Im off down to awesome gti's detailed bash at the end of the month and im thinking about buying a full set of poly bushes for the suspension on my fab, mostly due to them all being worn....

Has anyone else done this? any tips or other bushes to get?

Im also thinking about a rear anti-roll bar, mostly due to the stance of my car but are the worth getting and will they work on a low car?

Any advice or pics would be great

Thanks

TomTom

All worthwhile doing ! Had mine done at awesome too. The rear arb will improve your handling greatly if you drive hard.

its mainly because my cars so low with the a8s on, il defo go for the bushes

Rumour has it that if you already run quite a stiff setup the rarb isn't as noticeable. But I have one on my car at standard ride height and the difference is amazing. I love it, I think I'd buy one at the same time as I buy a car in future!

A lowered car will roll MORE than a std height one as the roll centre migrates, so arb will have big benefit.

I decided to fit std bushes when my console ones needed replacing. All things considered, such as increased NVH, ride quality, higher maintenance, and the fact Skoda have uprated the console bush for a more durable design now

If you have a lowered car then the best option is to fit the Superpro "anti-lift" console bush........read my post here......

http://www.briskoda.net/forums/topic/200949-upgrade-the-bushes/

A lowered car will roll MORE than a std height one as the roll centre migrates

Since when has lowering a car had a negative effect on body roll?

Since when has lowering a car had a negative effect on body roll?

+1

Lowering a vehicle reduces it's centre of gravity and therefore decreases body roll and the likelihood of a rollover. Just look at a Landrover Defender versus an F1 vehicle, now which one do you think will suffer from more body roll when driving around a track at speed?

With a MacPhearson strut design suspension (and other types too) the all important roll couple will increase with lowering, giving MORE roll. This is not what folk expect when lowering their cars.

The roll couple is the distance between the roll centre and the centre of gravity of the car. The shorter this distance the better

Lowering the Fabia by anything more than 30mm will see the roll centre most likely below the ground with a large(r than std) roll couple. This is why I said a stiffer rear ARB is beneficial after lowering

There are are many more negative handling trade-offs with over-lowering. Basically if looks good it probably handles like poo

A lowered car will roll MORE than a std height one as the roll centre migrates, so arb will have big benefit.

...

With a MacPhearson strut design suspension (and other types too) the all important roll couple will increase with lowering, giving MORE roll. This is not what folk expect when lowering their cars.

The roll couple is the distance between the roll centre and the centre of gravity of the car. The shorter this distance the better

Lowering the Fabia by anything more than 30mm will see the roll centre most likely below the ground with a large(r than std) roll couple. This is why I said a stiffer rear ARB is beneficial after lowering

There are are many more negative handling trade-offs with over-lowering. Basically if looks good it probably handles like poo

I would say that you're right in terms of the front suspension. Problem is that if you're running a properly designed lowering spring setup it'll be a lot stiffer than standard. That offsets the negatives somewhat. Rear suspension is semi-TA and doesn't suffer like McPherson strut.

Anyone interested in seeing/sorting out this sort of problem, have a look at the angle of your front bottom arms. They should angle down slightly, from the console to the wheel. If they point the other way you've lost any mechanical resistance to rolling AND the tendency to roll will increase with lean.

You can reclaim the situation somewhat but it involves lowering the ball joint under the front hub. Given the forces acting on it this isn't something to undertake lightly, if at all. It's also easy to get wrong. The balljoint has to move lower relative to the hub/wheel/axle. Anything else is effort expended for nowt as the geometry of the suspension is unaffected.

J.

I really don't get what you are trying state as it goes against mechanical logic..........

I managed to find this in wikipedia re Roll couple....under sway bars..........bloody americanisms!!!!!!!

In a turn the sprung mass of the vehicle's body produces a lateral force at the centre of gravity (CG), proportional to lateral acceleration. Because the CG is usually not on the roll axis, the lateral force creates a moment about the roll axis that tends to roll the body. (The roll axis is a line that joins the front and rear roll centers (SAEJ670e)). The moment is called the roll couple.

Roll couple is resisted by the suspension roll stiffness, which is a function of the spring rate of the vehicle's springs and of the anti-roll bars, if any. The use of anti-roll bars allows designers to reduce roll without making the suspension's springs stiffer in the vertical plane, which allows improved body control with less compromise of ride quality.

One effect of body (frame) lean, for typical suspension geometry, is positive camber of the wheels on the outside of the turn and negative on the inside, which reduces their cornering grip (especially with cross ply tires).

In english.......the sprung mass of the vehicle when cornering puts a sideways load on the cars suspension. This sideways load is increased by the speed of the car/sharpness of the corner and affected by where the center of gravity of the car is. These loads are resisted by the car dampers, springs, tyres, ARB's..........

Say a car has a ride height of 20cm......and has std soft suspension.........and you go around a tight 60deg bend at 40mph and the car leans over........going faster will cause the load/force transfer to increase on the outside wheels causing the suspension to compess untill it bottoms out.......the load on the inside wheels will decrease until the suspension can not extend any more resulting in the inside wheel lifting into the air.

If you fitted stiffer dampers to this car (like Koni FSD's) then they would be able resist the downward force placed on the outside wheels...thus keeping the car more level and the same previous speed....thus enabling the car to got through that same corner at a higher speed until the supension bottoms out etc etc.....

If you just fitted stiffer (thicker) ARB's to the car then the ARB's will act sooner to take over from the soft dampers....but as an ARB wants to make both wheels on the same axle level, it would also not allow the inside damper to extend thus lifting it earlier (there are plenty of pics on here of cars with stiff arbs parked across slopes with the rear inside wheels way in the air!!!! (fitting thicker arbs can be very bad with std suspension!!!)

If you just fitted wider lower profile tyres this would increase the sideways (lateral) grip of the car as there is more tyre/ and less sidewall flex......but you will still have the supension bottoming out lots of roll etc...etc..

So go back to the std car a fit lower springs (lower the ride height from 20cm to 15cm). There are two ways this can be done. 1. using a sort of dual stage spring to match the OEM damper fully extended length which has a bit of the spring to absorb the weight of the car and give the lower ride height, and then the rest of the spring to do the "normal" job........or 2. to fit shorted stiffer springs. Both will lower the center of gavity of the car, but with the "dual stage" type the inside wheel will keep in contact longer as the spring can fully extend the damper......the shorter springs can "pop out" and not fully extend the damper on the inside wheel!

So to get the best you fit shortened dampers with matched springs...so no "Pop out" of the spring.... dampers that can resist the cornering loads....and a lower ride height resulting in a lower center of gravity! So with a lower centre of gavity the car needs to exert more force to get the same angle of roll compared to a std car. So a much higher speed throught the corner can be achived. With the shorter & stiffer springs and dampers fitted the car can resist the side loads/load transfer to the outside alot better thus keeping the car more level, and more of the contact patch of the tyre on the road........

BUT then fitting very stiff ARB's can stop the inside wheel dropping down to make contact, and thus you still have the inside wheel in the air!

Effectively you are making a car into a go-kart........and either the car kicks up the inside wheels (like a DTM car..... or it slides as a whole) ...........I think it was Colin Chapman who stated that ARB's where added to cars to cover up for bad suspension design.......he hated them!!!!.......

I have std ride height but with Koni FSD dampers, and fully poly bushed suspension..........on bumpy back country roads I can go faster than my mates lowerd car as I have more extension on the dampers.....so my tyres stay in contact with the road for longer........his inside tyres kick up and the car gets "bounced" everywhere.......BUT on smoother roads......he pastes my car around the corners.

END OF LECTURE.........I need a stiff drink....

To the OP....fit a set of these from super-pro

SPF3273K List Price £83.97 plus VAT Front Control Arm, Rear Bush Kit With Anti Lift

As per the SPF3271K this improved design bush will out last OEM bushes significantly however, these bushes have been designed with an offset mounting. This allows for a greater caster angle to be achieved cutting down on wheel hop and spin.

Comes with SuperPro's unrivalled 3 Year, 36,000 Mile Warranty.

This bush kit is also available in car sets KIT5229ADJK.

These will allow the front wishbones to move freely in the correct plane, and restrrict in all unwanted planes.......also they increase the caster...etc

I would say that you're right in terms of the front suspension. Problem is that if you're running a properly designed lowering spring setup it'll be a lot stiffer than standard. That offsets the negatives somewhat. Rear suspension is semi-TA and doesn't suffer like McPherson strut.

Anyone interested in seeing/sorting out this sort of problem, have a look at the angle of your front bottom arms. They should angle down slightly, from the console to the wheel. If they point the other way you've lost any mechanical resistance to rolling AND the tendency to roll will increase with lean.

You can reclaim the situation somewhat but it involves lowering the ball joint under the front hub. Given the forces acting on it this isn't something to undertake lightly, if at all. It's also easy to get wrong. The balljoint has to move lower relative to the hub/wheel/axle. Anything else is effort expended for nowt as the geometry of the suspension is unaffected.

J.

I think that you are correct with what bonesetter is saying........BUT this mainly affects steering.

What you both are referring to is the effect of "bump steer" and "roll steer"............

Example: Volkswager Driver magazine had a MK4 Golf which they had on lowered Coilover suspension Cast wishbones from the Audi TT etc etc.......They then fitted a set a Audi TT hub carriers as the distance between the bottom ball joint and the drive shaft is greater, and the steering arm is positioned closer to the road.

If you lower a car to much the steering arms and the wishbones point upwards, when infact the wishbones should point downwards and the steering arms remain level.

BUMP STEER;.......this occurs where the vertical movement of the supension struts, and the steering knuckle which it is attached to cause the steering arms to arc and affect the tracking of the vehicle (felt by the car tugging/pulling at the steering wheel). This is worsened when the steering arm (track rod arm) angle is compromised in it's static (resting) position away from the horizontal. (very low suspension will make it point upwards).

ROLL STEER:..........this is basically the above but when cornering...mainly this refers to the ouside (compressed side) and the worst effect is when encountering a bump mid corner which causes the ball joint to bind and restrict movement.

Aahh, if only manufacturers made decent 'lowering' springs... as things stand they are usually too short (over-lower), or too soft (bouncy) and not progressive enough (similar thing in a way). I suppose that's what most folk want though - a car that looks the way they want it - low/slammed etc.

Whiteline & SuperPro make extended ball joints for most cars (as Vindaloo says) which alters suspension pick-up points, negating much of the over-lowering induced roll (roll centre correction kits). I don't know if these are available for the Fabia...?

Fabdavrav - I agree with what you're saying, although I think your dampers should be springs lol. My Fabia came with Eibach Pro springs, which I think are terrible. Too low, too bouncy and I don't like the progression of them (on std dampers), all makes for a crashy ride, especially on the bumpy B-roads. Not nice. So what I've done is gone for the Bilstein B8 damper (nice monotubed, inverted) which has a shortened travel. The spring I've gone for is a KW, stiffer than std, and lowers by just 20mm. The reasoning behind this combo is my priority is to maintain as much travel as possible, and not over lower the car. This will protect the dynamic geometry (and travel), plus I'll get more travel from less lowering combined with the shortened damper which will give max travel possible on a lowered setup - nice (hopefully). More here

I like the look of the offset SuperPro caster/anti lift bush. I ran one on an Impreza to good effect

I really don't get what you are trying state as it goes against mechanical logic..........

END OF LECTURE.........I need a stiff drink....

It wasn't a lecture. You're confused between steady state cornering; and transient weight transfer.

Show me the diagrams, show me the maths and physics! I'd love to dig out my old notes, unfortunately they're under a bed in my old dear's spare room! Vehicle dynamics is bloody complicated; it isn't something you can just generalise like (no offence) above, I'm afraid. I hated it.

Haha is forgot started this thread, defo going to polybush the whole underside and some shorter front arb links