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TR4 lower trunion tech note

To: Triumphs@autox.team.net
Subject: TR4 lower trunion tech note
From: "Brad Kahler" <brad.kahler@141.com>
Date: Tue, 23 Feb 1999 20:19:53 -0600
Listers, included in the original TR4 service manual that I have was one 
service information sheet.  I thought I would include it here since there 
seem to be quite a few people doing front end rebuilds right now.  There is 
an important section towards the bottom about final assembly.  I believe 
this would apply to all TR4's, TR4A's and probably later cars as well.  
Lately there have been some people on the list saying their suspension was 
extremely tight after reassembly.  Maybe this will have something to do 
with that????

============================

Reference number 4/32.

INCREASED CASTOR ANGLE

T.R.4. Only

At commission # CT6344 (for wire wheels) and CT6390 (for disc wheels), 
the castor angle was increased from 0 deg to 3 deg positive.  This alteration 
has resuilted in dimensional changes and necessitated a number of new 
parts, particularly the bottom trunnions which now incorporate a 3 deg 
angle, and are not interchangeable with each other.

The modified parts which are not interchangeable with those fitted to 
vehicles prior to the above commission #'s, have been allocated new part 
numbers as follows:-

0 deg castor
---------------
Bottom trunnion sub. assy.                              101557 replaced by 
                                                                                
(133838 rh and 133839 lh)

Upper wishbone ball joint assy. RH              200771 replaced by 109225

Upper wishbone ball joint assy. RH              200772 replaced by 109225

Upper wishbone ball grease nipple               56934 replaced by 501024

Attachment of vertical link to ball joint -
                                                washer                  WP0011 
same as before (2)
                                                nut                             
LN2211 replaced by YN2911 (2)   
                                                pin                             
PC0020  no longer used

Attachment of top ball joint to upper wishbone -
                                                distance piece  100697 replaced 
by bolt 112347 (4)
                                                washer                  WP0025 
replace by WP0045 (4)
                                                nut                             
61302 replaced by YN2909 (4)
                                                pin                             
PC0012 no longer used

                                                        0 deg castor            
3 deg castor
Upper wishbone assy
        Front LHS                               132632          both are
        Front RHS                               132633          replaced by 
133504 (2)

Upper wishbone assy
        Rear RHS                                132632          both are
        Rear LHS                                132633          replaced by 
133507 (2)

Tie rod lever RH                        127830 replaced by 129836
Tie rod lever LH                        127831 replaced by 129837

When replacements are required for vehicles prior to the above change, use 
the earlier details.

If for any reason it is desired to modify the castor angle, replace all of the 
above 0 deg components with the 3 deg components.  Merely replacing the 
trunnions will cause mis-alignment and result in breakage.

NOTE : - Overtightening the pivot pin nuts will cause a bending movement 
in the vertical link and ultimate failure.

(IMPORTANT)********************
When overhauling the front suspension, it is vitally important to adopt the 
following procedure, when assembling the lower wishbones to the 
trunnions.

1.      Assemble the parts as shown in the illustration.

2.      Equally tighten each nut (47), to maintain the correct relationship 
between the pivot and the bronze trunnion.

3.      Continue tightening the nuts equally, to an initial torque load of 30 
lb.ft.  This permits the outer washer (46) to be serrated by the self cutting 
splines located against the thrust washer (37).

4.      Slacken the nuts and retighten to a torque load of 4 lb.ft.

5.      Slacken the nuts by 1 1/2 to 2 flats to suit split pin insertion and to 
permit 0.004" - 0.012" end float in the bearing.

6.      Check the assembly for freedom of movement over its full range of 
operation.  Re-adjust if necessary.

================

I check my TR4 service manual and in the book itself it doesn't mention the 
30 ft.lb first torque step.  It sounds like its a fairly important one as well.

Hope this helps someone!

Brad  (Lincoln Nebraska 402-464-1502)
My Web Site Http://www.141.com/triumphs (updated 2/15/99)

1964 Spitfire4 BFC25720L
1962 TR4 CT288L          -- 1965 TR4 CT38888LO parts car?
1959 TR3A TS41311L       -- 1959 TR3A TS53523L parts car
1951 1/2 ton Dodge Truck B-3-B-108

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