swing axle camber copensator
  • Help
Page 1 of 2 12 Last
Results 1 to 25 of 35
  1. #1
    1000+ Posts
    Join Date
    Feb 2005
    Location
    rosevale/tasmania
    Posts
    2,870

    Default swing axle camber copensator

    A small diversion of the Unusual R8 Photos thread was occurring after I posted a photo of my R8's camber compensator so I've started a thread rather than continue the diversion. Actually, there was an extended thread on this some time back (or maybe it was an extended diversion) but no matter. So, does it work in performing its intended function of ameliorating the tendency of swing axles to move to positive camber under lateral load &, via a vicious positive feedback system, jack up the transaxle, thus inducing more positive camber & so on? Yes & before I explain why, I should first point out that the design is a well established one & one key reference showing the design is the American handling Bible "How to make your car handle" which I have sitting somewhere.

    A key thing in understanding why it works is realising that the spring is under considerable tension in static mode. You'll see how much by comparing the photo of it (untensed) under my R8 on the hoist & tensed (near flat) under my 4CV. Another thing to realise is where (via its straps over the axle tubes) it applies its forces. It's about half way between trunnion & wheel.

    Advertisement


    These features mean that a vertical force is applied (via the axle tube as a lever) tending to keep the wheel in negative camber. For it to move into +ve camber means raising the axle tube at the point where the straps of the CC go over the tube & that rise is resisted by spring tension.

    Does it cure the faults of swing axles? - No; but it does ameliorate them.
    Is it still wise to raise rear pressures, shorten droop straps, lower the rear to lower C.G. & to have 2-3 degrees of static -ve camber & widen the track with wider wheels & tyres? - Yes, of course; these measures will further ameliorate the faults of the design. I've done all of these things on my 4CV & most on my R8 but I've had the CC springs on each for thirty years & this was, with the R8, without any other modifications in the early part of this period (my mother was still alive & driving it). It made a difference to the smoothness of the transition on the limit - this is a vehicle that I started fanging when it was first bought in 66 and bog standard except for raised pressures.

    Could the spring be mounted more compactly on the transaxle? - Perhaps; but it is intended to be mounted such that it can rock so that as one side goes up, the other goes down. Hence the V shape of the bracket & the rubber bush between spring & bracket. (See one close-up photo.)

    Why doesn't the lack of clearance matter much? -There are basically two places one can whack something: on the central mount or along the spring.

    The spring is mounted to the bracket by a vertical bolt so it will pivot in a horizontal plane around that axis of the bolt (at least as far as the straps permit). Given that restraint by straps, it's not a huge arc of travel but it seems enough to avoid damage when I have hit things along the spring somewhere. This has happened about a dozen times over the years (usually a road kill corpse that I haven't been able to avoid - possums, wallabies & once a wombat, which also bent a front A arm) .

    The way the arms of the bracket are mounted to side bolts on the transaxle mean that if the bracket is thumped, then it swivels up & to the rear. This rotation is nominally resisted by a thin metal strap that mounts onto the bell housing but it is designed to sacrificially bend as the bracket pivots back. I have had this happen a few times over the years - mostly road kill corpses but once a bulge in the tarmac (the 4CV is quite low). No drama, one simply removes & bends back that rear strap.

    cheers! Peter

    swing axle camber copensator-rear-view.jpgswing axle camber copensator-rear-strap.jpgswing axle camber copensator-750-007-camb.-comp..jpg
    Last edited by 4cvg; 1st December 2012 at 10:41 PM.

  2. #2
    Member dauphproto's Avatar
    Join Date
    Jun 2012
    Location
    Perth Scotland
    Posts
    68

    Default

    They are very effective
    I have always wondered if the EMPI ones made for beetles would be a straightforward fit they were pinched between 2 rollers so there was no roll stiffness added
    I decided to make a Z bar for my 8 which is a bit of a bind as there is so little space available for one,but I got there in the end
    As to its effectiveness I rode one of the kerbs at knockhill a bit hard and there was a sound like a rifleshot which was the driving link of the Z bar snapping
    I thought the rear tyres were melting as the car was so tail happy, and as I trundled across the paddock after the race there was this persistent tinkling noise which was the rod end and broken bar end trailing along the ground.
    Proof positive of the effectiveness of controlling negative (upwards) movement in a swing axle setup but only in vertical motion not in roll
    Anyone interested should read the excellent Fred Phun "How to make your car handle" it is a very old book but he touches on swing axle VW's and formula V racers which are very interesting from an old Renault racer's point of view
    He states in the book a camber compensator is a good idea on a stock VW even if you only go to the shops and back
    I will try to get some pics of the Z bar on here
    cheers
    Well if it was easy everybody would do it

  3. #3
    COL
    COL is offline
    A110 COL's Avatar
    Join Date
    Mar 2002
    Location
    Van Diemen's Land
    Posts
    4,331

    Default

    Hi dauphproto

    Would love to see some pics of your "Z bar" setup. Have been thinking about a z bar for my Alpine A110 but as you say there is very little room for it. Although I read "Mille Miles" regularly I have never seen an article in there about camber compensation, perhaps they think its un-neccassary on the Alpine.
    Regards Col

    1973 Renault R12 Station Wagon
    1976 Renault R12 Station Wagon
    2002 Renault Laguna V6
    1973 Alpine A110

    http://alpine-a110.weebly.com/

  4. #4
    1000+ Posts
    Join Date
    Feb 2005
    Location
    rosevale/tasmania
    Posts
    2,870

    Default

    Quote Originally Posted by dauphproto View Post
    <snip>

    I decided to make a Z bar

    <snip>
    gee Steve, I gave up on a Z bar (despite them being better than a transverse leaf) because, like Col, I couldn't see how to physically fit it in the space. Some pics would be good.

    cheers! Peter

    (incidentally, the thread title is misspelt because the edit function doesn't operate on it & so my original bungle is perpetuated)

  5. #5
    COL
    COL is offline
    A110 COL's Avatar
    Join Date
    Mar 2002
    Location
    Van Diemen's Land
    Posts
    4,331

    Default

    Quote Originally Posted by 4cvg View Post
    (incidentally, the thread title is misspelt because the edit function doesn't operate on it & so my original bungle is perpetuated)
    Hi Peter

    If you click on "Edit Post", then click on "Go Advanced" you can edit the title.
    Regards Col

    1973 Renault R12 Station Wagon
    1976 Renault R12 Station Wagon
    2002 Renault Laguna V6
    1973 Alpine A110

    http://alpine-a110.weebly.com/

  6. #6
    1000+ Posts
    Join Date
    Feb 2005
    Location
    rosevale/tasmania
    Posts
    2,870

    Default

    hmm! don't seem to work

    oh well . . .

  7. #7
    Fellow Frogger! Ross's Avatar
    Join Date
    Jul 2001
    Location
    Auckland NZ
    Posts
    380

    Default

    I went down the same route when planning the new Dauphine but after talking to the Formula Vee guys and looking at a few new Formula Vees I decided not to go with the CC or the Zbar but with a floating/swinging top link. You can see part of it in the attached photo. Yet to be proven on a Renault but in theory it should work.

    Apparently the Formula Vee guys dropped the zbar many years ago and now exclusively use this floating top link. It provides zero roll stiffnes which is what you want to keep both wheels on the ground at all times.

    Im hoping all my talk and theorising will be put to the test early next year when the Dauphine finally hits the road.
    Attached Thumbnails Attached Thumbnails swing axle camber copensator-img_2557.jpg  
    Ross:

    1989 Alpine GTA Twin Turbo
    1963 Renault R8
    1996 Peugeot 106 S16
    1967 NSU Prinz 1200TT
    1989 Peugeot 205 GTi

  8. #8
    1000+ Posts
    Join Date
    May 2005
    Location
    Boonah Qld
    Posts
    2,632

    Default

    Ross,
    How does it work?
    Rob

  9. #9
    Member dauphproto's Avatar
    Join Date
    Jun 2012
    Location
    Perth Scotland
    Posts
    68

    Default

    The problem with a swing axle is the effect of camber change in vertical motion coupled with the rise and fall of roll centre

    Put simply as you brake and turn the rear end starts to lift and roll, as it lifts and rolls it causes it's own roll centre to move upwards and makes the car roll more and a vicious circle starts which Terminates in the vehicle turning over completely. Normally the car would spin out before this happens
    The only way to stop this happening is to limit the travel of the rear suspension.I would say it is better to use shorter harder springs than using short checkstraps as when the rear wheel lifts in roll the car spins suddenly and violently (been there done that)

    Ideally we want to limit the vertical motion of the rear suspension, but not its ability to roll this is where all of these contraptions come into play

    1: camber compensator basically a 3rd spring which is mounted across the axle this works as a spring as the rear rises and falls only, as the centre mount is free to articulate it has no effect as the body rolls

    2: Z bar just like an anti roll bar which is a spring which only works in roll and is U shaped the Z bar forms a Z across the axle which prevents the whole axle rising and falling but has no part in controlling body roll. this can be made slightly more intelligent as the bars can be a blade design and adjustable like a touring car anti roll bar this is the set up I have on the 8G

    It uses 1200lb inch springs up front 5" free length and 6" 375lb inch at the rear with spacers and helpers but with the Z bar it is more like having 550lb inch rears on vertical motion only falling to 375 lb inch on roll
    If I jack up my 8G across the rear the wheels go from 4 deg negative at ride height to zero camber when clear of the ground as the bar is holding both mainsprings under tension this is a benefit of the system that you can set the bars zero point at ride height or at 1" compression so that it is more effective controlling upward movement than adding to overall compression The formula Vee guys I spoke to over 10 years ago favoured this method they had 2 guys stand on the rear and then fitted the bar so that it always held the main springs in tension giving a very firm vertical ride with very low roll resistance. If I jack the 8 up on 1 side I can see the front wheel is 3" off the deck before the rear wheel lifts off as its roll resistance is so low

    3 : The system in the picture of the Dauph has springs on either end for vertical motion controll, but is free to pivot in the middle giving zero roll stiffness very clever indeed and a fair project to make all the parts
    It should work very well the only drawback may be that a formula Vee has a very low mass centroid, the rear roll centre will be the same as an R8 or Dauph (middle of the diff at ride height),but it has no body or weight above 400mm off the deck to generate roll unlike a saloon car HOWEVER I suppose that a 3rd coilover unit( very soft like a motorcycle unit) could be fitted between the body and the rocking frame to give precise roll controll the ideall solution with stiff mainsprings to combat excessive movement and a soft spring to controll body roll. I for one will be very interested to hear how the Dauph works out in the end
    PS its minus 2 here and snowing, so I have not had a chance to photograph the underside of the 8, but I will do it
    Well if it was easy everybody would do it

  10. #10
    Fellow Frogger! Ross's Avatar
    Join Date
    Jul 2001
    Location
    Auckland NZ
    Posts
    380

    Default

    Dauphproto - thanks for your thoughts on my rear suspension, I can see what you are saying about the soft damper. I will keep it mind.
    Ross:

    1989 Alpine GTA Twin Turbo
    1963 Renault R8
    1996 Peugeot 106 S16
    1967 NSU Prinz 1200TT
    1989 Peugeot 205 GTi

  11. #11
    1000+ Posts
    Join Date
    Feb 2005
    Location
    rosevale/tasmania
    Posts
    2,870

    Default

    Just bumping this up to the thread head again to remind Steve to say more about his Z bar's attachment (& give some pics when it's next on a hoist).

    cheers! Peter

  12. #12
    Member dauphproto's Avatar
    Join Date
    Jun 2012
    Location
    Perth Scotland
    Posts
    68

    Default

    It's still below zero here,but I will do it
    Well if it was easy everybody would do it

  13. #13
    1000+ Posts
    Join Date
    Feb 2005
    Location
    rosevale/tasmania
    Posts
    2,870

    Default

    Quote Originally Posted by dauphproto View Post
    It's still below zero here,but I will do it
    lucky bastard, I love such temperatures.
    thanks & I'll await events then

    cheers! Peter

  14. #14
    1000+ Posts Kim Luck's Avatar
    Join Date
    Nov 2010
    Location
    Melbourne, Aus.
    Posts
    18,563

    Default

    My R10 never upside downed. The magic article when talking about rear engined swing axles is/was prudence. In the case of the works R8 Gordinis it didn't appear to involve much more than ride height and constant oversteer produced by radically controlled horsepower. I did get to drive Mal McPhersons car!
    Don't it always seem to go that you don't know what you've got 'til it's gone............

  15. #15
    Fellow Frogger! bingham driver's Avatar
    Join Date
    Jan 2011
    Location
    Myers Flat
    Posts
    182

    Default

    Hi all, had some piccies taken of the MK3 at Winton Melbourne cup day & old jaw nearly hit the floor. Pic No1 showed 'murray' negotiating a right hander with the outside 295/60/15 having so much pos camber it was showing daylight under a good 50% of the tread (shiver). Came home with a brand new plan, get on AF, & what should I find but this thread. After considering both strap & leafspring, I came up with the idea to run a cable from one shocker mount up thru an existing chassis x-member(added) & down to the other shocker mount. Cable length was set to allow approx one degree positive camber on each wheel in full droop. In effect, if the outside wheel is to tuck under it must lift the inside one to do it. Worked a treat Sunday, would have been happy to achieve a 1.8 second time improvement, so 4.1 was a woo-hoo moment after session 0ne. It feels GOOOOD when a 43 y/old race car with 1389cc can beat a 5ltr Mustang & 7ltr Commodore! Thanks AF.
    Once I thought I was wrong but, I was mistaken

  16. #16
    VIP Sponsor 59 Floride's Avatar
    Join Date
    Oct 2010
    Location
    It's how I roll...Brisbane
    Posts
    33,944

    Default

    Quote Originally Posted by bingham driver View Post
    Hi all, had some piccies taken of the MK3 at Winton Melbourne cup day & old jaw nearly hit the floor. Pic No1 showed 'murray' negotiating a right hander with the outside 295/60/15 having so much pos camber it was showing daylight under a good 50% of the tread (shiver). Came home with a brand new plan, get on AF, & what should I find but this thread. After considering both strap & leafspring, I came up with the idea to run a cable from one shocker mount up thru an existing chassis x-member(added) & down to the other shocker mount. Cable length was set to allow approx one degree positive camber on each wheel in full droop. In effect, if the outside wheel is to tuck under it must lift the inside one to do it. Worked a treat Sunday, would have been happy to achieve a 1.8 second time improvement, so 4.1 was a woo-hoo moment after session 0ne. It feels GOOOOD when a 43 y/old race car with 1389cc can beat a 5ltr Mustang & 7ltr Commodore! Thanks AF.
    errr! any chance of getting a look at said piccies?
    Every day when I wake up I reach up in the darkness with my eyes shut and if I cannot feel anything that resembles a wooden lid I know it will be a good day. No lid today.

  17. #17
    1000+ Posts
    Join Date
    Feb 2005
    Location
    rosevale/tasmania
    Posts
    2,870

    Default

    Quote Originally Posted by bingham driver View Post
    Hi all, had some piccies taken of the MK3 at Winton Melbourne cup day & old jaw nearly hit the floor. Pic No1 showed 'murray' negotiating a right hander with the outside 295/60/15 having so much pos camber it was showing daylight under a good 50% of the tread (shiver). Came home with a brand new plan, get on AF, & what should I find but this thread. After considering both strap & leafspring, I came up with the idea to run a cable from one shocker mount up thru an existing chassis x-member(added) & down to the other shocker mount. Cable length was set to allow approx one degree positive camber on each wheel in full droop. In effect, if the outside wheel is to tuck under it must lift the inside one to do it. Worked a treat Sunday, would have been happy to achieve a 1.8 second time improvement, so 4.1 was a woo-hoo moment after session 0ne. It feels GOOOOD when a 43 y/old race car with 1389cc can beat a 5ltr Mustang & 7ltr Commodore! Thanks AF.
    Yep, this is another variation on the theme. I have came across it as a fitment to Triumph Herald/Vitesse /Spitfire swing axles. My recollection is that the way it was done was with a largish pulley mounted in the middle somewhere & with the cable running over the pulley. One disadvantage that I recall is that, as you say, it works by using the inside spring to resist droop of the opposite half axle. This means that, as the outer wheel moves into positive camber, the inner wheel is moved up & thus, on tighter turns, one increases the tendency to spin the more unloaded inside wheel. Shortening Renault droop straps has the same increased tendency to wheelspin but the transverse leaf CC acting via straps over the axle tubes ameliorates this by pulling the inside half-axle down.
    cheers, Peter

  18. #18
    Member dauphproto's Avatar
    Join Date
    Jun 2012
    Location
    Perth Scotland
    Posts
    68

    Default

    Sorry this has taken so long Guys,but it has been mental here
    Finally some pics of the Z bar on the 8Gswing axle camber copensator-z-bar-details-005.jpgswing axle camber copensator-z-bar-details-001.jpgswing axle camber copensator-z-bar-details-002.jpgswing axle camber copensator-z-bar-details-003.jpgswing axle camber copensator-z-bar-details-004.jpg
    Well if it was easy everybody would do it

  19. #19
    1000+ Posts
    Join Date
    Nov 2010
    Location
    Newcastle
    Posts
    2,797

    Default Z bar

    Hi,
    Veerry neat
    Not much clearance for the road.
    The whole setup looks very professional. Are there any original R8G bits left Shows what you can do with good ideas and plenty of work.
    Jaahn
    AF seems to be in a odd mode this morning. The format is very unusual.

  20. #20
    COL
    COL is offline
    A110 COL's Avatar
    Join Date
    Mar 2002
    Location
    Van Diemen's Land
    Posts
    4,331

    Default

    Nice neat work there Steve
    Regards Col

    1973 Renault R12 Station Wagon
    1976 Renault R12 Station Wagon
    2002 Renault Laguna V6
    1973 Alpine A110

    http://alpine-a110.weebly.com/

  21. #21
    1000+ Posts
    Join Date
    Feb 2005
    Location
    rosevale/tasmania
    Posts
    2,870

    Default

    Quote Originally Posted by dauphproto View Post
    Sorry this has taken so long Guys,but it has been mental here
    Finally some pics of the Z bar on the 8GClick image for larger version. 

Name:	Z bar details 005.jpg 
Views:	2284 
Size:	96.8 KB 
ID:	45396Click image for larger version. 

Name:	Z bar details 001.jpg 
Views:	802 
Size:	89.6 KB 
ID:	45397Click image for larger version. 

Name:	Z bar details 002.jpg 
Views:	724 
Size:	89.6 KB 
ID:	45398Click image for larger version. 

Name:	Z bar details 003.jpg 
Views:	1273 
Size:	91.9 KB 
ID:	45399Click image for larger version. 

Name:	Z bar details 004.jpg 
Views:	5109 
Size:	96.8 KB 
ID:	45400
    Nice! Rather a lot of thought & work there & I can see why I put it into a "too-hard" basket.
    Also, like Jahn, I think that there would be a bit of danger on "C" roads with the clearance. Given that it's a rigid mounting system, whacking something would be a bother. Although physically superior to the transverse leaf CC, I think that I'd still choose the latter for a a road car just because, although its clearance is no better (& possibly worse), it is tolerant of getting a thump.

    cheers! Peter

  22. #22
    Fellow Frogger!
    Join Date
    Oct 2012
    Location
    Sydney
    Posts
    601

    Default

    Is it possible to run a Z bar over the top of the gearbox? I imagine it would be a little tight, if not impossible.

  23. #23
    Tadpole
    Join Date
    May 2017
    Location
    Mexico
    Posts
    4

    Default Adjustable rear damper

    Hello there, hope you are doing great... what kind of dampers are you using in the rear?? and front ?? They looks great are they adjustable ??? ... also I can see that you have a coil over in the rear ??? Adjustable spring too ??

  24. #24
    1000+ Posts renault8&10's Avatar
    Join Date
    Mar 2002
    Location
    Sydney
    Posts
    4,425

    Default

    You may not get an answer out of dauphproto. He sold the car a couple of years ago and I don’t think visits here much anymore.
    There was a post on here where the car came up for sale/auction and there was a detailed spec sheet. If you can find that, it may have some info.
    KB


  25. #25
    1000+ Posts
    Join Date
    Nov 2010
    Location
    Newcastle
    Posts
    2,797

    Default

    Quote Originally Posted by ducato796m View Post
    Hello there, hope you are doing great... what kind of dampers are you using in the rear?? and front ?? They looks great are they adjustable ??? ... also I can see that you have a coil over in the rear ??? Adjustable spring too ??
    Hi ducato
    You may not have noticed that this thread is very old. The last posting is 5 years ago. As Renault 8&10 said the z bar poster, dauphproto, has moved on !!
    Good luck and keep looking at Aussie Frogs. Do start another thread if you want to get some specific information.
    Jaahn
    PS read this thread and you might contact him direct with a PM perhaps.
    Steve Swans Website

Page 1 of 2 12 Last

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •