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Re: '76 TR6 Trailing Arm brackets

To: "conrade2" <conrade2@msn.com>,
Subject: Re: '76 TR6 Trailing Arm brackets
From: "levilevi" <levilevi@attbi.com>
Date: Sat, 2 Feb 2002 11:06:46 -0700
Eric,

Check this site out.  Brian Lanoway put a lot of effort into this to save us
all a lot of time.

http://members.visi.net/~kohout/trailarm.html


Plus below is a cut and paste from an email from Brian with some tips in his
own words.

Bud Rolofson
71TR6 CC57365 (Good 6)
66TR4A CTC57806 (The Wreck-Almost Parts)
66TR4A CTC57529 (The Project)

>From 5/25/2001 post by Brian Lanoway:

I've republished a corrected version of the original posting below.  I've
double checked the 36 combinations against my original data and the list is
now correct.   Hopefully, this hasn't caused too much frustration from those
who might have used the old, incorrect list at that camber angle.

Brian Lanoway
73 TR6  CF6985U
Winnipeg, Canada

Here's the original posting:

Subject: TR6 rear camber adjustment - long
Date: Thursday, August 27, 1998 12:49 PM


 It's now taken me 2 years, but I finally think that I've got the camber
 on both my rear wheels right and I thought the list might benefit from
 some of the 'science' I've applied to the task.   There's been some
 traffic on the list last spring about this subject, but I haven't seen a
 comprehensive approach to this yet.  I hope this helps.

 First some background.  Last year, I installed new trailing arm up-rated
 rubber bushings, springs and rubber spring packings, only to find that
 the rear camber was still excessive - with the driver's side sagging
 more than the other.  This spring, I mixed and matched the trailing arm
 brackets - using the same mirror-image combination on both sides - the
 net result being the proper camber on the passenger side with some sag
 still remaining on the driver's side.  Finally, I remixed the brackets
 on the driver's side alone to get that right. I now have both sides at
 the proper camber angle - primarily through using various trailing arm
 bracket combinations.

 Since there are 36 possible trailing arm bracket combinations with the
 one notch, two notch and three notch brackets - either in the 'up' or
 'down' positions, I measured the bracket and trailing arm geometry,
 applied some trigonometry, and then created the following table to
 determine the range of camber adjustment possible using the 36
 combinations.  Please note that the camber angle shown in the table is
 the RELATIVE angle between bracket combinations, the actual angle you'll
 end up with depends on the camber angle you're starting with.  Also note
 that the negative camber angle DECREASES as you go down the table.
 By the  way, 3U means positioning the bracket with the three notches up,
etc.

 Here's the table:

 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

 The actual angle you achieve may differ somewhat from that listed above
 because the rubber bushings distort when you force the bushing bolts
 through to meet the new bracket holes.

 I found that it's best to change only one bracket per trailing arm at a
 time.  If you want to leave the ride height alone, change the inner
 bracket.  If you want to raise (or lower) the ride height while changing
 the camber angle, change the outer one.  To use the table, figure out
 which bracket you're going to leave as is and then find the next
 combination that allows you to do this while achieving the approximate
 camber angle change desired.

 In my particular case, the combination I ended up with was: passenger
 side; outer = 1D inner = 2U, driver's side; outer = 3D inner = 2U.

 I should point out that it is very possible to change out a bracket
 while leaving the rest of the rear suspension intact.  To do this, place
 the rear of your TR on jack stands, jack up the trailing arm so that you
 can support it (and take the spring pressure) with a secure support
 under the trailing arm, place your jack under the arm where it joins the
 bracket, remove the bushing bolt, remove the nuts on the bracket to
 frame bolts, raise or lower the jack so you can get the frame bolts out,
 remove the bracket and install the new one.  Make sure you replace the
 alignment shims as you found them.  There is some grunt work involved in
 getting the trailing arm back into the new bracket and aligning the
 bushing bolt holes (I've found that a pipe clamp is a great help in
 forcing the trailing arm back into the bracket) but the whole job can be
 accomplished in about an hour and a half.

 Couple of cautions: make sure the trailing arm is securely supported
 while you do this; that rear spring can cause a severe injury if it lets
 go.  Secondly, go this bracket change-out route only after you've
 renewed the trailing arm bushings, springs and packings as required.

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