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Drew21

Need a nice Touring

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colder temps will mean lower pressures in the 4 supporting pistons, meaning more of the push would need to come from the pump. For the first bit of opening the leverage angle for the hydraulic ramp is very poor

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Anyone ever come across a more powerful pump that would fit in the space?

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The pump in Tourings is identical to the ones in Saloons & it's more than adequate for lifting a bootlid, 'least when there is enough of the correct fluid in them!

(They do not like power steering fluid!).

 

As mentioned, the problem with the Touring's set-up is the crazy angle through which the ram has to apply force to the hinge to lift the tailgate.

 

On saloons, there is a decent distance between the pivot point and the mount for the ram. 

On Tourings, the mount is very close to the pivot, hence the need for substantial reinforcement & the marginal operation on initial powered opening.

 

The hydraulic pistons & springs that hold the tailgate open on standard, non-powered tailgates are pretty hefty, when they fail (as on my car...) you get a good idea of just how much work they have to do to keep the damn thing open when you try to lift the unassisted tailgate...

 

A more powerful pump might start ripping things to bits!  :lol:

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I was sent a 'how to' to get mine working when I first bought the car. It said to use ATF.  Trisman, are you saying use something else?

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^ ^ Yup! Apparently ATF is too thick & it wreaks the pump pretty rapidly.

I got the info online somewhere, I'll have to have a look & see if I can find the link(s).

The stuff you're supposed to use is an aircraft spec. fluid.
It is surprisingly thin & ludicrously expensive if you get it from BMW.

I got some from a specialist aviation fluid supplier.
It came in a 1 litre tin & cost less than £20 inc. post.

I think I may have some left. (The pump didn't take much!).

 

 

EDIT: 

 

I think they're positive displacement, reason I say is there is a pressure relief valve in the pump housing (called the emergency valve!). 

Given the pressure it probably needs to generate, (40 bar IIRC?) wouldn't it have to be positive displacement? 

 

As for the fluid spec, looks like its: AeroShell Fluid 4 Mineral Hydraulic Oil  MIL-PRF-5606H

Edited by Trisman

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This stuff:

post-28557-0-29614400-1415477149_thumb.j

 

Weird, thin purple stuff.  Loads left if anyone needs some.

Edited by Trisman

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I bought the kit from BMW to go on my old B10, think it was about £50 for a very small pot of the fluid, plus a bunch of washers and bushes. But it did the trick!

 

still looking......!

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Also this:  linky thingy

 

CHF fluid?   I think that's the stuff for old Jags (XJ40s) & some Citroens?   Thick green stuff IIRC.

 

It's also synthetic, the stuff for the tailgate ram is mineral based.

 

I've no idea what would happen if (say) ATF was used in the tailgate system, but when I looked into it, there were enough warnings about not using it to make it worthwhile searching out the correct stuff.   It's a lot thinner than ATF (& what I recall of CHF) & I read warnings about seals & grenaded pumps, so why not use the proper stuff?

 

Plus, the pump was either about £800 or £2,000, so if it had failed, some normal boot rams would have replaced it.   Not as much fun...

 

(Boot goes up, boot goes down... Boot goes up, boot goes down.  Repeat until the thermal cut-out engages... Sad D'oh... :( )

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Mines had ATF in it for about 4 years now and apart from the 'dozy when cold' thing it's ok. Do you think a mineral hydraulic oil would improve it?  How about brake fluid?

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^ ^ Dunno!  But as it's a much thinner fluid, it could be better on cold days?

 

Likewise, I don't know whether brake fluid would be an option.  This stuff is thinner, but brake fluid is also thinner than ATF & is mineral based...

 

The stuff specified (Aeroshell 41) is apparently used in aircraft undercarriage systems. 

Dunno what that says about lubrication qualities, but surely it should have good low temperature performance?

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