I like the way Opentracker does his arms. A piece of bar stock, welded to the arm against the flat of the nut.

I think there's some misconceptions about what this mod does, so here's why guys do it:

The way a rubber bushing like this works is that the outer shell doesn't move.  The inner sleeve rotates and the rubber, being bonded both to the shell and sleeve, twists.  The resistance to twisting is based on the durometer of the rubber. 

A secondary function they serve is as an insulator between the wheel and the chassis.  The rubber transmits less of the NVH (Noise/Vibration/Harshness) to the occupants.  The stiffer the rubber, or if you use polyurethane which is much stiffer, the more NVH transmission to the occupants.  The downside to the stiffer rubber or poly is that it can bind during suspension travel.  That bind tends to be unpredictable, creating potentially dangerous limit handling. 

From a performance standpoint a lot of guys will opt to replace rubber bushings with poly, increasing NVH, because some of what is lost in the interest of reducing NVH is road feel, and also the deflection of the rubber bushings creates a suspension and steering that is less than precise during spirited driving. 

Some guys take it even further by running arms that use rod ends or roller bearings instead of bushings.  The idea is that the suspension reacts instantly, and there is not deflection to make it imprecise.  Obviously this is also the worst way to do it from a NVH standpoint.  This does however alleviate any concern about bind in the suspension as is cycles. 

Tack welding the nuts, or otherwise preventing the nuts from rotating is done to eliminate the twisting action of the rubber as the suspension cycles.  Its a way of allowing the shaft to rotate freely, while maintaining the rubber bushing to keep NVH as low as possible.  In essence its a way to try and have the best of both worlds; get the free movement of a rod end with the cushioning ability of rubber. 

It should have negligible effect on the car returning to ride height.  IME a car where the springs have already taken a set will return to ride height in a trip around the block.  That's all I've ever had to do to verify alignment settings, link bar settings, etc.

TKO, WTF???  There are no rubber bushing in UCA. Except on Grande Mustangs where they did try to make them ride smoother.  Unfortunately they used a design that did not keep the ID of the bushing’s metal parts from rotating on an unlubricated shaft and they squeaked worse than the metal-on-metal bushings.

There are two reasons I started welding the nuts to the arms.  The first is that most of those double-lead, fine threads are stripped out on control arms being rebuilt. If you don’t weld them in place, they will come apart. That said, a good weld in three places on the big nut is required.  Otherwise, they WILL come apart. Thread locker just won’t add the required strength. Welding only a piece on there as Opentracker does will work ONLY if the threads are not stripped.  And if you want to adjust the position for free rotation on the shaft, might not allow the nuts to be torqued in place first.   Second reason, as an added benefit resulting from them being welded in, was the ability to adjust the nuts so they turn freely on the threaded shaft. That simply makes them rotate easier, thus lasting longer. And not getting that annoying squeak.

On control arms where the threads are still good in the arm’s holes, you CAN tighten them to 75 ft/lb and they will stay in place, but the threads between the bushing shaft and the nut will be in a terrible bind.  Who wants to assemble something that is obviously not working properly.  This condition is notated because the shafts and arms are very difficult to rotate. They almost feel like they cannot rotate.

Check out my UCA rebuild on the TIPS page. I also figured out if you cut a groove in the shaft, it allows grease to travel all the way through the bushing. The groove goes on the bottom of the shaft where it is not loaded due to the car’s weight.  And I make that groove go all the way past the o-ring or external seal so grease has an escape path.  This keeps the orings from blowing out after you grease the bushing with the car up in the air.  The process of setting the car on the ground rotates that bushing, trying to compress the space by threading action, trying to compress that  incompressible grease and that is what blows out the orings.

As for being difficult to take apart...  I say, so what?  I am not building these parts to be taken apart.  I am building them so they function in the best manner they can possibly function WHILE IN USE.  If I have to throw away a set of old upper control arms after I put them through their SECOND 100,000 mile lifespan, so be it.  But, with some careful, or even brutal, cutoff wheel work, they can be rebuilt many times. 

The good part is that when they are rebuilt so they rotate freely and with the groove cut in the bottom, chances are you will never wear them out again. I have never had occasion to need to rebuild a set of these that I have rebuilt using this method.

Huh.  Bad assumption on my part it seems.  Turns out I never rebuilt my UCAs; I bought a front end kit that had new upper and lower arms with the bushings already in them.  This having been 26 years ago at this point I incorrectly assumed that there were rubber bushings in the UCAs.  As it turns out there's no rubber except an o-ring to keep the grease in.  FWIW, all GM cars do have bushings in the UCAs, and the last set of UCAs I did was for a '74 Nova.  Even the 2,000 yard receiver occasionally drops a pass...

Last edited by TKOPerformance (1/09/2021 6:35 AM)

MS wrote:

Answers where direct experience are involved are always best.

I'd already done the groove mod and have been messing around with doing some other stuff (offsetting the shaft to increase camber) but did notice that when the nuts were tightened fully the shaft was really hard to move and the car didn't readily settle to ride height.  But if the nuts were not torqued the shaft rotated much more easily so I thought that maybe ...

Anyway, you answered my questions fully.  Thanks Steve!

Last edited by John Ha (1/08/2021 9:57 AM)

John Ha wrote:

TKOPerformance wrote:

Even the 2,000 yard receiver occasionally drops a pass...

I don't mean to be a troll but I've been on this board since shortly after it started and the only 2000 yard receiver who's ever been on it is Mustang Steve.  

That's not taking away anything from any of the other members who are, by and large, Mustang-competent and who traditionally only post to either offer value-added inputs to a question or to ask a technical question - as opposed to taking the opportunity to flap their gums on every thread that's posted.

 
Right-you-are John.... (from a gum-flapper/pontificator maybe)
Many times "us-guys" tend to treat this board as a great-big-bench-racing event we can go to every day.
MS is not only a moderator butt an orchestra leader !!
Ya gotta admit......the man 'do-know-his-Mustang-age'(dat a word? )
We all try to add  'a little knowledge'(which is a terrible thing) or humor...or some of both! and sometimes or fingers get ahead of our brain. That's where MS comes in!
   I hereby relinquish my soap box on this ....rainy....boring....non-working-on-your-Mustang-day...to your regularly  scheduled  program!
  6sally6

Mustangage.

I like that.