Air suspension and vibration... (1 Viewer)

[stevielomax135]

Dear All

I've recently been giving my 2005 Swift Freestyle 2.8jtd (244 Ducato) some tlc.... based on advice from the good memebers of this forum I renewed my brake calipers to help sort out fuel efficiency problems (worn square cut seal) and bingo! Thanks guys much improved!

However I also needed to replace my air assist suspension as one of the bags had a slow puncture.... I bought Dunlop replacements and after a fair bit of messing (including having to cut the u bolts off as they were seized) I got the new ones on and things felt much improved. However on the first run out I noticed that at any speed of 54mph I start to get terrible vibration through the van, as I speed up this doesn't go away (as I would expect with a wheel balance issue). Something clearly isn't right.... I was towing my small car behind but this is nothing unusual and nothing done to the car itself...

I assumed firstly that I'd got a wheel on wonky, but a quick look (without jacking van etc) would suggest they are ok. I really don't know where to go from here. Does anyone have experience of anything similar? Can anyone suggest where I should start looking? The van didn't used to do this with the original air bags and although the new ones are of more modern design they are the correct Ines for the vehicle. I'm really worried I've done something significantly wrong here - I'm an engineer by trade so not a total amateur but could easily have missed something important!

Many thanks for any advice

Steve

 

[Al-Di]

when you removed your wheels(to do calipers) did you put them back exactly the same, and did you tighten them up properly,

 

[Blue Knight]

Steve, do you have alloys fitted. If so then can you recall if they have spigot rings or not.

Cheers,

Andrew

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[Blue Knight]

A quick afterthought: I use AP Racing 6-pot calipers on my sporty cars and after replacing a set I forgot to replace one of the 1mm-thick washers on the bracket. The tolerance of the system allowed the car to function fine at low speed but at higher speed I experienced a degree of vibration due to the 1mm misalignment of the caliper on the mount and how it mated with the disc face.

I would revisit the brake mounts and see if there is any obvious misalignment.

Check for disc warping too.

 

[stevielomax135]

Thanks for the quick replies guys. Al-Di - I put them back on in the same location on the van if that's what you mean....? I didn't torque them down but gave a good tighten.

Andrew, yes they are alloys but don't know what spigot rings are I'm sorry to say.... Obviously not that good of an engineer I will check the calipers again but don't remember any washers or spacers but may well have missed this so good shout. What's the significance of the spigot rings?

Cheers

Steve

 

[Blue Knight]

Andrew, yes they are alloys but don't know what spigot rings are I'm sorry to say.... Obviously not that good of an engineer I will check the calipers again but don't remember any washers or spacers but may well have missed this so good shout. What's the significance of the spigot rings?

Cheers

Steve

Hi Steve, in lots of cases an alloy wheel has a bore on the inside of the wheel which needs filling correctly for the wheel to fit in a fully aligned manner. These infills are called spigot rings and they are often made of plastic and alloy.

Over a period of time the dirt will cover the spigots and therefore to most people they will just look like part of the wheel.

If a Spigot has deteriorated, perished or is missing entirely then the wheel will not mate correctly (slightly out of alignment) and this will cause vibrations at speed.

The fact that your wheels have 4 or 5 bolts on a certain PCD will retain the wheel but it may not necessarily allow it to sit central if there is a problem with the spigots.

If you can check the inside of the bore and take a photo if possible.

All the best,

Andrew

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[stevielomax135]

Thanks Andrew, will attempt to do so on Sunday when back at base

 

[Blue Knight]

Thanks Andrew, will attempt to do so on Sunday when back at base

Good luck Steve

 

[stevielomax135]

Folks, many thanks again for the replies - they really set me on the right track!

Checked all the callipers etc - they looked ok as far as I could see.

Andrew - looked at the wheels again. No spigot rings that I could see, so I jacked one saide and spun the wheel with me head to the floor to watch rotation. Maybe some small variation in shape but minimal (perhaps 1mm). Checked the other side - a good 10mm wobble!

Removed the wheel and sure enough its lobed with a section of the thread uneven - difficult to see unless you're looking for it. Threw spare on and jobs a goodun! No vibration!!

Thank you again for the advice - I don't think I would have considered wheels as cause without those questions.

Best regards

Steve

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[Blue Knight]

Well done on getting it sorted so quickly Steve

All the best,

Andrew