't think the Drop links on the Whiteline are cosmetic and as mentioned they add a little functionality to the bar which is something Jabb bar doesn't have (It's either on or off and for some people it's a bit sharp)

The Jabba bar IS a hefty piece of girder with no drop links and as this is the ultimate in terms of performance (And price....) when it comes to Fabia RARBS it's far from a Pikey Mod!

In practice, minor differences in the centres of the ARB fixings and the axle fixings means they'll tend to rotate in slightly different arcs. This is before one takes a twisting beam into account.

This is exactly my point. The RARB cannot move independent of the rear suspension as it's only attached to the rear suspension. Like I say, I buy the brace argument, and like any other brace (strut brace, for example), you surely want it to be as rigid as possible to resist the tendency of whatever it's bracing to flex...???

Interesting to hear that the Jabba one is more like what I was talking about - as shown here (as demonstrated on Shifty's motor when you click on the thumbnail to get a bigger image!)

This is exactly my point. The RARB cannot move independent of the rear suspension as it's only attached to the rear suspension. Like I say, I buy the brace argument, and like any other brace (strut brace, for example), you surely want it to be as rigid as possible to resist the tendency of whatever it's bracing to flex...???

Interesting to hear that the Jabba one is more like what I was talking about - as shown here (as demonstrated on Shifty's motor when you click on the thumbnail to get a bigger image!)

The connections between the trailing arms and the rear beam are not rigid joints, so there is some independance of movement of the rear wheels. Does that cover your query?

The connections between the trailing arms and the rear beam are not rigid joints, so there is some independance of movement of the rear wheels. Does that cover your query?

No, because they're as rigid a connection as a single pressing can be (or presumably two pressings welded together). There's a pic of one off a Corrado here, which is obviously a different car, but works on the same principle.

And while there might be some flex along the trailing arm between beam and hub, surely it's that flexion that you want to stop, and putting a flexible link in there won't be very efficient at that? This is why I'm so interested to hear / see that the Jabba one is just a solid bar, and also that it's so much more effective (although possibly too much so...)

There is no such thing in real life as a "perfectly rigid joint" which you are assuming. Accordingly, there is some independance (but not complete independance; claiming that most VAG FWD cars have independant rear suspension is wrong; semi-independant would be about right) of movement between the 2 wheel ends of the assembly.

.

see that the Jabba one is just a solid bar

if it were made of a normal steel bar you would make he rear beam so stiff there would be no flexion at all which would make the car very tail happy due to the fact it has no 'give' in the beam.

this rarb or indeed any arb is made from a special grade of spring steel of at least SAE 5160 grade which is them heat treated and tempered after forming

Ah well, maybe that's it. As I say, looks like Jabba had my take on things before I even did, so I'm happy to leave the debate where it now is...

Good on you for asking the question though. Makes interesting reading and debate.

And remember: Just because it's a "well known fact" doesn't mean it's true