Morris Minor Owners Club

My morris , based in Ireland,is very bumpy for those sitting in the back , so I have the two rear dampers off. Have recently fitted a reconditioned engine and gearbox .Would appreciate a response to the following queries

(1) what is the best fluid to use? I have read a lot of threads. Motorbike fork fluid seems to be the better option because SAE 30,40 or 50 may have additives which may compromise the seals in the unit and render them less effective. I am willing to order from a UK supplier, if necessary, so as to use the most appropriate fluid available.

(2) some posts do not recommend that the damper be washed out with kerosene. What's the best way to wash the damper out when before filling it. What about flushing it out first - a few times- with petrol and then with a small amount of the fluid you are going to use to - hopefully- remove any remnants of the petrol before finally replenishing it with the 'correct ' fluid.

(3) what kind of resistance in the arm should I experience when it is full with fluid - to just under the filler nut? Could it be moved by holding the damper housing in one hand and the arm in the other hand or would the damper need to be held in a vice?

I know that the ultimate test is to fit the newly fluided dampers on and take the car for a drive or to buy two new/reconditioned dampers. I could also sit in the back of a few morrises who's' owners are 'adamant ' that their dampers are A1

Your problem will be that the springs have flattened and the suspension is sitting
On the bump stops. You can cut 1" off the stops if you wish. DO NOT flush the dampers out with anything other than new oil. Use SAE 40 engine oil. Maybe fill and empty then fill again. held in the hand it should be virtually impossible to move the arm. Clamp the damper in a vice an it will move 'with difficulty'.

Tks for that advice Bmcecosse

Don't clamp the damper in the vice, make a mounting plate to bolt the damper to. If you grip the damper body in a vice too tightly you may crack the mounting while pumping the oil through the damper.

It really just needs to be 'held' .. Perhaps clamp was not the right word...

Before I removed the drain screw at the opposite end of the damper I came across a post which showed the various parts that the drain screw was keeping in - about a 1 1/2" rod with a spring on it and which can be very easily pulled off it. The post also showed a small washer which is put on the rod after the spring is put on.
I then very carefully removed the drain plug from both dampers but did not find the said washer. There's are three possibilities:-
(1) it is stuck inside the housing though I gave it 'a gentle poke' and nothing appeared
(2) it was never fitted in the first place
(3) the poster who found it in his damper might have had the washer fitted to somehow enhance the effectiveness of the damper.

If there was a washer originally fitted Would it be essential that I reassemble the damper and include the washer?

It may have been lost years ago. The washer just gives the spring something to seat against. Adding a few more preloads the spring so the overload valve opens at a higher pressure. However compared to the increased viscosity of 40 oil the effect is negligible. Catch all the oil coming out and filter it to see if the washer is there. Otherwise fit some if you have them, or put back as it came out.

Tks for that . I will get a washer and use 40 oil to get the best out of the unit. Re vice - I would have been catching it gently anyway.

Just note the oil is straight SAE 40, not 10/W40