Lower susp. arm bushings won't go in.

[Andrew Pullin]

Hi folks.

So, I am finally putting my front suspension back together. In doing so, I ordered one of the super-duper kits of front suspension parts from Kanter's, which includes lower inner shafts, and the corresponding bushings between those and the the lower suspension arms.

The problem I'm having is that I can't get the steel bushing to do into the suspension arms very well. Even the old ones I removed don't go in too well. If you're familiar with these bushings, they have a pseudo-thread on the outside of them; I would try chasing out the corresponding threads on the arm if I had the tapping tool for it, but I can't really tell if it is a standard thread or not.

When I'm screwing them back in, it's to the point that it feels like I'll need a breaker bar or an impact gun to thread them all the way in. I've tried chassis lube grease and anti-sieze on the threads, but neither magically solves the problem.

Am I supposed to just "smash" them in there with an impact gun or something?

[Bill Ingler #7799]

Hi Andrew: Those bushing, as you know, are difficult to screw into the arm. Use a big breaker arm with socket as pictured below. If you run out of arm strength then find someone with an air wrench to seat the bushings.      Bill Ingler

[David King (kz78hy)]

I  broke my torque wrench on one of those as it seems the torque is different between the upper and lower ones.  There was one that was in limits of the tool and the other was beyond.

I had my control arms power coated and they got some in the threads which made it worse.  A little grease and breaker bar will get it done.  Do not rush, just think, this is a hobby, this is supposed to be fun...

David

This is for a 57/58

[The Tassie Devil(le)]

Use a 3/4" Drive Socket and Breaker Bar, and then use a strong piece of pipe on the end of the bar to extend it if necessary.

Bruce.

[Andrew Pullin]

OK, it sounds like the consensus is to use judicious force with a breaker bar / impact gun to get them in there. And here I was worried for a minute! 

Thanks for the input. I am still curious what that pseudo-thread that it's using is, and why it's done like that, instead of with a proper thread, in case anyone knows ...

[Roger Zimmermann]

To have a regular thread into the arm would require more thickess. This funny thread bypass this necessity and, as the bushings are not removed every second day, this is good enough.

[Caddy Wizard]

The thread is more or less an interference fit, not the smooth, easy fit of normal threaded parts.  It takes a lot more force (torque) than you would normally guess to unscrew these or screw them in.  Personally, I use either an impact gun or my enormous breaker bar (3/4" drive, 4 feet long) to force them home.  They are supposed to be hard to get in and out, in large part so they can't work themselves loose while the car is abused by the road.  Keep in mind that these bushings are fixed and don't rotate, while the lower shafts rotate within the bushings.  So the bushings need to be really snug and not rotate at all.


Art Gardner

[Andrew Pullin]

So, they are all in there now. However, my passenger side A-arm doesn't rotate freely. It will move when pushed, but then it stays in place. The driver's side one rotates freely, though. Also, oddly, I can't pump any grease into the front side grease fitting.
It now occurs to me that the two bushings form effectively one "synchronized" thread, since they connect the rigid mounting arm with threads on each end, and maybe I need to unbolt the mounting arm, and spin it backwards a few turns, and then reattach.
I suppose it's also possible that this arm is slightly warped from time or damage so those bushings aren't quite coaxial, in which case ... well, then I'm totally hosed. Just put it together and see how it drives ...

[Roger Zimmermann]

In fact, the suspension arms should not turn easely. If one is free, like you described, it means that there will be some play when the car is on the road. Play in suspension elements is the ennemy...

[Steve Passmore]

Andrew, you have to be sure you have the suspension arm central to the shaft before tightening up the bush's, It sounds as if the shaft has bottomed on the inside of one of the bush's preventing grease from entering, I have had this happen, so everything off, reposition the arm and start again.

[David King (kz78hy)]

In the '57 and '58 service manual, they show a tool that spreads the control arm ears during the bushing installation.  I made one up when I did mine.  As long as you deflect the ears around 0.040 inch when you assemble, you should be OK.  I think this reload's bushing to shaft interface.

My 2 cents

David

[Steve Passmore]

I don't think that applies to the earlier cars Dave.

[PHIL WHYTE CLC 14192]

What year car are you working on? I have the control arm spreader tool for my 54 CDV.
Phil

[Andrew Pullin]

I'm working on a 1940. The service manual is very terse when it comes to it. It just say "reassemble it and reinstall it". No mention of any special tools. As I conjectured, and others have now validated, it's likely that the mounting shaft was not centered in the area that it was being "captured" in by the bushings, so I'll just need to thread it backwards a few turns. (as long as I haven't permanently damaged anything)

Although, at the same time, it's not exactly clear to me how such a system could actually work, mechanically. The two bushings have threads on the inside, so as one bushing comes closer to the other, it seems like the mounting arm should jam on those threads instantly. Maybe the bushing OD and ID threads are the same pitch, and this somehow accommodates for it?

[Steve Passmore]

The Bush's should not thread up completely on the shaft Andrew, they usually leave a half a turn if they are both screwed up equally and about 1/4 turn on the bush is all the travel needed on the suspension arm. The upward action of the bottom "A" frame in action actually moves it to the left of the shaft slightly, so some thread still visible to the right hand bush is desired.