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Re: Camber, Caster and so on... (Shorter)

To: triumphs@autox.team.net
Subject: Re: Camber, Caster and so on... (Shorter)
From: Michael Hargreave Mawson <OC@46thFoot.com>
Date: Fri, 7 Feb 2003 10:01:02 +0000
References: <200302061039_MC3-1-28B8-CA4@compuserve.com>
User-agent: Turnpike/6.02-U (<LxVf5jpHTJ4KxZf4nSFlqLdH9U>)
On Thu, 6 Feb 2003, at around 10:38:41 local time, Dave Massey 
<105671.471@compuserve.com> wrote:
>Message text written by Michael Hargreave Mawson
>>Front Camber
>>^^^^^^^^^^^^
><snip>
>As was pointed out earlier, the camber is constantly changing as the car
>moves up and down due to the unequal lengths of the upper and lower A-arms.
> This is why it is recommended to set the suspension with the car loaded as
>normal.

Got it.   As far as I know, the wheel alignment centre I used measures 
the camber without a driver in the driver's seat - and presumably makes 
adjustments with this in mind.

>  Setting the camber and then changing the springs will likely cause
>the car to sit at a different height and cause the camber to change.

Splendid - that explains that, then.

>Camber differences can cause the car to pull to one side.  So will caster
>differences (side to side)

Understood.
>
>
>>Front Caster
>>^^^^^^^^^^^^
>>All the front suspension bushes (and, indeed, all the front suspension
>>components) were replaced within the last month, so it seems that I
>>would need to shim the A-arm mount to bring the front caster in line
>>with spec.   However, the consensus appears to be that this is
>>unnecessary.   That's good. :-)
>
>I disagree with that.  If the car was re-aligned recently (before the
>bushing replacement) then the adjustments were made to compensate for the
>bushes sagging and deformation.  Replacing the bushings will put the
>geometry back to niminal and the previous alignment is now incorrect and a
>realignment is recommended.

Sorry, I seem to have misled you here.   I had the alignment done 
immediately *after* I had changed all the suspension components. 
Theoretically, therefore, the wheels should now be aligned correctly.
>
>>Front Toe
>>^^^^^^^^^
>>Fourteen months ago, my toe was set within the specified parameters at
>>+11 mins.   When the car went in for alignment this year, it was -18
>>mins.   What causes this?   Pot-holes?
>
>Changing the suspension bushings could cause this.  Or even a little
>settling in the bushings.  Or the car setting a little higher or lower on
>the springs could cause that.  28 minutes is not much.

OK, thanks.
>
>>Rear Camber
>>^^^^^^^^^^^
<snip>

>Once again, the suspension should be checked with the normal expected load
>in the car.  Load the driver's seat with enough weight to simulate your
>weight (or sit in it yourself) and be sure the tires are not bound up by
>rolling the car fore and aft before measurement.
>
>They don't call this a swing axle for nothing.  If the car is raised off of
>the ground and returned to the ground the tyres will contact the ground in
>a stance that is narrower than normal and the forces applied to the tyres
>will cause the suspension to set higher than normal.  Rolling the car will
>allow the tyres to find their desired position.

Understood - thanks again.
>
>>Rear Toe
>>^^^^^^^^
>>Opinions seem divided on this one - so I deduce that the asymmetrical 11
>>min of toe-out is only borderline problematic.   Is that a fair
>>assessment?   If I did decide that I wanted to remove a shim from the
>>left, how easy is it for a ham-fisted mechanical ignoramus such as I to
>>do this?
>
>Asymetrical rear toe will cause the car to "dog track" which is to say the
>car will drive down the street a bit sideways.  This is most common to live
>axle cars with leaf springs where the axle has shifted on the spring on one
>side.  I'm not familiar with this suspension but isn't the adjustment for
>this done with shims inserted in the U-joint attachments to the diff?

It may well be.   I shall get the manuals out and see if I can track 
down the answer.
>
>I hope this helps.

Very much.   Thank you once again for all your help - and for your 
patience!

ATB
-- 
Mike
Ellie  - 1963 White Herald 1200 Convertible GA125624 CV
Connie - 1968 Conifer Herald 1200 Saloon GA237511 DL
Carly  - 1977 Inca Yellow Spitfire 1500 FH105671

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