How long should a ram last?

Unread post by **DHallworth** » 09 Feb 2010, 11:38

I had a look at mine whilst it was on the ramp last night.

Mine is leaking from the little return pipe that goes into the ram.

The pipe looks like it can be just lifted out of the ram.

Is there a cure for this or is it a case of leave it till it gets really bad and get it a new ram?

David.

XantiaMan · Unread post by **XantiaMan** » 09 Feb 2010, 11:58

Make sure you have a really close look, as that pipe is a snug fit, but not a lot of it goes into the stub. Give it a good clean and look for signs of perishing. Mines is in perfect condition at the moment!

Unread post by **DHallworth** » 09 Feb 2010, 12:31

It appears to be a loose fit, I can pull the pipe out with my fingers.

Going to try and get a better look at it tomorrow.

Just seen the guide in the stickies section which looks interesting.

My rear ram is quite wet but the front ram appears to be bone dry which is handy.

OFF TOPIC: Xantiaman - how do you find the ST220? I've looked at these a few times but never bitten the bullet.

David.

XantiaMan · Unread post by **XantiaMan** » 09 Feb 2010, 12:39

DHallworth wrote:It appears to be a loose fit, I can pull the pipe out with my fingers.

Going to try and get a better look at it tomorrow.

Just seen the guide in the stickies section which looks interesting.

My rear ram is quite wet but the front ram appears to be bone dry which is handy.

OFF TOPIC: Xantiaman - how do you find the ST220? I've looked at these a few times but never bitten the bullet.

David.

OT- Lovely car. Very solid feeling with a charismatic engine, loving the leather Recaros and six speed box. I got it for a good price, now just about affordable at this age, and got lucky with a vast service history and one previous owner, it had to be snapped up.

Back on topic, give the pipe a good clean and degrease, mine was a very tight fit but if covered in LHM it may give the impression of being loose.

Does seem to be the rear rams going first, possibly due to them getting dirtier and tend to stay damp for longer than the front, which has some engine heat.

Unread post by **CitroJim** » 20 Feb 2010, 14:32

I may just have hit on something. I don't know, just a theory...

On my Activa project, both rams are weepy, f the front slightly more so than the rear. I looked at the front one closely today and it is weeping from the round seal at the base and not from the ram itself. That in itself is good.

Now, whilst looking around under the car, I noticed the roll corrector has a leak.

Odd.

I checked a bit further and reckon the weepy rams and the weepy roll corrector are related.

I then discovered the roll corrector linkages are totally and utterly seized.

This got me thinking...

The rams and roll corrector don't work in a conventional hydraulic way and have two modes of operation.

Each ram has full hydraulic pressure on one side of it always, as supplied from the Activa accumulator. The other side has slightly less than system pressure on it as this side is supplied from the roll corrector. It can either apply system pressure or bleed pressure away to make the ram go up or down. However, the front and rear are connected via the Activa Balancing sphere that acts as a spring buffer between the two rams.

I noticed that the ram leakage return is only active when the ram is working one way and is being forced to lengthen or shorten (the front and rear work in opposite senses) due to height changes say, during Citarobics. The rams leak under these circumstances because their pistons are being forced against full system pressure by a a larger force than it can resist and there is nowhere for the fluid that needs to be displaced to make room for the piston to go. Normally, on cornering one ram equalises itself (via the balancing sphere) with the other so no overall leakage but on falling/rising height, the fluid that would need to be displaced has nowhere to go except to leakage and this is what happens.

Now, if the roll corrector linkage is seized, so effectively rendering the roll corrector inoperative, the same applies: The ram pistons have to move on changing height/cornering but the displaced fluid has nowhere to go except to leakage and because this is very excessive leakage, the leakage return lines become overwhelmed and make the ram and roll corrector weep.

Just a theory. It may be rubbish but I'll soon know if this is indeed the case on my project.

I've checked and given the linkage a good lube on my red Activa.

It would also give a plausible reason why this problem is seen more often in nasty, cold weather - a partially seized roll corrector linkage will be a lot stiffer in sub-zero temperatures.

You may not feel much change in roll correction ability as a lot of roll correction is carried out by fluid displacement between rams - just like the Hydrolastic system fitted to BMC cars in the sixties. The roll corrector works in concert but is not the only roll correction mechanism in the Activa system.

So, check that your roll corrector linkages and mechanism is well lubricated and moving freely at all times. Treat like a height corrector.

Sl4yer · Unread post by **Sl4yer** » 20 Feb 2010, 15:43

Interesting Jim.

Would a sinking rear end cause the same effect on the rear ram? Mine is sinking more than it used to, and I've been wondering if this is tied to the leak?

James

Unread post by **CitroJim** » 20 Feb 2010, 17:45

Yes, but with a caveat James. Ram movement as a result of slow sinking should be OK as the "give" in the Activa accumulator and the Activa balancing sphere should be able to absorb the displaced fluid.

However, if either or both Activa spheres are flat then this cannot happen and then the fluid has nowhere to go.

I'm suspicious my sliver machine has a totally flat Activa accumulator as when the security valve opens (and thus opens a path to charge the Activa accumulator) there follows a series of very rapid ticks and jumping in the rams.

If you have no history of swapping these spheres then my advice would be to do it sooner rather than later. The spheres are unavailable from GSF but Pleiades can repressurise an anti-sink sphere to 62 bars to become an Activa accumulator and change the pressure in a normal accumulator to 30 bar for the Activa balancing sphere.

I'll be ordering two accumulators from Martin shortly as I'm not happy that the one on my red Activa is 100% healthy.

Sl4yer · Unread post by **Sl4yer** » 20 Feb 2010, 20:18

CitroJim wrote:I'm suspicious my sliver machine has a totally flat Activa accumulator as when the security valve opens (and thus opens a path to charge the Activa accumulator) there follows a series of very rapid ticks and jumping in the rams.

I've suspected this on mine for a while due to the sideways lurch it often does when the valve opens (often mistaken by some for the Activa Shuffle caused by worn rods/blocks). Hence my suspicions about a certain Manchester-based sphere refiller. Might be a good place to start!

James

Unread post by **CitroJim** » 20 Feb 2010, 20:36

Sl4yer wrote:Hence my suspicions about a certain Manchester-based sphere refiller.

Funny you should say that James, that's the origin of mine....

Yep, the lurch as the security valve opens is a good pointer. Mine never used to but it does now...

Check the lubrication of your roll corrector mechanism. I gave mine a good squirt today and it's made a difference..

I've just done a 40 mile round trip to our 6 mile away Tesco just because I was in the Activa and it was feeling so lovely