waddisme

According to guy at Pfadt, i must have messed up some of the splines when I intalled these, or, I did buy them used and they could have already been messed up. Either way, one of the arms worked its way off the bar while I was dd, not on track fortunately. Bolts were torqued correctly, but still not enough to hold. Arms do not move around bar, they just slide side to side.

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Splines in the arms still look OK. Weld? Some kind of locking ring to hold bar in place? Red Loctite? Some kind of demon key? Waiting to hear from Pfadt. Suggestions?

John Shiels

Pfadt can put a new spline in it?

gkmccready

I think the splines are machined and not inserted...

2000BSME

What are the materials involved?

waddisme

Just got this from Pfadt:

"Hey Johnny. A couple observations here, in picture number 2 you can see where the shoulder of the bolt that runs through the arm has chewed it's way onto the inside splines, there really isn't a way to repair that damage that's been done. The difficulty in welding the arm to the bar lies in the fact it's a Zinc plated Chromolly bar being welded to an anodized Aluminum arm, even if you ground the zinc plating from the bar and the anodization from the arm it's still going to be REALLY difficult to get a good weld Steel to aluminum.

Another option that may work is to bang the arms back onto the bar, apply high strength red loctite to the arm and bar, and really crank down on that arm bolt. That may hold short term, but I wouldn't expect that solution to last for very long, and certainly not under a hard driving situation"

Sounds like welding is out. I would like to say they also offered me a great deal on a set of new ones. If I can salvage these, then I would like to do the wing and splitter, but if I had to choose, I would choose the new bars. I may try the loctite at RA next Friday to see how they do. Not a big deal to change out if I have too. Any other suggestions?

gkmccready

See if a local machine shop can build you chromoly arms and then you can weld them?

Z06_505

Use a bolt with threads that go all the way up to the head. The bolts that came with the new bar were not threaded all the way and the non-threaded part bottomed out before the arm was squeezed tight. I changed to different bolts and have never had a problem. My buddy did not know this when he installed his bar and his arm came off as well. I discovered the problem during the install.

John Shiels

yea I see that now it is one piece me dummy! I was looking at it as my CF kayak paddle with an insert.

Try clean spline up a bit it doesn't look to bad if you locktite it. Worth a try just mark them so you know if they are turning and not holding.

waddisme

Interesting. Might be a good place to start.

Pfadt Racing

Hey guys. Judging by the design of the arm these bars are pretty old and have given the owners years of good use. Looking at the damage on the bar there is a good chance that at some point there were some installation issues, but it's impossible to say. Unfortionately that's part of the chance taken when purchasing used race parts. We stand behind our products and want to see waddisme back on the road as soon as possible.

Let us know if we can do anything else for you!

dbratten

I noticed the bottoming out as well but chose to keep the original bolts as the thicker non-threaded part really should extend into the grooved part of the bar to give a better obstruction to the arms sliding off the end of the bar. The clamping force of the torqued arms isn't really enough to keep them on which is why the bar is grooved. My solution was to slightly deepen the hole for the bolts (in the arms) with a drill.

UstaB-GS549

I might try removing the burrs from spline first. Then get an AN bolt that has a slightly shorter grip. Look in Pegasus catalogue and see if they have something suitable.

1ED1

Get the arm back on bar in the correct location with red loctite put the bolt in then take it to a welder and have him weld the outer edge of the steel bar so that the arm can not slide off.

fatbillybob

red loctite will become inactive by the heat of welding. I could save that bar but it would take time and I'm cheap. I would weld up the bad part of the bar and hand recut the splines. There is not that much damage. You need the spline part for the action of the sway and the cut out recess to lock against the grip of the bolt to prevent sliding of the arm on the spline shaft. You can take up some play on the grip banging into the threaded part of the arm by properly threading the bolt for grip length or putting a washer on the bolt head to shorten the grip length is it is a small amount. That would take some pressure off the recess as the only feature preventing the arm from sliding. If you don't have the hand skill to recut the spline/recess look at your first picture of what looks like a small washer on a larger diameter washer. You could bolt the arm on the spline which probably does not move inboard. I think what you want is to prevent the arm moving outboard and off the sway (I have never seen a pfadt bar up close). If I'm right then I would cut a steel unit on my lathe that looks like the washer arrangement in your first picture. I would source a locking c-clip to fit the diameter of the smaller washer. I would weld my creation to then end of the sway. Slide the arm on and hold it with the c-clip. If you want to be real cheap you could weld a small washer to the bar and have a c-clip that size and that thin. Weld a larger washer on top of the small one. Now you can retain the arm with the c-clip.

froggy47

Take the deal.

waddisme

I am thinking with a dremel and file I can clean up most of the splines. Not that I am that cheap, but just improvising a lock ring to keep it from sliding off would fix the bars. The arms do not rotate when installed, they just work their way off the end of the bar.

I am not going to spend too much energy on this. I like the bars too much to stay with stock. I installed them and did the R compound tires at the same time, so I never really noticed what they did until I hit the uphill esses at VIR without them.

waddisme

Well, I took my bolts and ran a die over them to add about 3 threads. Not comfortable drilling into arms. I took my dremel and cleaned up the splines that I had messed up. I flipped the bar itself so the bad spot where the bolt holds the arm would not come into play. I test fitted everything on the car. I then put some "bearing mount" loctite like stuff that my mechanic friend gave me on bars and arms. Lined up bolt and tighten bolts down. It feels solid as a rock now. Just to be sure, the maintenance guy at the plant is going to weld a blob on the exposed outer part of bar to prevent arm from coming off. If it comes loose, new bars for me. Hopefully it will hold so I can do my wing and splitter. Thanks for the ideas.

BTW - I hope everyone noticed how Pfadt stepped in and went above and beyond to help me. Got to love this forum.

Solofast

Not sure if the new bars are better, but these earlier Pfadt aluminum end arms are a particularly poor design (sorry Aaron, but that's the truth).

The reason is that the end arm is angled across the bar and then clamped. If you are clamping around a round object it is critcal to have hoop material directly across from where you are clamping, at right angles to the bar you are clamping around. In this case the arm is angled and there is nothing directly across from where the clamping bolt is located. This makes the clamping ineffective because if the end arm straightens up relative to the bar, the hole is now an oval and doesn't have any clamping load on the forward and aft parts of the bar. This is why these arms loosen up over time. The hole and splines yield and the arm is trying to straighten up on the bar.

If the clamp was steel you might have a chance, but aluminum is pretty soft so you have a recipe for those things loosening up. Either the arm will yield from the clamping or it will try to straighten up and loosen up because the hole will yield.

I saw a post at one time where somebody who was autocrossing broke the arm by reefing down on the clamping bolt trying to keep the arm tight. That post was pretty quickly taken down and Pfadt quickly fixed the probelm and replaced the end arm. The post was only up for a few days, but the fact remains there have been other failures of end arms on Pfadt bars with the splined aluminum arms.

While the parts we are talking about in this thread are "old" parts, I don't believe that suspension parts should have a limited life. I don't want anything in my suspension working loose, or god forbid, failing outright when I am on the track.

While many people use these things on the street and have no problem with them, the design is, from a structual analysis standpoint pretty poor. We use these parts a lot harder in a track car than they ever will be used on the street. Add in sticky tires and you have a lot higher loads on the bars than and street car will ever see.

In order to fix it the arm needs to cross the bar at 90 degrees, and the splined part of the arm should be thicker to reduce the spline stress and the effect of the offset load on the edges of the splines. Unless the design is revised to do that, I'd probably stay away from these bars for a serious track car.

There haven't been any pics of the arm in question, but since you now need more travel on the clamping bolt it is obvious that the splined hole in the arm has changed shape and now it requires more clamping distance to get it tight. This is likely the result of yielding of the aluminum on the sides of the arm around the hole. You need to watch carefully the section across from the clamping bolt, that is where the other arm that I saw failed after it was tightened to try to get the clamping loads back up.

I would do as Pfadt suggests and dump the bar. While you did get it tight again it isn't going to stay tight and you are just asking for trouble. The arm is going to go next and you don't want that to happen at speed on the track.

GOTHAM VETTE

Why don't you put the kit together and then drill and pin the arm?

geerookie

This is the best advice you have gotten! Is it worth wadding the car up when it lets go....and it will.
Ask me how I know