I've had this motorcycle lift for well over eight years and I haven't used it the last 2-3 years; it's been sitting in the garage ,covered in junk. More recently I have decided to drag it out and repair it. The reason I haven't used it is because it is quite dangerous.

It is dangerous because it drops like a stone.

It is not the first time I have attempted to solve the problem I dismantled the whole motorcycle lift, taking the main part, the pump into the parts department of where I bought it from. They could not supply a replacement as it was obsolete. Are then rather naïvely thought I could buy a newer version of the pump and modify the motorcycle lift… When it arrived in the post I decided this was a little bit too difficult for me and I reluctantly returned it.

pump - release valve on left

pump; release valve on left

This time around, I started to think a bit harder and looked closer at the mechanism. I took the following actions to try and remedy the problem. Each action was followed by testing the lowering of the left to no avail.

1. Dismantled release mechanism, I found the central pin was bent – It was straightened using a lathe and dial gauge. I replaced the O ring on the central pin (see photo)

 

(edit) added this sketch to describe assembly

2. Adjusted the lever bar inwards (as advised by the seller’s technical department) – all the way in, but no more adjustment was available.

3. Vented the oil – checked many times.

4. Changed the oil and re-vented hydraulic system by raising it and lowering it. Holding ot fully up overnight to release trapped air etc.

Still have no idea what could be wrong with it. It pumps up ok and hold its position pumped up but drops down really fast in an alarming way.

The terrible parts diagram on Clarke International’s website – the only one I can find. (Pump highlighted in red)


The release action feels ‘notchy’ its either on <notch> or off…It you understand.

Advice from my friends on BM Bikes Forum have suggested that I clean up the tapered pin/seat interface to remove the ‘notchyness’ – Suggested ideas included using grinding paste with sharpened wooden dowel. I have already polished the pin smooth. It was VERY rough. The pin/seat holds oil (does not allow the ram to leak) but the erratic actio  i.e. all on or all off may be due to a ‘lip’ on the seat side.

Using Fusion 360, I drew up some drawings and I have.STP or .STEP files for fabrication now.

https://a360.co/3egn61A
https://a360.co/3asNtQC

 

Since this morning I’ve removed the ram

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And I have tried examining a little bit closer the area of concern…I made a little pointy wooden peg and pushed it into the hole, you can feel a slight ‘click’ when pushing the wooden peg in. This is how the lift actuates the descent. The tapered pin has nothing to do with sealing/controlling flow, apart from pushing something inside. I guess that something would be a ball bearing and spring… but I cant be sure until I get the ram (jack basically) apart. It is a real shame that this ram uses this mechanism and not a conventional floor jack twisty operation.

I will have another go tomorrow and open it up and to see whats inside.

I used a jewellers eye loupe on my iPhone to get some close-ups of the hole for the lowering valve.

Different form factor, release valve in particular but this shows functions clearly

(picture credit: https://www.tec-science.com/mechanics/gases-and-liquids/pascal-law-hydraulic-jack/)

Sunday 18th April

Having already noticed that the central release pin was bent, it was straightened by a friend with a lathe. I re-assembled the jack and tested it. It was still ‘notchy’. So, I decided to completely dismantle the lift and remove the jack for further inspection.

I removed the central release pin again from the jack, and, to my dismay, it was bent again! I set the pin up as best as I could using my elecric drill which was the only way I have to hand to rotate the pin and measure the run out with my dial guage. I have a dial guage and stand but no lathe! So it turns out (no pun) that the run out was approximately 5.5 mm…

I made a little video …

The theory I have now is that the bent pin, when under pressure rubs against the inside of its enclosure, causing erratic control of the release pin itself. In my opinion, the valve that stops the release works fine… it is just very abrupt.

Now, I am unsure why the pin bent itself out of shape? Could it be that the previous attempt to re-stainghten it was not accurate enough and the pin collapsed back out of shape again as a result? I might no have to another pin to be made as the part is not obtainable on its own.

Last week, I contacted a couple of specialists who repair hydraulic rams and they responded with the advice to buy another ram. I really would, but this particular model is no longer in production. I will explore the possiblity of making a new part and take it from there…

Mick At Machine Mart technical department gave me a sketch of myy obsolete Clarke CML1 Ram:

the story will continue and be updated here….

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