Technical ARB bushes

[pondweed]

that's perfect, thanks - will order some. Pointless opening them up and not replacing them with something that will never need doing again...

 

[pondweed]

stop press..
I've just posted on 'tother side too... as they are also talking about.
ok, the FIATforum Multipla forum lot are using the 18mm OD Saab 9000 poly bushes from Chris Witor, and cutting them down 1mm wider than the bushes taken out. about £18 a set. Good reports heard - better on road etc.
Chris said today that it will be 5 week to make a up proper stock item (from Australia), but they need the bracket/clamps from the roll bar to do this. I know he has an old bush already. So he has obviously decided its a goer - he replied "we would add as a stock line if developed"
Has anyone got access to some clamps from a scrapper we could send to him?
regards

 

[BikeDoc]

...Pointless opening them up and not replacing them with something that will never need doing again...

If you come up with a material that never wears out, either for the bushes or the bar itself, you'll never have to work again .

I need to look at mine soon as there's a very light knocking from somewhere under the front.
Might have to crank up my Lathe and/or Milling Machine in the next few days...:idea:

 

[BikeDoc]

I ordered some Polyurethane rod on Saturday, I'll see how feasable it is to machine the bushes.
What are the bushes in the drop-links like?
I presume they are bonded-in, and not (technically) replaceable?

 

[Peat]

When you say drop-link bushes do you mean ARB bushes? I would think to machine and fit the drop-link bushes is not practicable where-as the ARB bushes may well be see item 6 on this thread & item 6 on 'Front anti roll bar d bush' thread where it has the dimensions.

HTH
Peat

 

[pondweed]

Pete at uglybug has a spare old ARB which he has offered to put forward for the poly arb bushes to be made... but he also pointed out that the metal bar wears in addition to the bushes.
So is it really practical to replace arb bushes at all... or is the metal wear v.minimal?

 

[BikeDoc]

When you say drop-link bushes do you mean ARB bushes? ...

Both really.
I'm going to try making the 'main' bushes that fit on the bar (in the brackets)
I'll also look at doing the ones in the ends of the two drop-links that connect the ARB to the suspension struts.
I just wanted to know what those link bushes are like.
I'm guessing they're rubber, bonded into the ends of the links, with a bonded-in metal bush where the bolt fits.

In my experience, the bars themselves don't wear too much, not enough to worry about anyway, unless it's had a lot of abrasive debris (e.g. sand) get in between the bar and bush.
So unless you do a lot of beach driving I doubt you'll have a problem .
Rubber bushes tend to polish the bar more than wear it.

With soft(er) rubber bushes, the rubber should wear out long before the metal bar, but with some of the harder plastics (Nylon for example), the metal in contact with it can wear fairly quickly, depending on the metal used.
It also depnds on the design of the bush assembly, and how the parts move in relation to each other, which is why suspension bushes are usually bonded into the arms, and have a metal sleeve over the pivot bolt (and clamped tightly by it).
The wear occurs between the plastic or rubber bush and the sleeve, and not on the (more critical/expensive) arm or pivot bolt.
It's also a safety (or fail-safe) design, if the arm or bolt were to wear, the pivot joint could fail.

 

[pondweed]

so in your opinion, if someone is making up some poly bushes for the arb, would you think they would only need the clamp parts and not the bar...?
I must admit - why dont they just make a mould of one of the new rubber bushes from FiaT??!

 

[BikeDoc]

If the bar isn't worn, and they know the diameter (18mm), than there's no need to actually have the bar to hand as far as I can see.

 

[Peat]

In reply to wear on both the ARB & the bushes.

I would say that the bar is 'polished' rather than worn although the protective coating has gone which may constitute wear.

When fitting my 'chiseled' SAAB 18mm Powerflex bushes there was no sign of slackness on the bar and if there had have been it would have been taken up by the fact that I made my bushes slightly larger and compressed them with the bracket which was also 'polished' on the inside.

Peat

 

[BikeDoc]

With any pivoting (or sliding, rotating, etc) parts, there are many different considerations to look at when they're designed with regards to the bearing surface(s) chosen.
What material(s) to use, how much load is on them, how 'critical' they are (i.e. what would happen if they failed), how long you want them to last before they need replacement, how much maintenance they'll get, and probably the most important in the maker's case, cost .

If you want/need something to last a very long time, you use the best material(s), for toughness, strength, weight etc.
Then you add a 'sacrificial' layer that wears out before the expensive and/or critical part.
E.g. A crankshaft. You have the 'white metal' bearing shells between the crankpin journals and the con-rods.
The shells are softer than the journals, so they wear and not the crank.

At the other end of the scale we have the ARB, the only way it could be a 'shorter lasting' design is if it had no rubbers, just the bar mounted in the metal clamps .
It could be improved immensely by just having sleeves on it where the rubbers are.
Two-part sleeves, just like the big-end bearings on a crankshaft, that are fixed to the bar to take the wear instead of the bar itself.

I might look into doing this on mine.

Edit; My bar of Polyurethane came this morning.
As I was expecting, it's somewhere between Rubber and Nylon, hardness-wise.

Hopefully I'll get a chance to look at my ARB soon, don't hold you're breath for the next week or so though

 

[BikeDoc]

Took a quick look at mine yesterday, as I suspected, the bushes are worn.

Didn't have time to do anything with them though.
I couldn't seperate the clamps in-situ (not in the time I had anyway), but as the bar itself is in such a state (rust spots and flaking paint) I'll be taking it out to rework it anyway.
What I'm planning is to sleeve the bar at the bush points and make some larger clamps, then I should be able to make the bushes without a slit as the bore should be large enough to slip them over the ends of the bar.
That's the plan at the moment anyway.
The drop links seem OK, other than the very rusty surface.
I know it's a Fiat, but we're in the 21st century for crying out loud
Don't they realise it can be prevented easily nowadays...

 

[ukmarc]

hello my Multi was banging and creaking like a good one so i checked ARB bushes they were worn badly .
Phoned SAF wanted £29 each sh.t I thought phoned Fiat dont do em want me to replace whole AR bar at well over £130 plus the dreaded ...
took them off put a chisel between the brackets split real easy, trimmed about 2mm of split in Bush greased and packed inbetween bottom bracket and bush with 4mm rubber matting .
Reassembled connected drop links.......
BINGO no more knocks and Bangs and better on corners ...
Took about and Hour cost sweet FA
I love the good old ways .
Marc :slayer:

 

[pondweed]

good good. where does one get the aforementioned rubber matting?

 

[BikeDoc]

You may find that with the grease applied, the rubber mat you added may work it's way out.
Keep an eye on it.

 

[pondweed]

presumably you could bond the rubber to the rubber with a bike tyre repair kit glue?

 

[ukmarc]

the rubber matting was similar to that of a conveyor heavy duty I just found mine in our workshop.
And no need to bond it as when you split the steel bush enclosure you just trap it between the two at the bottom.
Marc

 

[BikeDoc]

Ah, I see.
You could make it like a strap with a hole at each end to slip the bolts through.

 

[klytus]

i need to replace our arb bushes and have read this thread through with interest
was looking through and noticed a link to superflex bushes
anyway i found these hxxp://www.superflex.co.uk/photopage.php?part_id=162
for a fiat croma, now i know the base of them is smaller than the multipla ones but that shouldnt matter if they are held tightly by the brackets thus no movement
any thoughts on these as they look like there's little to no modification needed to them plus there priced well
peace

 

[pondweed]

these are the same ones/same part number as for the Saab that Peat whittled down....