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Re: LCA poly bushings walking out of the shell when install
[Re: 340duster340]
#1677965
09/28/14 03:58 PM
09/28/14 03:58 PM
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Joined: Nov 2005
Posts: 15,118
85086
moparpollack
Lil Herman
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Lil Herman
Joined: Nov 2005
Posts: 15,118
85086
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Yes, they walk. I went back to rubber lower bushings.
56 Plaza 63 D100 step side 67 Coronet, 68 Roadrunner, 69 Super Bees, 69 Coronet 500 convertible, 70 Roadrunner Post, 79 D150 360, and a severe case of Mopar a,d,d
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Re: LCA poly bushings walking out of the shell when install
[Re: 340duster340]
#1677971
09/30/14 10:27 PM
09/30/14 10:27 PM
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Joined: Oct 2006
Posts: 387
Montreal PQ, Canada
74_360_Cuda
enthusiast
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enthusiast
Joined: Oct 2006
Posts: 387
Montreal PQ, Canada
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In my humble opinion poly bushings for LCA's are an aberration. This is simple physics based on the geometry and load path of the suspension, even if it is probably relatively small there will always have some axial load to be reacted there so using a floating arrangement is wrong IMO... Just think when you are braking in reverse.
I've tried them and even with adjustable struts your LCA will move Aft on the pins. Maybe some people put more pre-load on their struts and have some luck with it but I would assume the axis of the LCA's is no longer co-axial with the axis of the pins...
I went back to stock bushings. BTW I love everything I've purchased from Hotchkis so far but their poly bushing were way over sized for my LCA's and could not be installed even with a press, Moogs were perfect fit. Would be nice to have a properly designed replacement LCA's that use bearing instead of bushing no?
Last edited by 74_360_Cuda; 09/30/14 10:46 PM.
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Re: LCA poly bushings walking out of the shell when install
[Re: 74_360_Cuda]
#1677972
10/01/14 12:57 AM
10/01/14 12:57 AM
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Joined: Aug 2013
Posts: 106
Central IL
Trojmn
member
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member
Joined: Aug 2013
Posts: 106
Central IL
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Quote:
In my humble opinion poly bushings for LCA's are an aberration. This is simple physics based on the geometry and load path of the suspension, even if it is probably relatively small there will always have some axial load to be reacted there so using a floating arrangement is wrong IMO... Just think when you are braking in reverse
i dont follow. The brake force is on the strut rod no matter what direction the car is moving. its not like rubber bonded to a shell is not bending/twisting in all sorts of of axis/directions.
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Re: LCA poly bushings walking out of the shell when install
[Re: 74_360_Cuda]
#1677974
10/01/14 12:33 PM
10/01/14 12:33 PM
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Joined: May 2012
Posts: 841
Santa Fe Springs, CA
Dan@Hotchkis
super stock
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super stock
Joined: May 2012
Posts: 841
Santa Fe Springs, CA
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Quote:
...poly bushing were way over sized for my LCA's and could not be installed even with a press...
Something there doesn't sound right at all. I can do most of the assembly by hand and usually have an issue over-installing them. Glad you got it sorted out.
I'd love to design a better mouse wheel for the LCA's, but after looking at it and whipping up a couple prototypes it wasn't cost effective.
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Re: LCA poly bushings walking out of the shell when install
[Re: Dan@Hotchkis]
#1677975
10/01/14 02:23 PM
10/01/14 02:23 PM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
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Quote:
Quote:
...poly bushing were way over sized for my LCA's and could not be installed even with a press...
Something there doesn't sound right at all. I can do most of the assembly by hand and usually have an issue over-installing them. Glad you got it sorted out
Any Poly/Delrin/Nylon LCA bushings I've ever installed (I've been doing poly installs for about 3 decades), were done by hand, the bushing is intended to rotate in the LCA bore (which is why you retain the stock outer steel sleeve from the stock rubber bushing in the LCA bore) and to rotate on the LCA pivot shaft, which are best replaced with aftermarket grease-able units, Poly bushing should be lubricated during their initial install with a non petroleum base grease, when using poly LCA bushings, either use the correct poly brake/relay rod poly bushings, or adjustable brake/relay rods to relocate the LCA "forward", otherwise the LCA will "walk" on the poly bushing and or pivot shaft,...IMHO I can see the OP's LCA bushing are going to fail sooner, than later 
Who's bushings did you use?, PN#/application?
Mike
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Re: LCA poly bushings walking out of the shell when install
[Re: Trojmn]
#1677976
10/02/14 12:14 AM
10/02/14 12:14 AM
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Joined: Oct 2006
Posts: 387
Montreal PQ, Canada
74_360_Cuda
enthusiast
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enthusiast
Joined: Oct 2006
Posts: 387
Montreal PQ, Canada
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Quote:
i dont follow. The brake force is on the strut rod no matter what direction the car is moving. its not like rubber bonded to a shell is not bending/twisting in all sorts of of axis/directions.
The braking force is creating a moment on the LCA. The strut rod alone cannot react a moment, there will be some axial load on the bushing as well. When braking in fwd direction the load will push the bushing against the shoulder of the pin but when braking in reverse the force will move the bushing aft on the pin and there is no shoulder to stop it so the LCA wil move aft. This won't happend with the stock bushing because the busing is bonded on inner and outer sleeves and press fitted in the LCA and on the pins, the rubber is twisting every time the LCA is moving up or down but this allow the bushing to react axial load.
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Re: LCA poly bushings walking out of the shell when install
[Re: DAYCLONA]
#1677977
10/02/14 12:26 AM
10/02/14 12:26 AM
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Joined: Oct 2006
Posts: 387
Montreal PQ, Canada
74_360_Cuda
enthusiast
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enthusiast
Joined: Oct 2006
Posts: 387
Montreal PQ, Canada
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Quote:
Quote:
Quote:
...poly bushing were way over sized for my LCA's and could not be installed even with a press...
Something there doesn't sound right at all. I can do most of the assembly by hand and usually have an issue over-installing them. Glad you got it sorted out
Any Poly/Delrin/Nylon LCA bushings I've ever installed (I've been doing poly installs for about 3 decades), were done by hand, the bushing is intended to rotate in the LCA bore (which is why you retain the stock outer steel sleeve from the stock rubber bushing in the LCA bore) and to rotate on the LCA pivot shaft, which are best replaced with aftermarket grease-able units, Poly bushing should be lubricated during their initial install with a non petroleum base grease, when using poly LCA bushings, either use the correct poly brake/relay rod poly bushings, or adjustable brake/relay rods to relocate the LCA "forward", otherwise the LCA will "walk" on the poly bushing and or pivot shaft,...IMHO I can see the OP's LCA bushing are going to fail sooner, than later
Who's bushings did you use?, PN#/application?
Mike
They came with the greasable pins that I have purchased from Hotchkis. They have machined grooves for the grease. I had to grind them until there was no grooves until they would fit like the Moogs but I ended up using the stock bushings for the reasons explained above. Yes I have used proper grease and no there was no outer sleave left in the LCA, Not my first time either, the bushings were simply oversized.
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Re: LCA poly bushings walking out of the shell when install
[Re: 74_360_Cuda]
#1677978
10/02/14 12:09 PM
10/02/14 12:09 PM
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Joined: May 2012
Posts: 841
Santa Fe Springs, CA
Dan@Hotchkis
super stock
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super stock
Joined: May 2012
Posts: 841
Santa Fe Springs, CA
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Quote:
They came with the greasable pins that I have purchased from Hotchkis. They have machined grooves for the grease. I had to grind them until there was no grooves until they would fit like the Moogs but I ended up using the stock bushings for the reasons explained above. Yes I have used proper grease and no there was no outer sleave left in the LCA, Not my first time either, the bushings were simply oversized.
DO you by chance still have the bushings? And did you happen to get the OD of the pin prior to machining them down? WE use Energy suspension stuff and I've had a couple consistency issues with some of their bits lately.
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Re: LCA poly bushings walking out of the shell when install
[Re: 74_360_Cuda]
#1677980
10/02/14 09:51 PM
10/02/14 09:51 PM
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Joined: Aug 2013
Posts: 106
Central IL
Trojmn
member
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member
Joined: Aug 2013
Posts: 106
Central IL
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Quote:
Quote:
i dont follow. The brake force is on the strut rod no matter what direction the car is moving. its not like rubber bonded to a shell is not bending/twisting in all sorts of of axis/directions.
The braking force is creating a moment on the LCA. The strut rod alone cannot react a moment, there will be some axial load on the bushing as well. When braking in fwd direction the load will push the bushing against the shoulder of the pin but when braking in reverse the force will move the bushing aft on the pin and there is no shoulder to stop it so the LCA wil move aft. This won't happend with the stock bushing because the busing is bonded on inner and outer sleeves and press fitted in the LCA and on the pins, the rubber is twisting every time the LCA is moving up or down but this allow the bushing to react axial load.
a proper length rod/bushing will keep the LCA where it needs to be. I wouldn't trust any real physics"moment" on bonded rubber. the fact that bonded rubber survives tells you its doing WAY less than you think locating the LCA fore/aft. Besides the attachment of the strut in inboard of the BJ so if its getting cockeyed on the pin from for/aft moments, a stiffer bushing will locate the LBJ better when you experience those moments. And the strut rod is in TENSION during forward braking not compression. literally pulling the car to a stop from the K and those two strut nuts  . If any moving is going on its the outer bushing of the strut getting squashed. the LCA being the triangulated link should go inward
if the LCA moves at all the strut rod assy will put it back assuming it was installed correctly in the first place to locate the LCA. again the strut rod assy locates the LCA/LBJ not the LCA bushing. if the LCA is moving aft, the strut is too long and/or in the wrong position due to the strut rod bushing. it is pushed back not pulled.
<<<< IM NOT a Mech Engineer >>>>>
want to keep the LCA from moving aft? a springloaded TB retainer/cap (pat pending! ;-) is a simple idea. probably too simple that if needed someone would sell them already. wont be difficult to put the gopro underneath to see all this LCA walkabout.
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Re: LCA poly bushings walking out of the shell when install
[Re: 74_360_Cuda]
#1677982
10/04/14 04:25 AM
10/04/14 04:25 AM
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Joined: Jan 2003
Posts: 27,467
So Cal
autoxcuda
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,467
So Cal
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Quote:
....
I went back to stock bushings. BTW I love everything I've purchased from Hotchkis so far but their poly bushing were way over sized for my LCA's and could not be installed even with a press, Moogs were perfect fit. Would be nice to have a properly designed replacement LCA's that use bearing instead of bushing no?
I had the same problem with the Energy poly LCA bushing I installed in 1998.
I had to carefully sand off material around the OD of the poly bushing.
On the LCA other shell, I sandpaper scrolled and die grinder buffer attachment polished the ID. Like sanding then polishing an aluminum intake.
On the stock pin you have to leave the original inner rubber bushing sleeve. I did that and polished that on a buffer to a mirror finish.
After all that I would press together with force. Been running those since 1998 and 40K+ miles. Took it apart in 2010 to put Hotchkis stuff on. Showed it to Hotchkis and they said it was still fine and to run it.
Back in 1988 most all the poly bushings available were not made with shells installed on them. Most all came like the Mopar LCA polys where you use the old shells from the old rubber bushings. Guldstrand Engineering sold, installed, and manufactured (for them) custom poly bushing inserts.
Problem with those insert-only poly bushing was the variability in the thickness of the shells in aftermarket rubber bushings. The metal shells you reused, would not all have the same ID or OD. Guldstrand would have over the counter parts customers every once in a while that would not be able to press the insert-only bushings together. It was a big PITA for them. In about 1992 Guldstrand was selling the new Energy bushings that had the poly inserts with shells manufactured around them.
BTW in 1990 Guldstrand was designing a Corvette supercar called the GS90 (ala Hennessy). The young hot shot car designer from the famed Pasadena Art Center Design.... a young John Hotchkis. I remember John walking around the old Culver City shop in the typical lab coat all Guldstrand employee wore. Fast forward 25 years, I've seen John Hotchkis walk around his own prototype shop in a labcoat sticking out like a sore thumb. ONLY ONE in the shop wearing a labcoat.
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