6.9 Suspension blocks

[Oversize]

Hi all,

Wondering if anyone's had a set of blocks copied yet? After working on the suspension, it's rather frustrating having to wait an extended period while a 6.9 pumps up off your much-needed trolley jack! If not careful, it's possible to jamb your hands between the jack handle & chassis, or worse still bend panels with the jack handle. I'm often jacking up the whole car & when I remove the stands from the rear, my jack is getting stuck. Is it possible to drop the rear on the jack, start the car to pump up the rear (have a coffee), remove the jack, then drop the front, start the car to pump up the front (have another coffee) and finally remove the jack? Seems hellish time consuming & I'll be climbing the walls on caffeine! Putting timber blocks under the chassis often prevents the control valves from opening & raising up the car. Any other solutions (apart from buying another trolley jack, or a hoist)??

Mark

 

[Michel]

Have you tried working on the car with the (control) disc on service (centre position on the knob on the dash)?

That should keep your suspension from changing position when jacked

 

[John S]

If someone had a set (or even 1?) it should be possible to make a cheap mould and make some using RTV rubber compound, not RTV732 but a specific moulding rubber. I had some 40 years ago so I assume some is still available, and probably much better product using later technology.

 

[Styria]

Hi JohnS and Oversize, the possible re-manufacturing of the suspension blocks is an old and well trodden subject. Lots of suggestions but to the best of my knowledge, nothing has ever come to fruition. I am fortunate in having the four blocks and, whatsmore, I have or even had to use them - this was at a time when I was pretty green with 6.9s. I can assure everyone that, with even only the front ones in place, the cars are almost undriveable at any speeds above twenty kilometers an hour. I tend to think that they are more of a poseur value or when the car is being transported on a flat bed truck or rail carriage.

It would seem, Mark (Oversize) that you are starting to cut your teeth on the 6.9 suspension system. The first thing you need is a very good quality floor jack that will respond slowly and gently when you come to let the car down - you must have full control over this operation as it is so easy to damage the front 6.9 lip spoiler - and I am not even talking about an AMG reproduction unit. If the locking system does not work, it is in fact the alloy sump that comes to rest on the body of the jack. Not something I particularly like. The rear end is probably worse as the differential is such a long way in - and it is in fact the base of that unit that's supposed to be the jacking point.

I have always assumed that the locking mechanism on any 6.9 is non- operative. Therefore, before I make any attempt to lower the car, I place wooden blocks (150mm by 60mm) under the front or back wheels. It's usually the front, because that's the area most likely to be worked on. Thus, you can be secure in the knowledge that you will at least be able to withdraw the floor jack, even if the suspension is collapsed. It also pays to have additional timbers half that height to act as ramps when you wish to move the car - whichever direction. If you don't have those additional pieces of timber, the big blocks are too tall and likely to catch under the sill panels when you come to move the car. Again, hope that helps. Regards Styria

 

[Oversize]

Yes, I have tried locking the suspension before jacking them up, but to no avail. I suspect the locked position is only effective for towing. I knew it was an old topic, but hadn't heard if anyone had made progress.

Styria, I'd imagine your rubber blocks have gone hard over time (like all rubber products) & they may've been more useable when new.... Yes I do have a good trolley jack & I'm very carefull lowering my cars, but it's still frustrating if both ends of the car have depressurized. Great idea about the wooden blocks; I'd actually used something similar on other lowered vehicles in the past, but didn't think of using that method on the 6.9s as they drop so close to the ground. In the short term, i'll look at making some wooden ramps with a short, flat platform on the top & post a few pics & dimensions when they're done.

I still think rubber suspension blocks would be handy for long-term storage, especially if a car has developed some external hydraulic leaks. It'd protect the bump stops & struts, possibly even the gas cells. With the emergency 'rubber buffers' in place it'd also be much quicker to move the car, rather than supporting the chassis on wooden blocks & having to wait for the suspension to pump up off them. Of course that's assuming the engine even runs.... Moving a collapsed 6.9 without a running engine is almost impossible. Long story, but one of mine was moved without my knowledge by someone that knew nothing about hydraulic suspension & cared even less about people's property (part of the reason 4248 is now a parts car). If I had the buffers & a set of go-jacks I might've been able to save the car....

Styria, would you be able to post some pics of your rubber blocks along with some basic dimensions?

Mark

 

[WGB]

One of our western members has a set and he has offered to lend them to me so that I can get moulds made but I have never really needed them.

I am fortunate that I have my hoist so I can drop the car to just below ride height while on the hoist and then start the engine. It never takes more than about 10 or 15 seconds to pressurise.

My lock position on the disc seems to work fine but I never bother to use it.

I have on a couple of occasions driven off with it in the lock position and it tightens up the dampers beautifully - probably not good for the hydraulics but very similar to using "Sport Mode" on my air suspended ML500.

Bill

 

[Styria]

WGB can possibly correct me on this, but locking the suspension will not stop the car from sinking if you're driving the car. The way I understand it, you engage the lock position prior to commencing jacking the car, and if it is operative, the car will not sink in the stationary position.
I have driven 'Gleaming Beauty' with the suspension in 'LOCK' mode, and it does not pump up the car, nor does it prevent it from lowering itself. Regards Styria

 

[WGB]

I must go and have a look at the diagrams but as far as I know the lock position most likely locks both the return as well as the pressure line so there is neither fluid in or out.

I am sure you are correct Styria that if driven in this position with healthy spheres the car will slowly sink due to leakage at the various valves and pistons but it does hold itself up for a considerable time as on one occasion I was driving for about 15 minutes before I realised what was going on.

I was enjoying the extra precision while driving home from a trip to the air-condtioning shop a couple of years ago and the ride height seems to stay up quite well.

It is my understanding that the fluid controls the damping as well as the ride height but the springing is provided by the spheres once the fluid volume has set the ride height.

Bill

 

[Lukas]

I stuck mine into the lock position a few weeks ago prior to jacking the front of car up for an oil change. It seems to prevent lots of hissing and carry on from the suspension when you jack it up, and possibly also prevents the free wheels drooping too far down. It has also kept that position for the ~3 weeks it has been on stands (even a simple oil change is going to take me over 1 month - long story).

Jacking points is an interesting question - I don't have much experience here, but I try to look for nice solid parts that would be load bearing if the car was sitting normally. Under the base of the struts would be ideal, but they are too close to the wheel and thus the jack won't fit. I think I used a nearby part of the suspension arms in the end, and later the center of the front subframe (the body coloured part made out of thick sheet). The stands go under the large round bar behind the sump, near where that bar connects to the rest of the chassis.

PS: The manual is quite stern on driving around with the suspension in the lock position.

 

[TJ 450]

Yes, the hissing is the system depressurising, and this will occur if you raise the car without using the service position.

In my case, the service position improved matters, but it still came down at the front even so.

I was faced with many difficult and dangerous situations when having to lower the car from the stands. It's not something you want to do every day.

Tim

 

[Styria]

Hi Oversize, sorry it has taken a bit of time to display pictures of the suspension blocks - the two on the left are the front ones, and the others obviously the rears. I have also included pics of the choking blocks that should be used when jacking the car with the standard jack.

I have previously offered my opinion that the design of the standard jacks leave a lot to be desired. Invariably I use a block of timber as a base, but even with that I have had the odd occasion when a bar has moved either way whilst in the jacked up position - luckily enough, never with subsequent damage or problems to either car or personnel, but it is still a somewhat disconcerting situation.



Regards Styria

 

[SEL_69L]

It seems to me that the only times that suspension blocks are needed is when the cars were originally shipped from the factory, and when you need to drag the car onto a flat bed breakdown truck, usually because the suspension has developed a massive leak of oil, due to suspension failure.

In the first case, even with a new, ex factory 6.9, there is an allowable sink rate, and the car, when shipped or parked for a considerable amount of time, may have sunk quite significantly, and certainly by enough to make impossible to negotiate humps or ramps on and off a ship. In the second case, the entry and departure angles with a totally collapsed suspension will not permit the car to be dragged onto a flatbed breakdown vehicle.

It is quite common for current vehicles with low under car clearances to be shipped with temporary suspension blocks in place.

 

[Lukas]

Is there any reason a set of blocks couldn't be made out of wood?

 

[Styria]

Is there any reason a set of blocks couldn't be made out of wood?

Hi Lukas, there really is no valid reason not to use timber blocks for storage purposes. Mind you, the rubber blocks were also designed to be used in an emergency as a means of 'getting your car to the nearest authorized repair shop'.
That, of course, can mean driving the car, rather than having it towed or trucked, and if you have driven your 6.9 with the rubber blocks installed, you would realize that timber blocks just about render the car undriveable. So rubber blocks it should be - in my 'humbel' opinion. Regards Styria

BTW, does anyone know FOR CERTAIN if the rubber blocks were an option when the car was new, or were they part of purchasing the car ? I've heard different stories.

 

[SEL_69L]

I do not have rubber blocks, but I have seen a 6.9 driven over an angled driveway with wood blocks (basically, hunks of wood) in place. The distance driven? - only about 100 metres in total, but the pieces of wood served their purpose.

Maybe, if your 6.9 is stranded and needs to be flatbed trucked, this could be your answer to getting your 6.9 onto the truck. Could be helpful if you need breakdown recovery or your car has been in an accident, and the suspension has 'let go'.

 

[Michel]

I do not have rubber blocks, but I have seen a 6.9 driven over an angled driveway with wood blocks (basically, hunks of wood) in place. The distance driven? - only about 100 metres in total, but the pieces of wood served their purpose.

Maybe, if your 6.9 is stranded and needs to be flatbed trucked, this could be your answer to getting your 6.9 onto the truck. Could be helpful if you need breakdown recovery or your car has been in an accident, and the suspension has 'let go'.

What I can't understand, is HOW do you fit them if you've lost pressure and the car is flat on the ground?

 

[Styria]

Very simple Michel. You start using the vehicle jack, wound right down, with preferably a solid piece of timber underneath the jack. I would imagine, no I know, that you will need various bits of timber to eventually give you sufficient height to be able to insert the rubber blocks.

Invariably, you will have to remove your road wheels as well, and one precaution I always take is to place the removed tyres underneath the sill panel, with a four by four sitting between the rim and any lower panel on the INSIDE of the sill panel itself. Sill panels, because of rust, even if not visible, can considerably have soft metal in the sill panel. Also, I think it is almost a 'must' to have another piece of timber act as a base under the jack - in my opinion, the jack is of poor design. Easy enough for a car to roll off its jack !

So Michel, that's one wheel at a time and it does take time, and effort, to organize things properly. You could almost allow a couple of hours for the job. Regards Styria

 

[Oversize]

Styria, thanks for posting the pics! It's the first time I've actually seen any, apart from in the manual.... Maybe we should see how many members would be interested in having a set of blocks? Then we could get a quote from a rubber manufacturer to calculate how much they would cost per set. I'd certainly be interested in at least one set (maybe more), as my suspension will hit the deck when I pull the engine for lengthy panel repairs.....

 

[SEL_69L]

I stand to be corrected, but I guess that a copy set of blocks would be made by the lost wax cast investment method, only the final product is rubber, not metal. Not that even this uninformed opinion is important, because if you were going to have a copy set made, you would take the originals to a business who makes engine mounts; they would have the know how. Quite a common requirement when a vehicle is re- engined with something quite different from the original engine. Such people would also understand what would be the correct rubber compound mix to use.

 

[Oversize]

Well after moving 7x non running 6.9s I think Ive sussed out the emergency block situation.... Solved with timber, nails & zip ties. Some tweaking would be of benefit. Specs & pix to follow soon