Removing the most COMPLEX classic car steering system!

[@TK42138]

Robert Opron to Pierre Bercot; "How complex does it need to be?" Bercot: "Yes"

[@perakesson6022]

I believe steering ratios for Citroëns with Diravi is: SM 2,0 CX Turbo 2,0 Other CX 2,5 XM 3,0 I love the Diravi on my CX. Fast and precise steering. You do not feel any vibrations from the weels. No torque steering on 6:09 acceleration. You can make a turn and hit a pot hole with one wheel and the steering wheel will not move one bit. Fantastic engineering!

[@normandiebryant6989]

Yes, no torque steer and bump steer on any Citroen with centre-point steering. DS power steering had 3.0 turns lock to lock, and GS (manual steering) had 3.7 turns lock to lock. As an aside, that heart-shaped cam on the DS steering column was totally useless. I've never met anyone who could feel anything from it or who noticed if the little sprung roller came off the cam. The DS (and GS) just tracked in a dead straight line over all surfaces and camber-changes just by the castor but the centre-point steering geometry prevents bumps, etc, from knocking it off path. I think the GS had the best steering of any car I've driven. I've driven around 10-15km or so up a freeway without ever moving the steering wheel at all. You just never needed to correct it, right up to maximum speed of 140+ km/h.

[@jncg2311]

I'm not sure the CX DIRAVI got different gearing, all CX DIRAVI cars had 2.5 turns lock to lock I believe. The early non power steering cars had much longer steering gearing though as the weight distribution, something like 70:30 biased to the front made that necessary. I also love my CX steering and sometimes realise just how I have become used to it when I get into a modern PAS car again. The best feature, and linked to the centre point geometry that Rich mentions and DIRAVI back pressure system is that it is unaffected by tyre issues too. I was told a story by a neighbour of them travelling to family in their CX and hearing a strange noise at the back of the car while on the motorway, they stopped at the next exit to find that one of the rear tyres had punctured and delaminated, what they had been hearing was shreds of the tyre carcass flailing off the wheelarch. The car was so stable and unaffected, even under braking that they had no idea when it had happened.

[@MrLekatt]

I've never worked on a SM but had to change steering rack on a CX once. It was driven on mud roads with one boot loose that filled the rack with mud and contaminated the LHM. Most of the Diravi self-centering mechanism/hydraulics are under the dash on the CX and I took it out to examine it. Not that complicated actually but won't like dirty oil. The hight pressure to one side of the rack/hydraulic cylinder is directed by a sliding valve mechanically but the other side depends on a spring to push the slide back the other way. If that slide is contaminated you will feel a slight resistance when turning the steering wheel in one direction but not in the other direction. I tried the system by taking out the rod connecting the Diravi unit to the steering rack and drove it like that. The rod acts, not as a steering column, but as a feedback from the rack to the Diravi unit. When turning the wheel slightly and hold it there, it would feed the rack with regulated high pressure oil until it's full lock at the wheels. Like walking on a string.. Fun though.. 😎 >>

[@conradharcourt8263]

I wonder if there was ever a point in the development of the SM when anyone said "No we can't do that, it would be too complicated." Thank you for the fantastic tutorial on steering, I have really learned things today!😊

[@UPnDOWN]

They would have been fired immediately.

[@thomasalbrecht5914]

Excellent explanation of the Diravi system, well done! I have driven an SM twice, but too briefly to get really used to the system. The car was designed for motorway cruising at high speeds, for which the steering is certainly excellent. I drove one once in a suburban context and once on small winding roads, and when it’s not even your car, but a somebody else’s nice condition pride and joy, this steering is your enemy on the first day in such conditions. You’re always steering too much because it’s so direct and you have to cope with the counter pressure, which just doesn’t compare to the way that an ordinary steering geometry feels. It takes much more getting used than your average rental car.

[@michaelwright2986]

I'm really liking the discovery of the way it's put together as you go. I realised that it gives me the same pleasure as Time Team. The archaeology of the automobile. I also feel a little tingle of vicarious pleasure whenever a fixing comes apart the way it's meant to--delight that 40 years ago, a company and the people cared enough to do it right. BTW, be of good cheer. Christmas will soon be over.

[@UPnDOWN]

In a weird way, it's actually one of the bits I'm enjoying. I like discovering (at my own pace) how things work and exploring mechanical components. You start getting into the minds of the engineers who designed it all.

[@robinwells8879]

The utter joy of Citroen engineering being that they looked at everything that everyone else did, acknowledged the admirable logic of it and then went off on their own thing and redesigned the wheel! You really do have to admire the Gaelic ingenuity of that. Always the path less trodden.😂. Hugely economically non viable but an engineering tour de force and sold to Audi to be used on the 100 Avant (possibly the DS and not the diravi version). ❤

[@Mickhanic-garage]

Good progress on the most complex car in the world... Videos help no end with work like this... Look forward to seeing the progress

[@wanderingorganist]

I am Mr Clueless about technical stuff on cars. But somehow this is essential viewing. Thank you, and hope you and the family have a good Christmas.

[@guillaumeromain6694]

It's fabulous work, this! I really enjoy your approach to it. Informative and fun as usual. You are very talented. Thank you for sharing!

[@mclouj]

Bloody ripper it's SM Tuesday. Good progress being made.

[@docnele]

I am confident that your wife loves the SM, since she will know exactly where you are at least for the next ten years ;)

[@romac9516]

I can now talk about scrub radii with more confidence. Love the SM updates, cheers

[@silkdestroyer]

I'm find these vids very educational. I spent 2 days last April driving my SM, (fitted with a Merak SS engine,) back to Durham from Sweden. It went straight into storage, while I went through the process of registering it, and out came my 2002 Merc CLK 320. Now, I love the Merc, (have to say, a smoother engine,) but, after 2 days of SMing, when I drove away in the Merc, I thought that something had gone wrong with it's steering! It just felt a bit dead and heavy. The SM steering, once you get used to it, (especially the powerful self centering,) really is good. Poor So-Fee, (SM), hasn't seen the light of day since. Yes, I know that's bad and that they like to be used, but I work at sea, so for the moment at least, I can' quite give her the attention she deserves. I have her registered now, but I'm looking at a private plate, which ends in the numbers 114. Only SM affectionados would understand it.

[@klauswassermann8054]

What a snakepit of a car's front end. I do admire your dedication and bravery just as much as the SM's many intriguing idiosyncrasies.

[@gafrers]

Fantastic, love that steering system. Nothing beats seeing it in action irl and not only in sketches. 👌👌 Well explained as always

[@bondbug73]

Your SM is touch wood (huh huh) is still coming apart really well for a 1973 car. Very interesting descriptions and amazing progress getting to that engine out stage. Well done Rich. Have a good one. 🎄

[@HowardLeVert]

The first time I encountered that self-centring mechanism as used on the DS was on a Sony VTR edit controller - it allowed the shuttle control to centre automatically. Very enjoyable video again!

[@Madpegasusmax]

nice work, the inboard rotors and calipers on the front are quite nice ,high performance stuff , giving a huge steering angle for a traction , and the reduced suspended weight... but a nightmare to service/replace, My father's GS had the same system ,fortunately the disks are massive so almost no use , only the service pads where changed , the small parking pads where small like a big coin and never get used if well tuned , and my father added a microswitch to the parking brake lever and connect it to a unused dashboard light (red convertisseur warning -||- ) to use it as a parking brake reminder :D

[@simonprime5541]

Another informative and interesting vid. Merry Xmas to you and your family. !!

[@torresalex]

This is fricking excellent stuff. I had always thought DIRAVI was to keep the car going in a straight line when going down roads with choppy surfaces. Thanks for clearing that up, though I feel foolish now for not knowing the correct reason.

[@Wired_Mike]

Just in awe watching this work progress ...

[@MysteriousFigure]

Fantastic to see yet more action on this car, great work!

[@smhorse]

The CX also has DIRAVI, but with 2.5 turns, lock to lock

[@studisco2327]

Enjoying the pitter patter of tiny feet as you move around the car during the brace removal at just after 13 minutes.. Nice to see the progress, It pleases me to see a machine so well put together that it comes apart again, even after so many years. I'm really looking forward to seeing this return to the road.

[@mrcogginsgarage7062]

Good progress Richard Merry Christmas and a Happy New Year to you and yours .

[@anthonygregg862]

Hi Kitch. Sm action simply marvellous. Happy christmas and new year.

[@PeterMorris-lu5us]

Whilst there is not a Haynes manual you can buy the Citroen SM manuals prepared by Citroen for their garages. Generally the copies are in French with somewhat poorly copied photos - but they are a huge help in this sort of work, let alone servicing.

[@davidflamee]

"Not stretch Armstrong" lovely analogy.

[@rolandfaragher-horwell1547]

Driveshafts just pull out of the triax housings after you remove the two cross-point screws at the hub face (between lug bolts). No need to touch the big bolts at the inboard end.

[@Canalsman]

Fabulous progress. It's all looking surprisingly good as you remove more and more. Well Done! Have a Happy Christmas Kitch....

[@UPnDOWN]

Thanks, you too!

[@davefrench3608]

What a task. And what top quality engineering and materials.

[@Tagora2664]

Cracking vid as always. 👍

[@ukzoinks]

Great video - now things are getting really exciting.

[@joopjansen9102]

Thanks for the excellent vid! I hope you hade a nice Christmas. Now onwards an' upwards! Take care mate ;-)

[@nicjackson5741]

Brilliant Content look for ward to Sundays/Monday mornings to watch this. Keep up the great work fella.

[@deviatefishy]

I love how you say 'fixings'.

[@niallsommerville9813]

Perhaps he doesn't want to sound posh by calling them fasteners darling 😉

[@OneDullMan]

Great.video - was worried for ya as I thought the beast within the SM was attempting to rise from the dead and thwart your attempts at disassembly

[@richardbaron7106]

Wow, much progress being made. The windscreen is clean and shiny - you know a certain Hubnut is itching to do a wiper test 😂

[@Zadster]

To start with, I thought this would fight you every centimetre of the way. I'm pleased to say that, so far, I am completely wrong! For once, it actually seems to want to be rebuilt and restored. The engine and general area looks way better than 90% of all "classics". I'm not saying there won't be problems and a lot of work. But so far, so good.

[@TheSoundsnake]

Hm, the GS (A) also has centre point geometry, no Diravi (or any form of steering assistance), but they do self centre, are in fact very stable. Isn’t it the caster that actually determines the straight line stability? If you reduce that, the DIRAVI self centering will help. Much more likely they created the DIRAVI to cope with the engine power, and reduce feedback to zero. In fact, the wheels are hydraulically locked into position, the steering will (edit: wheel) is just there to tell the hydraulics where to point the car. The self centering is a second part of the DIRAVI system, which makes it return to centre, with an artificial speed-dependent feedback. My £0.02.

[@mikecleasby709]

Great to see the progress! Oddly, the further you get into dismantling, It doesn’t seem to be as frighteningly complex as I expected 🤔 Keep up the great work! Happy Christmas to you and yours!

[@UPnDOWN]

I don't think it is. There are parts that genuinely are a bit mad, but it's less complex than the C6, I'd say. Cheers, you too

[@mikecleasby709]

@UPnDOWN Hmm, is it a bit mad, or just “Pure Citroen” 🤔 I think that a lot of what the designers and engineers at Citroen did was have the balls to think out of the box for their solutions and then apply them in their production processes…. Madness and Genius are only one step apart!! 🤔😉👍 It’s just a shame that the PSA takeover etc. started the trend towards more conventional designs….with an odd exception in more recent times…. 😕

[@grayfool]

This will really help me when I strip my SM. Well, I might get one one day, maybe. I might, you never know.

[@Invisibleman7]

Progress made.Wishing you and your family the merriest Christmas 🎄

[@martinenstrom8206]

You’re doing allright! Keep unwinding those fixings.

[@jayslittleprojects1431]

almost at 20k :) good video as always

[@martyndyer4444]

Entertaining and informative. Looking forward to the next installment. Have a good Christmas.

[@UPnDOWN]

Same to you

[@davidflamee]

Loving your video record. Better than a Haynes, in many ways. Could this be a first? Look after your footage. It's gold.

[@stephandolby]

Nice work... have a good Christmas.

[@tomwinch9107]

Still impressed with how easily everything is undoing, are you sure you didn't accidentally dip it in a bath if BDX? Glad you solved the stuck nearside wheel - are handbrake pads available for an SM? I still remember finding out the downside to having a handbrake operate on the front disks - I had a Xantia that rolled slowly across a car park at work as the disks cooled down - such fun having security arrive at my desk to let me know!

[@uwekall6281]

Yay, SM content, nice! That car is really comparable to Clement. So it was a good training at least. It would also be really Interesting if it's possible to retrofit diravi to a DS... Is the width of the steering rack the same as the DS one? The diameter and steering column connection also look pretty familiar..

[@johnwaga3702]

Another great video!

[@landiepete]

Ah, the very first variable assistance power steering !

[@Nino500]

To attach it to the rotisserie, some sort of mega-jig, perhaps?

[@UPnDOWN]

It's going to need something!

[@Blind-Dave]

Cracking upd ate, this SM wants to be rescued with the ease tge bolts are coming out ;so far(.

[@isaacplaysbass8568]

Superb!

[@MattBrownbill]

Have a goodun fella. 🎅

[@Ben_306]

I own a CX, got it up to 170 kph on the autobahn (yes I know they can go faster), and it felt very stable, like 120kph with some more wind noise. The Diravi is perfect on the highway, I've since had to drive some cars with normal power steering and it's a nuisance in comparison. That being said the amount of hydraulic lines on that SM looks scary.

[@MartinE63]

Now you’ve cleaned the windscreen it’s time to clean the rest of the glass 😀

[@kimmohietala5359]

It is so weird that the only thing common (broadly speaking ) between SM and CX is the steering system. They surely started CX design from a clean plate. CX is still my favourite car though I have run out of skill when trying to get my CX back on the road. Maybe I need to buy another one that is a runner.

[@mrsmith697]

Happy Christmas 🎉

[@lesklower7281]

How different is this Citroen SM and complicated also great explanation of the steering again so different but the steering works

[@jfv65]

I don't really know if a CX has DERAVI but i did drive 1 at high speed (200+km/h in a turbo2) and it is very stable but i notice that when you try to micro-correct the steering at high speed that is contra productive. Just holding the steering wheel in a very gentle relaxed way works best. Done that way the car gobbles up the Autobahn like it's nothing. Great travel GT cars. I suspect that the SM will be similar. BTW a little anekdote: did you know that Johan Cruyff, the Ajax/FC Bracelona soccer player/trainer used to own a green SM? Later in his carreer he lived in Spain. i can imagine him blasting through France on his way back to the Netherlands.

[@MauiWauiPineappleExpress]

DIRAVI (In the UK, it was marketed as VariPower and in the U.S. as SpeedFeel.) is fitted to Citroën SM, Citroën CX (most), Citroën XM (most V6 PRVs, and left-hand drive only), Maserati Quattroporte II, and Maserati Khamsin.

[@ksouster6839]

Complicated yes, but mechanically complicated rather than loads of electronics so good chance of getting it to work 😉

[@niallsommerville9813]

Get your Diravi's around that lot. Wonderful, you'll be able to push it around a lot easier now 🤣

[@Morecheeeeese]

Always wondered why DIRAVI was so special that people have a festival to celebrate it, now i know why and it seems more than justified - it's a bloody amazing idea! But why don't they celebrate with croissants?🤔

[@smhorse]

A croissant-shaped steering wheel might work....

[@nigelh4617]

Festival of light engineering

[@robinwells8879]

I wonder if there’s anything on that car that is off the shelf, other than the spark plugs obviously?

[@robingray1302]

Methinks a bit of castor angle would have made things much simpler, my theory is that they used so much on 2CVs there was none left for anything else........

[@iangrice329]

Those discs are so thin 😮.

[@iosilver9920]

OK, since you aks, what is 'Derarvee'?

[@MrButtonpresser]

The entire Apollo program was much less complicated than an SM. This is the mechanics equivalent of a full blown PhD course.

[@rimmersbryggeri]

No haynes on the SM? Weak!

[@robertsedgwick1629]

ok i'll play along! what's diravi? 😂

[@iamthenotbenamed365]

you could use a 'Hole'-Looker with a Camera-Cable ...

[@smhorse]

I wonder if the fellas at Brodie Engineering and SM2a have been shown these videos? Maybe they could add their professional input....

[@nigelh4617]

(Looks at thumbnail)... looks like a premier league footballer has borrowed it for an evening drive.

[@grumpytorque8905]

Nice rack!

[@UPnDOWN]

😆

[@grumpy2.0]

Ahh you beat me to it.

[@cbmsysmobile]

Inboard brakes are all very nice until you have to change the pads....

[@Bowerprods2011]

Not SM - Simple Mechanic's

[@jasonnelson6276]

S m sunday means something completely different to my sunday

[@gillscorner794]

99.2

[@groeacht8525]

Luftballons 🎈

[@jongillman6006]

kzbin.info/www/bejne/kGmlY4ifhJuYqKMsi=B1gll3MYD_SWMn6H

[@Mr_Spegru]

Scope for an SM joke?

[@MrTimcoronel]

kzbin.info/www/bejne/f4XUmWCKr9hmh68

[@stefanbadass5357]

That car is a nightmare, WTF were they thinking when they "designed" it????????