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Asymmetric steering/suspension

katar83
Posts: 2647
Joined: Tue Aug 23, 2011 11:17 am
Location: Cambridge

Re: Asymmetric steering/suspension

Postby katar83 » Mon Mar 11, 2019 11:13 pm

Brake buster wrote:the bolt arrowed will adjust camber at the rear on late xj40 ( 1993 1994 )


It's not rear camber(as I thought initially too) but toe that is adjusted by this bolt. Camber as mentioned earlier is adjusted by spacers on the halfshafts.
1997, 4.0 LWB X300 - Unlucky car but still a daily driver.
1988, 3.6S XJS - Never ending restoration project.
1994, 3.2S X300 - Accident damaged, October 2015. Gone!
1994, 3.2S XJ40 - Long gone.

Brake buster
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Re: Asymmetric steering/suspension

Postby Brake buster » Mon Mar 11, 2019 11:22 pm

i beg to differ, as the action of the casting equally moving in and out of the lower wishbone is a camber movement,

however


it could be the ' bolt with welded on concentric washer ' adjusts camber moving the whole casting in and out, and then the front nut ( with welded on concentric washer ) will adjust a toe ( or thrust angle ) movement

i took my xj8 in for a 4 wheel alignment, ( exact same setup as this ) and was told it cant be done at the back until i showed them this adjustment, looking through the manuals they discovered it could be adjusted and brought my car right back to factory settings , and then the front wheels are then set up using the rear wheels as the reference , we were there for nearly two hours in total , lol but it left perfect after x4 new tyres

that was Protyre gloucester,

BB
1994 3.2S in Morocco red and Doeskin/Ruby red interior
1989 V12 XJS White with Mulberry interior
2004 2.1 X-Type Platinum with Champagne Leather interior

previously ,
1999 V8 Sovereign in Seafrost with Oatmeal and Antelope interior

katar83
Posts: 2647
Joined: Tue Aug 23, 2011 11:17 am
Location: Cambridge

Re: Asymmetric steering/suspension

Postby katar83 » Mon Mar 11, 2019 11:34 pm

Brake buster wrote:it could be the ' bolt with welded on concentric washer ' adjusts camber moving the whole casting in and out, and then the front nut ( with welded on concentric washer ) will adjust a toe ( or thrust angle ) movement


Apparently that's how this works there and that's what Jaguarforums and everyone there will told you, that this bolt adjusts toe and camber is adjusted by spacers, number 3 here:

https://www.jaguarclassicparts.com/uk/j ... t-assembly

which will also move the wheel in and out.

Mind you there is also another spacer on that center fulcrum bolt, just in front of the bearing, that is also used for toe adjustment, not entirely sure how exactly this works but there are multiple thickness spacers available from JCP.
1997, 4.0 LWB X300 - Unlucky car but still a daily driver.
1988, 3.6S XJS - Never ending restoration project.
1994, 3.2S X300 - Accident damaged, October 2015. Gone!
1994, 3.2S XJ40 - Long gone.

XJ4081
Posts: 198
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Asymmetric steering/suspension

Postby XJ4081 » Tue Mar 12, 2019 10:16 pm

Just to be sure I was translating toe correctly:

This drawing shows the concept of toe:
Image

Transferred to rear hub and bolt #14 this would mean: when I turn the bolt, one end will come closer to the centre of the car and the other end will move away.

When I look at the protocol of my last 4-wheel alignment, toe at the rear track was out of factory tolerance. It should be between 0 and -0,10, but it was -0,26 and -0,15. So in which direction would I have to move the bolt?

If bolt #14 would affect caster, the lower section of the hub (attached to #14) would turn, causing the upper end of the hub to either move closer to the center of the car or away from it.

On thursday I will have another chance to crawl under the car and see what I can find out. And then it will be high time to place my orders since Brexit is coming closer and closer :? .
1993 XJ12

Brake buster
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Re: Asymmetric steering/suspension

Postby Brake buster » Tue Mar 12, 2019 11:14 pm

XJ4081 wrote:Just to be sure I was translating toe correctly:


If bolt #14 would affect caster, the lower section of the hub (attached to #14) would turn, causing the upper end of the hub to either move closer to the center of the car or away from it.
.



that is not castor, that is camber ,

there is Toe, as you surmise, camber and castor ,

Toe is also described as the ' thrust angle ' as when accelerating the physics of the thrust forward negates the Toe setting making the wheels actually run true , if set true when stationary then the thrust would make them Toe out at speed ,

castor is like on a shopping trolly ,,the wheel follows behind the vertical upright making it track straight by its self

camber allows for the contact patch of the tyre to stay in better contact with the road surface given a certain load on the suspension causing the the wheel to travel in a vertical arc under load
( remember the old Triumph herald, if you lifted the car, the rear wheels tucked under, resulting in extreme camber lol )

its an 'imperfect system ' for the DIY mechanic, as the manufacturers have calculated the best case scenario for the best running and wear to tyres and driving feel as a compromise, hence ' factory settings ' of the different angles for everything on different cars.

BB
1994 3.2S in Morocco red and Doeskin/Ruby red interior
1989 V12 XJS White with Mulberry interior
2004 2.1 X-Type Platinum with Champagne Leather interior

previously ,
1999 V8 Sovereign in Seafrost with Oatmeal and Antelope interior

XJ4081
Posts: 198
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Asymmetric steering/suspension

Postby XJ4081 » Tue Mar 12, 2019 11:45 pm

Brake buster wrote:
XJ4081 wrote:Just to be sure I was translating toe correctly:


If bolt #14 would affect caster, the lower section of the hub (attached to #14) would turn, causing the upper end of the hub to either move closer to the center of the car or away from it.
.



that is not castor, that is camber ,


BB


I actually wanted to write camber but for unknown reason wrote caster instead - the words are just too similar :D .
1993 XJ12

Brake buster
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Re: Asymmetric steering/suspension

Postby Brake buster » Tue Mar 12, 2019 11:53 pm

XJ4081 wrote:
Brake buster wrote:
XJ4081 wrote:Just to be sure I was translating toe correctly:


If bolt #14 would affect caster, the lower section of the hub (attached to #14) would turn, causing the upper end of the hub to either move closer to the center of the car or away from it.
.



that is not castor, that is camber ,


BB


I actually wanted to write camber but for unknown reason wrote caster instead - the words are just too similar :D .



wars have been fought over lesser communication mistakes.....lol

BB
1994 3.2S in Morocco red and Doeskin/Ruby red interior
1989 V12 XJS White with Mulberry interior
2004 2.1 X-Type Platinum with Champagne Leather interior

previously ,
1999 V8 Sovereign in Seafrost with Oatmeal and Antelope interior

katar83
Posts: 2647
Joined: Tue Aug 23, 2011 11:17 am
Location: Cambridge

Re: Asymmetric steering/suspension

Postby katar83 » Wed Mar 13, 2019 12:13 am

XJ4081 wrote:(...)And then it will be high time to place my orders since Brexit is coming closer and closer :?


You didn't hear? It was cancelled few hours ago... :lol:
1997, 4.0 LWB X300 - Unlucky car but still a daily driver.
1988, 3.6S XJS - Never ending restoration project.
1994, 3.2S X300 - Accident damaged, October 2015. Gone!
1994, 3.2S XJ40 - Long gone.

XJ4081
Posts: 198
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Asymmetric steering/suspension

Postby XJ4081 » Thu Mar 14, 2019 10:01 pm

katar83 wrote:
XJ4081 wrote:(...)And then it will be high time to place my orders since Brexit is coming closer and closer :?


You didn't hear? It was cancelled few hours ago... :lol:


That's still not sure, even after british parliament voted for Brexit delay today, all 27 EU States have to approve. Anyway, the sooner I get things sorted out and fixed, the better.

Lay under the car again today but could not get that bold out, even with a larger hammer it doesn't move a single bit. Though it's not that easy to put force on it because I didn't want to damage my wheel arch while striking out nor did I want to hammer away my jack :? . Better get it done on a car lift.

I also turned the bolt and watched out for any kind of movement but that's difficult to tell without the wheel on.

Then I checked again my ride height by measuring the length of my springs and shocks. And indeed, my left spring/shock is about 1cm shorter than the right one. I think this should also affect camber because the shorter spring will 'move up' the wishbone/hub and thereby change the angle of the rear wheel towards the road. Do you agree? If that's true, it probably would only make sense to replace both shock and springs on both sides, doesn't it?

Or any other part that I should inspect/consider? I have to tell that my rear suspension has already been retrofitted from SLS to conventional by a previous owner and I don't think it has done that many miles since then. Compared to original SLS-ride height, its rear now is lifted up a bit too much for my taste.
1993 XJ12

pimgmx
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Location: South East of the Netherlands

Re: Asymmetric steering/suspension

Postby pimgmx » Fri Mar 15, 2019 9:23 am

Front height difference could be caused by something as prosaic as a missing/damaged spring packer on one side...

Image
(part No 2 in diagram)

Hard to diagnose without releasing the springs, unfortunately.

I would never replace only one side/spring: you do not know how worn the item is on the side you will not be replacing.
With all the spring ratings Jag used you will also run the risk that your single replacement spring is of slightly different spec (softer/harder) than the original item left in. Springs are relatively affordable parts; my recommendation is to always order in pairs.

My two cents on wheel geometry adjustment: it's something I've always outsourced and always will.
My home workshop is good enough to get subframes out, rebuild suspension arms, fit dampers/bushes/veemounts and much, much more, but I will always leave geometry setup of any of my cars to a trusted professional.

The difference between 'just so' (i.e. driving my Sovereign after I put a completely rebuilt front subframe/suspension back in) versus 'spot-on' (after it went thru 3D alignment at a Jag specialist) might be marginal when you count the number of bolt turns required, but is enormous when driving your car, not even mentioning driving it fast!

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