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LCAs: Rotos on both ends, or Roto/Poly combo?

This is a discussion on LCAs: Rotos on both ends, or Roto/Poly combo? within the Suspension and Handling forums, part of the General Help category; I'm trying to decide between picking up the UMI LCAs with roto-joints, but I'm at an impasse. I currently have ...

  1. #1
    Senior Member Naaman's Avatar
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    LCAs: Rotos on both ends, or Roto/Poly combo?

    I'm trying to decide between picking up the UMI LCAs with roto-joints, but I'm at an impasse.

    I currently have some adjustable LCAs with rod-ends, which, I suppose are the "best" for performance. However, I do not like the noise they transfer into the passenger compartment. I have never driven the car with "regular" LCAs on it, so I do not have a basis for a performance comparison.

    Right now, my car is in for service and I'm looking at having the LCAs replaced. The two options I'm looking at are the roto/poly option from UMI and the roto/roto option. From other correspondence I've had with UMI, it seems that the rotos will transfer some noise into the cabin, but, not as much, I guess. However, the roto/poly option seems (from its description) to be intended specifically to reduce noise/shock transfer.

    What I cannot wrap my head around is what the benefit of roto-joints (or rod-ends) is on both ends of the LCA, if only the rear end needs to move.

    Both the roto and rod-end allow for 28 degrees of movement. If each end allows this movement, does that mean that a total of 56 degrees is possible? And if so, what is the benefit of rotating more than the 28 degrees provided by the one ended roto/rod-end?

    In other words, what would I be giving up by installing an LCA with only one end capable of rotation?

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    With joints on both ends you generally do not have to remove the component to adjust its length. Loosen both jam nuts and then turn the component to shorten or lengthen it. I run UMI non-adjustable LCA's and panhard in our car and have had zero issue or noise from them. On the other hand, the tunnel mount torque arm is a noisy SOB... but it sure does help the car hook.

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    Spaz is My Mentor SMWS6TA's Avatar
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    Roto-joints for straight line track use or normal driving = not so much benefit. However if you are into autoX or road courses the roto-joints articulation help keep the power planted as you go through the corners better then just poly regular LCA's. As you corner with non-roto LCA's there is a point that the car will lift the inside wheel of the turn simple because the LCA joints can't move as far as roto-joints do. Think of it like the difference between OEM shocks vs Koni's. They are both shocks but one is engineer to be so much better.



    I have the roto-joint at the axle and poly at the body from UMI. I have to say corner handling has greatly improved over the stock. I have a off ramp that not only is it 180* u -turn, it also descends. Prior to the suspension upgrades I had to slow down to around 40mph. After the suspension upgrades* I can hit it @50-55mph and not even squeal a tire. Not something I do regularly but I know I can. And as far as road noise...honestly I can't hear anything with the tops down, radio & headers.


    * - The suspension upgrades were UMI's:

    Part# 2001 Weld in SFC's
    Part# 2205 Adjustable Torque Arm, Full Length
    Part #2207 Transmission Cross-member with TA Relocation
    Part# 2039 LCA's Single Adjustable w/Roto-joint
    Part# 2037 Panhard Bar, Single Adjustable
    Part # 2005 Tower Strut Brace

    Also Hotchkis 1" Drop Springs

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    Senior Member Naaman's Avatar
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    Quote Originally Posted by pajeff02 View Post
    With joints on both ends you generally do not have to remove the component to adjust its length. Loosen both jam nuts and then turn the component to shorten or lengthen it. I run UMI non-adjustable LCA's and panhard in our car and have had zero issue or noise from them. On the other hand, the tunnel mount torque arm is a noisy SOB... but it sure does help the car hook.
    Okay. So, there is no performance lost between a single-end rotating and a dual-end rotating? If so, my choice is easy!

    Quote Originally Posted by SMWS6TA View Post
    Roto-joints for straight line track use or normal driving = not so much benefit. However if you are into autoX or road courses the roto-joints articulation help keep the power planted as you go through the corners better then just poly regular LCA's. As you corner with non-roto LCA's there is a point that the car will lift the inside wheel of the turn simple because the LCA joints can't move as far as roto-joints do. Think of it like the difference between OEM shocks vs Koni's. They are both shocks but one is engineer to be so much better.

    I have the roto-joint at the axle and poly at the body from UMI. I have to say corner handling has greatly improved over the stock. I have a off ramp that not only is it 180* u -turn, it also descends. Prior to the suspension upgrades I had to slow down to around 40mph. After the suspension upgrades* I can hit it @50-55mph and not even squeal a tire. Not something I do regularly but I know I can. And as far as road noise...honestly I can't hear anything with the tops down, radio & headers.


    * - The suspension upgrades were UMI's:

    Part# 2001 Weld in SFC's
    Part# 2205 Adjustable Torque Arm, Full Length
    Part #2207 Transmission Cross-member with TA Relocation
    Part# 2039 LCA's Single Adjustable w/Roto-joint
    Part# 2037 Panhard Bar, Single Adjustable
    Part # 2005 Tower Strut Brace

    Also Hotchkis 1" Drop Springs
    I'm not much into drag racing, but I do like to carve out a canyon every chance I get, so I definitely want as much handling as I can afford. But eliminating the clunking noise would also be a bonus, especially if it does not come at the expense of performance. Your suspension list is similar to mine, but I do not have a cross member or a torque arm... but I do have Strano sway bars.

    Pending a response from UMI, I'm leaning toward the poly/roto option.
    Lid, Throttle Body, LS6 Intake, Heads, Cam, Magnaflow, LS7 Clutch, SFCs, STB, Panhard Bar, Strano Springs, Hollow Sway Bars, Poly/Roto LCAs, Konis, MGW Shifter

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    Spaz is My Mentor SMWS6TA's Avatar
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    LCAs: Rotos on both ends, or Roto/Poly combo?

    sway bars are next on my list. If I can get it up and running....
    http://www.ls1.com/forums/f7/my-6-liter-build-174257/

    http://www.ls1.com/forums/f8/my-8-8-rear-build-165553/

    6.0L Block - Forged 403 built, breaking it in , Polluter Stg3 Cam, FAST 102mm Intake, NW102 TB, MSD wires, NGK TR6 plugs, Truck Coil Packs, LS3 Fuel Injectors, CC Pacesetter LT Headers, TS&P ORY, QTP e-Cutout, Magnaflow Muffler, 104mm Air Lid & Line Lock, Catch Can, Stage 2 T56 w/Viper shaft, PRO 5.0 Shifter, Tick MC, Monster Stg 4 Clutch, QT SFI BH, MWC DSL, UMI: SFC, PHB, LCA's, LCA Relocation Brackets & TA, Hotchkis Springs (1" Drop), YR1 Snowflake Wheels wrapped in NT555 tires & Custom Fab Ford 8.8 rear w/4.10 Yukon Gears, WSQ Hood, 3"CM Strange Eng Drive Shaft.

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    Still running the stock sway bar out back and removed the front one last year on our car.

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    Moderator 98TransAmWs-6's Avatar
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    I personally have the non-adjustable roto-joints on both ends. I wish I had gotten rod ends or the double adjustable roto-joints though for my application.

    What I have is what UMI suggests for the best of both worlds while not having to be adjustable, meaning they provide the best performance (rod end like) without being too noisy like rod ends can be.
    Last edited by 98TransAmWs-6; 06-05-2014 at 10:29 PM.
    1998 Trans Am WS6 - Phantom
    421 CI LQ9, Tick Performance Custom Cam, TFS 255cc LS3 heads, Kooks 2" LT headers, Kooks 3" True Duals w/ high flow cats, FTP 104 lid, Speed Density Tune, 4" silicon tube, LS6 VCT, FAST 102 Intake, NW 102 TB, Oil Catch Can, SLP Bilstein Shocks w/ Vogtland Springs, CTS-V 4-piston Calipers w/C6 Z06 rotors, Stainless Steel Brake Lines, R1 concepts premium rotors, Hawk HP+ brake pads, VFN WSQ Hood, C5-R timing chain, SLP oil pump, E85 tune, Walbro 450 fuel pump, Deatschwerkz 95# injectors, Breathless performance headlights, Frost Tune, !HVAC.
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    Senior Member Naaman's Avatar
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    Quote Originally Posted by 98TransAmWs-6 View Post
    I personally have the non-adjustable roto-joints on both ends. I wish I had gotten rod ends or the double adjustable roto-joints though for my application.

    What I have is what UMI suggests for the best of both worlds while not having to be adjustable, meaning they provide the best performance (rod end like) without being too noisy like rod ends can be.
    Yeah, that's why I want the rotos.
    Why do you want rod-ends? Are they known to yield better performance than the rotos? The rod-ends make an annoying noise, for sure.

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    Moderator 98TransAmWs-6's Avatar
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    It's not that I necessarily want rod ends but I want the adjustable capability now which comes down to either rod ends or roto-joints. If I could I would have adjustable roto-joints on my whole suspension but you can't have it up front as there is no room. I do like that rod ends maintenance are virtually maintenance free not that it is a big deal to grease up the joints on suspension components.

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    Senior Member Naaman's Avatar
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    According to UMI, rod-ends have the shortest lifespan. Based on UMI's application guide, I'm having a hard time distinguishing what advantages the rod-ends would have over the rotos, other than that they might be "stronger." For the rotos, UMI says that they are good for "light drag racing." Whereas the rod-ends are good for "drag racing."

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