23 replies to this topic

[Homersimpson]

 

Before you move down the shockabsorber line I would make sure there is no air in the system, any air trapped in the units can give the symptoms you describe.

You really need the correct pump unit to evacuate the system of all fluid and to pull a vacumm before it ic refilled and set to the correct height.

I just spoke to the owner and they’d replaced two of the displacers, but they didn’t have the equipment to evacuate the system, so they’ve just been pumped up. I’m guessing then that it may be air in them that’s causing the soft bouncy ride?

 

It might be but on the hydrolastic mini's i've worked on i've never been able to vaccum the systems out so have always just filled them up and its been fine.  The pressure is so high that any air in there would be compressed significantly to the point that its probably not an issue.

 

Just as a side anacdote, I knew a chap once who tried pumping up his hydrolastic mini with his air compressor, as you can image the end result was one low mini and a compressor full of hydrolastic fluid!

[madalicesdad]

Yes. Air is compressible (IE springy). Liquids are incompressible.
The liquid transfers the upwards motion at one end of the car to downward at the other. Instead of transferring a force, the air is being compressed.

[Spider]

 

 

Before you move down the shockabsorber line I would make sure there is no air in the system, any air trapped in the units can give the symptoms you describe.

You really need the correct pump unit to evacuate the system of all fluid and to pull a vacumm before it ic refilled and set to the correct height.

I just spoke to the owner and they’d replaced two of the displacers, but they didn’t have the equipment to evacuate the system, so they’ve just been pumped up. I’m guessing then that it may be air in them that’s causing the soft bouncy ride?

 

It might be but on the hydrolastic mini's i've worked on i've never been able to vaccum the systems out so have always just filled them up and its been fine.  The pressure is so high that any air in there would be compressed significantly to the point that its probably not an issue.

 

Just as a side anacdote, I knew a chap once who tried pumping up his hydrolastic mini with his air compressor, as you can image the end result was one low mini and a compressor full of hydrolastic fluid!

 

 

Yes.

If there's that much air in the system that it'll affect the damping, you won't raise it off the bump stops.

Static, there's circa 300 PSI in the system. In use, that routinely hits 1000 PSI +.

The 1100 has an added advantage in that the fill valves are up front and at one of the highest points in the system, so it's dead easy to purge any air from them without applying vacuum, though, that's best, but not for damping, only to reduce corrosion.

[weef]

Google   " Tony Cripps Hydrolastic Pump "   for a description of the procedure for suspension fluid filling and pressureising

[Clip]

Google   " Tony Cripps Hydrolastic Pump "   for a description of the procedure for suspension fluid filling and pressureising

That’s great, many thanks weef.

http://www.leylandau...lastic Pump.pdf

[Clip]

Are the 1100 displacers the same as in the minis, or are the different/larger etc?

[Spider]

Are the 1100 displacers the same as in the minis, or are the different/larger etc?

 

They are a bigger and different displacer to those fitted to the Mini.

[Clip]

 

Are the 1100 displacers the same as in the minis, or are the different/larger etc?

 

They are a bigger and different displacer to those fitted to the Mini.

 

Spider you are such a wealth of information and always so helpful. Thank you so much 

Edited by Clip, 08 October 2023 - 04:57 AM.

[Pete649]

Google   " Tony Cripps Hydrolastic Pump "   for a description of the procedure for suspension fluid filling and pressureising

 

Interesting read.

 

Always wondered what made it green.