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To lower the rear.
Jack van up, undo lower shock absorber mount, remove spring, fit new, refit shock absorber.
Done.
To lower the front.
Jack up van, support on axle stands.
Have a grovel underneath, find the end of the torsion barsbehind the fuel tank, you'll know when you find it as there is a long 18mm ish thread pointing down with a 27mm nut about 4" up it.
This is the nut that sets the tension on the torsion bar, basically if you undo the nut it releases the tension, and lowers the suspension.
The way I do it is to clean up the threads first, then mark the thread where you want to move it to.
If you work on this simple rule you won't be far away.
10mm at the adjuster nut = about 25mm at the wheel.
So, if you have fitted -50mm springs then moving the adjuster by 20mm will lower the front suspension by 50mm.
Obvoiusly, all vans are different so once it's lowered take it for a spin, park it on level ground and check the trim height with a tape measure (wheel centre to wheel arch) and make adjustments to the adjuster nuts as to achieve a level ride.
There are a couple of gotchas, make sure it's on stands as if the upper adjusting bolt thingy comes dislocated the van drops, on you! and if it does come loose, it's a bit of a bastard getting it back in, so just be careful if the adjuster nut is stiffer that it should be.
Now, if you look around at what springs are for sale, and which ones are TUV approved (German standards) you will probably notice that they only seem to go to -45 to -50mm, I think the reason for this is the amount of adjustment there is on the front torsion bar.
It is easier to described once you have seen the set up but basically the adjusting bolt is sort of T shaped at the top, and if there isn't enough pre load on the torsion bar this T shaped piece can be moved about, Now I believe the knack to lowering a T4 and it still stay safe is to lower the nut only enough to leave some pre load on the adjuster bolt.
Leave no preload and the T shaped piece that fits in the chassis and you run the risk of it become dislodged, maybe changing a tyre, or working on the front end.
Lowering anymore that 50mm I would say is probably unsafe, plus they start to drive really baaaad.
I know it's not as cool to not be scraping the ground, but it's safe and is going to handle better using the torsion bars as springs rather than using the bumpstops as springs!!
Done, lowered, easy.
On axles stands, outside your Mums house I would say this is gunna take an hour start to finish.
The most important part is to check the wheel alignment afterwards, very, very important as the T4 seems to be more affected by camber and tracking changes than the T3 is!
Camber is easy in theory, bit of a pain in practise.
If you take the front wheels off you will see the top ball joint, okay, if you just slacken the big balljoint bolt (24mm) then undo the 18mm camber adjuster bolt at the top side of the ball joint, then moving the quadrant changes the camber. if you tap the quadrant towards the front you will get negative camber, towards the rear you will get positive adjustment.
All well and good saying this, but doing it in situ is a bit of an arse of a job.
Another thing worth mentioning is that just like the T3 there is only a certain amount of adjustment on the camber adjusting quadrant, lowering much more than the 50mm and your gunna run out of adjustment and not be able to set the camber up right after you've done your work, which will mean dubious handling and it's gunna scrub the rather expensive tyres you just bought.
Once camber is set, then check and reset tracking.
I reckon on about 1 hour to set wheel alignment at the front.
Also, we have to mention the rear brake load proportioning valve.
Dunno how much you know about these things, so a bit of background first...
Under the van, in the middle, between where the rear arms bolt up is a hydraulic valve attached to each arm by the means of springs, going into the valve assembly are 2 brake pipes carrying basically unregulated brake pressure from the front of the van.
Out of the valve are 2 more pipes going to the rear brakes.
This valve reduces the amount of pressure going to the back brakes, when the van is loaded it opens the valve to increase braking effort to the rear.
In laymans terms it stops the arse end of your van locking up when you anchor on with nowt in't back..
As the valve is attched to the rear arms it basically reads the suspension height and gives proportionally more braking pressure to the rear brakes the more weight you have in.
What cocks this all up is when you lower the van as the valve thinks you have a load in, and gives you more braking effort, which could lead to you locking the rear before the front, which means you could end up in a spin as anyone will remember from their peddaling to school days, locking the back wheel wehn turning usually ends up in tears.
To make our job more difficult, vw have the suspesnion set at a certain height (stock!) to set the valve up, obviosuly when you lower the van you are no longer at stock height and the measurements and readings you are meant to get are kinda worthless.
So, be careful! Something I am thinking about is a sensible way of getting around this niggle that people will be able to implement themselves..
Now, they don't tell you that when your buying springs do they?!
Thats it, job jobbed.
Brickwerks can sell you
KW suspensions
AVO
Weitec
H&R
Bilstein
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