Fitting Adjustable Ride Height Trumpets
To start off I will state this is the method I
used on my own mini, this method worked for me however you fit these parts at your own risk, this is just a guideline therefore
I will not be held responsible should anything go wrong. It is your choice to use these guidelines or not.
Adjustable ride height trumpets (often called hi-los/adjusta rides)
I advice fitting
the following parts as a matter of servicing:
- Knuckle Joints x4
- Rebound Rubbers x2
- Rubber Cones (if you can afford it)
- Cone Compressor Tool
- 34mm Socket
- Socket set (1/2" drive for the 34mm socket)
- Spanners (9/16" for shock mounts and whatever size your hi-los take to adjust)
- Trolley Jack
- Axle Stands
- Screw driver (+)
- Penetrating Fluid
- Copper Grease
Give yourself a good day to get the front and rears done working at a leisurely pace!
Front: (one side at a time)
- Look at your mini and decide how much of a drop in ride height you want, go too crazy and more than likely you will have
to raise it again! For severe drops in ride height "lowered" shock absorbers are recommended
- Jack up the front end of the mini, chock the rear wheels and rest the car on axle stands (I use the flats of the front
subframe). Remove the road wheel and bonnet (gives easier access).
- Undo the front subframe tower bolt using the 34mm socket and ratchet. The tower bolt can be found one each side of the
engine bay, you cannot miss them as they are huge! Screw in the threaded section of the cone compressor tool into the thread
that the tower bolt came out of, turn till it is tight (this is screwing the tool into the rubber cone/doughnut). Once tightened
then the outer section of the tool can be tightened (this pulls the rubber cone upwards, compressing it to allow for the trumpet
to be removed)
- Undo the top and bottom shock absorber mounts and remove the shock absorber. Place a jack under the wheel hub and rise
until it takes the weight off the suspension arms and the rebound rubber. The rebound rubber can be found under the top suspension
arm, it is held in by a single cross head screw and once removed allows the suspension arm to sit a little bit lower giving
more allowance for the trumpet to come out. I replaced the rebound rubbers with new ones. Drop the jack holding the hub.
- Follow the top suspension arm up and you will see the trumpet that needs to be removed. The trumpet sits between the rubber
cone and the top suspension arm. The trumpet should have separated itself from the rubber cone after it was compressed, if
not you will have to try and separate it yourself. At the bottom of the trumpet where it meets the suspension arm is the knuckle
joint, I recommend fitting new knuckle joints and nylon cups.
- Once the trumpet is out compare it to the front adjustable ride height trumpets (We'll call them Hi-Los for sake of time
saving) you have, adjust the hi-lo until it is the same length as the removed trumpet. There is a ratio to work out the drop/rise
in ride height, on the front it is a ratio of 5:1, i.e. if you adjust the hi-lo 10mm shorter than the original trumpet it
will give you a 50mm drop in ride height. Adjust the hi-lo to your desired length, tighten the lock nut and refit into the
top suspension arm.
- Refit the rebound rubber and retaining screw as well as the shock absorber
- Loosen the outer section of the compressor tool (decompressing the rubber cone), do this in small amounts and check the
hi-lo trumpet is seated within the rubber cone, remove the centre threaded bar of the tool and bolt in the tower bolts.
- Do the other side!
- Refit the road wheels, bonnet and remove from the axle stands. The drop in ride height will not be immediately obvious
as the suspension needs time to settle, just take it for a drive!
Rear: (one side at a time)
- Again take the time to have a look at the mini and decide what drop in height you require, it is not always the same as
- Chock the front wheels, jack up the rear on the flats of the subframe and place on axle stands, remove road wheels, I
also found it less painful to remove the bootlid!
- Place a jack under the brake drum and undo the top suspension mount. On the N/S the top shock mount is behind the petrol
tank so this has to be moved to one side. Simply undo the tank retaining strap and the petrol cap (better to do it when low
on juice!) and move the tank out of the way, replace the tank cap. You should not have to undo any thing from the petrol tank;
there is enough stretch in the cables and pipes. Unbolt the top bolt of the shock absorber, I found this just rotated the
top of the shocker so I used a 7mm open ended spanner on the squared off top of the thread to hold the shock whilst undoing
the nut (9/16" spanner) I found removing the bootlid gave greater access. The radius arm and brake drum will fall down once
this mount is undone hence the jack underneath. Undo the bottom shock mount to get the shock out of the way.
- Lower the drum and radius arm on the jack until it is as low as the radius arm will allow, keep the jack under to keep
the strain off the radius arm. Look into the rear subframe and you will see the trumpet (much longer this time) and the rubber
cone, there is no need to compress the cone for the rears.
- The trumpet is attached at the knuckle joint end to the radius arm, lowering the radius arm takes the pressure off the
trumpet. If you are very lucky the trumpet will separate from the cone when the radius arm is lowered leaving the cone in
place, this is rarely the case! A combination of wiggling, hitting and swearing at it should remove the trumpet from the subframe,
usually with the rubber cone fused on the end.
- Remove the rubber cone from the trumpet (so much easier typed than done, I advise if you can afford it or have doubts
over your rubber cones to replace them as it'll save a whole lot of time and frustration!) Once the cone is removed, have
a beer, well done, then, as we did up front, set the hi-lo trumpet to the same length as the removed trumpet, stick on a new
knuckle joint and cup and adjust to the desired length and tighten the lock nut. As with the fronts there is a ratio, this
time the ratio is 3:1 i.e. a 10mm decrease in trumpet length will cause a 30mm drop in ride height. Refit the trumpet and
rubber cone into position.
- Raise the jack under the rear brake drum, as the radius arm raises it will put pressure on the hi-lo trumpet and in turn
the rubber cone, make sure the hi-lo seats correctly in the knuckle joint cup and in the rubber cone and the rubber cone seats
correctly in the subframe. Refit the shock absorber.
- Refit the road wheels, lower the car off the axle stands and refit the petrol tank and bootlid if removed.
- Take for a drive to let the suspension settle, wash your hands, kick back with your favourite tipple and admire your work!
I gave everything I was going to remove a good squirt of penetrating fluid to aid disassembly then a smearing
of copper grease to make future adjustment or removal less of a chore.