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Re: rear end alignment question

To: triumphstag@gmail.com, triumphs@autox.team.net
Subject: Re: rear end alignment question
From: Dave1massey@cs.com
Date: Thu, 26 May 2005 16:56:25 EDT
In a message dated 5/26/2005 3:18:49 PM Central Standard Time, 
triumphstag@gmail.com writes: 
> have a rear end alignment question on a Stag, but the rear end is
> very similar to the TR6.  No-one on the Stag list replied.
> 
> 
> Do the shims that change the toe-in and toe out of the
> rear wheels come in different thickness?
> 
> If not, what is the normal thickness of them?
> 
> If I remove one or add one, how much will the toe-in
> or toe out change?  (I'd prefer the answer in inches
> or mm / not in degrees)
> 
> I just got the car back from the aligment shop and am
> sure I'll have more questions.
> 
I can only talk about the TR6 but perhaps assuming the Stag is very similar 
won't get us into too much trouble.

I have seen rear shims only in one thickness but you can stack them as deep 
as the bolt length will allow.

I don't know the thickness offhand.

I don't know how the toein changes with the addition of shims but it is 
always best to have it checked after adjustment anyway.

By the way, The TR6 has three trailing arm mounts with different offsets for 
the pivot points and these can be swapped around to adjust the camber.  Below 
is a table showing how these brackets effect camber.  

TR6 rear camber:
outer bracket - inner bracket - relative camber angle (degrees)
 3D - 3U - 0.00
 3D - 2D - 0.98 (was previously published in error as 3D 2U)
 2U - 3U - 1.50
 3D - 1U - 2.11
 1D - 3U - 2.42
 2U - 2D - 2.49
 1D - 2D - 3.40
 3D - 1D - 3.49
 2U - 1U - 3.61
 1U - 3U - 3.80
 3D - 2U - 4.40
 1D - 1U - 4.53
 1U - 2D - 4.78
 2D - 3U - 4.93
 2U - 1D - 4.99
 3U - 3U - 5.91
 2D - 2D - 5.91
 1U - 1U - 5.91
 1D - 1D - 5.91
 2U - 2U - 5.91
 3D - 3D - 5.91
 1D - 2U - 6.83
 3U - 2D - 6.89
 2D - 1U - 7.04
 1U - 1D - 7.29
 2U - 3D - 7.42
 3U - 1U - 8.02
 1U - 2U - 8.21
 1D - 3D - 8.33
 2D - 1D - 8.42
 2D - 2U - 9.33
 3U - 1D - 9.40
 1U - 3D - 9.71
 3U - 2U - 10.32
 2D - 3D - 10.84
 3U - 3D - 11.82

This is based on a "nominal" frame and since frames can bend were often less 
than perfect from the factory and if you have had any frame repair it 
certainly won't be perfect.  Once again it is important to have the alignment 
checked 
by a properly equipped shop.  I had set up my TR6 with both sides equal.  That 
means it had the same brackets and shims on both sides.  When I had the 
alignment checked one side was off by a significant amount.  I had to swap 
around a 
bracket and remove a shim on one side to bring it in.  Here's where the above 
table comes in handy.  I looked at my configuration and read the 
corresponding "camber."  Then I calculated the "new camber" but adding (or 
subtracting) 
the amount I was off and determined the new bracket arrangement that I needed.  
Once I swapped out the bracket and returned to the shop the rear alignment was 
spot on.

Once again, this is for TR6.  I don't know if the Stag has a similar 
arrangement but if it does this may be of help to you.

Cheers


Dave Massey
57 TR3
71 TR6
80 TR8




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