TR4 front suspension changes

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????

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INCREASED CASTOR ANGLE

TR4 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 resulted 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:-

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 misalignment 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. Readjust if necessary.

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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

Hi Brad,

I have twice ordered replacements for those trunnion washers and never rec'd anything remotely similar to the original, there was no way they were going to fit. Appeared to be made from too hard & heavy a material (for the "serration process", OK maybe at 300 ft lbs!), & were incorrect diameter, too small to retain the dust seals. I gave up and reused the originals.

Also found the both new trunnions had been too deeply machined at the inner dust seals, so had to use a handful of shims (12 or 16 total per trunnion) to take up the extra slack. This doesn't effect the fit of the actual joints, which are very good, just fills in around the dust seal.

 Finally, where the vertical link threads into the trunnion, the new dust seals were smaller than original and left a lot exposed, so I "expanded" the seal by slipping one of the old dust seals (from the horizontal portion) over it. Not concourse, I know, but...

I'm still trying to decide whether to drill the new trunnions to accept a cotter pin with castlated nut, or just hope and pray the nyloc "replacement" nuts, "torqued" to 4 whole ft lbs, stay in place at race speeds over at Sears Point, or at even higher velocities during a commute up Highway 101!

I'm printing your note and adding it to my factory manual! Thanks for posting it.

Alan Myers
San Jose, Calif.

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