baz walton

Hi all, are these something I'm going to have to make or does someone make them?

Basicly I'm after some angled plates/shims for between the rear hubs and arms to correct the rear camber that appears after dropping the coilovers.

cheers
Baz

Ima Racing

iTrader: (1)

mike rainbird is your man... r&b motorsport

charlie luciano

iTrader: (3)

For once I actually agree with what you've said

as it made sense


Luciano

col93saphcos

iTrader: (2)

is possible to do yourself with shim/washers,im pretty sure 23 thou moves it 1 degree,will look for my info later and let you know,
maybe worth shimming for toe in when your doing it,
colin

baz walton

cheers for the info guys,

Arms are fully rose jointed for toe and caster it's just the camber that needs sorting when on road/slicks.

cheers
baz

Ima Racing

iTrader: (1)

There not dear from Mike + you got instructions no more than Ł20 for the correct items

baz walton

I've just looked at Mikes website, his appear to be for toe in, but will check if rotating them also works for camber.

Captain Cotswold

..

Mike1

Are you talking about the rear of the car still? Or do you mean the front?

baz walton

Rear arms.

Mike1

Just out of interest Baz, how do you adjust the caster on the rear?

baz walton

Adjusting the front/rear vertical allignment isnt something that I do deliberately, the outer rose joints just mean that it can be kept equal and correct, if it goes out slightly when adjusting the toe in with the inner rose joints.

col93saphcos

iTrader: (2)

my camber is adjusted by the inner(near diff) rose joint,its an adrenaline beam,
have seen camber shims on ebay before,and a mate was using a set,
looks like a wedge going from approx 7mm to 3mm,4 holes for bolts and big hole for drive shaft,only thing we noticed was wedge took up so much room the hub was not located on spigot bit just the bolts held it in place,
will get exact sizes if you like,
colin

steve4i

i put some on my sierra what a difference they made 6mm at the top and 2mm at the bottom wedge think i paid about Ł25 delivered

col93saphcos

iTrader: (2)

that'll be the ones

baz walton

Delivered from where????

steve4i

was from a lad on the fsoc there's always people selling them on there

Toe Knee

iTrader: (2)

as said mike rainbird!!! R&B motorsport!!

Mike1

Have a look at the link below and see if it is what you're after - those are the ones
Mike R does. He can arrange delivery as well


http://www.randbmotorsport.co.uk/sho...?ProductID=178

It's Czech Mate

Rear Castor

baz walton

As i said, i have already seen the ones on mikes site, i was asking steve where he got his.

mondeo man, enlighten me as to the correct terminology for the for/aft vertical allignment of the rear springs/dampers then??

Mike Rainbird

iTrader: (3)

My ones only do the toe. They could be fitted in the top to do the camber, but in tests we did it made the car fall into corners and felt very odd, so it is not something I would recommend. I also don't like the wedges, as they look to me like they would be stressing the hub bolts too much for my own personal liking.....

Hope this helps.

It's Czech Mate

https://passionford.com/forum/genera...grey-lo-2.html

I dont think you undserstand how suspension works, ask Rick

baz walton

Cheers Mike, I was going to contact you to ask about yours, but that clears it up.

baz walton

Mondeo man, my knowlage of susspension gets me by ok thanks, and you didnt answer my question?

Captain Cotswold

I'm interested to read the response to this.

It's Czech Mate

Not sure what you'd call it. There is no castor effect tho as the rear shock doesnt turn about its axis to 'steer'

I'm fully aware of the adjustment for bump steer but whatever its called it aint castor on the rear

Mike Rainbird

iTrader: (3)

I think he just means that caster only has an effect on wheels that turn...

Touring Car Spares

iTrader: (6)

Best mod for a GpN car i ever made , DOME used to make the wedges for me ,max 3 degrees possible before the ABS ring on the Driveshaft interferes with the rear arm . I raced for years with these fitted ,never created a problem and found me loads of time for very little money !

baz walton

Well, when you are, come back and take the piss then.

baz walton

Looks like getting some made up then is going to be the way forward, I'll mock up a template and get the boys to make some tapering from 6mm to 2, see how they sit.
Cheers
Baz

steve4i

well my tyres have lasted over a year on the rear with them in

wheels sit perfectly straight aswell compared to mates on his sierra there cocked right in lol and its lowerd the same as mine 40mm

grcossie

Check out my picture down at this tread
https://passionford.com/forum/ford-e...ar-camber.html

baz walton

Excellent, thats saved a lot of measuring. cheers Grcossie.

It's Czech Mate

rear wheels dont steer = no castor there is no 'kingpin' axis.

I know the alignment ofthe shock absorber is adjusted for bumpsteer but it isnt castor, unless you disagree?

I think the scentence in red highlights why it ISNT called castor on the rear wheels.

HTH

Castor

THE PURPOSE OF THIS PAPER is to define the caster angle of a steerable vehicle wheel to be referenced to the thrust line of the non-steerable wheels. A further purpose is to derive and characterize an optimal method of measuring caster which can be implemented in a practical manner.
Recent years have seen the development of the “total alignment” concept, which relates the toe angles of the steerable vehicle wheels to the thrust line of the nonsteerable wheels. Increased sophistication of vehicle suspension systems has made this more important, while advances in alignment measurement instrumentation have incorporated the concept and assumed the corresponding computational burden.
Referencing caster to the thrust angle is part of the total alignment concept, but caster of a steerable wheel is difficult to measure. It is the angle between the vertical and the projection of the invisible steering axis onto a vertical plane containing the thrust line of the vehicle. It is not easy to attach measuring devices to a projection of an invisible axis. Indirect measurement methods are available that are very accurate, if they are implemented properly and certain restrictions are observed.
REFERENCING CASTER TO THE THRUST LINE
Caster has been defined as follows:
“6.2.1 Caster Angle – The angle in side elevation between the steering axis and the vertical. It is considered positive when the steering axis is inclined rearward (in the upward direction) and negative when the steering axis is inclined forward.” (1)*
* Numbers in parentheses designate references at end of paper.
Positive caster tends to produce a stable steering system by generating counterbalancing torques about the steering axes as the wheels roll. The torques vary as the steer (toe) angles change. An equilibrium condition exists when the steer angles of the wheels remain constant with no driver-applied torque to the steering wheel. Ideally, the front wheels steer the vehicle in a straight line in this “neutral steer” condition.
Left and right caster must be equal for this condition to occur, other factors being equal. However, the straight line direction of travel is the thrust line of the nonsteerable rear wheels. If the thrust angle of the rear wheels is altered, the neutral steer direction of the front wheels no longer coincides with the thrust line. See Figure 1. The vehicle then rolls in a circle unless the driver steers the front wheels by applying a torque to the steering wheel. The vehicle “pulls” to the side.
Clearly caster must be defined relative to the thrust line. This is easily done:
Caster Angle – The angle, in side elevation PARALLEL TO THE THRUST LINE OF THE NON-STEERABLE WHEELS, between the steering axis and the vertical. It is considered positive when the steering axis is inclined rearward (in the upward direction) and negative when the steering axis is inclined forward.
This improved definition brings caster measurement in accord with the total alignment concept, where individual toe angles are referenced to the thrust line of the rear wheels.
CASTER MEASUREMENT METHODOLOGY
Caster cannot be measured directly, since one cannot mount a sensor on an imaginary steering axis. Instead, caster can be computed from changes in camber as the wheel toe angle is changed. The methodology is easily derived.

The camber of a steerable wheel is determined by the caster, steering axis inclination (SAI), toe angle, and the camber angle at zero toe. The equation describing this relation (derived in Appendix A) is as follows:whereThe variation in camber as the toe angle changes is illustrated in Figure 2.
The caster measurement procedure is to steer the wheel to two toe angles T1 and T2 where respective camber measurements C1 and C2 are made. Applying (C1,T1) and (C2,T2) to Eq. (1) yields

Note that Eq. (5) is independent of camber at zero toe (C0), which is highly desirable, since C0 need not be measured to Compute caster. Unfortunately, Eq. (5) is dependent on SAI (S), which is highly undesirable, since SAI is unknown. Dependence on SAI can be made negligible by making one approximation and one restriction in procedure.
The camber angles measured during this “caster turn” procedure are very small, usually under two degrees. The approximation cos C = 1 is made, the error at two degrees being only 0.06%. Eq. (5) then reduces to

A restriction is made that the “caster turn” be symmetric about the thrust line, that is T2 =-T1. The usual procedure is to steer to the left to toe angle T1 and measure C1, then steer to the right to toe angle T2 =-T1 and measure C2. With this restriction, Eq. (6) reduces to

K=tan­1sin C1–sin C2(7)( sin T2–sin T1

Eq. (7) allows caster to be APPROXIMATELY computed directly from toe and camber measurements, provided the toe and camber measurements comply with the restrictions discussed above. The computations required can be simplified even further, especially for use in analog instruments. If two further approximations are made. These are

where x is in degrees. These approximations are quite good at the small angles commonly encountered in measuring caster, and their errors tend to cancel when substituted in Eq. (7), which then simplifies to

LIMITATIONS OF PROCEDURE
The procedure described above and using Eq. (8) to compute caster will measure caster relative to the thrust line of the vehicle if two requirements are met:
1) The toe angles T1 and T2 must be measured relative to the thrust line of the non–steerable wheels.
2) The caster turn must be symmetric about the thrust line, i.e. T2 =-T1.
If the turn is not symmetric, then the second term of the right hand side of Eq. (6) is not zero. In effect, this produces crosstalk between the measurements of SAI and caster by invalidating the assumptions that lead to Eq. (7) and Eq. (8).
This can be visualized quite easily. A more rigorous definition of caster isThe caster turn measurement procedure measures the angle in the plane which bisects the total turn angle. If the thrustline does not coincide with the bisector of the turn, then the projection of the steering axis onto the plane is at a different angle from the vertical, and so is not the angle defined to be caster.
This can be intuitively understood in another way. Eq. (8) shows that caster is computed from a change in camber (C1 -C2) as the wheel is steered through a turn angle (T2-T1), assuming T2 =-T1. If the turn is offset to as to be the same total amount but asymmetric, then the change in camber will be different, because camber does not vary proportionately to toe, as Figure 2 shows.
What practical effect does turn asymmetry have on caster adjustment? If caster is measured by an asymmetric turn procedure and adjusted to be “equal” on both wheels, it will not be equal on both wheels relative to the thrust line. This may generate a pull to the side if the side-to-side caster difference is significant and the suspension is sensitive to this difference.
The theoretical accuracy of measuring caster using Eq. (8) is shown in Figures 3 and 4. Figure 3 illustrates the error in measured caster as a function of actual caster for various amounts of turn asymmetry. Figure 4 illustrates the error in measured caster as a function of caster for various combinations of SAI and camber at zero toe, assuming a symmetric turn. It is obvious from these figures that the method is theoretically quite accurate. provided the restrictions in procedure are met.
PRACTICAL CASTER MEASUREMENT
A practical implementation of this method of measuring caster must adhere to the restrictions enumerated above. This is most easily accomplished using a microcomputer and electronic toe and camber sensors. The sensors must be capable of measuring camber and toe during the caster turn procedure, and toe must be measured relative to the thrust line.
The usual procedure begins with steering a wheel to the left to a specified toe angle, usually -10 to -15 degrees, and measuring and storing both camber and toe (C1 and T1). The wheel is then steered to the right to the opposite toe angle (T2 =-T1) where camber and toe are again stored (C2 and T2). Finally, caster is computed using Eq. (8).
Notice that this procedure measures the caster of only one wheel, the one which is steered to the proper toe angles. If the left wheel is steered to the proper angles but camber and toe are stored and caster computed for both left and right wheels, the right caster can be expected to be in error, since the turn of the right wheel can be expected to be asymmetric. The asymmetry is due to the difference in turn angles of the two wheels (toe-out-on-turns) and due to total toe, which is usually not zero. Figure 3 illustrates the seriousness of this asymmetry error.
This asymmetry error can be eliminated by steering the left wheel to the correct angles to measure left camber and left toe, then steering the right wheel to the correct angles to measure right camber and right toe. The procedures can be mixed by steering the left wheel to the left, the right wheel to the left, the left wheel to the right, and the right wheel to the right. Obviously, other variations are also possible.
A potential error source in this type of steering procedure is hysteresis in the wheel suspension during the turn. This can be caused, for example, by compliance in rubber suspension parts, in tires, and in the turnplates on which the tires rest. An optimum procedure is to steer too far to the left, then steer toward the right to the proper left turn angle and measure camber and toe, then steer toward the right to the proper right turn angle and measure camber and toe. For example, steer to the left to -15ş, then to the right to -10ş and measure camber and toe, then steer to the right to +10ş and measure camber and toe. Recall that caster is computed from the CHANGE in camber during this steering procedure.In practice, if one steer angle is approached from the left while the other is approached from the right, the camber change measured during the turn will be in error due to suspension hysteresis. For example, if camber is offset only 0.05ş due to hysteresis, the error in measured caster is

Certainly this error should be avoided if possible.
Note also that the sensors must have substantial resolution and accuracy to measure caster properly, especially when their outputs are digitized. If the turn is made to -10 and +10 degrees, Eq. (8) becomes

The resolution of caster is approximately one third the resolution of camber, thus showing the need for accurate, high resolution camber sensors when measuring caster. Fortunately, this computation method does not require accurate zero calibration of the camber sensor. Since only the change is measured, only the range calibration need tee accurate.
PRACTICAL STEERING DURING THE CASTER TURN PROCEDURE
During the caster turn procedure, the alignment technician is required to steer to somewhat precise toe angles and cause the alignment instrument to record the camber and toe angles. The intelligence of a microcomputer can be put to good use in directing and automating this activity.
For example, consider the caster measurement procedure used with the C111 Alignment System manufactured by Hunter Engineering Co. The console directs the steer operations by the use of “bar graph” indicators which direct the technician to steer to the proper angle by turning the steering wheel until a moving pointer is centered or “pulled” on a horizontal scale. When the bar graph is pulled, the wheel is steered to the proper angle, within a small tolerance.
The technician begins by instructing the console to measure caster, which responds by directing the technician to steer the wheels to an approximately straight ahead position. At this point the console records the offset between the front longitudinal toe sensors and the individual toe angles of the respective front wheels, so that the front toe angles can be measured during the turn procedure using only these longitudinal sensors. This is necessary because the line-of-sight of the transverse sensors might be blocked during the turn by large diameter tires.
The console then presents two bar graphs, one for each front wheel, which direct the technician to steer 10ş to the left, within a tolerance of +/ - 1/4 degree. When a wheel is steered correctly and the sensors' signals are not changing, the console records the camber and toe angles of that wheel, and turns off the pointer of the bar graph. The process is then repeated with the other bar graph and the other wheel. The technician may steer the left wheel correctly first, then the right, or vice-versa, or both may be steered correctly at the same time (provided the steering geometry and total toe make it possible).
When both wheels have been steered correctly to the left and measurements have been recorded, the technician is directed to repeat the procedure by steering 10ş to the right, within the same tolerance of +/ - 1/4 degree. After recording the camber and toe readings of both wheels while steered to the right, the console displays only one bargraph to direct the technician to steer approximately straight ahead, at which point the caster angles are computed and displayed.
By directing the technician to steer to within 1/4 degree of the correct angle, the turn asymmetry is held to a maximum of 1/4 degree. Notice that the actual steer angles are measured and used to compute caster, thereby keeping errors to a minimum.
STEERING USING TURNPLATE GAUGES
It is possible to measure caster by less sophisticated apparatus, but a compromise in accuracy and turn symmetry must be accepted. A common method is to turn the wheels to the correct angle by watching the gauges of the turnplates on which the wheels rest, then actuate a switch to record the camber measurements.
There are several limitations of this procedure. The first is the possibility of offset between the scale of the turnplate and the toe angle of the wheel relative to the thrust line. A common procedure to minimize this offset is as follows:
1) Jack the front wheels up so they clear the turnplates.
2) Steer the front wheels straight ahead, so that they have equal toe relative to the thrust line.
3) Rotate the turnplates until their pointers match the toe angles.
4) Lower the front wheels and jounce.
5) Steer and measure caster.
A possible problem with this procedure is that the toe angles change as the wheels are raised, but the turnplates might not turn to match the wheels as they are lowered. The step of jacking and lowering the wheels is also highly undesirable from a practical point of view.
A second limitation of this procedure is that the technician must steer the wheel by pushing and pulling directly on the tire, instead of simply turning the steering wheel. Eliminating the effects of suspension hysteresis is quite difficult under this condition.
A third limitation is that the actual turn angles are not measured. The computations performed by the alignment instrument assume the technician steered to the correct angles. If camber is not measured at these assumed turn angles, the caster computed will be in error. Figure 5 illustrates the sensitivity of caster measurement to this error, assuming a symmetric turn.
These limitations can be somewhat overcome by instrumenting the turnplate, such that the console can correlate the turnplate angle with the actual toe angle, and thereby measure the actual turn angles. This also eliminates the undesirable step of jacking up the front wheels prior to measuring caster, but increases the expense, complexity, and maintenance requirements of the turnplate.
MECHANICAL SYSTEMS
Totally mechanical alignment instruments can easily implement this method of measuring caster, but are subject to the same requirements to produce accurate results. This type of instrument generally uses turnplates to guide the turn, and so suffers from the same limitations discussed in the previous section.
Atypical method of measuring camber is to rotate a cam to level a bubble level and then read camber from a scale attached to the cam. Caster can be measured with this type of camber sensor if a proper caster scale is used. The procedure is to steer to the left to the correct angle, rotate the cam to level the bubble level, and rotate the caster scale to indicate zero. Then steer to the right to the correct angle, level the bubble level, and read caster from the scale.
The caster scale is easily computed from Eq. (8). The procedure requires the technician to steer to predetermined angles T1 and T2, so the scale factor is

STEERING AXIS INCLINATION (SAI)
SAI is defined in a manner similar to caster:SAI is essentially an angle similar to caster, but is measured in a plane 90 degrees to the plane in which caster is measured. SAI can thus be computed from the changes in a camber-type sensor mounted 90ş to the usual camber sensor. (Such a sensor is normally used when adjusting caster.) The only extra requirement is that, during the turn procedure, the sensor assembly must be locked to the adapter which mounts it to the wheel, and the brakes must be locked. Such a sensor measures the same angular change a “camber” sensor would measure if it were mounted on a horizontal axle at 90ş to the wheel axle.
In fact, both caster and SAI can be measured simultaneously during the caster turn procedure. The alignment instrument must have both a camber sensor and a “caster adjust” sensor, and the sensor and brakes must be locked, as described above. During the turn procedure, the camber sensor is tilted to the front or rear, and the angle it measures is altered by the cosine of the tilt angle. Since this angle is normally less than two degrees, the error introduced is virtually unmeasurable. The “caster adjust” sensor is tilted in the camber direction in the same manner, and the error here is also negligible.
SUMMARY
The definition of caster has been expanded such that it is referenced to the thrust line of the non-steerable wheels, thereby incorporating caster into the “total alignment” concept. A method for measuring caster according to this definition has been derived, and the restrictions, limitations, and potential accuracy investigated. Practical procedures have been suggested for implementing this method, such that the alignment technician is guided through the procedure in accordance with the necessary restrictions.

baz walton

well, what can I say, that obviously came straight from the heart!! And after having sat, theorised and then typed out that very long (and actually quite interesting) reply that succinctly and emotionaly informed me why I shouldnt use the word caster......
what did you decide would be the correct term for me to use then when explaining the for/aft vertical allignment of the rear damper/springs?? (which everyone else on the thread seemed to understand via the now illigal "C" word.)

It's Czech Mate

I did link you to the thread where itoriginated. If you search it, its a bit of a forum joke.

grcossie

Cheers mate, easy to make some of this, and it works

baz walton

you can send me links, or pages of info till the proverbial bovines return home, we both know it was nothing to do with the technicalities that I chose to reply to, and not just ignore, your comments.
I enjoy the banter and piss taking as much as anyone else, but to just laugh at someone "you" think is wrong, without having the Right answer Yourself is at best, childish.
Just ask yourself a simple question, "in what way did my contribution to this thread help?"

IAN RS2k

iTrader: (2)

On a 3dr Sierra 2wd I shimed it to take out toe & take out too much camber to get good traction in a straight line as its lowered alot. What camber is best for the rear for trackdays
IAN