Boxing stock front control arms

Rusty67

Dirt-Old 20+Year Member
Dec 3, 2002
3,749
37
109
Seattle area, WA
Anyone ever box these bad boys up ?

Please no comments telling me to buy an aftermarket arm. I've already got the arms out of the car and the bushings/ball joints out of the arms as well.

Any suguestions as to how to box them up or what the weak spots in the front control arms are ?

I've got the Motorsport ball joint kit (same as the Steeda 2x) as well as a set of poly bushings for the front arms.

Also, for those who don't have a press or a torch, I've devised an EASY way to make your own tool which makes bushing removal a snap, no torch/press required ! If you guys want the info on that let me know and I'll write a post on that but I didn't take pictures, I forgot my camera at home today.

Interestingly enough, I noticed that the larger rubber bushing on both arms was totally fine even after well over 100,000 miles, much of which were rough. The smaller bushing in both arms however were warped and starting to crack, the drivers side was worse.
 
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I want some info on the tool, I may be required to move some bushings around as soon as tomorrow evening. :(

Ok, since I don't have any pictures I'll have to use my words as well as my limited ASCII art ability. F33r my l33t 4SC|| 4rt sk1llz.

====== <------ threaded rod stock, I used 1/2 inch because it was what was lying around and it fit in the metal bushing sleeves.

oooo <----- washers

* <----- nuts

B <----- big bushing

b <----- little bushing

| | <----- control arm where the bushing goes through

_____ <----- empty space since &nbsp; is not giving me white space in this post (wierd because it usually works fine....)

Ok so basically what you do is get a piece of threaded rod stock that is a little longer then the with of the control arm bushing to bushing by a few inches on each end or so. Insert the rod into one end and stack a hole bunch of washers on it towards the bushing you are inserting the rod end from, it should look something like this so far:

=================|B|oooo________|b|

Next screw 2 nuts onto the threaded rod and push more rod through. Now it should look something like this:

======|B|======oooo*===*====____|b|

Now add some more washers to it, push the threaded rod all the way through the other metal sleeve and screw the thing down hand tight on both sides. It should look like this:

===|B|oooo*======*oooo|b|====

Use 2 wrenches, 1 to hold one nut and one to turn the other nut. The larger bushing should come out without too much fuss. Now you are asking what do you mean the large one will come out, how do I get the smaller one out ? Now what you have to do is change the configuration of the tool and use the larger bushing

With the tool removed, your arm should now look something like this:

___| |________________|b|___

Put the threaded rod up through the small bushing with the washers and nut in place like so:

___| |____========*oooo===|b|===========

Now take another nut and a washer or 3 and put it on the rod from the inside of the arm like this:

___| |____===o*=====*oooo===|b|=========

Now put the big bushing on next to the washer(s) you just added and put a washer and then a nut on it like so (MAKE SURE THE SIDE OF THE BUSHING WITH THE LIP IS FACING THE OUSIDE OF THE ARM):

___| |_=*oBo*========*oooo===|b|===

Tighten the 2 nuts on both sides of the big bushing good and snug. Butt the bushing up agains the arm and snug the nut and washers next to the small bushings hand tight. Be careful and make sure the big bushing is seated properly against the arm. It should now look like this:

===|*o|Bo*========*oooo|b|===

Now simply tighten the nut at the smaller bushing end until the washers/nut drive the bushing out of the arm.

The other arm is lather rinse repeate since they are basically symetrical. You can use some sort of spray lubricant on the bushing if you wish, it can't hurt anything since you are replacing them and the rest of the arm is metal.

One word of caution. The bushing will come out with a rather forceful pop and it is provably a good idea to clear the area of anything brakeable/dentable or killable (it would provably just hurt but some people might have soft skulls).

Anyways, have fun with that. If you want to reuse this tool I recomend greasing the threads so you don't screw them up.


I really doubt the stock front control arms flex.... Them bishes is stiff! I think the only time you would have a control arm fail is with zero deflection bushings (delrin for example) and racing...or if you got yourself into a wreck :rlaugh:

Regaurdless of the fact that the stock arms are stout, I've got the arms out and completely dissasembled. Why not box them while I'm at it ? If they didn't flex much before, when I box them they wont flex at all.
 
Regaurdless of the fact that the stock arms are stout, I've got the arms out and completely dissasembled. Why not box them while I'm at it ? If they didn't flex much before, when I box them they wont flex at all.

Because you're adding weight where a mustang doesn't need it, the front. The stock stamped FLCA's are already quite heavy, adding a 1-5lbs in more steel is just silly.
 
I don't know for sure, but all us vintage guys boxed both our upper & lower control arms on our early Mustangs. Shelby & Bud Moore did this as a routine during their chassis building. I did it on my 67 Coupe vintage Mustang race car. Of course we are not allowed to use modern tubular control arms for vintage racing. The late Mustang upper control arms are very similar in design. They are just heavier & larger. Under hard cornering, I would think that boxing would help control arm stressing. Just my .02. How was it installing those FRPP ball joints anyway?
 
I'll let you know. I don't have them in yet. Geting them out, well I didn't get them out. I'm doing this at my friends exhaust shop and he was a front end mechanic for YEARS. I smacked the ball join 3 times with a BFH and it came right out. WHACK, WHACK, POP ! I'll take pictures of them after they are boxed. I made a cardboard template last night.

I should have posted this in the classic tech, would have gotten much better answers...
 
Machine shops and automotive shops press in bushings and ball joints for 10 bucks a peice if you don't want to make the tool. I just had MOOGS bushings and ball joints pressed in my old 91 a arms. The ball joints are so tight, it actually hurts your hands and wrist to move them. Don't buy Made in China parts.
 
Alright, well its all done. I boxed the front control arms, installed Prothane poly bushings and installed a pair of Ford Motorsport lowering ball joints (same as Steeda X2 for much cheaper price). I also put a Baer Tracker kit on at the same time.

I'm not sure how much most of it helped. I think the biggest difference I will see is from the bushings. The smaller control arm bushing in both arms were warped. I have no idea why Ford used 2 different sized bushings, that was stupid. The larger rubber bushings in both arms were completely fine and the small ones in both arms were both done. They should have just put in larger bushings in both holes of the arms....

The net result of everything is that my car is now driving WAY more comfortably. There is definately an increase in the handling ability of the car but compaired to the difference in road feel it is totally secondary for me. The car is MUCH smoother over bumps/dips/pot holes/ect. and it is actually braking better.

I think the main issue was that the control arm bushings were binding because they were warped which was causing the front suspension to behave improperly. Before, when I would brake hard, the front wheels would hop. It was improved quite a bit when I replaced my sway bar bushings (which were TOTALY shot) with poly bushings and put shorter end links in. The problem definately still existed. After all the work I've done, the problem has completely gone away.

Next mods, I've got a set of Bullit calipers and a Cobra rear brake bracket kit. Some custome full length subframe connectors are also in order. Then the V8/manual conversion and finally a watts link. Then I'll take it to Willow Springs for some REAL fun. :)
 
Pics of the boxing? And what do you mean you might get a better response in classic?? Maybe because the OLD stuff could benefit boxing (heavy cars, worse metals, etc.)...ours would not IMO...and I can honestly say I've never seen anyone sheer a stock lower control arm unless they went off track or wrecked their car.
 
+1 unsprung weight is bad. You typically want to remove it where you can..not add it

I think adding roughly 1lb per control arm is no big deal.

Pics of the boxing? And what do you mean you might get a better response in classic?? Maybe because the OLD stuff could benefit boxing (heavy cars, worse metals, etc.)...ours would not IMO...and I can honestly say I've never seen anyone sheer a stock lower control arm unless they went off track or wrecked their car.

What do I mean by a better response in classic ? I mean they would have given me tips and insight into how to properly box the arm instead of talking about the arm being stiff enough already just being no one has seen these particular arms done before.

Classic Mustangs are slightly lighter then the SN95 Mustangs so I don't know what you mean about a heavier car....

Boxing a control arm is not just to prevent a control arm from breaking. It stops the arms from flexing in key locations which can cause unpredictible changest in the handling of the car at speed.
 
I think the real change in the feel was probably the ball joints as they relocate the spindle to the proper position, which helps correct your roll center. I'm here in So Cal, so let me know when you are heading up to Willow. I'd like to check it out. I probably ran Willow over a hundred times in the 70s and 80s. I've attended several vintage races as of late up there as well.

I installed the Cobra brake upgrade on the front and rear and it made a world of difference. Direct bolt on and an easy install. For the money, it's hard to beat.
 
I wont be going up there for a while. I've got my plans for the future of this car made way a head of what my budget can do in the short term. I might go up there with my cousine and watch him race his Ferrari around the 17th, but I wont be driving my car up there yet. But I'll be sure to let you know when I go up none the less.

I'm not sure if it was the ball joint that made the biggest difference or the bushings. I know for sure that the smaller bushing was binding in both arms and replacing them definately made a big difference. I could also see how correcting the roll center would allow the suspension to travel through a more normal range of motion in terms of where is was designed to function out of the box. Suspensions functioning towards the extremes of its travel have less play in one direction or the other and most definately will not function as well.

Reguardless of what corrected the problems with my front suspension, I can definately say that puting those parts in was a HUGE improvement and completely worth my time.