Mk IV UCA Failure

[jakester888]

Popular topic at least on FFCars. Wondering if anyone else has seen this?

1500 miles in, my driver's side upper control arm snapped while driving (I was turning left, stopped and felt something snap... just before a SEMI missed me). I limped along about 40 yds down the road, pulled over and saw the driver's side front tire with a hell-of-a-lot of instant positive camber.

I towed her home.

Jacked her up, took off the tire and saw this.

UCA Fail sm.jpg

Seems to be a commonly broken part according to other posts. I called FFR, ordered 2 new front UCA's. The parts girl at FFR was not aware of a failure rate (and no hint of replacing this). She was in a hurry to leave as it was 5pm Friday... so I just went ahead and paid the 2x$229 and had them shipped. I plan to replace both sides while I'm at it.

*NOTE* Incase it matters : I am using donor Mustang OEM lower control arms.

Kind of un-nerving. Any similar experiences? Did I do something incorrect? Some suggest a lack of lube. I am suspecting the UCA itself. Please share your thoughts.

[michael everson]

Does the part that is still attached rotate or is it seized? This can also happen of the bolts are not loosened slightly during adjustments.
Mike

[Jeff Kleiner]

99% chance that you will find that the rotating link is seized to the cross shaft due to lack of lube.

The new style arms are more willing to accept lubricant. They are physically different than what you have now with angled ball joint plates rather than straight. The joint needs to angle outward and one side will have the fixed leg forward and it will be to the rear on the other.

Good luck,
Jeff

[CraigS]

Is that pivot the older steel on steel style or the newer one w/ a plastic insert? Will it rotate on the shaft?

[Ray W.]

Isn't there supposed to be a washer between the sleeve and the retaining nut? My inserts/bushings show about 1/16" of exposed material on each side, if I remember correctly. It looks like the nut is against the sleeve in this pic.

[Mike N]

In addition to the above comments the through bolt between the pivot and the arm needs to be loosened when making alignment adjustments or you will induce bind in the pivot.

[Todd Buttrick]

Isn't there supposed to be a washer between the sleeve and the retaining nut?

Not that I"m aware of. Tie rod end adjustment sleeve is same with no washer on either side.

[Ray W.]

Not that I"m aware of. Tie rod end adjustment sleeve is same with no washer on either side.

This is what I'm talking about. (circled in the pic below) Page 94 of the MK4 manual has a pic of an upper control arm with no washers, which I'm assuming is the older type shown in jakester888's pic. I have the newer type control arms depicted on page 95, which has washers and about 1/16" of exposed bushing flange on both ends.

UCA Fail sm.jpg

[aarvig]

I am not a metallurgist but looking at that it appears the part failed in shear (vertically). Could be a weld issue if thats the case...especially if the part has freedom of movement. If it doesn't move, or binds, that may be the problem as others have mentioned.

[gunkk]

I am not a metallurgist but looking at that it appears the part failed in shear (vertically). Could be a weld issue if thats the case...especially if the part has freedom of movement. If it doesn't move, or binds, that may be the problem as others have mentioned.

More like bending around the UCA pivot axis, not shear. It's brittle fracture, probably initiated on the side not visible, further away from the weld. I am sure the weld-induced embrittlement did not help.

The comments about lube and binding are likely correct, based on the angle of the fracture surface.

(no, I am not a professional mettalurgist, but I have 5 years of education in the field :-) )

Jeff

[Jeff Kleiner]

There is no weld on the part that broke. Those UCAs have a long history of not accepting lube at the cross shaft to pivot joint. Anyone running these needs to assure that lube is going in and through; i.e., coming out both sides of the pivot (this one appears dry with no grease visible). This is what happens when it does not.

Jeff

[greydog]

I am finishing a old kit, a Mk2. Should I upgrade the UCA's?

[aarvig]

There is no weld on the part that broke. Those UCAs have a long history of not accepting lube at the cross shaft to pivot joint. Anyone running these needs to assure that lube is going in and through; i.e., comeing out both sides of the pivot (this one appears dry with no grease visible). This is what happens when it does not.

Jeff

You're right, I thought those were welded, looking closer they are not. Thanks for correcting.

[Jeff Kleiner]

I am finishing a old kit, a Mk2. Should I upgrade the UCA's?

Most Mk2s used Pole Position/SPC uppers like the latest Mk4 arms which are not prone to cross shaft galling. Post a photo and we can identify them.

Jeff

[CraigS]

I am finishing a old kit, a Mk2. Should I upgrade the UCA's?

I would. I recently installed new cross shafts and pivots on my MKII and re-used the rest of the UCA. These plastic bushing pivots have very well done grease channels so the grease disperses rather than just leaking out at the easiest path. I ordered from Summit
2qty SPS-93400 cross shaft
4qty SPS-92025 pivots
Verify that the threads in your sleeves are 3/4 inch like mine before ordering.

[Raceral]

http://www.summitracing.com/search/b...%20Performance

What is the part number of the latest F5 control arm....

[CraigS]

Jakester where are you?

[jakester888]

Jakester where are you?

I am in Dallas.

[jakester888]

New vs Old. Finally back on the road as of today.

UCA Fix.jpg UCA Fail.jpg

[Jeff Kleiner]

Bad news Jake---you have assembled your control arms wrong (well I assume you did them both the same anyway). The ball joints are supposed to angle outward as shown in the photo below, not in as you have it.



You'll need to disassemble, remove the ball joint and flip the ball joint plate portion over then reinstall the joint and put it all back together.

Jeff

[Mark Reynolds]

The thing that scares me about the SPC's is the tiny minimum cross sectional area where the clevis is bored through for the bolt - its about 1/4" square total for the 4 remaining connections. I will be checking the lube on Mk3 UCA's before this coming driving season and encourage everyone else to do so.

[Jeff Kleiner]

The thing that scares me about the SPC's is the tiny minimum cross sectional area where the clevis is bored through for the bolt - its about 1/4" square total for the 4 remaining connections....

Me too Mark.

Jeff

[jakester888]

Crap!

[mike w]

Lesson learned is grease, grease, and more grease!!!!!!

[CraigS]

Me too Mark.

Jeff

Here is the solution I am running.
http://www.mcmaster.com/#rod-ends/=114h8pu
Next to the bottom # 4749T211. Two notes: 1- The hole is 3/8 so needs to be drilled to 7/16. The slot is 3/8 so I found a 7/16 washer that is 1/8 thick to take up the space. These have much more meat around the pinch bolt. I had them on though the last half of the 2015 autocross season running 295 Hoosier A7s on 10.5 wheels.

[Derald Rice]

This is what I'm talking about. (circled in the pic below) Page 94 of the MK4 manual has a pic of an upper control arm with no washers, which I'm assuming is the older type shown in jakester888's pic. I have the newer type control arms depicted on page 95, which has washers and about 1/16" of exposed bushing flange on both ends.

UCA Fail sm.jpg

Page 128 of the SPC catalog shows a cross shaft with washers under the nuts on the cross shaft. I was just at SPC on friday getting some parts for my arms, and I compared the old vs new shafts. I am staying with the old.

The current part number for a roadster is 92142

I will also add that the guys at SPC were great to deal with.

Derald.

[Gumball]

This isn't my photo, but it was from a similar thread where the owner took a picture of the old versus new style UCA when replacing his due to a very similar failure that is posted here.

This picture is what convinced me to swap my UCAs for the new style, even though my Mk3 was just about finished. My old-style UCAs only did go-kart miles and then were retired for the upgraded units.



Here is my then-new suspension...

[CraigS]

These are my comments on my thread on the other forum when I upgraded to the new cross shafts and delrin pivots.
"Two items:
1- the shafts are shorter than my old ones by about an inch. Ok for me but could be a problem for others if your front sleeves are close to the spring already.
2- the delrin bushings have very well done grease channels. I greased by hand prior to assembly. Once on the car I got the grease gun out. I got six small streams of grease equally spaced around the circumference on both sides of the pivot. What a nice change from the old stuff."

[jakester888]

Bad news Jake---you have assembled your control arms wrong (well I assume you did them both the same anyway). The ball joints are supposed to angle outward as shown in the photo below, not in as you have it.

You'll need to disassemble, remove the ball joint and flip the ball joint plate portion over then reinstall the joint and put it all back together.

Jeff

OK - flipped and re-installed.

Photo evidence (before & after).

UCA Fix.jpg UCA Fix2.jpg

[Jeff Kleiner]

OK - flipped and re-installed.

Photo evidence (before & after).

UCA Fix.jpg UCA Fix2.jpg

You're getting closer Jake...notice that I said to flip the ball joint plate. You also did the shaft and attached pivots. Yours are now upside down; their grease fitting should point up like in your "before" photo.

Jeff

[ram_g]

You're getting closer Jake...notice that I said to flip the ball joint plate. You also did the shaft and attached pivots. Yours are now upside down; their grease fitting should point up like in your "before" photo.

Jeff

Just an interested bystander...you may be right, but why? Why does it matter which way the grease nipples point? Or is it something asymmetrical about the shaft and the grease nipples are just an indicator of which way it's installed?

[Jeff Kleiner]

Just an interested bystander...you may be right, but why? Why does it matter which way the grease nipples point? Or is it something asymmetrical about the shaft and the grease nipples are just an indicator of which way it's installed?

Ram,
Your 2008 vintage UCAs are like Jake's failed originals and have non-directional pivots however the new style from SPC that he replaced his failed ones with have an upside and a down side. The direction the grease fittings are pointing is simply the quick visual giveaway. The pivots are not symmetrical as you can see in this photo which shows them oriented incorrectly (as is the angle of the ball joint):



See how when installed this way the the links join the pivots below the cross shaft?

Here is the same front corner after the builder corrected both the direction of the ball joint plate and pivots:



The questions:
With the pivots oriented upside down is the suspension geometry significantly changed? ---Probably not. Is it how they were designed to be installed?---No. Will it make it difficult to lubricate?---Yes (and lack of pivot lubrication was what caused Jake's upper control arm problems to begin with).

Jeff

[JIMOCO]

I had installed mine upside down and found that I could not turn the steering wheel without a lot of effort. It was binding at the ball joint. After looking at the manual and playing what's wrong with this picture for a while I realized what I had done wrong. Once flipped back all was fine. The worst part was getting the ball joint out after a bit too much thread locker. Lots of heat and they came out fine.

[Jim Schenck]

The inner clevises being upside down won't affect the geometry since the center of the pivot remains the same, however I agree with Jeff it is much easier to grease the fittings with them pointing up.

[jakester888]

I thought about just reversing the plate... but then I reasoned not to because that was the way they were shipped from FFR.

I hope the arrangement I have will work. Since it's a pain in the arse to take that thing apart again. But hey, I'm getting pretty good at it by now.

[AC Bill]

I've always looked for the grease oozing out to ensure adequate lubrication, on my older MK3.1 control arms. Some of the arms from earlier models the grease wasn't getting in where it belonged, and some builders were taking them apart and adding custom made grease channels. I think FFR recognized the problem, and made the needed improvements on the next generation of arms to make sure grease was flowing into the bushings.

What, if any, is the advantage with the newest arms? Just the addition of plastic bushings? How long are they expected to last, being plastic?

[CraigS]

Jakester I think you will be fine. To make greasing easier I used to separate the pivot from the sleeve so I could spin the pivot around while greasing. That really helped w/ the old steel on steel setup. The delrin doesn't need that for grease dispersion but could be done for easier access to the grease nipple. And separating it this way doesn't affect alignment. Also, w/ the delrin, I suspect greasing will be maybe a once a year deal.

[NukeMMC]

Is it really that difficult to remove the cross-shaft nuts, lift up on the spindle and slide the pivot collars off the end of the cross-shaft, flip them over and then reassemble? You could either unbolt the upper coilover mount or use a jack to raise the spindle.