3 Link Rear Panhard Failure

[GT_Rich]

As summer winds down and our race schedule eases up, I wanted to take a minute to update folks on this board about something I encountered this year. This was my second season racing the Coupe. Honestly, I am still sorting through spring, shock, and brake changes to really make this car perform, but I am getting there. Reason for this post is a panhard bar bracket failure I encountered in June.

For a 3 link suspension, the panhard bar transmits all lateral load. On the axle, the FFR supplied axle side bracket mounts to the lower control arm bracket on a Ford 8.8 housing. Ford's intent for this bracket was to carry fwd/aft load, not lateral. FFR's design puts the Ford welds in bending, which is not good.

I had a complete failure of the axle side bracket at an autocross event in June. When this happens, the rear is no longer located side to side, so it will go all the way to the unloaded side until something collides. In my case, the driveshaft collided with safety loop at about the same time the inside of tire was into the chassis. One of my rear shock shafts bent in the carnage of it all. Not fun to fix this when it happens.

I have some pics showing how I repaired it and how I gusseted it.

This repair really changed the handling of the car. Before this change, I battled a snap oversteer condition constantly. Many spring and shock changes trying to make it go away with no luck. Prior to this breaking, I had 360'd the car three times at the event I was running. Since this fix (knock on the proverbial wood here), I have over 100 autocross laps and a road course daywithout spinning the car. The oversteer traits are now "catchable". I truly believe this bracket has been flexing since day 1 for this car and that flexing nature was putting the rear suspension in a position that made oversteer difficult to control.

I contacted FFR and they say the weld from Ford was bad and that they have sold over 10,000 kits without this happening. However, since then, I've had two others reach out to tell me this also happened to them.

In my opinion, if you street drive your car or casually autocross it with true street tires (not extreme 200tw tires), you will have no problems. However, if you actually race and compete with your car on a regular basis with a good tire, this should be on your radar. I have a 2 post lift and inspect my car a lot, and I did not catch any signs of this failing, so be careful. The time and cost to brace up this bracket is nearly zero compared to the time and cost to fix a failure. And if this were to fail at speed on a road course, good Lord...

For what it's worth, mine failed using a budget 200tw tire, which is the tire I've been running since putting the kit together. I was running a parking lot autocross when it failed.

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[GT_Rich]

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[GoDadGo]

Thanks For Sharing This Rich!

[RoadRacer]

Thanks for this. At autocross and circuits my car runs 315’s all round with sticky 200’s (RT660 or A052’s) and we’re cornering pretty hard nowadays. I’m certainly going to look into that bracing.

[Gordon Levy]

Not uncommon on cars that raced hard. The panhard mount has known to snap at the upper pass side.

[GT_Rich]

Gordon, where exactly, do they fail? Can you post pics? Is this experience for a Gen 3? It would be nice to have all this information in one place.

[Jeff Kleiner]

Interesting, and certainly something for us to be aware of. To be fully accurate though this is not a "panhard failure" but rather a failure of the axle mounting bracket although I agree that the loads induced by the panhard bar certainly must contribute.

Question: is this a Ford OEM assembly or is it a Moser?

FWIW, I made hundreds if not over 1,000 autocross runs and ran numerous track days on R Comps with my 3 link roadster using an OEM Ford rear axle harvested from a Fox Mustang. I had the rear end out of the car and the FFR brackets removed and reinstalled earlier this year and did not note any signs of fatigue.

Jeff

[GT_Rich]

Interesting, and certainly something for us to be aware of. To be fully accurate though this is not a "panhard failure" but rather a failure of the axle mounting bracket although I agree that the loads induced by the panhard bar certainly must contribute.

Question: is this a Ford OEM assembly or is it a Moser?

FWIW, I made hundreds if not over 1,000 autocross runs and ran numerous track days on R Comps with my 3 link roadster using an OEM Ford rear axle harvested from a Fox Mustang. I had the rear end out of the car and the FFR brackets removed and reinstalled earlier this year and did not note any signs of fatigue.

Jeff

This is an OEM Ford axle harvested from a fox body Mustang. I believe it came from an '85. Low miles, rust free.

Another consideration is the weight of a Coupe R, especially rear weight, has to be a lot more than a Roadster.

And, yes, the PHB itself did not fail. I tried to make a short/simple title thread that would be searchable later.

[RoadRacer]

I’m still bracing mine this week. The effort to brace it is almost zero, especially compared to what you’ve been through. It’s a bit like the banana bracket brace we all use

[Gordon Levy]

Rich, the breaks I have seen are mostly in spec racers. Upper pass side within 1" of the mount.

[J R Jones]

A box gusset is appropriate where the welds are in shear and compression, not bending.
jim

[GoDadGo]

Not uncommon on cars that raced hard. The panhard mount has known to snap at the upper pass side.

What about folks that just like to play a bit on the twisty back roads?

[Gordon Levy]

Street tire and relatively normal use like twisty mountains not so much.

[turbodon]

This was well known racing/autocross issue on the other Forum before this one started.

A gusset for side load is needed. A piece of square 2" tubing cut and welded in for side load support.

[ehansen007]

Yeah the bolt on bracket should always be welded. Surprised they still offer it as a bolt on... I learned that the hard way but surprised to hear it failing up top. Good to know. Could someone share a pic of the gusset?

[turbodon]

My pics from 2006 are not to be found.