By on November 27, 2009


In times like these, folks keep their cars longer (just ask Comrade Fidel’s oppressed masses of loyal subjects). Unfortunately, faster-spinning odometers have the nasty side effect of more quickly chewing up your car’s normal wear items. Some of these components (like brakes) can get downright demanding as they die. Others, like shock absorbers and their MacPherson strut cousins, just blend into the woodwork and stay there. Much like the guy in your high school yearbook that you can’t remember, your vehicle’s shocks and/or struts get Rodney Dangerfield-levels of respect and even less attention. Symptoms of worn shocks or struts include excessive floating after traversing even small bumps in the road, greater-than-normal body roll during cornering, increased braking distance, and extreme front end dive under moderate-to-hard braking.

Having experienced all of the above in larger quantities than is acceptable even for a 2001 Mercury Grand Marquis (a GS model, no factory air suspension), I decided my OEM shocks should call it a day after 168,749 miles of absolutely mediocre service. Bilsteins not being my thing, I immediately hopped online and ordered the extremely vanilla Monroe Sensa-Trac front gas shocks (to replace the oil-filled originals) and Monroe Max-Air rear air shocks (to replace the original gas-charged rears). Including shipping, my total came to $92.

Installation varies by vehicle; however, Monroe throws in everything you need, including reasonable facsimiles of all factory bushings, nuts, bolts and mounts. The rear air shocks come with a very concise, tri-lingual instruction sheet along with an installation kit that includes a tee-valve (to be located wherever in your trunk is convenient and safely-drillable), a barely adequate amount of air line, tiny O-rings for the air fittings, and a handful of mounting brackets. Everything but the shocks and the O-rings are plastic and feel extremely questionable. Also, would it have killed Monroe to spend two cents more per package and provide an additional foot (or three) of air line? Everything went together perfectly, though, and no trips to the parts store were necessary.

I wanted rear air shocks because I frequently pull a 2,000-pound utility trailer and hooking it up always caused the back of my big Merc to go for the limbo-dancing gold. Monroe claimed its Max-Air product was just the trick, with ride height-fixing pressure being easily adjustable from a stock-looking (and feeling) 20 PSI all the way up to a coil spring-bustin’, hip-hop-video-starring 140 PSI. (But avoid extended use above 90 PSI, Monroe says, implying, perhaps, that you should only go higher for occasional heavy loads or drive-by shootings.)

Ass-in-the-air antics aside, my new pneumatic nozzles never leaked and both front and rear shocks performed magnificently: Monroe took the OEM ride and handling specs and improved on them brilliantly.

Reduced body roll rivals my car’s P71 Police Interceptor cousin, but without the slightly harsher ride of that car’s stiffer springs and shocks. Jounce is minimized surprisingly, although this reduction doesn’t seem as affected by vehicle speed as Monroe’s “Road Sensing Technology” marketing materials claim. Rebound is similarly well-attenuated – it doesn’t make the car BMW-firm, but most traditional full-sized sedan customers aren’t looking for that, anyway. (Think “less float,” not “no float.”) Only in braking do these Monroes not best their costlier OEM competitors; however, they’re certainly no worse: Nose-dive under hard stopping still happens, but it’s no longer as dramatic.

Sealing the deal for my resounding endorsement was the miracle wrought in the trailer-hauling department. A very comfortable (if slightly rear-end elevating) 60 PSI kept the Mercury’s hindquarters completely level when attached to my five-by-eight band equipment hauler. But the real story came from behind the wheel, where the transformation was downright astonishing. The nagging yaw I’d taken for granted was gone, and the up-and-down pitching motion brought on by braking had similarly vanished. Each move the vehicle made when hitched was more positive than ever before; definitely better than with similar trailers I’ve pulled behind factory rear-air-suspension-equipped Panthers.

Bottom line: If you’re not a Bilstein-level load hauler or a Koni-loving corner-carver, and you own a fairly conventional ride that serves as basic, daily transportation (but you like it and don’t plan on trading), you would be hard-pressed to find a product more capable of providing such immediately-tangible ride and handling improvements while simultaneously doing the right thing for your vehicle’s suspension.

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29 Comments on “Product Review: Monroe Shock Absorbers (Sensa-Trac and Max-Air)...”

  • avatar

    I just installed 4 Sensa-Trac struts on my 01 Elantra with 140k miles on it.  They work well and were made even more affordable with a $60 rebate.

  • avatar

    Sensa-Tracs really improved my old 1997 Ford Escort LX wagon when installed at 8 years of age (it only had 60,000 miles on it but the shocks were definitely gone).

  • avatar

    Another cool thing Monroe sells is the QuickStrut. A prepackaged strut,spring and bearing assembly. Great for the DIYer afraid of shaky spring compressors and often on old cars the spring and bearing is worn out as well.

  • avatar

    When I bought Detroit Iron I used to replace the rear shocks with Monroe’s air shocks as soon as I could. They are a great idea and work well. Not sure if my import minivan has shocks or not, but I will keep an eye on them and see how well it pulls my 2k trailer. May need to upgrade to a heavier strut/shock if the tail end drags down.

  • avatar

    In times like these, folks keep their cars longer (just ask Comrade Fidel’s oppressed masses of loyal subjects).
    That’s actually one of the side benefits of Cuba: if you’re an old-car nut, there’s piles of well-kept pre-Castro American iron running day-in, day-out.  I have a friend down there who drives taxis, and while he swears by the current (Korean and Japanese) stuff they have now, the American cars from the 50s, even hacked to run on cane alcohol and/or sporting the engine from a Mazda 323, were better than anything the Russians gave them (which invariably smoked, leaked and died within days and were real bears to keep running).  He himself has a 57 Chevrolet that was in continuous use by various family members—starting from his granddad—for years.
    I’m sure the cars aren’t particularly safe and they sure as hell aren’t fast, but they’re not pristine show-queens either, they’re daily drivers that happen to be over half a century old.  It’s really neat to see, and if I was a better writer or photographer I’d try and do something next time I go down.
    Cuba is a funny case.  I’m sure that the American marques would like to sell cars to what is probably the more stable, healthy and educated population in Latin America (outside of Costa Rica), but they can’t.  When relations with Cuba normalize, they’ve probably lost the market already, which is unfortunate because their economy is pretty much pre-loaded with a nice, healthy, educated population that’s just starving for commerce.
    And yet you can trade freely with China and Russia.  Weird.

  • avatar

    Monroe’s are fine replacements for your average mom-mobile, or a beater that needs to get through one more year of college, but that’s about it.  As far as replacement dampers are concerned, there are only three names to consider if you are a true hoon:


    I had a set of Tokico Blues in a Mazda MX-6.  Around the curves, that car would give a 3  Series a run for it’s money.

    • 0 avatar

      All too expensive, especially Konis
      KYB, good and cheap for handling
      Boge if you want your European car to have the same ride it came out of the factory with.

    • 0 avatar

      skor:  I concur.  Monroe went downhill in my opinion when they came out with the Sensitrac…way too ride biased.  Even my station car has adjustable Konis; I have the “Blues” in my Probe GT.  Would have went Koni there too, but they were not available.
      That said, the Monroes are still much better than what comes on cars like CVs.  Anybody who can ride on an overly softly sprung car with dampers that are 90K past replacement probably would not appreciate the real value that comes with truly premium dampers.  But, to each his own.  The smart way to go Monroe on the cheap is to buy them on sale and install them when the factory item has past its life.  Most full size Fords of that era will show signs of damper degradation at 60K or so, at least on Northeast roads.  Keep the receipt and get free replacements every 60K.  I did that in the years past.  Last set was the then-new Sensitracs…that’s how I know first hand that they went soft.

    • 0 avatar

      In my experience, Tokico’s can be had pretty reasonably, but KYB’s are even cheaper. Having said that, the jury is still out whether KYB’s are as durable.

      Of course, either is in the $250-$350 range for all 4 wheels…considerably more expensive than Monroes. But, compared to the cost of labor, or time, if you are doing it yourself, the price might be justified.

      I didn’t consider Monroe on my last job. If I recall, I could only find the “Quick-strut” and I wanted to change the springs to something a bit stiffer and lower. The stock springs on my Avalon were wayyyy too soft and sagged ridiculously in 10 years (wonder if the previous owner used to haul bricks in the back.) I went with Vogtland….German manufactured, heat treated progressive springs with about 1.5″ lower ride height.

  • avatar

    hip-hop-video-starring 140 PSI. (But avoid extended use above 90 PSI, Monroe says, implying, perhaps, that you should only go higher for occasional heavy loads or drive-by shootings.)

    Not sure about your ‘hood, but the look is generally the front way up in the air with the rear end draggin’. Tho most of the Donks, Boxes and Bubbles I’ve seen are jacked up all the way ’round to hold the 24s…

     All that aside, great article. It is amazing the transformation that a new set of shocks will perform on an older ride. I put a set of the Monroes on my old shop van and it was orders of magintude better. (And they didn’t fail even after I filled the poor thing with rock, fully bottoming it out, and then left it sit for 6 months. Amazing.) 

  • avatar

    I’m not surprised the new shocks didn’t do anything to stop nosedive in hard braking.  If you want to significantly reduce the nosedive you need to change your spring rate.  I had a GMC fullsize van that had terrible nosedive.  Installed some shocks that had integral “helper” coil springs on the outside.  That fixed it.
    Nobody has mentioned KYB shocks yet.  From what I’ve read, KYB gas-a-justs are considered better than Monroes but not as good as Bilsteins.
    Our ’78 Olds has aftermarket air shocks in the back with an onboard air pump and an under-dash panel with pressure gauge and controls to raise or lower the pressure.  The pump and control unit came as a kit.

  • avatar

    The mention of reduced body roll and nosedive in this review
    indicates the lack of understanding on the authors part of the
    function of dampers. However the air shocks do act like a secondary
    spring so there is some stiffening effect.

    Also the discussion of braking is irrelevant, braking is almost entirely a function of the tires, there is nothing to do with shocks here.

    If you want to review shocks, you should spend some time on the Google learning what a shock does first.

    The rest of the review referring to ride quality and towing is very useful.

  • avatar
    Don Gammill

    @ Power6:  Saying that nosedive, braking, and body roll are not affected by dampers is a complete misconception.

    Yes, the primary component controling these motions is the spring, but dampers, be they shocks or struts, help control the rate at which the spring instantaneously compresses and expands, effectively attenuating the degree to which it is able to do its job.

    Find any 70′s land yacht with OE-spec shocks and then replace them with a set of stiff, heavy-duty Bilstiens.  Then come back and tell me that front-end dive, body roll, and braking aren’t affected by shocks.

    • 0 avatar

      but dampers, be they shocks or struts, help control the rate at which the spring instantaneously compresses and expands, effectively attenuating the degree to which it is able to do its job.

      I think we are talking about two different things, the dampers do control transtional behavior, i.e. body roll or nose dive rate during transition. It is certainly not technically correct to say damping affects body roll or nosedive in steady state cornering or braking, but if that is how it feels due to transitional behavior, then I am fine with that.

      I just felt the review offered up some objective data with no testing to back it up. Subjective review is fine. If you want to say “braking feels more stable” with new shocks I would probably agree with that. To say braking is better I think is weak without doing testing. I went back again and you didn’t say that braking was better, so my bad I realize you were talking more about feel than numbers.

  • avatar

    I’ve only bought Monroe Sensa-trac and Max-air shocks and struts as oem replacements.  I’ve never had to replace the Monroe’s.

    I put the air shocks on the back of a ’79 Impala station wagon that saw frequent use carrying heavy loads on logging roads.  For highway driving, I found the shocks made body roll worse.  My theory was that the air lines connected both sides, and the cornerning forces would move air from the side with more pressure on it (outside wheel) to the one with less pressure on it (inside wheel).  This would tend to result in worse body roll than non-air shocks.
    My solution was to discard the “T”, separate the lines for the two sides and have two valves to add air to the shocks.  I used the licence plate bolt holes for this, so it ended up fairly neat.  Of course, you had to use a tire guage to make sure the two sides had equal pressure.

  • avatar

    Also the discussion of braking is irrelevant, braking is almost entirely a function of the tires, there is nothing to do with shocks here.

    Don, You’re 100% correct. 

    Just to deal with the other bit of misinformation from power6… Braking is a function of the entire wheel and suspension system. Shocks and springs manage the contact between the tire and the road surface. If your alignment is off, braking will suffer. If your shocks are shot, your tire may bounce off the frickin’ ground when you brake. Too much nosedive too quickly will cause the weight shift to shift forward more than stock, which stresses said tires and brakes.

    • 0 avatar

      OK I will give you that if the tire is not in contact with the ground during braking that is a problem, but I have never seen a shock that bad, but I suppose it is possible. I suppose alignment has an effect, but only something that affects contact patch like static camber. Can’t see how toe or caster affects contact patch friction, care to explain that one?

      But you are picking nits, the fact is stopping a car is friction between tires and surface, everything else is a minor detail.

      You were doing ok until your last sentence…Too much nosedive too quickly will cause the weight shift to shift forward more than stock…If you think spring stiffness determines amount of weight transfer, you need to go back to suspension 101. I will grant you that thinking so is a common misconception.

      Edit: Here is a link for you to read about suspension and weight transfer, explains it much better than I possibly could:

  • avatar
    John Horner

    I recently helped a friend install Sensa-Tracs all around to replace the very worn original shocks on an older Toyota 4Runner. The improvement in ride and handling was very noticeable. They seem to be an excellent shock absorber considering the relatively bargain price they can be found for. Sure they aren’t in Koni or Bilstein territory, but there is no way my friend was going to put $600 or more worth of dampers on an old 4Runner.
    In real world use shock absorbers do have some effect on braking because they control the rate of weight transfer during brake application. The extreme case would be a full on panic stop in an ABS equipped vehicle.

    • 0 avatar

      I recently helped a friend install Sensa-Tracs all around to replace the very worn original shocks on an older Toyota 4Runner. The improvement in ride and handling was very noticeable.
      Seconding this.  I put Sensa-Tracs at all four corners of my genI 4Runner and wished I’d done so sooner.  Granted, the truck  already had over 120K on it when I bought it…

  • avatar

    I installed four Monroe Sensa-Tracs on my ’04 Scion Xb, at about 30K miles from new (it rode pretty hard from the factory).  Definitely softened the ride but certainly didn’t corner as well.
    The front pair failed well before another 50K miles.  They do have a lifetime warranty though.  I don’t know if this had to do with the durability of the shocks themselves, or the fit to that specific model (the Scion was a brand new model when I had them installed).

  • avatar
    Sammy Hagar

    I recently did the rotors, pads & bearings on my ’98 Ranger and, since I had everything off, I went ahead and replaced the original shocks (108K miles) with super-el-cheapo Monroe Gas-Matic LT’s ($28/pair).  Not the same as the Sensa-Tracs, but I’m pretty happy with these…especially at that price point and relative to the number of miles this truck gets driven (<3500 per year).  It was a total surprise as to how easy it was to do the brakes and shocks;  maybe 4 hours total and this was the first time I’ve ever done a brake job.  Parts were from a local chain and were less than $250 (and $50 of that was for an upgrade to ceramic pads…could have went w/semi-metallic for $20);  compare that with a shop (>$500) and I’m a total convert now to doing my own brakes from this point forward.  It’s like with oil changes…you can spend $35 for bulk oil and mystery filter (or worse, $50+ at a dealer) or you can get a decent synthetic and filter for $25 and do it yourself.
    BTW Don:  Please keep these reviews coming…they’re becoming my favorite posts on TTAC.

  • avatar

    “You were doing ok until your last sentence…Too much nosedive too quickly will cause the weight shift to shift forward more than stock…If you think spring stiffness determines amount of weight transfer, you need to go back to suspension 101. I will grant you that thinking so is a common misconception.”

    Oops. Missed the second ‘quickly’ when I re-read. It goes in between ‘more’ and ‘than’.
    Mea Culpa. Spring rates most definately effect the rate of weight transfer. They might not cover that in 101.  

    As to being nitpicky,  3 or 4 little nitpicky things slightly out of spec will add up to noticeably diminished performance.  If  you’ve never seen a shock worn to the point of failure, or one that has failed,  you lead a charmed life.

    As far as toe and camber and such affecting braking,  slightly off settings are not going to double the braking distance.  Does it matter a lot? No.  But it does matter.

    If you’re going to PRI this year, we can meet up and I’ll introduce you to some F1 guys. They can rattle off the numbers and formulae much quicker than I and have the telem to back it up.  

  • avatar
    also Tom

    I have a set of Sensatracs on my B4000 pick-up. It was a big POS before I put them on. Now it’s a big POS with an improved ride.

  • avatar

    Great article.  As I clicked, I thought “what  are the chances this is for a Grand Marquis?’  Boom, it’s for a Grand Marquis.  Mine is getting ready to turn 100K.  It was silky smooth when I bought it…now it’s a bit harsh.  So I’m thinking it’s time.  So at least for me, your post was very timely.
    I really don’t care much about the handling, not in this baby.  I’m all about big detroit smooth ride.  I don’t even care if there is wallow.  Can you help a brother out?  What is the best (read softest) shock out there I can get, that will just about rock my tired ass to sleep?  I want to smoke a cigar, listen to some Mel Torme (not really), ease the seat back, and crooooooooooooooooze on down the highway.
    Thanks in advance…

  • avatar
    johnny ro

    i put NAPA shocks on my Mom’s 2001 protege. I think they were Monroes, configured as struts. Also got new upper mounts and a small box of suspension fittings.

    It went from twitchy steering bouncy jouncy ratletrap to pretty quiet, fairly balanced handling car again. It helped that I put on new brakes all around. Front inner pads had separated from backing plate and I think were causing irregular twitchy steering by momentarily jamming and releasing on bumpy twisty roads.

    This repair was just-in-time.

  • avatar

    I installed Quick-Struts in the back of my mom’s 2002 Mercury Sable at about 50,000 miles. Both coil springs had broken, which I consider to be a Ford design flaw – they said it was due to corrosion. Luckily, the springs did not cut the tires.

    There were problems getting the single lower bolt out – both bolts broke off and I had to drill one out, and used an EZ-out on the other. There was a Monroe rebate on the struts, and it cost me only $200 for both. She had been quoted $600 to have it done at a tire shop, so I saved her $400. Hopefully, the springs on the replacements won’t break.

  • avatar

    kyb used to be a good product. now a poorly constructed, cheap product. the problem on the konis and billsteins are the limited applications and cost.  Tokico has even less coverage. for the average consumer monroe has a good product at an affordable pricing structure. thats my take. from someone who has been installing them for 25 years.

  • avatar

    I installed Monroe sensatrac shocks on my 1999 grand Marquis P/N 5993 front & 5960St rear on Mar 15, 2011 at 10142 miles. Now at 10452 miles on June 10, 2011 3 shocks are leaking & 4th doesn’t seem to be holding up on controling bounce. Admittedly they will be replaced free under warranty but if they were made better I wouldn’t have to go through this time wasting process. Anyone else had any similar bad luck with this product?

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