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Delete PAS or up the resistance?


Shackleton
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Thinking of going back to the manual steering box in my RR and reinstating the original early three spoke steering wheel (currently using a late RRC item which is much smaller in diameter).

Anyone have a suggestion for keeping drive to the Td5 water pump once I've deleted the PAS pump? I'd have to keep the pulley for the sake of the aux belt. I'm wondering if I could gut the PAS pump just keeping enough to support the drive from the pulley to the water pump? Are the bearings in the pump lubricated by the PAS fluid?

I could keep power steering, in which case can anyone tell me who does proper PAS box rebuilds - I've heard that many of the so called reconditioners don't do a proper job at all.

I'd need to dial back the power assistance as my original early (big) wheel would make things dangerous. I know I could put more resistance in the steering by playing with the shims on the swivel pins, but is this the way and will it have a negative effect on the PAS or wear of the swivel pins? And is there something I could do on the PAS box itself to decrease the power?

Basically looking for some opinions so I can weigh up the options.

Thanks,

George

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The thing that defines the amount of assistance is the line-pressure from the PAS pump. This is set by a pressure-relief valve. It should be possible to split the PAS pump and replace the relief-valve spring with a weaker one to reduce the line-pressure.

Some trial and error (and a box of differently-rated springs) may be needed to get the right value.

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You can also restrict the output of the pump, there's a piece that unscrews on some pumps which I have opened up to allow more flow, giving much more assistance, the opposite should be true... make the hole smaller somehow!

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It should be fine actually, just quite light, I suspect the TD5 PAS pump is likely higher pressure than the earlier LR pumps, c. 1400psi, rather than 900, which makes a fair difference.

Personally I would just try the large wheel and see how you get on, will be like one of those yank mobiles, finger light steering, but they are safe, well sort of :)

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It's a pre PAS RR with a Td5 in it C.Drumstick and at the mo it does drive very like a late RRC. I tried the original wheel when I first put in the Td5/PAS and it was so light to the touch there was no feeling from the front wheels what so ever. Big time unnerving. The front wheels could have been on holiday in Ibiza for all I knew.

Interesting about restricting the pump and/or changing relief valve springs, forgive my ignorance but where would I find those springs in varying values?

Part of me would love to just ditch the PAS. Weight saving isn't high on priorities of course but I do think there's something about having to work a little bit and the old unassisted steering wasn't too heavy anyway. There's also the bonus of simplicity and potentially freeing up a hp or two from the engine.

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I too believe the ZF pumps have a restriction in the output port that some have removed or enlarged (ISTR Dirtydiesel doing it). I wonder if ZF themselves might have any info as most of their pumps seem to have the same body etc. perhaps they just vary a couple of components to set pressure/flow, and you could lift one from another vehicle & bolt it in.

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Apart from a knackered steering box giving so much play the tracking boys had a difficult job, it drives great. I'm just regretting the loss of a lot of the charm of the original driving experience. The thick rimmed, small diameter late steering wheel just doesn't suit it. Nor do the late instruments I've installed so I can make use of the leccy signal from the trans for the speedo - so I'll be bending ears for suggestions on who to go to or how to get late speedo internals inside an early instrument cluster next :D

Interesting about the pump FF and Mike. Mike did you just plug the pump inlet/outlets with bolts or something?

I've lots to go on here, just need to make the decision on whether to go back to fully manual, or mod the PAS pump. Thanks lads.

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