Rear LCA experiences over the years

Laga

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I have the BMR non-adjustable lower, and adjustable upper control arms. No relocation brackets. Only the passenger side lower had loosened. All other fasteners were torqued to spec. When I torqued it this time, I used Locktite Orange. About 2 years ago, I had to loosened both lowers to get enough room to install DSS one piece driveshaft. I would have used an air impact to reinstall. I do not remember checking with torque wrench back then. Clunk sound started about this time last year. Car only sees 2.5K-3K miles a year. 60K miles total.
 

pass1over

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Sounds similar to my issue with the amount of new hardware and parts. I let mine go for a while, which resulted in hogged-out holes, mostly in the chassis end, and I had to put in stepped weld-washers to fix that problem. At the time it was definitely torque loss due to things compressing, but I've basically resolved it, yet the exact same clunk remains. All that's left is the shocks.

If you back off the gas in gear, and then punch it again, do you get an almighty clack? I do. It's not like normal gear lash or shifting clunk/clack when letting the clutch out too fast. This is much, much louder, jerks the whole car. I'm still at a loss, but hopefully will be inspecting the shock mounts in the body, and removing the sway bar this weekend to see if either are causing it.

On top of it, the wife basically killed the clutch in my main car, while hers is down for a cylinder head rebuild from bent valves. This broken-car crap is getting out of hand. It's like some disease.

I don't get the almighty clack when punching it after letting off. But it makes quite the racket on my bumpy, pot-hole filled limestone driveway/private road. It really sounds as if the rear end is going to come out of the car. I'll check out the LCA holes in the front to see if they've been misshapen in any way.

Sorry to hear about the other car issues, I understand your dilemma. I have a Ford '03 6.0 diesel in my fleet, lol
 

crjackson

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So, a “little” (but not much) off-topic question here. I purchased 2 2014’s at the same time 1 new, 1 slightly used (his/hers). Both exactly alike. Twins…

1st thing I noticed was the clunking when shifting gears (both cars), and I always assumed it’s a by-product of the 2 piece driveshaft.

After talking to many owners who have went to 1-pc shafts, they said the clunking didn’t change. What gives?

What DOES cause the clunking so inherent in Mustangs?

I have eventually learned to “drive around” the issue and prevent it by leading with my clutch, rather that my accelerator, but I’d like to eliminate it if possible.
 

Unexplodedcow

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The clunk, even with a one-piece driveshaft, is often gear lash. My rear end has a whole lot of it (3.73 gears from the factory), and though the pinion doesn't move inward or not, I have noticed gear noise when under a load compared to coasting. Kind of like a mild supercharger whine. Car came that way, Ford says it's normal.

That *will* cause clunks, but I've avoided that by ensuring the parking brake is on, in neutral, when checking for control arm clunk.

I still haven't figured it out, and still waiting on clutch parts for my car, but got the wife's car running, so that's progress.
 

crjackson

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Thanks, as I feared. I think there is some slop in the transmission that adds to this as well. Both of mine (Track-Pacs) came with 3.73:1 gears MT82. I’ve learned to drive around it (never presenting clunk) but it takes some effort to make it a habit/normal reflex. My wife can’t seem to master it. I think that’s because she really just doesn’t care. She hates the noise, but doesn’t want to learn other driving habits or methods.

I don’t really notice any gear-whine on either car, but that could be due to my hearing. Although the wife doesn’t notice any either.

I do also have headers, no cats, GT500 axle-backs, and a supercharger, so there’s a good chance it’s drowned out anyway.
 

PonyDNA

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I have own a 2010 GT since 2012. Shortly after getting it, I decided to get J&M polyball rear LCAs. Never had a problem that I knew of.

Around 2017 or so, I lowered the car, changed out the sway bars, and added in LCA relocation brackets. Steeda sport springs, Maximum relocation brackets, and UMI upper, lower, and panhard bars with rotojoints and poly. Here are my thoughts about all that.

The OE LCAs use very large crush sleeves. In the torque box, they have small, .5mm textures to hold it in place at the body, and the OE torque is high (probably from having to torque through the bolt, and not the nut).

The J&M arms say to torque to OE (129 ft. lbs). The UMI arms say to torque to 72 ft. lbs. That's a large difference. So, what could happen with that torque spec?

Well, I've had the arms on my car about 1500 miles tops, mostly cruising, a few medium/hard launches on a slightly modified car (canned tune, 1 piece driveshaft), and even on stock tires sometimes. The J&M arms never had an issue with things, and never loosened up.

The UMI ones, however, have been extremely problematic. Some people say they clunk. Yup, they do...when the crush sleeves are hammering the bolts from sliding back and forth. I have been under the car to torque the bolts about 30 times in a few years, barely driving it.

I finally took the time (about a week) to really shakedown the car and trace the cause. The bolts were not loosening. I noticed problems at both ends. Elongated (wallowed-out) holes at both the chassis torque box, and in the relocation brackets, and hammered bolts/sleeves.

The body side is worse, particularly at the inner hole, where the stock bolt uses threads. The hole is probably 5/8 diameter (16mm). and not overly elongated. Ford used too large of a hole, IMO. Each aftermarket arm has crush sleeves that are much, much smaller, around 19mm outside diameter. This causes the sleeve to torque up fine, but partially extrude itself through the hole, and tear it up, along with the threads. The J&M clamped in just fine. UMI seems to use a stainless steel sleeve that kept getting worse and worse, losing about 3mm of length as it was pushed *through* the chassis hole. Increasing torque only made things worse.

I had some 1" OD, and 9/16" ID crush sleeves sitting around from a spare front control arm bushing (Prothane 6-218). They were a bit long, so I cut them down to 50mm and drilled out the poly front bushings to fit. I went with slightly upsides hardware (9/16" 18 thread) and used large flange washers on the inside (late 90s Humvee lug nuts, actually). The shank end fit well, while about 1/16" slop remained for the 9/16" threaded end. Torqued to OE spec 129 ft. lbs. and the arm does not move. Larger sleeves and hardware solved the issue.

The axle end is another story. UMI specs 72 ft. lbs on the roto joints. They can go slightly above this, to about 90 ft. lbs, but will otherwise collapse if torqued to 100+. The rear LCA bolt holes were also damaged, more on the shank sides. Larger 9/16" hardware and flange nuts again, and that worked, but the roto-joint collapses under higher torque is still a problem. Torquing to UMI spec will, 100% of the time, result in clunks. This is the roto-joint slipping in the LCA bracket, and hammering the bolt (not a good idea).

I even tried without the relocation brackets. Same problem exists, except worse. A shorter lever imparts higher loads on whatever is pushing against it, so the stock axle tabs are a shorter lever than with an LCA relocation bracket. Clunks were worse, and torque beyond 90 also collapsed the roto-joint. Yes, I ordered additional hardware and rebuilt the joints.

How is this fixed? Larger sleeves are needed front and back, so they can take the pressure without collapsing or extruding through/damaging the hole. Despite the massive ends on the OE hardware, those don't have issues with moving around. The downside to them is massive wheelhop.

Future plan is to expand the holes and weld in chromoly stepped washers to prevent the problem from happening again, while still using larger sleeves. I have no fix for the roto-joints, and am going to let UMI know my findings. I'm doubtful one random person will make a difference, but with the problems I've experienced with movement and yielding, I can't recommend the UMI rotojoint arms.

The panhard bar and UCA both use larger joints, by the way, and were able to handle higher torque loads to stop moving. I will say their bracket fit the stock 14mm bolt *tight* that it had to be seated in place with a small hammer. It moved slightly under UMI torque spec, but I increased torque without issue. It's holding well, and has been the entire time. The differential bushing is a BMR multi-piece urethane type. While difficult to get in the car with the axle in place, it's also worked out fine. The panhard bar simply works, and has given zero issues. The roto-joints themselves are built tightly, and I've seen zero wear inside. They do require good greasing, while assembling, and after, through the zerk fitting.

The quality of the UMI part is good. It's not like it's a cheap piece, or sloppily designed, but it comes down to failing to hold torque due to collapse and extrusion.

So, moral of the story: if you're having clunks and think it's a normal part of the joint or suspension design, it certainly is not. Something is loose, and requires tightening. If it fails under tightening, it's not a viable part.

This is a known issue that found in 2005 on my GT when I installed Steeda the then new fully adjustable LCAs and UCA which I later upgraded to the multi-position UCA bracket and 3-piece bushing. I brought this to Steeda's attention then and they said they never saw this issue. I called B.S. and the said they would warranty the parts. Those were the parts I used to make the opened up bushings for the fabricated sleeves.

There is nothing wrong with the way Ford did the fasteners and pick-up points. The problem is the under sized bushing sleeves every aftermarket company decided to use. It was simple to fully resolve the issue, I drilled the right size hole in a piece of aluminum, centered up the new sleeve and turned the OD to about 0.25" larger than the OE bushing sleeves, I also took the new Steeda bushings and put them in the LCA arm and then single point cut the bushing ID to be a press in fit for the new aluminum sleeves. I then just used new Ford fasteners and torque specs. Problem solved, no more movement or damage to the chassis pick-up points. that was 70K miles ago and they were still perfect when checked a few years ago.

This solution seems to work just fine. That said do not go too big on the sleeve or you run the risk of too much ride harshness because you are essentially making the bushings harder by replacing the poly material with aluminium. Not ideal for street cars trust me.
 

pass1over

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so the bushing sleeve is too tight on the bolt and the solution you've found is to make a new bushing sleeve for it. I have been wondering if the sleeve was grabbing the bolt and suspension travel was causing it to loosen itself. Is there not enough material in the bushing sleeve already in there to just open it up a little bit? I'll have to get the car back on the lift this weekend and check it out.

Does anyone know the dimensions of the forward LCA bolt off hand?
 

crjackson

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Although not as firm as the poly-bushed aftermarket LCA’s, is it a safe bet that the Roush LCA’s don’t suffer from this?

I was considering replacing with the Roush LCA’s, and a Steeda Adjustable UCA/bracket/Diff bushing kit.
 

pass1over

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I checked the torque on my LCA's last weekend, and they were indeed a little loose. So I put them back to 130 ft/lbs. Noises went away for about 2 days, then returned.

Put the car back on the lift, and the LCA bolts are still at 130 ft/lbs, they haven't loosened. But the sound is still there when going down my bumpy, pot-hole riddled driveway/private road. I'm not sure my noise is coming from the LCA's.

I've been thinking about getting one of those chassis ears setups and try to figure out exactly what part is making that damn racket back there.
 

Unexplodedcow

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Mine was good for a bit, clacky, but not terrible. It worsened significantly after the bumps, to the point that it sounds like a truck's trackbar when it has no bushings left...just tons of rattling/clacking noises, and the worse let off/ apply gas clack I've heard. Axle is very slightly, but visibly moving. Something loosened up significantly.

I went through the relocation brackets: they've never moved. Torque loosened on LCAs before due to sleeve extrusion and hole wallowing in the chassis (very mild in the brackets, too). Seemed to be resolved with a larger bushing sleeve, drilling out the bushings, and mildly upsizing the hardware to 9/16 18 thread, with using orange loctite along with a Grade 8 nut to jam in place (also with orange loctite). I highly doubt that loosened.

The roto joints probably collapsed, and caused the loss of compression from the bolt. I'll have to get the thing up in the air again to see. Could also be the UCA roto joint giving grief. I'd assume some noise from the spherical bearing in the diff. housing now, as that's a pretty harsh thing, but I should not be hearing sounds like the axle is going to exit the car, see extremely slight movement while rocking the car by hand.

I should've sold the car when I had the chance. Ugh.
 

GriffX

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I checked the torque on my LCA's last weekend, and they were indeed a little loose. So I put them back to 130 ft/lbs. Noises went away for about 2 days, then returned.

Put the car back on the lift, and the LCA bolts are still at 130 ft/lbs, they haven't loosened. But the sound is still there when going down my bumpy, pot-hole riddled driveway/private road. I'm not sure my noise is coming from the LCA's.

I've been thinking about getting one of those chassis ears setups and try to figure out exactly what part is making that damn racket back there.

I had the same issue after installing the J&M Extreme LCA. Torque was in spec but I had terrible noise from the rear axle. I over-torqued the bolt to the cassis a bit (+ 5Nm) and it was fine.

When I read your post I was wondering if this has something to do with the bolts. I think they are TTY bolts you should replace, because they get streched. If you strech them twice they have probably not the same clamping force compared to new?
 

Unexplodedcow

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I think they are TTY bolts you should replace, because they get streched. If you strech them twice they have probably not the same clamping force compared to new?

Torque to yield bolts usually have a numerical followed by an angular torque spec which will yield a bolt.

However, when a numerical torque is provided, the bolt is almost certainly not going to yield, as a torque number is going to have variance on it per torque wrench, thread quality and if any lube was used. Clean, dry threads are the standard.

Likewise, the maximum elastic strength of an M14 2.0mm pitch bolt (clean, dry threads) is going to measure around 155 ft. Ford specifies 129, which is within that amount. I have also taken micrometers to measure length and diameter of the bolts, and did not measure any change between new, used once, or multiple times.

I believe what can happen with multiple reuse of a bolt would be thread damage, at least in the form of brinelling or galling. Prevailing torque nuts (nylon washer types, for example) also won't have the same torque holding ability when reused. Thread locker needs to be removed, otherwise it will contaminate any reapplication (it's an adhesive).

Now, I have encountered actual TTY bolts in, say, the front of a late model Focus. Those will give, say, an 80+ pound numerical torque, followed with a 90 degree angular torque. This works out to about 170ish pounds of torque, which is beyond what an M14 bolt can handle, and it will measurably yield. The change is not visible, but can be measured with even cheap digital calipers, but a micrometer is better, and easier to measure in the diameter of the bolt.
 

pass1over

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Yea, they're not TTY bolts. Just regular 10.9 grade M14 bolts. I'm gonna replace them anyways, since I can get hardware for stupid cheap.

TTY bolts i've encountered are Ford 6.0 diesel head bolts.
Torque to 65, then to 85. Then clockwise 90 degrees, 3 times, in a pattern
 

Unexplodedcow

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The first time I noted TTY head bolts in a Ford was the 80s Escorts. Ford switched in...'83, I think, because the heads were warping when the engine overheated, and uneven torque was the cause (reusable bolts). So, they switched to TTY bolts, problem was better solved.

Of course, they could've gone with a better gasket and studs, but hey, go cheap. Fun little engines, regardless, and I've seen them make some crazy power: 1.6L pushing 320 HP to the wheels, from a single "overhead" cam, 8 valve hemi-head design.
 

Laga

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Are not TTY bolts completely buried in their applications? Like a head bolt and not where the end of the bolt travels through and sticks out. Like on a nut?
 

Unexplodedcow

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Not always. TTY is really about the application. Any bolt can be yielded with enough torque applied, which is why specifications and bolt grades exist - the higher grades resist yielding/deforming to a greater degree. However, once their limit is reach, they too will yield.

A TTY torque spec is more about consistent application of torque, and it requires using a bolt that's "too small" for the application, but is able to apply all of its clamping force and not back off. The whole idea is pretty neat, and from an engineering standpoint makes sense. However, it's costly, especially when a bolt might cost $10, and 10 are needed.
 

pass1over

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put new bolts in the front of the LCAs, where it attached to chassis. Don't think it helped at all, noises are still there.
However, yesterday otw home, I had about 350lbs in my trunk, and going down my dirt pothole filled road driveway, most of the noises and sounds were gone. So extra weight/compression on the rear of my car almost silenced it. Does this point to anything specific I should look at?
 

Unexplodedcow

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In your case, I would suspect shock mounts at either top or bottom, perhaps even swaybar mounts.
 

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