Coilovers and Ball joint problems?

[sleepless]

Have any of you had issues with the ball joint popping out of the lower front control arm when using a coilover setup?

I'm down at Thunderhill Raceway this weekend and both the left and right ball joints have popped out of the lower control arm.

I've been running the MM coilovers for a while with no issues. However, just before heading to the track we noticed that the original ball joints were showing wear so we replaced them with OEM parts. They are pressed fitted from the bottom of the control arms. The new ones popped out through the bottom after a few sessions! After fitting them back into the control arms I had them tack welded to keep them from popping out again.

Has anyone else had problems with the ball joint popping out of the lower control arm? It is very frustrating, if not dangerous...

 

[Lumpydogs]

I have not heard of that happening before. I'm very interested to see what others write in. I just installed the MM coil overs on my cobra over the winter, so I'm curious to say the least.

 

[steve121]

I don't understand how that can happen. There is a counter bore on the control arms for the ball joint to bottom out on. Maybe they gave you the wrong ball joints? Are you using MM control arms? maybe there's a crack in the control arm that's allowing the hole to expand.

 

[racebronco2]

On corner-carvers they talked about stock or steeda ball joint not fitting correctly in aftermarket a-arms. The cure was to tack weld in a couple of places. When i used the steeda ball joints in my mmr a-arms i too had to tack weld in a couple of places.

 

[sleepless]

stock control arms

 

[sleepless]

Well, after talking to MM, I find this all a bit unsettling.

First, the joints popped out the bottom, the same way they are pressed in.

MM says that unless you build up some material in the control arm's hole before pressing in the new ball joints, that having them pop out is a fairly common problem with replacement ball joints.

As far as I can tell, this is mainly an issue with coil overs since in the stock spring configuration, there is almost no force applied on the ball joint in the "push it out the bottom direction", while with the coil over setup, since the spring is now connected to the carrier and the sway bar is still connected to the lower control arm, in hard cornering the force of the sway bar and the force of the spring conspire to pull the controll arm up and off the ball joint. So, with a stock suspension, you can easily get a way with replacing the ball joint just by simply pressing it back into the control arm. But, with the coilover setup, you have to make it a tighter fit. I know some people also tack weld the ball joint to the control arm.

Ultimately, a control arm with threaded ball joints would be much much more robust and safer; it was not fun having these joints pop out in a 60MPH corner!

The most unsettling thing to me is that you really can't be certain that the ball joint is pressed in tight enough; so it is like playing Russian Roulette...

 

[sunburned]

Wonderful. I'm getting MM control arms tomorrow and I'll be pressing new bushings into them. Guess I'll try the tack welding trick so mine don't pop out as well. Hopefully they will hold up fine on the street.

 

[sleepless]

Wonderful. I'm getting MM control arms tomorrow and I'll be pressing new bushings into them. Guess I'll try the tack welding trick so mine don't pop out as well. Hopefully they will hold up fine on the street.

Plz note I'm talking about the ball joints, not the bushings.

Also, I'm not singling out MM; all the "normal" coilovers have this potential weakness. SLAs like the one from Agent47 places the shock/spring onto the A-arm so it won't have this issue. It's only when the spring is on the carrier when you get this opposing force of the spring and the sway bar tugging on the ball joint. Stupid design really...

 

[sunburned]

Plz note I'm talking about the ball joints, not the bushings.

Also, I'm not singling out MM; all the "normal" coilovers have this potential weakness. SLAs like the one from Agent47 places the shock/spring onto the A-arm so it won't have this issue. It's only when the spring is on the carrier when you get this opposing force of the spring and the sway bar tugging on the ball joint. Stupid design really...

Sorry, I meant ball joints too. And didn't say you were singling out MM a-arms, just saying those are the ones I'm getting. Hopefully 3 or 4 small MIG tacks will hold them in ok.

 

[sleepless]

The tacks work great. After mine popped out at the track and we put them back in, I had them welded trackside and they were fine for the rest of the weekend.

It's a shame that the makers of the coilover conversions don't make a point of telling people that the coilovers put extra stress on the pressed fitting of the ball joint and that it should be tacked.

 

[sunburned]

Sounds good.

I think the ball joints should be connected somehow to the a-arm somehow other than a press fit in the opposite direction as the force. You are just asking for it to pop out. I guess technically, there isn't an upward force on the a-arm so they shouldn't come out at all, I've never heard of this problem before now, but I've only had a mustang for a few years.

 

[sleepless]

Regarding the upward force: It comes from the sway bar.

Under hard cornering or over uneven roads, the sway bar pulls up on the control arm.

With the stock configuration, the inboard spring absorbs this force so it does not put force on the pressed fitting of the ball joint.

When you convert to coilovers, the spring is moved to the carrier which is on the opposite side of the pressed fitting. So, now you have the force of the outboard spring pushing down one the ball joint and the swaybar (under hard cornering) pulling up on the control arm (this is on the inside wheel in a corner).

So, coilovers definitely put a new force that tries to pull control arm off the ball joint under hard cornering. This pressed fitting was never designed to have such force put on it.

 

[sunburned]

Yup, didn't even think of the sway bars, good call. I'll definitely be welding these in because I don't need something going wrong on the street, even if street driving might not be enough force to pop them out.

 

[N/Angel]

interesting topic, I have the KW suspensions coilovers and they require the use of 'locking' balljoints. I have yet to order the balljoints as the coilover kit does not include them. I have no detailed pictures of what the balljoints look like other then random internet pics I've found. but maybe it's worth a try? they cost 70 swiss francs which equals to about 70$. they also recommend using tubular a-arms with the coilovers.

here's the link to a pic showing the balljoints and the kit I have on my car:
http://www.focustuning.com/New_mustang_coilover.htm

 

[sunburned]

That seems like a great idea for the ball joints.

I bought Moog replacement ball joints for my MM a-arms and apparently they are the wrong ones since they aren't anywhere close to fitting. So yeah, gotta get that figured out before I complain about the ball joints coming out.