Control arm rubbing on brake disc

[Intrepid Fox]

Hi Guys

I've got a 72 HQ Kingswood, lately the lower control arms have started hitting the brake discs on full lock. The discs are aftermarket ones but are the same size as the originals and have been on the car for 25 years. The rims are 18" and have been on the car for the last couple of years. Its only just started happening and I'm at a loss at what might be causing it?

Anyone had this issue before or might know what's causing it?

 

cheers

[AllTorque]

How are the ball joints?

[440bbm]

10 minutes ago, AllTorque said:

How are the ball joints?

 

and quite possibly wheel bearings?

[cletus]

8 hours ago, AllTorque said:

How are the ball joints?

This, don't drive it any more till you've jacked it up and figured it out

If the joint separates when you're driving, you're going to have a bad time

[Intrepid Fox]

The ball joints seem to be alright, the hubs needed nipping up a little but haven't checked the wheel bearings yet, will check those out and see how they are.

[440bbm]

Jack the corner up off the ground on axle stands and get  amate with a lever/plank of wood to lift the wheel up and down and you watch where all the play is coming from. You may not see the major wear untill it get a bit of force. 

If the hubs needed nipping up, how did you do this? Do you know the correct procedure to carry this out?

[cletus]

6 minutes ago, 440bbm said:

Jack the corner up off the ground on axle stands and get  amate with a lever/plank of wood to lift the wheel up and down and you watch where all the play is coming from. You may not see the major wear untill it get a bit of force. 

 

This- 

Put a Jack, or big block of wood under the spring cup on the lower arm, so the tyre is far enough off the ground to fit some sort of lever under it- sometimes there's enough spring tension to disguise the play, jacking it up under the spring cup takes this out of the equation 

[azzurro]

Agree, there is no way that should be happening absent major issues in the front hubs/ball joints/spindles/steering and you are perhaps moments away from complete loss of steering due to catastrophic failure.

the spindles or steering arms have stops that hit the control arms preventing them from steering angle pivoting that far that the discs can even get close

something in the front end has had its retaining fasteners come loose, or is worn out/broken, or a combo of all three

Be interesting to know what the issue ends up being when you find it!

 

My guess is worn ball joints.

Pic from my recent front end rebuild might help visualizing whats going on behind the backing plate

[Intrepid Fox]

I had it in for a WOF a few weeks ago and mentioned it to the mechanic, he said hubs were a bit loose and they nipped them up, and the ball joints looked alright, but other than that he said they didn't really see anything and to bring it back if it keeps playing up. I had it out on the weekend and it's getting worse, so I'm definitely not driving it any more until its sorted. 

It does it both sides so I would of thought that both ball joints going at the same time wouldn't really happen, but I suppose it's still possible. Do you think it could possibly be something with the steering box?

I will also go and do what you guys have suggested with jacking the car up this weekend. 

[Nominal]

3 minutes ago, Intrepid Fox said:

I had it in for a WOF a few weeks ago and mentioned it to the mechanic, he said hubs were a bit loose and they nipped them up, and the ball joints looked alright, but other than that he said they didn't really see anything and to bring it back if it keeps playing up. I had it out on the weekend and it's getting worse, so I'm definitely not driving it any more until its sorted. 

It does it both sides so I would of thought that both ball joints going at the same time wouldn't really happen, but I suppose it's still possible. Do you think it could possibly be something with the steering box?

I will also go and do what you guys have suggested with jacking the car up this weekend. 

Nothing about the steering box could cause the discs to hit the control arm. The spindle that the wheel rotates on is constrained by the ball joints and the steering stop, so something must have movement/slop that shouldn't be present.

Hopefully the mechanic did the check mentioned above rather than a visual inspection.

[Intrepid Fox]

7 minutes ago, Nominal said:

Nothing about the steering box could cause the discs to hit the control arm. The spindle that the wheel rotates on is constrained by the ball joints and the steering stop, so something must have movement/slop that shouldn't be present.

Hopefully the mechanic did the check mentioned above rather than a visual inspection.

Yeah I'm thinking it was just a visual inspection they did, I will have a good look at the ball joints this weekend.

[sr2]

 

What type of HQ steering arms are you running?

(The HQ “power steering" arms are 90 mm from the centre of the ball joint hole to the centre of the next closest hole, the "non power steering arms are 120mm).

[Bearded Baldy]

Where are you based @Intrepid Fox?

[Intrepid Fox]

On 16/04/2025 at 15:32, sr2 said:

 

What type of HQ steering arms are you running?

(The HQ “power steering" arms are 90 mm from the centre of the ball joint hole to the centre of the next closest hole, the "non power steering arms are 120mm).

It's non power steering. Based in Tauranga

[Bearded Baldy]

I would say everything points to the lower balljoints being flogged out, if you were closer to Taupo i would have offered to come check it out for you.

I suspect, without trying to throw shade at the wof guy, that he jacked off the wrong point when checking the balljoints so they stayed loaded and showed no play.

That, or the steering stops have bustes off somehow, which should have been noticed at wof too.

[Intrepid Fox]

8 hours ago, Bearded Baldy said:

I would say everything points to the lower balljoints being flogged out, if you were closer to Taupo i would have offered to come check it out for you.

I suspect, without trying to throw shade at the wof guy, that he jacked off the wrong point when checking the balljoints so they stayed loaded and showed no play.

That, or the steering stops have bustes off somehow, which should have been noticed at wof too.

Yeah Tauranga is a bit of a hike from Taupo, but I appreciate the offer all the same.

I got under it today and did as suggested above, I was by myself so it was a bit hard to move the wheel and try and see what was moving around at the same time, but what I could see when I turned the wheel, simulating turning a corner, was that the end of the connecting rod where the tie rod and the idler arm connect, would move up and down vertically instead of what I'd imagine should be on a horizontal plane. When I followed it back to the steering arm it looked as if the connecting rod moved up vertical enough it would drag the bottom of the steering knuckle over on full lock which would cause the disc to hit the control arm.

From what I could see it's the bottom ball joint that would be causing all of this to happen (just as everyone has suggested) as it's allowing the bottom of the steering knuckle to move over too much. The steering lock tabs are still there so it's not them.

I hope my explanation makes sense, it was a bit hard to try and get it all down in to words.

Anyway, I might have it all wrong, but I'm going to replace the bottom ball joints and see what happens from there. I'll keep everybody posted.