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De-powering a rack?
liam.mccaffrey - 30/7/15 at 01:31 PM

Is depowering a PAS rack acceptable to MOT/IVA?

snapper - 30/7/15 at 01:40 PM

Yes, we usually keep fluid in and join the pipes together

coozer - 30/7/15 at 03:30 PM

There's a detailed explanation on how to remove the pas from the mx5 rack in the Midlana book.

I'm a bit suspicious at the moment whether this will be acceptable for IVA.

It tells how to remove the central seal and take away all the pas fittings but leaves the input covered in holes... I've plugged the big ones so far (mainly to keep dirt out)

There's a pic in my Midlana thread....

loggyboy - 30/7/15 at 04:07 PM

Iffy in my experience, my dad a MK2 golf with de-ac PAS which failed on it.

Wording is if its standard fit it should not be deactivated, but if it was an option then it can be.

[Edited on 30-7-15 by loggyboy]

maccmike - 30/7/15 at 04:12 PM

I de powered my rack - by fitting a genuine manual rack. Did this because concerned about IVA.

liam.mccaffrey - 30/7/15 at 05:37 PM

My midlana book arrived yesterday, oddly enough. Might press on with the de powered Pas rack for now . if I need a manual rack then I can source one. Crap thing is I gave a mk1 mx5 manual steering rack away when I stripped the car

MikeRJ - 30/7/15 at 07:56 PM

If you use a PAS rack without the assistance you have introduced a torsion spring into the steering column, just what you don't want for precision steering.

scootz - 30/7/15 at 09:53 PM

quote:
Originally posted by MikeRJ
If you use a PAS rack without the assistance you have introduced a torsion spring into the steering column, just what you don't want for precision steering.


Would that also be the case for speed-sensitive electronically-assisted racks (thinking specifically about the Smart Roadster rack).

MikeRJ - 31/7/15 at 08:54 AM

quote:
Originally posted by scootz
quote:
Originally posted by MikeRJ
If you use a PAS rack without the assistance you have introduced a torsion spring into the steering column, just what you don't want for precision steering.


Would that also be the case for speed-sensitive electronically-assisted racks (thinking specifically about the Smart Roadster rack).


There is still a torque sensor which is built into the rack in the case of the Smart Roadster. Some EPAS systems have the torque sensor built into the steering column.

The torque sensors have built in limit stops, it may be possible to design some packers to prevent any movement at all. I suppose it could be welded, though I'd be less keen on this as this will obviously see a lot of cyclic stress and a failure from embrittlement here would be terrifying and potentially fatal.

If you do this, then obviously remove the motor as well; the inertia of the motor armature is what makes most EPAS system feel so 'dead', as it effectively filters out any vibration passed up from the road wheels.

I don't suppose the ForTwo rack is the same? They are available in manual versions.

scootz - 31/7/15 at 12:32 PM

Thanks Mike.

The ForTwo rack may very well be the same... will look into.

kb58 - 1/8/15 at 01:52 AM

quote:
Originally posted by MikeRJ
If you use a PAS rack without the assistance you have introduced a torsion spring into the steering column, just what you don't want for precision steering.

I discuss that in the book. In my own Midlana, the weight on the front tires is so much less than a Miata that I can't feel any "stretchiness" that a spring would cause. Even if I did, I discuss how to fix that.

Regarding using a PAS rack, you can always just cross-couple the lines and not even open the assembly.