So what is a coilover??

[Red Bicycle]

Dear all

Now that I've paid my deposit on bilstein coilovers and impatiently waiting for them to be air freighted in I've had time to ask what it is I'm actually buying and why is the design regarded so highly??

Wikipedia says that although similar to mcpherson struts in that they are coil over springs they are not to be considered the same but then doesn't really say what they are in the context of suspension design.

Can members provide any clarity please?

Best

Michael

[kaanage]

TECHNICALLY, a coilover is a suspension unit where the coil spring surrounds the damper (which includes MacPherson struts and also many double wishbone front ends) but this is not what you are after.

The conventional usage of the term "coilover" kit (coilies) is a set of MacPherson struts where there is a threaded adjuster for altering the base height and a set of rear suspension springs and dampers where the springs sit on perches with a threaded adjuster for altering the perch height, all so that the ride height can be changed. The rear units do not necessarily (and usually don't) have the dampers surrounded by the springs, since if the original suspension is not mounted this way, then major modifications would be needed.

The design is regarded highly as the ride height adjustment allows corner weighting and also it means the vehicle can easily be lowered. On this forum, the second reason is vastly more important than the first. In real performance terms, just replacing the dampers with higher quality units will often improve suspension behaviour as much as installing a coilover kit (but then the vehicle can't be slammed which buggers the behaviour anyway)

[Sunny43.5]

Geez Kaanage I thought I was the resident grumpy old fart , so many members have indicated that to me after my rants etc . But hey if you want it it's yours , nice write up by the way I have coil overs in our van and they make a big difference over stock . The van feels better on the road and as you said height adjustable to boot .

[Red Bicycle]

Thanks Kaanage

"...(but then the vehicle can't be slammed which buggers the behaviour anyway)..."

So it is basically the ability to dial in lowering but then I don't understand your last sentence. Do you imply that lowering somehow upsets the performance of the system?

Cheers

Michael

[Sunny43.5]

I think what he means is that if you lower it to the max then handling will be very different , you only have to watch how cars which have been "slammed " behave on the road . They rock like a boat in a storm and shake like hell as they have no ability left to absorb normal road undulations and rough surfaces. I could be wrong .

[Racemag]

most Bilstein coil-over units are not adjustable for spring seat. The adjustability does not equate to lowering only.

[Red Bicycle]

Sunny Is there a general agreement as to how far to lower the T5 with B14's on stock 16" rims?

Michael

[kaanage]

most Bilstein coil-over units are not adjustable for spring seat. The adjustability does not equate to lowering only.

So what is their basis for being a 'coilover'?

Both of the below have spring seat adjustment for height and corner weight adjustement
BILSTEIN B14 - PSS
BILSTEIN B16 - PSS9/PSS10

[brad]

Thanks Kaanage

"...(but then the vehicle can't be slammed which buggers the behaviour anyway)..."

So it is basically the ability to dial in lowering but then I don't understand your last sentence. Do you imply that lowering somehow upsets the performance of the system?

disregarding the affect on roll centres, bump steer, etc:

Reducing the ride height on a coilover equipped vehicle reduces the available suspension travel & also reduces the amount of preload on the spring.

When you hit a bump the spring reacts immediatly (if it was preloaded it would require a certain amount of force before it started moving). Moving immediately wouldn't be an issue if you had plenty of suspension travel available but you haven't - so the spring compresses quickly & eventually hits the bump stop & runs out of travel so the chassis behaves like a billy kart.

many coil overs have crazy high spring rates to try & counteract this "problem" & it works to a certain degree but is still a compromise.

You've bought a good quality kit which should work well providing you don't try & drop the thing into the weeds.

Some of the best handling cars I've owned were the ones that I raised rather than lowered.

[Red Bicycle]

Thanks Brad

I suppose I have two questions:

1. Is the 'no drop' ride height of the Bilsteins the same as stock?

2. What is a good compromise in terms of the benefits to handling from reducing the height above the road surface of the vehicle's centre of mass and available spring travel for our crappy roads?

[brad]

Thanks Brad

I suppose I have two questions:

1. Is the 'no drop' ride height of the Bilsteins the same as stock?

2. What is a good compromise in terms of the benefits to handling from reducing the height above the road surface of the vehicle's centre of mass and available spring travel for our crappy roads?

1) I've never fiddled with Bilsteins but on 2 other sets I've helped fit you could actually raise the height a fraction.

2) It depends on the vehicle, spring rate, available suspension travel and where the roll centre is in relation to the centre of gravity (nb: I still don't have a clear understanding of COG & roll centre). I've set cars up with heavier springs at stock height & they've been brilliant - but that's how the owner wanted it.

Your best idea is to set the ride height where you want it & see how it goes. If it's a bit crashy or appears to be belting the bump stops a lot then lift it up. Keep in mind that radical changes of the front height will require a tweak of the toe setting.

Some people are more than happy to lower their car into the weeds and have their fillings shake out.

[kaanage]

Lower CoG is rarely a bad thing. The problem when doing is that achieving it without major suspension changes will ruin everything else (including the roll centers)
I linked to some good posts on the subject here - http://www.vwwatercooled.com/forums/...nds-82194.html

[Izabarack]

Most comments above related to lowering the ride height; my intent/want is to raise the body for increased ground clearance. I have T5 4 Motion and am converting to a camper. "Lift kits" don't seem to be readily available under that name and all advice so far from those who should know (VW service and a couple of mechanics), tell me that a lift kit will upset CV joint angles and cause other problems. Essentially, all have advised something like a Bilsteins Coilover installation and wind the things up to create greater ground clearance. My online searching tells me that Pedders do a coilover and King's Springs on the Gold Coast do something similar. So, for that increase in ground clearance, am I on the right track?

Iza

[Syncrotek]

T5 Suspension codes

Hi Red Bicycle,

This list might be handy FYI:

T5 Suspension codes, from - JEWUWA | T5 T5 German Board - member, Translated from German. Words in italics are my edits.

For the Multivan T5 there are different undercarriages: (Suspensions) (I guess some of these didn't come to Oz)

1BA - Suspension and damping Standard: This is the standard suspension for the priority use on paved roads. against a closed vehicle (Vans) here is the Multivan already 2cm deep. (lower)
(Compared to panel vans, the Multivan is 20mm lower)

1BJ - * suspension / damping reinforced front and rear: This chassis is designed for use with bad roads (eg gravel). The Multivan here gets stiffer springs and stiffer dampers. This, however, the Multivan is again compared to the standard suspension 2cm higher and thus on the same level as a closed vehicle (Vans).

1BB - Suspension and damping in bad way design: This chassis should be selected in areas with hardly any paved roads. The Multivan gets hardest by springs and dampers hardest. The Multivan is then higher than a normal Multivan and at the same level as a closed vehicle (Vans) as 1BJ 2cm.

1BV - Sport chassis: This sports suspension is exclusively reserved for the Multivan. It is important for drivers with sporting ambitions. The benefits can be seen by reduced body roll and increased roll stability of the vehicle. Compared to the production model of the Multivan is a further lowering of 2 cm so. Thus, the Multivan is a total of 4 cm deeper than a closed vehicle (Vans). Thus, the suitability garage is at the height further improved. For use come harder and shorter springs and stiffer dampers. The sta-average front is 25mm and rear 28mm.

2MD - lowered suspension: By this suspension leads to a lowering just for aesthetic reasons. Benefits can also use the garage better fitness (analogous 1BV). The springs are the Multivan the same as in 1BV sports suspension. Dampers are at the state level but adjusted the damping behavior is the same chassis 1BA. For all vehicles (except Multivan) the fact that the admissible HA reduced by 50 kg.

additional chassis, which are not offered for the Multivan. Please inquire for yourself what T5 versions are these:

1BH - Suspension and dampers for vehicles with 3.2 t GVW: This chassis provides open a standard vehicle for Vans (closed & and Caravelle and Shuttle with choice of 3.2 t gross vehicle weight (GVW).

2MF - Suspension and dampers (standard) and reinforced stabilizers front and rear: This chassis is not offered for the Multivan and is used in the other T5 for a lower side tilt the chassis and higher roll stability and lower sensitivity to side winds. In open bodies from certain building height, this chassis is technically necessary.

2MG - enhanced cushioning and stabilizers front and rear with reinforced stabilization: ---

2MK - Rear suspension reinforced: This suspension should during frequent load on the rear axle up to the max. Axle load are used. It is used to compensate the vehicle standing height (eg for Tool Trolleys)

2ML - damping front and rear reinforced: This chassis comes only when open Vans used. and corresponds to the chassis 1BJ with closed bodies. Since the open bodies already the strongest springs are standard equipment, come here also only the dampers from 1BJ used.

End of codes.

I forget if B14 Billys have adjustable damping, but if they do then careful -trial / adjustment- is where you can gain a lot in ride /handling.

[brad]

If you just want to lift it then get a new set of springs made that have an increased spring rate & a bit more length. They'll fit onto the existing suspension. A good spring maker like k-mac or Kings will know exactly what to do to achieve your goals.

The CVs will be at a greater angle & possibly wear faster but how much do you intend to lift it?

Also, is it still sitting at "factory fresh" height or has it settled a bit?