BMR Poly UCA without the mount

Discussion in '2005+ Mustang GT 4.6L Tech' started by Macman45, Apr 8, 2020.

  1. Macman45

    Macman45 Resident Geriatric

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    Time to do the Poly UCA after doing the poly LCAs and I really wanna cheap out and not get the mount. Am I in for hella clunks? I read something about the stock mount having elongated holes so the BMR unit flops around, but UPR UPA's include some sleeves for this, BMR does not. The BMR unit is $70, UPR's is $120, and the damn mount is $150. Anyone upgrade just their UCA to poly? Thanks
     
  2. RED09GT

    RED09GT Senior Member S197 Team Member

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    With the correct inserts, it should work for stopping the clunk. I have the BMR adjustable and I have a UMI mount.
    The stock mount looks plenty strong, it is mostly the hole size that is the issue.
    One thing that you can do is go to the 2011+ mount and control arm and get the slightly improved geometry if you did want to go with the BMR. I have no idea how much of a difference it makes.
     
    Last edited: Apr 9, 2020
  3. bl817

    bl817 Member

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  4. 1950StangJump$

    1950StangJump$ forum member

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    For what it's worth, BMR told me over the phone that clunks are common if you try and use their UCA with the stock mount. The logic, as it was explained to me, is that they have two different flex rates. The new UCA is going to be stiffer and cause the stock mount to flex more than designed. That flex results in unintended consequences.

    Is it BS? I don't know. But, I know doing the UCA is a PITA, so paying for the mount was worth it to minimize the chance I would have to do it again.
     
  5. Macman45

    Macman45 Resident Geriatric

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    I think the flex is BS. I think the clunk is coming from the elongated holes and it’s actually moving, not flexing. I wonder about the sleeves working.

    you’re right but damn $150 for a little bracket is steep.
     
  6. Norm Peterson

    Norm Peterson corner barstool sitter

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    Gotta ask these questions first - is there anything about the OE UCA that's not meeting your expectations? Such as the UCA being step 2 in an attempt to eliminate wheel hop (where the LCAs were step 1)?


    Clunking of any polyurethane-bushed LCA or UCA can appear to be caused by too much bolt to hole clearance, but there is a fix that should cure the problem with the parts that you already have.

    Make sure that the inner sleeve that runs through the poly is longer than the poly. That way, all of your installation torque goes into clamping the sleeves inside their respective brackets and you aren't compressing the poly at all.

    When the poly is longer than the sleeves, and you add acceleration or braking force and get any vertical suspension movement, the suspension movement causes rotation of the poly inside the bracket (has to, else the suspension wouldn't be moving) and the fore-aft force then has an easy time making the bolt bottom out on one or the other sides of the holes. IOW, clunk.

    A pleasant side effect of sanding the length of each piece of poly down to be a tiny bit shorter than its sleeve is that you won't get nearly as much squeaking or have to do anywhere near as much re-lubing.


    Norm
     
  7. Macman45

    Macman45 Resident Geriatric

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    Excellent advice, thank you norm. Hadn't thought about shaving down the poly to ensure it was all metal to metal. That wont slide on each acceleration. And I dont really even have that bad of wheel hop but figured I have Poly LCAs I should have a Poly upper, its mismatched and forces more give on the remaining rubber (my logic anyways)
     
  8. Macman45

    Macman45 Resident Geriatric

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    Last question, is there ANY way I can do this without lowering the tank? I see mixed reviews, and if keeping the OEM mount, I thought maybe.
     
  9. Norm Peterson

    Norm Peterson corner barstool sitter

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    The polyurethane mod should work no matter where either the poly-bushed arm or the bracket was sourced from. Meaning that you could do the same thing to the LCA bushings.

    While you're at it, you might shape the flat ends of the poly into flat cones like this . . .

    Poly Bushing Mod.jpg

    If you're really serious about minimizing 'bind' (such as for road course driving) there's another trick you can try (not sure I've drawn a sketch of that one yet). This additional mod would be more applicable to the UCA, not so much to the LCAs. It involves a little drilling in certain places, and some care to avoid drilling too deep.

    There is an advantage to swapping the both the arm and the bracket up to the later arm & bracket. The arm is about an inch longer, and the rear suspension's side view geometry remains a bit more consistent throughout its travel as a result. Something else you probably need to be more serious about than most folks.​


    Norm
     
    Last edited: Apr 9, 2020
  10. 1950StangJump$

    1950StangJump$ forum member

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    Yea, lots of mixed messages on that, which frustrated me too.

    For the 05-09 models, you have to lower the tank. In later S197 models, the tank had extra space so you didn't have to.

    I'm only 90% sure the changeover occurred in 2010. Might be plus or minus a year.
     
  11. GlassTop09

    GlassTop09 Member

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    Why Norm.....are you mentioning to drill the solid poly UCA bushing to allow the UCA to allow the rear axle to articulate better at the bracket end of the UCA thru any body roll?
    The longer 2011+ UCA arm w\ it's matching bracket is to reduce pinion angle deflection during vertical rear end suspension travel vs the OEM unit, correct?
     
  12. WNYGT5-0

    WNYGT5-0 Member

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    I’ve no problems getting the UCA out and back in with the tank installed.
     
  13. RED09GT

    RED09GT Senior Member S197 Team Member

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    Agreed. I have even been able to adjust the upper control arm in-situ.
    The mount is the tough part, I remember having to run out and buy the correct torx socket for the gas tank straps. Cross threaded the stupid bolt putting it back in and had to replace it with a standard hex bolt.
     
  14. Macman45

    Macman45 Resident Geriatric

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    You're talking just remove and reinstall the UCA into the stock mount with the tank in place on 05-09? If im using sleeves and filing down the Poly I feel like that could work
     
  15. ghunt81

    ghunt81 New parts on old junk! S197 Team Member

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    I dropped my tank a few inches to install my mount but I don't see any reason to have to drop the tank just to do the UCA. You have to drop the tank for the mount because the front mount bolt is above the gas tank and you can't work the mount out without lowering the tank a little.
     
  16. bl817

    bl817 Member

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    OP, do you plan on addressing the upper differential bushing as well because all you keep referencing the poly UCA and its mount. the upper diff bushing is likely shot by this point and needs replaced as well. IMHO I would go with a poly insert as trying to get the stock one in there is a big PITA. not saying gutting the old one is much easier but it is, you just have to use the metal sleeve and gut the old rubber out.
     
  17. Laga

    Laga Member

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    I was able to install and adjust the UCA with the tank I place. Not easy, but it can be done.
     
  18. Norm Peterson

    Norm Peterson corner barstool sitter

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    I'd seriously consider replacing those non-standard Torx things with either hex-head or socket-head cap screws from the get-go.

    Memo to self here.


    Norm
     
  19. Norm Peterson

    Norm Peterson corner barstool sitter

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    Something like that. I did this for the LCAs on a 1979 Chevy Malibu (triangulated 4-link rear suspension much like the Fox/SN95).

    I haven't worked out the details for any S197 application yet, other than you probably don't need or want to drill any more than a quarter of the way in from each end in order to release a significant amount of 'bind'. Drill bit size and the number and orientation of holes as seen in side view are still up in the air.

    Poly Bushing Mod 2.jpg



    Yes, the amount of pinion angle change is reduced, and I'm pretty sure that SVIC (commonly known as simply "instant center") migration is reduced as well.


    Norm
     
    Last edited: Apr 10, 2020
  20. WNYGT5-0

    WNYGT5-0 Member

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    At Full Droop... you do not need to monkey with the tank at all. The UCA and the mount will come out and go back in. Piece of chocolate cheesecake. Here taking tank straps off means replacing them.
     
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