Spherical Bearings for Rear UCA's

JKady

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So from everything I've ever heard/read/seen LCA's with at least one end running a bearing vs a bushing is the way to go for performance. So, based on that and their fantastic reputation I'm planning on a set of Team-Z lower arms for the rear of my car. And since I'm gonna be in there I'd like to freshen up the upper arms as well. I was thinking a set of new rubber or urethane bushings on the body side and run a set of spherical "bushings" in the axle end from Team Z or SKRC. I don't see much mention on the internet of them and if they justify the cost.

And yes I know that they'll be harsher and noisier, my car is already "not a street car' by some folks' standards so I'm not really concerned with anything other than making it perform better at this point.
 

mcglsr2

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So from everything I've ever heard/read/seen LCA's with at least one end running a bearing vs a bushing is the way to go for performance. So, based on that and their fantastic reputation I'm planning on a set of Team-Z lower arms for the rear of my car. And since I'm gonna be in there I'd like to freshen up the upper arms as well. I was thinking a set of new rubber or urethane bushings on the body side and run a set of spherical "bushings" in the axle end from Team Z or SKRC. I don't see much mention on the internet of them and if they justify the cost.

And yes I know that they'll be harsher and noisier, my car is already "not a street car' by some folks' standards so I'm not really concerned with anything other than making it perform better at this point.

If that's the case, might I recommend these instead: MM Extreme duty LCA's. Spherical bushes on both ends. I currently run these, did not really notice that much increase in NVH. Or if you plan on going coilovers, then these (though you'll lose your stock sway bar mount point): MM Road Race LCA's.

As for the upper control arms, I'd suggest you use OEM rubber only, and *not* poly. On MM's replacement upper bushing page, here, these are the key reasons:
  • Never replace rear upper control arm bushings with urethane, due to induced binding, and resulting chassis damage.
  • Upper control arms must rotate and pivot with axle motion, and rubber is the only material that sufficiently allows for this twisting without chassis damage.

Of course, if you go with a T/A, you can remove the RUCA's all-together. What kind of performance are you looking for? Drag? Road Race? Street?
 

mcglsr2

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Oh, also while you are in there, if you haven't converted to SS brake lines and you want to, now's a good time. There's the 4 lines at each caliper of course, but there's one more line that goes from the chassis (under the trunk area) to the top of the pumpkin. That's rubber as well. MM sells a SS line for this (as might other companies) - you will be in that area anyway doing the RUCA's. Might as well swap that guy out as well if SS lines are a thing for you and you haven't done that one yet.
 

RichV

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Just remember, the stock setup has 8 rubber bushings. As you stiffen the bushings, all the deflection will go to the softest ones. So if you go poly or stiffer on the LCA, all the deflection is absorbed by the UCA bushings. If you go spherical on the axle bushings, everything is going into the UCA torque box bushing. When the deflection has nowhere to go, it tears up the torque box. Plus, it can cause binding.

I did a lot of research on this, I just replaced my LCA/UCA and all bushings. Decided on OEM axle bushings and the FR/MM HD UCA. When you put sticky tires on and actually use the suspension, it tears shit up. Check out what I removed:



 

DavidBoren

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Is there anything wrong with adding torque box reinforcement and going all spherical rod ends? Wouldn't that technically be the best option? If you are in the market for buying high quality parts, and performance is your goal, then why not eliminate all the deflection and turn what normally is wasted as suspension slop into forward motion? The spherical rod ends vs poly vs oem rubber has been brought up before, and someone went all spherical rod ends and tested the axle for range of motion... you still have full travel with all bearings on both ends of the upper and lower control arms. All you need to do it right is weld in readily available torque box reinforcements.
 

mcglsr2

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Just remember, the stock setup has 8 rubber bushings. As you stiffen the bushings, all the deflection will go to the softest ones. So if you go poly or stiffer on the LCA, all the deflection is absorbed by the UCA bushings. If you go spherical on the axle bushings, everything is going into the UCA torque box bushing. When the deflection has nowhere to go, it tears up the torque box. Plus, it can cause binding.

I did a lot of research on this, I just replaced my LCA/UCA and all bushings. Decided on OEM axle bushings and the FR/MM HD UCA. When you put sticky tires on and actually use the suspension, it tears shit up. Check out what I removed:

Hey RichV, I had a little trouble following that - are you saying you swapped all your RUCA & RLCA bushings to rubber ones? Or rubber for the RLCA alone?
 

DavidBoren

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I had a hard time sorting through that, as well. But I think Rich is saying he went with rubber bushings on the end of the arms that connect to the axle, or what he refers to as the axle bushings.
 

mcglsr2

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I had a hard time sorting through that, as well. But I think Rich is saying he went with rubber bushings on the end of the arms that connect to the axle, or what he refers to as the axle bushings.

Which arms, the uppers or the lowers? By axle, I assume him to mean the lowers, since the uppers "technically" connect to the diff. However, I'm making assumptions and I don't want to do that. I guess I'll wait for RichV to chime back in.
 

RichV

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Correct, stock UCA with stock bushing. And stock axle bushing. That's what I just replaced.
 

JKady

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As for the upper control arms, I'd suggest you use OEM rubber only, and *not* poly. On MM's replacement upper bushing page, here, these are the key reasons:
  • Never replace rear upper control arm bushings with urethane, due to induced binding, and resulting chassis damage.
  • Upper control arms must rotate and pivot with axle motion, and rubber is the only material that sufficiently allows for this twisting without chassis damage.

Of course, if you go with a T/A, you can remove the RUCA's all-together. What kind of performance are you looking for? Drag? Road Race? Street?

Well sphericals in the axle end would eliminate that bind and allow everything to roll easy. Street/"strip" car. Drive it 75 miles a day 4 times a week (With no a/c, radio, rear seat, carpet power windows etc... like I said, NVH is not a concern for me) for work and kick the snot out of it the rest of the time. Once I get my commuter running or get another one this car will get much more dedicated to drag racing. Staying a "stock suspension" car. I in no way doubt the quality of MM's stuff but if Dave Z can run a sub 10sec quarter on his parts I think they'll work just fine for me and they're a lot more budget friendly.

So Rich what you're saying is new rubber bushings in the uppers and a set of good solid lowers is the way to go? I plan on battle boxes ASAP to take care of any concerns with torque box strength.
 

RichV

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A straight line car can get away with a stiffer setup out back. Yes, do the torque box reinforcement because they will get hammered with launches and hard shifts. But you don't have to worry about articulation like road course does. So if the build is for the strip, I would go solid in the axle, and solid adjustable UCA so you can set the pinion angle for optimal traction.

Sorry, my brain is always in road race mode. :D
 

DavidBoren

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Why would spherical rod ends reduce articulation? With rod ends, the bolt holding the axle to the control arm can remain parallel to the axle throughout articulation, without influencing the control arm to twist. There is no way that the rubber bushings allow enough flex to keep the bolt parallel to the axle without twisting the control arms. It's just not possible for the rubber to compress enough. With a rod end, you can pivot the bolt to the point that it contacts the control arm, without the control arm twisting. You can't compress a rubber bushing to zero. Does that make sense? I could be completely off on this, and if I am, will someone please learn me up on why spherical rod ends limit articulation?


Can someone please confirm whether or not you still get complete articulation of the axle with all spherical rod ends? I can't remember who said that they had all spherical rod ends and tested the range of motion with no shocks or springs, and they said that you still have full flex with no more bind than the oem system. I just can't seem to find where I read that, but I am pretty sure that it was on this forum.
 

DavidBoren

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Yes, the upper arms would have to be capable of telescoping to match the arc of the longer lower links. But the rubber bushings don't allow enough movement to make up for this, they just lessen how much you notice when the upper links bind and jam into the chassis. The binding is still happening, and the mounting locations are still taking the full hit.

So spherical rod ends, even if installed on both ends of upper and lower control arms, are not going to induce or create a new binding situation that wasn't already there with a bone stock rubber bushingsbushing oem set-up.

Any time you have unequal length control arms, you will have bind, as they are competing against each other, trying to travel along different arcs. So if it's all but impossible to eliminate said binding, without entirely re-engineering the suspension and changing the body to accommodate new equal length links, then you might as well eliminate any and all slop in the suspension so that at least it's predictable.

Rubber bushings are in no way consistent. And consistency is predictable, predictability inspires confidence. I will gladly deal with having to reinforce the torque boxes, and a slightly harsher ride for a suspension that reacts the same way every time, all the time. It's going to bind no matter what, so I might as well be able to predict when it's going to happen and how the car handles when it does.

That's just me, though. Personally, I think the answer to all SN95 rear suspension questions is the irs swap. It's not the best irs out there by any means, but it sure beats a not the best solid rear axle suspension.
 

mcglsr2

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Yes, the upper arms would have to be capable of telescoping to match the arc of the longer lower links. But the rubber bushings don't allow enough movement to make up for this, they just lessen how much you notice when the upper links bind and jam into the chassis. The binding is still happening, and the mounting locations are still taking the full hit.

So spherical rod ends, even if installed on both ends of upper and lower control arms, are not going to induce or create a new binding situation that wasn't already there with a bone stock rubber bushingsbushing oem set-up.

Any time you have unequal length control arms, you will have bind, as they are competing against each other, trying to travel along different arcs. So if it's all but impossible to eliminate said binding, without entirely re-engineering the suspension and changing the body to accommodate new equal length links, then you might as well eliminate any and all slop in the suspension so that at least it's predictable.

Rubber bushings are in no way consistent. And consistency is predictable, predictability inspires confidence. I will gladly deal with having to reinforce the torque boxes, and a slightly harsher ride for a suspension that reacts the same way every time, all the time. It's going to bind no matter what, so I might as well be able to predict when it's going to happen and how the car handles when it does.

That's just me, though. Personally, I think the answer to all SN95 rear suspension questions is the irs swap. It's not the best irs out there by any means, but it sure beats a not the best solid rear axle suspension.

I think the concern here, that perhaps you might be missing, is this: it's a given that it's going to bind. Okay. And just so we are on the same page, binding here means that the suspension wants to move in an undesirable way, or direction that we don't want (read: undesirable way). Alright so we know this. Now, if you have rubber bush's in the UCA's, the movement that will lead to binding is somewhat absorbed in the deflection of the rubber. If the binding is severe enough, the rubber bush's alone will not stop it. They will only soften it somewhat. If the binding is not as severe, it's possible the rubber bush's will absorb all of the stress.

Okay. Now, if we change the rubber bush's in the UCA to spherical ones, they will not deflect. At all. Which means that when the binding comes, the stress does not get absorbed by any rubber bush's, and therefore whatever those spherical bush's are attached to now get the full stress of the binding. If this happens to be mounts that aren't designed for that kind of stress/angle of application, then you will distort the mount. In other words, you will damage the mount. If the mount is strong enough, but the bush happens to be weak, then the bush will distort. If the bush is strong (solid spherical), and the UCA is the weak point, *it* will distort. The point here is that without something to help absorb the binding, something else (that probably also happens to be expensive) will absorb the stress, and most likely distort/fail/break.

I think what you are missing here ultimately is that in NORMAL/DESIRABLE suspension travel, then yes, spherical bush's are super. However, due to the design of our rear suspension, in addition to NORMAL/DESIRABLE movement we also get ABNORMAL/UNDESIRABLE movement. This latter is what causes the issues with solid bush's.

The solution, obviously, is to remove the items that cause the ABNORMAL/UNDESIRABLE movement, in this case the 4-link. Swap to a torque/arm, panhard, and remove the UCA's, and run spherical bush's to your heart's content.
 

Addermk2

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Articulation through the full motion of the axle requires the UCA to shrink/contract, that's the job of the bushings since the UCA cannot really do that.

150% false. Not close, never will be.

The different lengths of the upper and lower arms create axle rotation through the arc of articulation. The necessity of the arms to be a variable length would only be justified at positions far beyond the limitations of physical space under the car.
 

RichV

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As the suspension moves, the rigid Panhard Bar causes the Mustang's rear axle to move through a different, and better path than the stock four-link design. This requires the upper arms to physically change length as the suspension moves. Obviously, the metal control arm cannot change length. But its effective length, the distance between the control arm's two pivot points, can change because of the inherent compliance of a rubber bushing. If the ability of the upper control arms to change their effective length is hindered by a noncompliant bushing material, the suspension will bind up, and not move freely. The resulting restriction in the ability of the rear suspension to freely articulate will cause poor handling; the car will have a tendency to oversteer, and it may do so in a sudden and unpredictable manner.

This is from MM's FAQ section, they are a lot smarter than I. So I'm just stating the way I understand it. Reading it again, may just be with a PHB in place, but I don't know how that would affect the UCAs.
 

Addermk2

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panhard bar specific.

As the suspension moves, the rigid Panhard Bar causes the Mustang's rear axle to move through a different... path than the stock four-link design.
 

JGcoupe

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OP:
Team Z can tell you what you need for your application and goals. In my opinion, anything is better than stock when it comes to performance. What type of performance your after is the real question.
 

wmfateam

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I have allllll spherical in the back. Absolutely love the feeling and how easily it is to rotate through corners. Zero bind. I'm hoping to get video of the back tomorrow, but it is supposed to rain. Hooray for first track day in the rain.
 

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