C5 steering rack

[MattBLancs]

Ok, difficult question to answer, but here goes!

You'll all be aware of the C5's fancy fixed hub wheel, but are you aware of how it does it?

I had a C4 with similar fixed hub wheel. It was worn on the rim so I picked up a leather one from a C4 Picasso and swapped it. Old one disassembled because why not!?

The steering column terminates in a gear, which runs against the steering wheel's annulus.

Two things about this, one which does not matter: this arrangement speeds up the rack, so would be more turns if you stuck a normal wheel on! (Performance upgrade for other PSA vehicles, not a "quick rack" but a rack quickening wheel? )

Ok, now the relevant thing: there's obviously a ratio between annulus and column gear, so I now wonder if it possible to have the column gear 360° out? Say the ratio was 4:1, 360° out on pinion shaft would be 90° out on the steering wheel.

Just a theory, but hypothesis seems plausible??

[bobins]

Would that be the difference between changing the rack with the existing steering wheel set to straight ahead but the wheels pointing 'one turn' to the right (or left), then putting the new rack in with the steering wheel set to straight ahead and also the new rack set to straight ahead ?
..... or vice versa.

[MattBLancs]

Would that be the difference between changing the rack with the existing steering wheel set to straight ahead but the wheels pointing 'one turn' to the right (or left), then putting the new rack in with the steering wheel set to straight ahead and also the new rack set to straight ahead ?
..... or vice versa.

That's how it would be with a normal wheel and column, but I'm wondering if that extra gear ratio in the wheel itself gives another combination again? I.e. steering column gear is one full turn to left or right, but the gear ratio in the wheel puts it at 90° instead.



I suppose I'm not being that helpful as I don't actually know the C5 gear/annulus ratio! But hopefully the theory makes sense?

[bobins]

Easy enough to work out the ratio - just mark the UJ at the bottom of the column and turn the steering wheel one turn and see where the UJ ends up

[Dunkah]

Wow!!!
Another complication in this equation……
You certainly get your moneys worth with Citroen don’t ya……
I’m definitely gonna look into that!
Thanks for pointing all that out though, I never would have considered that.
Everything was so much simpler in the 80’s

[MattBLancs]

The thought only occurred to me this evening, but yes plenty going on in what could be a simple system!

[MattBLancs]

Easy enough to work out the ratio - just mark the UJ at the bottom of the column and turn the steering wheel one turn and see where the UJ ends up

Will have a go when I get chance and report back.

As the wheel will turn the UJ faster, could be easier the other way round (as wheel is more accessible/ easier to work out / measure fraction of a turn) - minimise the amount of time spent with your head buried in the footwell

I.e. one full turn of UJ, measure degrees at wheel

[Jay-Bruce]

Matt is a Genius! Then again, the epicyclic / planetary gearbox arrangement in the column is also genius, and would explain the out of phase installation experienced by others in the past.

[MattBLancs]

Ha ha, genius, no! Nut case who takes broken things to bits just to see how they tick? That's me!

Trying to find a picture of the gear/ annulus but must be internal to the wheel (not visible once airbag removed)

I'll have a look in my scrap bin at the weekend, but pretty sure the dead C4 wheel gear setup is long gone. It was even smarter than described at present as it was actually 2 annulus gears, one sprung - that was to eliminate any backlash. Guess rather unpleasant free play sensation with just a standard (annulus) gear meshing with another.


Really interesting clever stuff, I could never fathom why the C6, otherwise pinnacle tour de force of Citroen technology had a boring normal steering wheel! If I had a C6 I think I'd be pondering if the C5 wheel could be made to fit!

[Dunkah]

Don’t be so modest, it really is a stroke of genius!

[Sloppysod]

I’m now quite convinced that either rack would fit either car so long as the pinion was pulled and turned through 90°. The pinions have 8 splines so a 2 spline turn would surely do it

Would really like to know, if you ever try this, as I have fully reconditioned rack in my garage loft that leaves the steering wheel at 90°, I am keeping it as spares, just in case.......🪵

[Paul-R]

You might find that the longer movement rack off the 16" wheel version will fit without problem until you turn the steering wheel to full lock and find that the fatter tyres rub against something.

Which brings up another point. The 16" wheel variants should have a tighter turning circle compared to the others. Can anyone confirm this hypothesis?

[Dunkah]

Sloppysod……
I’ll definitely let you know as soon as I get any answers on that, or the steering wheel gear ratio.
Paul r….
That definitely is what I’d have suspected too, but I haven’t ever noticed any rubbing on my car with 17” wheels and the incorrect rack

[Paul-R]

Maybe your incorrect rack was the correct rack but assembled incorrectly after being reconditioned?

[Dunkah]

Maybe your incorrect rack was the correct rack but assembled incorrectly after being reconditioned?

I did think that, but now that I have two that are out of the car, I’ve measured them, the one that fitted was incorrect travel length and the one that didn’t fit was the correct travel length, so I think whatever the issue was it wasn’t just the angle of the pinion