#106 Strut Replacement

Struts were replaced, giving a huge improvement in ride, noise and turning smoothness.

Besides making squeaking noises and a less-than-comfortable ride, the struts needed replacement because the spring seat on the right side was failing.  The rubber seat where the top of the strut spring sits is a well-known failure item on Volvo 850s.  If you take a wrench to the upper nut and turn it, there should be little movement on a good seat and it should quickly snap back to the relaxed position.  You can get quite a bit of twisting movement on spring seats that are failing and the nut spins freely when they are torn completely.  The nut could twist quite a bit on this car so needed a seat replacement along with the gas shocks and who knows what else in these strut assemblies.

If you can get any real movement out of these nuts at top of strut, the rubber spring seat is failing.

Struts should always be replaced in pairs to give equal ride on both sides, even if only one is bad.  In this case the right side strut had a torn spring seat while the left side was rather squeaky.  Both really did need replacement.

Started by lifting the front of the car securely on jackstands with the wheels removed.

Strut replacement begins with car on stands and wheels off.

Next is to support the wheel hub with a jack to just take a little load off the strut.

Support the wheel hub so the shock is not extended.

To free the strut for removal involves unscrewing six fasteners in three locations.  First unbolt the sway bar link from the  strut mount (one nut).

Sway bar link disconnected from strut.

Then unbolt the lower strut from the steering knuckle of the wheel hub (two bolts/nuts).

Strut unbolted from steering knuckle (wheel hub).

Finally unscrew the nuts securing the upper strut bearing mount under the hood (three nuts).

Top of strut (bearing plate) unbolted from under hood allows the strut to drop.

There is also an anti-lock brake (ABS) sensor cable grommet that needs to be pulled out of the bracket on the strut.

ABS sensor cable pulled out from bracket.

The actual sequence here is not important but all four things need to happen to free the strut from the car.  Now that it’s free, the support can be removed and the strut can simply be dropped down and removed from under the wheel well.  The old struts (not original, but not sure when they were last replaced) were very grimy, worn and torn up.

Struts in bad shape.

At this point the strut is typically disassembled with special tools and then reassembled with new parts as needed.  The spring is almost always salvaged and the other parts may be replaced depending on condition.  It’s generally a good idea to replace everything but the spring.

For this job, however, and this is where many Volvo purists will get upset, I did not rebuild the struts.  Instead I bought complete strut assemblies ready to go.  This gives us new gas shocks, coil springs, dust boot, bumper, bump stop, spring seat, bearing plate, retaining nut, upper cushion and top nut.  The quality of each of these may not be factory level but I’ll be happy if we get five years out of these.  I used Gabriel ReadyMount complete strut assemblies (G57040).  Three factors in choosing these: 1) Price was unbeatable with the pair running only $250 after instant rebate; 2) Time saved not rebuilding the struts; this cuts my effort down by at least three hours per car; 3) Favorable reports about these struts by certified buyers on their 850s.  Volvo forums lean towards factory only parts, or at least high quality after-market level.  I have no way of knowing where these complete assemblies fit in to this mix so this is something of an experiment.  I will update this post if and when there is an issue with the struts.

Comparing the old and new strut assemblies is very favorable.  The only missing detail is the ABS sensor wire bracket which needs to be screwed onto the appropriate side.

Complete strut assembly matches original perfectly.

Installation of the new strut assembly is straight-forward; just reverse the removal procedure.  Orientation of the strut is impossible to confuse as both top and bottom have to be turned a certain way to install.  The upper mounting is easy but the lower connection to the steering knuckle takes some effort to line up the bolt holes.  As long as you can move the wheel hub around it can be done.

Secure upper part of strut loosely with nuts.

Strut roughly fastened at top.

Strut roughly fastened at bottom.

One extra detail is to screw the ABS sensor cable bracket into the appropriate side.  The strut has holes pre-drilled for this and self-tapping screws are provided.

Screwing in ABS sensor cable bracket is easy.

Now it’s just tighten all the fasteners to the factory torque spec.  Again, in no special order:

Lower strut secured to steering knuckle.

New fasteners are recommended for the lower strut bolts but I didn’t order any so just re-used the old ones.

Sway bar link to strut nut.

Slip ABS sensor wire grommet into bracket. This takes a bit of forceful massaging.

Upper mounting nuts.

Once everything is replaced and secure on both sides, just put the wheels back on and lower the car and make a test drive.  Listen for any unusual sounds and feel how the front of the car rides and steers.  For this task the ride was much improved; all the squeaking and popping was eliminated and the turning was smoother.  I attribute much of the improved feel to the new springs which give more support than the originals with 17 years of compression on them.

New struts require front end alignment check and adjustment as needed because they alter the geometry of the front wheels, thus affecting caster, camber and toe.  Fortunately we purchased lifetime alignment at Firestone so I’ll bring the car in for free alignment shortly.

I dissected one of the struts to see how bad it was and present a short photo essay below.

You need some kind of convenient and sturdy work platform.

Top nut and cushion washer can be removed at any time; these are not under spring compression.

To disassemble the strut further, you must compress the spring to relieve axial force. These two-piece compressors are most common but the cheap ones are scary fragile.

Alternative spring compressor is this massive monster that is sturdy but awkward.

I like the sturdiness of the big red one but it doesn’t clamp the coils as neatly as the two-piece compressor which is less likely to damage the finish (and let the coil rust).  So the two-piece ones are probably better for these smaller coils (compared to larger vehicle springs).  Just keep a close eye on them in case they show any signs of breaking.

With spring compressed the retaining nut can be removed. This takes a special star-shaped tool and another tool to hold the gas cylinder shaft from spinning.

Retainer nut removed.

Bearing plate pulled out from rubber spring seat nipple. They may have to be pried apart.

Bearing plate in fair shape but bearings were a little rough and worn.  Rough bearing reduces steering smoothness.

Spring seat, the weakest link in the whole strut assembly. Many folks recommend using a more sturdy part from the XC90 which fits the 850.

You can see the rubber torn in a ring around the shaft sleeve on top…

…and bottom.

Bump stop almost disintegrated.

Shaft protective boot badly torn which lets dirt get into gas cylinder seal and make it slide roughly.

With gas shock removed all that’s left is a compressed spring.

At this point if you were rebuilding the strut you would put in a new gas shock and replace any other worn parts as it is re-assembled in reverse order.  There is a starting compression length for the spring that pre-loads the force when you tighten the retaining star nut.

Spring compression length spec when reassembling strut.

It’s also important to observe correct placement of the spring ends at top and bottom on the gas shock and spring seat, respectively.

$250 for two Gabriel ReadyMount complete strut assemblies on Amazon

Technical Notes:  Strut assemblies are the primary front end suspension components.  The coil spring around the gas cylinder provides the actual suspension of the chassis to the ground while the gas shock absorber provides dampening of the up/down motion for comfort and control.  Unlike the rear suspension which has separate shocks and coil springs, these are integrated for minimal use of space.  They need to rotate with the wheels when turning so there is a bearing at the top which allows for the struts to pivot with the wheels.

#70 Rear Brakes / Deep Rumbling

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****Note IMPORTANT safety update near end of posting****

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Rear brakes were done separately but could have been done at the same time as front brakes (#69) as one job.  As mentioned in that post, I wanted to verify that the vibration was due to rear brake problems, hence the separate topic.

The deep rumbling sound seems to be well-known with this model as a rear brake issue where the pads are set at a certain angle against the rotor surface.  This condition sets up a strong vibration through the car.  Volvo addresses this with a special shim kit that changes the angle of the pad very slightly or changes the deflection of the pad or something that improves the situation.  From what I have researched, it is more an issue with worn pads and old or resurfaced rotors, so often new pads and rotors solve the problem.  But to make doubly sure, I installed these special shims which didn’t cost much or add any real time.

Started by removing the rear wheels, brake pads and calipers.  Before removing the wheels I wiggled and spun each tire to make sure the rear wheel hub/bearing is not loose or noisy and that it spins freely.

Wheels off, ready for brake work.

Compare old brake pads to new ones. Old ones nearly worn down; very little material left.

Old rotor/disc off and caliper supported by box.

Unlike the front brakes, I am not replacing the rear calipers so supported them on a box where they wouldn’t hang on the fragile brake line.

Pulled rotors off and replaced with new Meyle discs.  The parking brake must be released for this because it works by clamping brake shoes inside the rear rotors.  The rotor is held on with only one small locating pin.  These came off with little effort for me but many people report the need to coax discs loose with a mallet.

Old rotors were not badly worn and didn’t have deep grooves. These might have been successfully resurfaced but new ones were so cheap I replaced them anyway.

Checked parking brake shoe pad thickness and condition as well as the spring, which were acceptable but the pads were worn fairly low; in hindsight I should have ordered new shoes but these don’t wear very quickly (only when you try to drive with them engaged or to stop the car by hand).

Scoured rust and dirt off the wheel hub with a wire brush and liberally washed down the whole wheel assembly and parking brake with brake cleaner spray.  The wheel hub needs to be relatively clean so that the rotor mates flush with it.

Cleaned up wheel hub and parking brake parts.

Washed down both faces of the new rotors with brake cleaner and wiped clean to make sure no oils or dust are present before installing them on the wheel.  I also smeared a little silicone brake lube on the wheel hub where the rotor mates up to ensure easy removal in the future (they tend to rust together).

Shiny new Meyle brake disc with rusty worn old rotor.

Hole sizes on the rotor allow the disc to be eccentric (not concentric) with respect to the wheel hub.  This can cause vibration and on the rear brakes it can cause the parking brake to wear badly.

Slop/play in rotor allows it to be eccentric (not perfectly concentric).

Using the cone-shaped wheel lug bolts to temporarily attach the rotor, they center the disc perfectly to secure with the locating pin.

Result is concentric rotor position to avoid vibration and parking brake wear.

New rotor installed. Beautiful disc won’t look this nice for long…

Inspected calipers for leakage or other damage/wear.  Finding none, I can avoid rebuilding the calipers and just need to clean them up a bit.

Caliper piston boots are in good shape and no sign of brake fluid leakage; rebuilding not needed. Pistons on both sides pushed back into caliper to accommodate new thicker brake pads.

After removing some brake fluid from the reservoir, pushed the pistons (one on each side of the rotor in the rear) back into the calipers to allow for new thicker pads.

Installed calipers back onto the wheel hub with bolts properly torqued.

Calipers cleaned up and reattached to wheel, ready for brake pads.

Installed new ATE pads using silicone brake lube on the backs as recommended.  Used special L-shaped shims which change the pad angle very slightly to avoid the horrible vibration.  Oriented with arrows up and lube on both sides.

Special shim solves noise problems with rear brakes. Piston pushes in center of pad so shim transfers more pressure on the half of the pad with the arrow. Used silicone brake lube on the back of the pads as well as the shim to minimize brake squeal.

Arrows point up on both inside and outside shims. On both L/R sides this is also the direction of wheel rotation going forward.

Pads and shims seated against rotor inside caliper, ready to secure with hardware.

Installed a new sheet metal pad retainer in the calipers along with properly lubricated new slide pins which tap into place.

Retainer secures pads in caliper while lubricated pins clamp the retainer and guide the pads in/out.

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 ****IMPORTANT safety update 6/14/14****

The retainer/guide pins that came with the hardware kit from FCP were improperly made.  The compression ferrules (C-shaped rings)  that hold the pin in the caliper body are too large and can’t be driven into the body.  Because of this the pins worked free on three of the four positions and the brake pads were loose and not fully functional.  This is an important safety consideration.  While perhaps not a high risk, the rear brake function was compromised.  Thanks very much to alert reader Ken Gill (who experienced this himself) who warned me about it.

When checking the situation I found that on the right side the upper pin was missing and the lower one was only partly inserted.  The retainer was completely gone.

Lower pin loose; upper pin and retainer missing.

The pads were still in place but swimming around and not doing much work, as evidenced by a lot of rust on the disc.

Rusty rotor indicates no braking action.

Left side was a little better but also had problems.  One pin was very loose while the other was mostly in place, as was the retainer.

Left side upper pin still in place but lower pin was halfway out.

Left side was better than right but still shows rust which indicates poor braking action.

Basic problem is that the compressible ferrules on the end of the pins are too large to fit in the mating hole in the caliper, even with reasonable hammering.  While these problematic pins were part of a kit from FCP I suspect they are generic commodities and could be supplied with other kits or pad sets.  Re-use of original pins is a good idea if you run into this situation.

Good new pins measure 7.4mm while bad ones are 8.0mm.  8mm is too large to hammer the pins into place to be properly retained.

Was tempted to buy genuine OEM Volvo parts but they are expensive and I would have to go on a weekday to buy them, delaying this repair.  So I bought a cheap ($9) kit from Autozone and it worked very well.

Duralast H5551 from Autozone works well and costs only $9 for both wheels.

Put the new retainer and pins (after lubing) in and tapped them all the way in as they are supposed to be secured.

Tapped pin heads all the way. Need punch to drive them beyond caliper body.

Properly secured pins should project well beyond caliper body.

Now that the rear pads are properly secured I can test drive the car.  To verify that they are now working, I took before and after photos of the worst performer, the right rear rotor.

With loose pins, this rotor was hardly used and rust built up on surface.

After driving around the neighborhood and braking just a little from moderate speeds, the rotor now shows proper use.

Because the rear brakes do only 20-25% of the work, rear brake problems are not noticeable unless you are looking for trouble.  If you suspect you have this problem, you can check it without lifting the car or pulling the wheels.  Just crawl under the rear with a strong light and visually inspect.  Retainer should be in place under both pins and those pins should be fully engaged in the caliper body.

Rear pins can be inspected from below rear of car without lifting. This example shows retainer and upper pin in place but lower pin halfway out.

** End of update; back to original post: **

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While brake lube is essential on slide pins and recommended to reduce noise on the backs of the pads, it is vital that no grease gets on the rotor faces or friction pad surfaces.

Re-adjusted parking brake for each wheel per factory specs and checked before putting wheels back on.

Installed new caps over the bleed ports since the original ones were very stiff and disintegrating.

New bleed port caps.

Put wheels back on and drove the car deliberately to condition the brake pads and rotors.  This brake bedding procedure involves multiple brake operations from 60mph to 10mph (no stopping) in rapid succession.

Brakes feel fine and respond firmly with no significant noise or vibration.  After driving quite a bit with the new pads, rotors and shims the horrible vibration problem seems to have gone away.  Will see how long this lasts…hopefully for years.  No such problems with my 850 sedan so it’s promising.

$29 Brake Pads, $72 Rotors, $15 Hardware Kit, $6 Shims, 2x$2 Bleed Caps = $126 Total

Technical Notes

Rear brakes have a similar design as the front but have smaller pads because they do much less of the work to stop the car (~25%).  The brakes are also slightly more complex because the parking brake mechanism is incorporated into the rear rotors.  See previous post #69 for more detailed description of rotor and caliper function.