Topping up rear dampers?

[katy]

Just wondering what the consensus is on topping up the rear dampers.

In the BMC manual they say that the dampers must be removed from the car to be refilled, although it appears that they could be refilled while on the car. All the sketches show them mounted on a piece of plate, in a vice, at approximately the same angle as they would be when installed on the car. They don’t say whether they should be topped up while in the vertical or the installed position.

In the Haynes manual they state that the damper must be held in the vertical position when filling.

So, should they be vertical or inclined while being filled?
Or does it really matter?

TIA, Ken

[bmcecosse]

Vertical - or near-as. One damper on the car is pretty much vertical, the other just needs one bolt undoing and slacken the other - then swivel it on the bolt till vertical. But ideally - take them off, mount in vice - remove drain plug/valve assy - pump out the horrible old oil and then refill with SAE 40 - pumping the handle up and down to eliminate air, and to feel how good the damping action is!

[katy]

Thanks, I'll keep that in mind. Just found that the rebuilt dampers I purchased are already full of fluid, so I don't have to fill them up as I had thought would be neded.

[bmcecosse]

It may be very 'thin' fluid........ How difficult is it to move the damper arms?

[simmitc]

BMC's advice is definitely the "right" way to do it, but I've been doing it on the cars for thirty years and never had any problems. Any top up required should be absolutely minimal. Any more than that suggests a leak that is probably visible. It's still a good idea to change the oil once in a while.

[katy]

[quote]How difficult is it to move the damper arms?[/quote

On a scale of 1 to 10, I'd say about a 4.

I'm replacing all 4 on the car w/rebuilt ones from BM, so I'll leave the existing fluid in them for now. When the car's finally on the road we'll see how they preform and then decide if the fluid needs replacing.

[bmcecosse]

With SAE 30 I would expect 6 on that scale, with SAE 40 expect 8, and with EP90 expect 10!!

[xpress]

what's the mod again bmc re putting motorcycle damper oil in them, does that improve damping, making them softer or firmer? what type of oil is this?

[bmcecosse]

Motorbike engine oil - SAE 40 = firmer.