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  1. #1

    Default I Need New Shock Absorbers...

    I need new heavy duty coil-over rear shock absorbers for my 1980 Fairmont Sedan. For many years I've purchased and installed 'Monroe Sensa-Trac Load Adjusting Coil-Over Shock Absorbers' part number 58428. (see attached)

    http://www.monroe.com/en-US/e-catalog/58428/

    However these shock absorbers are apparently now obsolete and I haven't been able to find them anywhere. I tried 'Bilstein' also but no luck there either. Does anybody have a good part number and brand name for a heavy duty coil-over rear shock absorber for a Fox Chassis Ford (something that will fit my application)?

    I'm a little surprised and very disappointed that the Monroe shocks that I've been using all these years are no longer available...
    Current Fox Fleet
    '82 Zephyr GS Two Door 3.3
    '80 Zephyr Sedan 3.3
    '80 Fairmont Sedan 3.3
    '81 Fairmont Sedan 5.0
    '86 Mustang LX 4.2

  2. #2

    Default

    We have several different shocks and coilover kits that will work in that application.

    Do you have any idea what the spring rate on the Monroe shocks was?
    Jack Hidley
    Maximum Motorsports Tech Support

  3. #3

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    Quote Originally Posted by Jack Hidley View Post
    We have several different shocks and coilover kits that will work in that application.

    Do you have any idea what the spring rate on the Monroe shocks was?
    Thanks for the reply. It is most appreciated.

    But no, I don't know what the spring rate on the Monroe shocks are. The Monroe website doesn't tell us and I wouldn't know how to determine that otherwise. Can you post a link to show me the type of kits that you're talking about? Would it be possible to use one of your 'kits' to remount the old spring onto a new shock absorber?

    Reusing the old spring on a new shock absorber was something that I had already considered doing but I hadn't yet figured out the best way to do that. I use the coil-over shocks because I often tow a small utility trailer with this car. The car is a sedan but it has station wagon rear springs. The max tongue weight on my trailer hitch is 200LBS...
    Current Fox Fleet
    '82 Zephyr GS Two Door 3.3
    '80 Zephyr Sedan 3.3
    '80 Fairmont Sedan 3.3
    '81 Fairmont Sedan 5.0
    '86 Mustang LX 4.2

  4. #4
    FEP Senior Member Patrick Olsen's Avatar
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    I searched for the part number (Monroe 58428.) on rockauto.com. The Parts Search did find that part number, but showed it as out of stock (as you said). When you click on the part number, it'll show you what make/model/year applications use that part number. You can also click the "Info" button to find out specs, including extended and compressed length. That info page shows "Spring Rate: 28" for the Monroe 58428. No dimensions there, but presumably that's 28lb/in?

    Looking through the Suspension - Shock Absorber listings for a couple of the other make/model/years listed, I see that there are some air lift setups - Monroe MA810 and Gabriel 49199 or 49196. The Gabriel 49196 looks too long - it's extended length is 3" longer - but the MA810 and 49196 both match up pretty well dimensionally to the Monroe 58428.

    Interestingly enough, Rock Auto shows that the full-size LTD used essentially the same rear shock absorber setup - the Applications list for the Monroe 58428 shows the '83-86 LTD Crown Victoria. So I went to the '85 LTD and found Monroe 550051 for the "Rear; Crown Victoria; w/ Police Package; For Towing and Hauling". It doesn't list the spring rate, but the dimensions look about right.

    Digging even further, if I click on the 550051 part number, it shows it fits the '83-86 LTD Crown Vic and the '93-02 Crown Vic. OK, so let's look at a later gen car. I pulled up the shocks for a '98 Crown Vic and in addition to the Monroe 550051 ("Rear; Police Interceptor; For Towing & Hauling") there's also a Monroe 58568 ("Rear; Base Model; LX Model; S Model; w/o Touring Suspension"). 19-7/8" extended length vs the 20-3/8" of the Monroe 58428, variable rate spring (looks like maybe it's a higher rate spring?).

    If you really want to dive into the rabbit hole, click on the part number for one of the "normal" (non-coilover) rear shocks, like the Motorcraft ASHV9 or Bilstein 24184755. That application list comes up with a bunch of classic, RWD solid axle cars - you could start digging through those to see if you find other coil-over options in addition to what I've come across so far.
    Last edited by Patrick Olsen; 04-12-2019 at 08:48 AM.
    '89 GT convertible - not a four-eye
    '82 Zephyr Z7 - future track car

  5. #5

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    @ Patrick Olsen

    Many thanks for that load of info! You've been most helpful!

    I am now considering (based on the information that you've provided) going with the Monroe 550051. It seems to be a pretty close match to the obsolete Monroe 58428. I also like the idea that the Monroe 550051 was for a heavier car. I do quite a bit of hauling with my Ford Fairmont.

    The Monroe 550051 is 1/3 of an inch shorter than the Monroe 58428 which I'm using now. I guessing that that shouldn't really make much difference...should it???

    (Also, it appears that the Monroe 550051 dimensions are very close to the shocks that the Monroe website shows fitting a 1980 Ford Fairmont
    http://www.monroe.com/en-US/e-catalog)
    Last edited by Autolite; 04-12-2019 at 02:27 PM.
    Current Fox Fleet
    '82 Zephyr GS Two Door 3.3
    '80 Zephyr Sedan 3.3
    '80 Fairmont Sedan 3.3
    '81 Fairmont Sedan 5.0
    '86 Mustang LX 4.2

  6. #6
    FEP Super Member gr79's Avatar
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    Could call or email them see what they say:

    http://www.monroe.com/en-US/resource.../contact-info/

    1-734-384-7809
    8:30 a.m. - 5:30 p.m. EST M-F

  7. #7

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    Quote Originally Posted by gr79 View Post
    Could call or email them see what they say:

    http://www.monroe.com/en-US/resource.../contact-info/

    1-734-384-7809
    8:30 a.m. - 5:30 p.m. EST M-F
    Actually I had already emailed Monroe. They told me that the shocks that I had initially wanted ( Monroe 58428 ) were obsolete and that they couldn't help me. I now have my local parts jobber trying to hunt down a pair of Monroe 550051 shocks. With all the information that Patrick Olsen provided me, it looks like the Monroe 550051 should work. The 550051 shock is almost the same size as the obsolete 58428 shock but it is just meant for a bigger and heavier car. Even the mounting hardware is the same.

    Being that the two shocks are for two different applications, I really doubt that Monroe would say that they are interchangeable even if they in fact are...
    Current Fox Fleet
    '82 Zephyr GS Two Door 3.3
    '80 Zephyr Sedan 3.3
    '80 Fairmont Sedan 3.3
    '81 Fairmont Sedan 5.0
    '86 Mustang LX 4.2

  8. #8

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    Autolite,

    I think it would help a lot if you told people what problem you are trying to fix here with the coilover shocks.

    If you trying to make it so you can drive the car with a trailer behind it and not have the rear ride height get so low, then installing some RLCAs with adjustable height lower spring perches is an easy fix. When you attach the trailer, just use a ratchet to raise the back of the car up.

    https://www.maximummotorsports.com/S...998-P1492.aspx
    Jack Hidley
    Maximum Motorsports Tech Support

  9. #9

    Default

    Quote Originally Posted by Jack Hidley View Post
    Autolite,

    I think it would help a lot if you told people what problem you are trying to fix here with the coilover shocks.

    If you trying to make it so you can drive the car with a trailer behind it and not have the rear ride height get so low, then installing some RLCAs with adjustable height lower spring perches is an easy fix. When you attach the trailer, just use a ratchet to raise the back of the car up.

    https://www.maximummotorsports.com/S...998-P1492.aspx
    Maintaining a decent ride height while hauling a load is indeed the goal. And I found that I was able to do that with those Monroe coil-over shocks that I had been using all these years. But thank you for your help, the link and the additional info. It's really good to know that there are other options...

    (BTW, I found out many years ago that the length of the RLCAs varies between the different Fox Fords. I believe that the Mustang has shorter arms than the Fairmont. What would be the reason for that?)
    Last edited by Autolite; 04-13-2019 at 08:52 AM.
    Current Fox Fleet
    '82 Zephyr GS Two Door 3.3
    '80 Zephyr Sedan 3.3
    '80 Fairmont Sedan 3.3
    '81 Fairmont Sedan 5.0
    '86 Mustang LX 4.2

  10. #10

    Default

    Thunderbird, Cougar and Lincoln Mark VII RLCAs are 0.39" longer than Mustang RLCAs. The reason is that these cars are designed to have a softer suspension than a Mustang, so they need to have more total travel. When you increase the total travel of the suspension, you need to make the RLCA longer so that the tire doesn't move too much fore/aft as the suspension moves up/down.

    All other Fox chassis cars use Mustang length RLCAs.
    Jack Hidley
    Maximum Motorsports Tech Support

  11. #11
    FEP Senior Member Patrick Olsen's Avatar
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    Default

    Glad I could help, Autolite. Sometimes it's intriguing to dig around the parts search engine and see what one can find.

    I was thinking maybe one of the air spring options would be better - that way you could air 'em up when you've got the trailer on there, and bleed 'em down when you don't need the extra help. I've never had such air springs, but the Gabriel listings say "• Easy to inflate at any service station, at home with an air compressor or with continued use of an existing onboard air management system", which makes it sound like it would be pretty easy to do.

    Anyway, keep us updated when you get the new parts installed.

  12. #12
    FEP Super Member gr79's Avatar
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    Default

    Alternatives:
    Monroe air shocks
    Air Lift brand inserts

  13. #13

    Default

    Quote Originally Posted by Jack Hidley View Post
    Thunderbird, Cougar and Lincoln Mark VII RLCAs are 0.39" longer than Mustang RLCAs. The reason is that these cars are designed to have a softer suspension than a Mustang, so they need to have more total travel. When you increase the total travel of the suspension, you need to make the RLCA longer so that the tire doesn't move too much fore/aft as the suspension moves up/down.

    All other Fox chassis cars use Mustang length RLCAs.
    Thanks for that info. I thought that it might have something to do with the ride and/or the weight of the vehicle but I just wasn't sure how the length made a difference...
    Current Fox Fleet
    '82 Zephyr GS Two Door 3.3
    '80 Zephyr Sedan 3.3
    '80 Fairmont Sedan 3.3
    '81 Fairmont Sedan 5.0
    '86 Mustang LX 4.2

  14. #14

    Default

    Quote Originally Posted by Patrick Olsen View Post
    Glad I could help, Autolite. Sometimes it's intriguing to dig around the parts search engine and see what one can find.

    Anyway, keep us updated when you get the new parts installed.
    I'm still waiting to hear back from my local parts jobber on the Monroe 550051 shocks that I'm wanting to get. I'm in Canada and finding this stuff can sometimes be a real bother. In the meantime, I have installed a serviceable pair of used Monroe 58428 shocks that I had removed from one of my wrecks. That'll have to do until they can find me the new Monroe 550051 shocks.

    Again, many sincere thanks to you and the others for all the help. It is much appreciated...
    Current Fox Fleet
    '82 Zephyr GS Two Door 3.3
    '80 Zephyr Sedan 3.3
    '80 Fairmont Sedan 3.3
    '81 Fairmont Sedan 5.0
    '86 Mustang LX 4.2

  15. #15

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    I have a 1986 LTD Crown Victoria that I'm shopping for rear shocks for.
    The Motorcraft shocks for the Panther chassis are the same as the Fox chassis part number.
    Monroe shows a 58568 which looks EXTREMELY similar to the 58428 you posted at the top.

    Jack: Bilstein question. I have a pair of used 2003 Cobra IRS Bilsteins that I'm not using (because I have the MM coilover Bilstein set for the Zephyr IRS).
    The IRS Bilsteins have the extension above the lower mounting eye, to clear the control arm; but otherwise the mounting and lengths are pretty close to the solid axle shocks.
    Can the IRS Bilstein be used in the Fox (or in my case, Panther) rear? The Panther of course is much heavier, and I do use mine for towing and more than an occasional trunk full of automotive or construction supplies. I have a new set of Bilsteins on the front as well.

    They're free, so I might just try it and see. I want the sag and sog out of the suspension; it's no performance car and I just want to be able to take corners without getting seasick.

  16. #16

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    The Mustang IRS shocks won't work in a solid axle application.

    The lower eyelet is setup for a 14mm bolt, not a 12mm bolt.

    The IRS shocks only have 5.4" of travel. SN95 Mustang solid axle shocks have 7.3" of travel.

    Because the IRS shocks are mounted inboard on the LCA, the low motion ratio requires that they have twice the overall damping of a solid axle shock. In addition because the IRS has 100lbs less unsprung mass than the solid axle, the amount of compression damping is much less and wouldn't work with a solid axle application.
    Jack Hidley
    Maximum Motorsports Tech Support

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