TR4/4A Help with deciphering front suspension problem

I had an "interesting" problem develop with front suspension on early TR4. The issue started when I began jacking the right side of the car. Just as the tire was lifting off the ground (thus weight transfer) there was a very loud BANG. I cannot identify anything that visually appears to be broken, bent misplaced etc. Here is what I do observe (and it may or may not be related to the bang). with the car on stands I can place hands on the tire at 12 and 6, and when I give an up and outward movement on the 6 hand I can see movement in the trunnion, vertical link, ball joint and upper A arm. No movement in lower A arm. Ball joint was new a year ago at which time I also replaced upper A arm bushes. At this point I plan to replace lower A arm bushes, trunnion bushes, seals etc as it seems prudent to do so. That said I would welcome thoughts on this issue and whether there is something I should specifically investigate.

"Loud" bang could be associated with the coil spring relocating as the weight is released.
As to the steering components movement, a detailed inspection with the wheel removed is in order. Fulcrum pin failure would be very unlikely.

From your description it's obvious something is entirely shot or missing. I can't tell from your description if it's one item or the entire suspension, though. If one part is loose or worn out, then everything will have motion. The question is if the motion is with the adjacent parts or apart from the adjacent!?!

Just a thought ... the bang occurred just after the tire left the ground.

Where was the jack placed? What spot was the jack lifting?

Tom M.

Thanks for the response. I wondered as well if the bang was spring relocating. Visual inspection did not show any signs of movement, not that that proves anything. I am beginning to think the bang had nothing to do with the movement I'm detecting.

thanks for the response. Close visual inspection does not show anything missing or broken. When I force the movement there is no independent movement between the trunion and the VL, the VL and the ball joint, or the ball joint and the upper arms. Where I see independent movement is the trunion to the lower A arms. Could this be as simple as worn bushes? Right or wrong I was leaning toward the problem being either associated to the trunion or the ball joint.

thanks for the response. the jack was placed on the frame about a foot behind the wheel

Can you drive the car or have you driven the car since detecting the problem. If you have had the car for a while, and driven it and not replaced the low brass bushing for the trunnions, they probably need to be fixed and would probably move. If nothing jumps at you with the loud bag, and you can see nothing, maybe drive it real slow. Or I guess the other front wheel could be loose and moved and made the noise or the whole problem is on the other side, maybe.

Quick update. Just studied the movement some more. It doesn’t appear that the trunion pins have play within the bushing but that the trunion is simply rotating a bit and that movement transfers all the way up. What should prevent that movement by hand and without engagement of the spring?

I had a coil spring hanging one time on the edge of the spring pocket up in the turret. It made a pretty loud pop once it was relocated to its proper position.

Cheers
Tush

The spring is caged in the housing and the weight of the car and engine balances the spring into a neutral kind of place. The trunnion and ball joint should turn together on the vertical link. Are you suggesting the vertical link might be broken down in the trunnion?
Steve

TRclassic3 said:

Quick update. Just studied the movement some more. It doesn’t appear that the trunion pins have play within the bushing but that the trunion is simply rotating a bit and that movement transfers all the way up. What should prevent that movement by hand and without engagement of the spring?

Click to expand...

The trunnion should prevent it. The trunnion to vertical link should have very tight tolerances...like .008". If you can see it move, then that is much more than .008". I don't understand your "rotating", as I thought the initial info was movement from up and down direction...are we talking suspension play or steering play...or both?

Also, I am not terribly concerned about the bang unless it reproduces itself. It was most likely something finding it's set. Suspension looseness is a concern, though. Trundles are known to come apart.