Front LCA Rear bush by Bilstein/Febi

[mrbrian200]

Just caught this. Looking closely rubber part of the bushing in the picture:


I hadn't noticed this before. It looks like Bilstein addressed one of my concerns with the OE bush. Specifically that the stress/flex within the rubber on the OE style bush is concentrated toward the inner diameter at the bolt sleeve, resulting in premature failure (the rubber tears inside right around the sleeve).
Somewhat weakening it around outer circumference of the rubber (most easily accomplished by making the rubber thinner toward the outer diameter) should result with the rubber flexing more evenly across it's diameter, thus relieving stress around the inner circle where the OE bush tears often after just a few thousand miles.
Look again closely, that's exactly what Febi did-- see thinner 'ring' to make it a little more 'flexy' around the outside circumference?
I'm going to give these a whirl. Bilstein is a quality supplier. I wish I had put their shocks/struts on the car instead of those Sachs ones that feel like an R in sport mode (not terribly comfortable for a DD except on perfectly smooth newly paved roads).

[oragex]

It is interesting, may indeed help with durability. I had Febi made in Germany (stamped) spring seats, unfortunately one developped a crack in less than 1 year. The rubber quality is critical in these parts.

I recently installed Lemforder control arm bushings, will see how they do (picture of a lemforder one)

md_838a7c21-7f4e-467c-84d8-2eb117a89d9c.jpg (6.77 KiB) Viewed 3076 times

The white sticker Sachs are not the best struts. The blue sticker ones are a little better but very fragile with potholes and poor roads and give a poor/jarring ride in no long when abused in this way. I also had Boge struts, not bad. I heard someone who had Meyle struts and was satisfied but again, perhaps not the smoothest ride. In the end, I went with original Volvo struts which have that small 'smooth' zone in the damping, not Cadillac like, still a rather firm european ride but with a 'smooth' end. They make the car 'feel' like a Volvo, can't explain it how, perhaps driving a new Volvo may give a better idea. I think these are the best option if the roads aren't 'autobahn' smooth like.

[mrbrian200]

Hmm. Might part of the issue with LCA bushes not lasting very long on these vehicles be that the procedure for installing the LCAs could be damaging the bushes? Hear me out:

In most cases we disconnect the ball joint by loosening the large bolt at the bottom, then force the LCA down which I believe is the Volvo procedure. This requires that the LCA be pulled several inches below where the strut would normally limit suspension travel/lower extension.

Getting an old LCA off isn't generally the issue.

I recall from installing the (currently on vehicle) LCAs that came preloaded with new bushes: After the LCA is bolted to the subframe, the bushes would flex fairly easily out to about where the normal end of suspension travel would be. But to get the ball joint into the LCA, we must press the LCA further down by several inches. The rubber really doesn't want to accommodate this extra few inches. So we force it using extra long pry bars with a lot of weight and/or attaching a winch strap to force it.

Is it possible that this damages the rubber bushes during installation right from the get go by forcing the bush past it's usable design limits thereby dramatically shortening service life?

Might a better method be to somehow devise a way to compress the strut/spring assembly a few inches rather than forcing the LCA down?

Alternate method would be to disconnect the ball joint at the bottom of the steering knuckle - in every case.

Thoughts, anyone?

Weather is becoming more hospitable. Pressed the Febi bushes I ordered back in January into the original LCAs that came off the car 2 years ago. They'll be back on the car once we get a reasonably warm day without rain, toward the end of next week maybe.

[oragex]

The thing is, once 'forced' downwards to clear the rod on the ball joint, the lca is not much far downwards that how it sits when the car is lifted off the ground. And when the wheel is up, the lca already has quite a bit of deflection downwards with respect of its position when the car in on the ground. So it has to absorb quite a bit of travel.

It's that the aftermarket is flooded since a few years with low quality parts. Companies that sell parts source them from new companies, many such sources have changed now with the new chinese and east european manufactures. Even Volvo was sourcing the spring seats from Sachs which were good for about 10 years, now they are sourcing it from a french company, Rein, which has merged with another company, CRP. I had the Volvo spring seats from Rein/CRP and they seemed a bit fragile after only 2 years of use.

Another story. The Lemforder bushing in my comment above has failed after 2 months of driving. I sourced for replacement two different control arms with bushings: one had recent bushings installed by Volvo and stamped Volvo. This bushing was much stiffer than the new Lemforder. Another control arm had a bushing sold in Volvo boxes for aftermarket: this one was softer than the bushing stamped Volvo, and was stiffer than the Lemforder bushing. So the Volvo bushings in blue boxes that are sold on the market separately are quite more soft than the bushing Volvo will install on a control arm (or sell as a new control arm).

Quality control

[vtl]

Febi does not last.

Lemforder has several levels of quality, look for part numbers with 1 at the end. I had Lemforders in LCA for quite a bit of miles (~35-40k), they were like new when I pulled them out for suspension refresh all around with Volvo parts.

Meyle struts died in my V70 in like 6 months. I mean, after 6 months I finally decided to replace them with new OE struts, they worked good for maybe couple of weeks.

Aftermarket is a head ache, doing same work every 6-12 years replacing bad parts. Once I decided to use parts in blue boxes I have no head ache any more Still buying some good OE parts that are meant to be put in blue boxes, like GKN axles or Hutchinson pads.

[mrbrian200]

As outlined, I'm interested that FEBI strategically placed that 'purposely weakened ring' near the outside of the rubber. They wouldn't have done that without a reason. Likely worked out in computer modeling and/or physical stress testing.

Another point of interest: the factory original rear bushes I pressed out of the OE LCA the other day were torn up pretty bad. However, the front OE bushes are still in useable condition. The torn rear rear bushes in this arrangement weren't knocking against the subframe over bumps and potholes like the aftermarket LCAs (IPD house brand 'HD') have from day one.

This might lend some credence to my theory mentioned in another thread a year or so ago that vertical stabilization of this rear bush is highly dependent on the mechanical properties of the front bush. In addition to not being to 'stiff' against normal suspension travel, the small amount of lateral deflection that he OE front bush design allows might be necessary. The aftermarket front bush tried to redesign this possibly in an attempt to tighten up steering response. This might transfer shock/stress force that would otherwise be dissipated at the front bushing through the LCA to cause more problems with rear bush that effectively becomes the weakest link. If I'm right about this an idea I had a long time ago (but not tested) to use a greased poly bush in the front and an OE rubber bush in the rear might not be ideal either as the poly bushes for the front location typically allow very little lateral deflection.

It may simply be that the OE design is what it is. Volvo already tweaked these bushes as well as can be and there might not be much anyone can do to improve upon it without serious unintended consequences. Now if the geometry of the LCA were different... Say, if the relative positions of the front bush to the ball joint remained the same but the rear bush was attached further toward the rear of the car, possibly as little as 3-4 inches, it might be a whole different ball game.

I'm doing this as sort of a test: does the FEBI bush that looks 'interesting' last when paired with a OE front bush? Only time will tell.

Thanks for the tip on the Lemforder part numbers. I'll remember that! The original bushes had ~80k miles on them when I pulled the LCAs off the car. They're going back on but they're not going to last forever. They're fine for probably 1-3 more years which should be enough time to gauge whether FEBI was 'on to something', just 'on something', or whether it's just me and I need to 'start taking something'.

[dlundblad]

I just did this LCA job last weekend. Used Lemforder arms, ball joints and sway bar end links. Sachs quick struts and rear shocks too.

For those of you removing the original control arms, my advice is to just buy new bolts. Vertical bolts at the minimum. IPD will set set you straight, but the vertical bolt is a M14x2 thread pitch and grade 8.8.

I had my doubts, but the horizontal bolts came out whereas bolt vertical bolts (for the above bushing) did not. On top of that, the bolt was stuck inside the aluminum sleeve and would not back out and just spin inside the bushing. A death grip by a set of nice vice grips on the bushing sleeve allowed me to walk the broken bolt out enough with a ratchet to get my pry bar under the head and zip it off with am impact. In the event of a horizontal bolt breaking, the engine can be lifted to get the driver side out.

Also, I didn't have anything low profile yet strong enough to get the horizontal bolts out so I ended up buying a 3/8" Craftsman breaker bar.

Doing this job exposed a cam seal leak, which is why I am here now...

[kcb203]

Why are these such a failure point compared to other cars? Is it the rubber quality, the design of the bushing, the overall geometry of the system, or quality control? I've gone through three sets of LCAs on my 05 XC70 with 110K miles. I've had a bunch of other cars and never had to replace this part on any of them. My first replacement was at about 50K miles. I used third-party parts, which failed in 20K miles That time, I went to the Volvo dealer and the service adviser gave me a hard time about not using OEM. I responded that I wanted to try something else--after all the OEM parts failed in 5 years with 50K miles.

[dlundblad]

Why are these such a failure point compared to other cars? Is it the rubber quality, the design of the bushing, the overall geometry of the system, or quality control? I've gone through three sets of LCAs on my 05 XC70 with 110K miles. I've had a bunch of other cars and never had to replace this part on any of them. My first replacement was at about 50K miles. I used third-party parts, which failed in 20K miles That time, I went to the Volvo dealer and the service adviser gave me a hard time about not using OEM. I responded that I wanted to try something else--after all the OEM parts failed in 5 years with 50K miles.

I blame the design.

The sleeve exceeds the width of the bushing and there's lots of up and down movement from the suspension.

How else could it have been done? Not sure. Maybe the bushing could've been running parallel with the frame?

[mrbrian200]

Its the geometry more than anything. This basic design lower A-arm with flange type bush in the front and a fixed joint type bush in the rear (that's supposed to act like a ball joint) is fairly common. My sister owned an '02 Jetta with this same basic of control arm/bushing design. The factory A-arm was still fine when she got rid of it with nearly 200,000 miles. On my Chrylser Cirrus I used to have (also similar lower front A-arm) the bushes lasted about 150,000 miles.

On most other makes (that almost always last a very long time) the geometry between the two bushes and the ball joint usually forms a right angle or is slightly obtuse at the flange bushing as shown:

Typical.JPG (26.61 KiB) Viewed 2760 times

In this arrangement, the vertical forces created through normal suspension travel (bumps, potholes etc) concentrates more on the front bushing. But because it's a flange bushing, by design it can take it so long as the rubber is of high quality, or the center post that attaches to the car isn't bonded to the rubber (aftermarket poly bushes).

The rear fixed bush, not subject to so much vertical force, behaves more like a fixed ball joint. A ball joint would work there, but would also transfer too much noise and vibration to the car. So they make it out of rubber.

On our Volvos this geometry is an acute angle, the three attachment points forming close to an equilateral trangle:

VolvoOddity.JPG (22.3 KiB) Viewed 2760 times

What happens now (on our Volvos) is, with the ball joint further back in the geometry, that rear bush is subject to higher vertical forces when you roll over a bump or pothole. Not only does the rear bush pivot like a ball joint, but the increased vertical forces back there will tend to press the LCA up or down at the same time stretching the rubber more than it would had the geometry benn more like the 'typical' design. Over time it's just too much repeated extreme stress and the bushing goes to pot. Usually the rubber tears.

Adding insult to injury, these are performance vehicles, well, at least the Turbo Variants are. I suspect any time we STOMP on the accelerator or brake hard this rear bush gets pressed up or down. Now this 'wheel torque force' against the bushing is not as dependent on geometry as spring loaded suspension travel. So any high performance vehicle with this same basic arrangement of bushings will have trouble with this bush if you consistently drive it hard regardless of geometry. Indeed: the Subaru WRXs, even with the more optimal control arm geometry ARE known for problems with their control arm bushings. Indeed, the rear bush goes bad fast.

Now, the WRX racing/enthusiast community came up with a real solution. They resigned to solve the issue with a 'high end' design normally used by street race circles known as a 'pillow ball'. It's made by STI. This is a hybrid design utilizing a steel ball joint surrounded by just enough rubber to absorb some NVH. Because the steel ball joint accommodates the necessary pivoting motion, when the LCA is forced up or down the combined forces don't stretch the rubber beyond it's practical limits.

Subaru WRX.JPG (109.48 KiB) Viewed 2760 times

Note: dust boot removed to show what's in there.

As I understand, Subaru agreed. The design was incorporated into the WRX OE control arms for MY2014+ and is available as a replacement LCA for older model years direct from the Subaru dealer. The control arm casting had to be modified to fit a larger diameter bushing assembly (as would also be the case with our Volvos).

Uh oh. Here comes the Evil commentary..

We lowly Volvo owners don't get the attention from high performance aftermarket suppliers as we probably should. Probably because our cars aren't marketed as muscle/race/sports cars and therefore not typically sought out by that 17-20-something crowd. We get largely ignored by the street race/performance parts industry. But Most Volvos are still performance vehicles that in some cases could benefit from a little engineering prowess by companies that can do proper R&D and FAB their own high quality stuff (like STI).

I'm pretty sure there are a hell of a lot more P2 Volvos on the road than there are Subaru WRXs. It could be a gold mine for them if we could just figure out a way to get their attention. Volvo owners are not just a bunch of little old ladies. We're every bit as nutty about our cars as some 22 year old with their first rice rocket. And frankly, those Volvo owners that do happen to be little old ladies might appreciate a more robust, lasting fix for these front suspension issues too.