TC Rear axle location.

[Ray White]

One thing that concerns me about my rear axle is that it is not located correctly. I know there should be 18" between the centre lines of the axle and the front pivot. Mine measures nearly 17.5". I have replaced the spring and I am wondering if the main leaf is faulty as some rear springs were made before with the locating dimple in the wrong place.

The odd thing to my mind, however, is that if the axle were to be set back any further, it would mean the damper arm would be canted over; which would not look right. At present, the damper arm is vertical and looks right. I don't even know if the damper could be assembled crookedly but I am doubtful that it should be.

What I am worried about, of course, is how the wheel will sit in the arch when I eventually get the new body tub.

[Steve Simmons]

Is it the same on both sides? Not that you could install the spring backwards, but I wonder if it was dimpled backwards. The factory chart shows 18" from center of front pivot to center dimple of leaf, and 18.5" from rear pivot to dimple. Perhaps measure both directions and ensure that the front is in fact 1/2" farther than the rear?

http://www.tcmotoringguild.org/techinfo ... g-data.jpg

[Ray White]

Yes I have checked both sides. They are the same. I must emphasise how the damper arm would need to be canted over if the axle went back any further and that would look completely wrong. My dilemma is that you can't have it both ways. Get the measurement right and the damper arm looks wrong or have the damper arm right and the axle is too far forward.

[Steve Simmons]

Learn something new every day. I just went and looked at my car, and I never noticed the rear links aren't perfectly vertical. They lean a bit. So I think you're ok. 1/2" at the axle won't translate to a whole lot the further down you go on the link. Maybe someone else can check theirs to make sure we don't both have an issue! Either that, or enjoy your short wheelbase racing version TC.

[Ray White]

Interesting! Another potential issue apart from wheel in arch might be the prop shaft. I have a Ford T9 5 speed gearbox with a shorter prop shaft than the MG one. The shaft was made before fitting new springs so I am losing 1/2" of spline travel. I don't know what is shortest safe gap between end of box and prop flange but there isn't that much on my car.

[jagman2]

well, you made me check mine. rear axle to front pivot is 18" on one side and 18 1/2" on the other side. rats!
i have new springs installed all around. now will probably have to dismantel to check it out.

[Ray White]

well, you made me check mine. rear axle to front pivot is 18" on one side and 18 1/2" on the other side. rats!
i have new springs installed all around. now will probably have to dismantel to check it out.

Please can you check the shock absorber arm for me? I believe it should be vertical to work efficiently. If it is not straight there is a good chance that the rubber bush will wear quickly. On the other hand if the measurement is more or less than the prescribed 18" then the position of the wheel in the arch will be affected. The prop shaft splines need to be projecting from the gearbox sufficiently to allow for in and out movement so in that respect a little more than 18" might be better than a bit less.

[jagman2]

ray
my shock absorber arms look quite good and the same on both sides. there could be variation but it is not apparent.

[Ray White]

So we have a conundrum.

On my car it would be impossible to have a correctly aligned damper arm at 18" between centres. It can only occur at 17 1/2".

To get the required 18" I could replace (or modify) the springs. That would push the axle back far enough. The only way I can see restoring the correct damper arm positions would be to physically move the dampers back by 1/2" but that means new holes in the chassis and distance pieces behind the brackets.
Oh heck!

[Steve Simmons]

My bushings have lasted tens of thousands of miles, so maybe it isn't as bad as it seems. But another solution might be to make a custom link. That would be better than drilling out the frame rivets, etc. You just need a short piece of pipe welded to a rod with a bend in it.

When you think about it, if the rod is vertical then the bushings are always being compressed at an angle, because they are off-center. A perfect solution would be for the shock arm to be directly over the lower mount, keep the bushings flat, and weld / bend the rod in at an angle.

[Ray White]

My bushings have lasted tens of thousands of miles, so maybe it isn't as bad as it seems. But another solution might be to make a custom link. That would be better than drilling out the frame rivets, etc. You just need a short piece of pipe welded to a rod with a bend in it.

When you think about it, if the rod is vertical then the bushings are always being compressed at an angle, because they are off-center. A perfect solution would be for the shock arm to be directly over the lower mount, keep the bushings flat, and weld / bend the rod in at an angle.

Steve. I am trying to visualise your suggested solution. ( It's 1.20 AM so too tired right now ; will try again later)

Thanks for your idea,

Ray.