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[Stempy]

OK here is one for you guys/girls. We presently have a late non independent rear TR4 chassis here on our Globaljig fixture bench. I have the factory dimensions off a sheet from the factory repair manual. I have the latest released manual on CD. It is a great sheet so far as data sheets go with one major exception! It is showing the lower front suspension cross shafts as being parallel to center line and as a result to each other. There are no special notes or angles provided to indicate otherwise. Same applies to the upper shock/suspension member mounting locations are shown as parallel. This is not that common. Zero caster is most likely what that means. Now I have been told that they modified the arms later on to provide a standard two or three degree caster. My concern is the controls points on the frame itself. The sheet says parallel is that a fact? Any help would be greatly appreciated. Thanks Jon Thompson

[TR3driver]

Earlier cars did have zero caster, and the change to add 3 degrees of caster was done without changing the frame or inner pivot points.  The upper A-arms were modified to relocate the arc of the upper ball joint and the trunnion (lower ball-joint equivalent) was modified to account for the tilt in the vertical link.  The steering lever was also changed to maintain steering geometry.

As far as I know, the inner pivots were parallel to the center line, but I've never tried to verify that for myself.

[Stempy]

Randall I do appreciate your help. So what I need to verify is the actual relationship of the cross shafts to the center line. Do you know anyone that has an untouched TR4 frame without the engine that I could measure. Jon

[TR3driver]

I'm sorry, I don't.  I'd offer you my old TR3A frame, but it's pivots are no longer parallel ... ripped out by the wreck.

[charley fitch]

As this site includes folks from across the country, I am assuming that even though I have a frame here without the engine on it you, you likely don't live that close.  I am in northern California.  If I can measure something for you I will try.  I do have all of the suspension ( rebuilt) on the frame.
Charley Fitch  

[Stempy]

Yes that would be great. Is the engine installed? If not could you measure the distance from the center of the lower front suspension cross shaft to the center of the opposing side cross shaft. From the front tip of the cross shaft side to side and also from the rear tip of the cross shaft side to side. In other words I am trying to determine if the left and right cros shafts are parallel to each other. The actual dimensions would be helpful as well. I would be happy to call you on my dime to explain. Thanks Jon

[fdmarsden]

Stempy,

You obviously have some good data; I have only memory.
As I see it, the lower wishbone pivot bar ia parallel to the centre line in plan view, the spacing is four inches wider than the TR3.

In side elevation the bar is parallel to the chassis datum, which it where it gets complicated and tests my memory, and finds holes in my knowledge.

On the TR3 the chassis datum is not horizontal but slopes down to the rear at an angle which I remember as one degree and some minutes, maybe twentythree, but I am not sure of the latter.

As the TR4 frame is the same as TR3, with the addition of the spacers which widen the front track, I expect that the datum is the same.

The TR3 chassis datum was also not the same as the body datum.

When I was a junior draughtsman at Standard Triumph, I drew, but cannot say designed, the spacers in question, on a model which I knew as TR3B, but which seems to be known now a Beta.

Hope this is of help, or if not, of interest

[Stempy]

fdmarsden I want to apoligize for not responding sooner. I have not touched that project in over a month maybe two. Boy what a resource you are having worked on the drawings for these cars. I have really tried to verify the dimensions I have. I appreciate the help from members on this site. Randall was a huge help. The chassis we are working on is a rust free example but was hit in the front and repaired (I use the term loosely). We use a jig/fixture bench but nothing available for the TR4. believe me we have worked off the factory specs and have fixtured some cars that were manufactured years before the fixture bench itself. The hard fixed points on this frame include all of the fixed suspension angle with no adjustments. So I am tryin to be sure that where I put the control points is where they belong. The thing is so hashed over that there is nothing up front that I trust. I have learned to trust the data sheets and the fixtures but this one is giving me a headache. I appreciate your help. Jon (Stempy)