Hydrolastic unit knuckle joint

[seandoyle]

Help & advice please ! I am trying to remove the old knuckle joint from the Displacer unit which is well & truly stuck ! Any advice on how to remove it without damaging the Displacer unit ? Thanks Sean

[rich@minispares.com]

bit of red hot water and some gentle prising should do the trick

[Spider]

bit of red hot water and some gentle prising should do the trick

And lots of words that sound like fire truck,,,,,,

[rich@minispares.com]

bit of red hot water and some gentle prising should do the trick

And lots of words that sound like fire truck,,,,,,

I didn't bother stating the obvious......


Don't use all your best swears straight away, you might need them later, and its bad form to use them more than once!

[nick rogers]

A word of warning, if you put the knuckle in a vise and pull the displacer you risk separating the metal insert section from the rubber part of the displacer (they are bonded together). They are a bugger to re-connect; we have tried. Even slightly pressurising the displacer so the rubber is pushed out does not help.
Often you see used ones for sale at shows with this part missing.
We currently have a few front displacers with knuckles stuck in them so if we devise a good system, I will let you know.

[seandoyle]

Thanks for all of the replies .As a retired Fireman I haven't stopped laughing about the use of Fire truck,something that I thought I'd stopped doing a few years back, but obviously I still use it a lot more than I thought. Will post any good news on the knuckle joint as and when I get it sorted.
Sean

[Dr S]

Ball joint fork just in the right place and plenty of reaction from an fbh

[360gts]

Let's look at why this sort of thing happens and then we can have a better idea as to the reason and the solution.
First, we have the issue of dissimilar metals. Then, this is further compounded by the introduction of salt and water causing corrosion build up......basically, a process we refer to as chemical welding ish!.
The result is a swelling of the steel knuckle inside an alloy base part.

The way to loosen the steel knuckle is to increase the swelling!!!!
Careful patient use of an acetylene welder applying direct heat to the steel knuckle will cause the steel to expand..
I say careful....being overly aggressive with a large flame will only cause damage to the displacer unit...like melting the alloy base..or burning the rubber.
Let it cool slightly...take a small ball hammer and tap the end of the knuckle joint...actually driving it inwards. You may need to heat and tap a few times but I guarantee this works...I have freed many "so called" useless displacers this way.
Good luck...and be careful..use a small flame!!!

[goff]

I would say 360gts is bang on what he says , I have never done any but it all makes sense , This could work also, get the knuckle hot quick ( using the burning torch ) then quench in water before the heat dissipates into the displacer , that again will expand then shrink the knuckle.

[nick rogers]

And when assembling it with the new knuckle joint, apply a coating of copper-slip and it will easily come apart next time. This goes for lots of bits of Mini which tend to seize.

[360gts]

Just wanted to add one little bit more...do not use a propane type unit (like a plumbers torch) as it will not produce enough direct heat...or enough temperature...the welder will direct the heat without spreading it all over the place.

[goff]

Just wanted to add one little bit more...do not use a propane type unit (like a plumbers torch) as it will not produce enough direct heat...or enough temperature...the welder will direct the heat without spreading it all over the place.

What 36gts is saying use oxy/acet welding torch or as I said if you competent enough with the burning torch and quenching , that's another option

Goff

[mikep]

You can sometimes get stuck things apart by using a shock that moves the outer tube. I set a blunt cold chisel in the vice and place the tube on this, a sharp tap with a hammer (not a swing with a club or 2lb er just a short sharp tap) then rotate, do this a few times and its surprising how things move. Often once it starts moving it can be helpful to tap it in again, this helps grind the rust a bit more. I can never make my mind up if easing oil is worth the mess, often if you can make the rust into dust it comes out better dry.

[seandoyle]

Thanks for all the advice.I managed to separate the knuckle joint by gently tapping the alloy with a small hammer whilst supported on the anvil plate on my vice. I then gently tapped a sharp chisel between the joint & alloy housing attached to the Displacer which separated the two.Once they started to come apart I sprayed it with more WD and left them for a few hours to soak. It was then straight forward to grip the alloy part and twist out the ball joint. A good clean & copper slip, meant it was ready for the new ball joint to be fitted. The work was very easy as the Displacer was already removed from the car. Once again a big thank you to all the advice I was given.

[Aussie Bill B]

Hello,
Just a comment on nick rogers warning about the metal skirt for the knuckle joint being bonded to the rubber of the displacer. They might be stuck over time, but they are not bonded, and can be prised - carefully - from the rubber. Some rubber grease lets them slip back into the displacer easily. I have been repairing/cleaning some displacers of mine recently and have had no problems with this. If you have displacers not serviceable due to this problem, there will be many interested people.
Regards,
Bill