LCA trouble
09-25-2007, 05:08 PM
#11
4th Gear Member
Join Date: Mar 2005
Location: California
Posts: 1,471
RE: LCA trouble
ORIGINAL: Slink
F1Fan,
Instead of the Ford fasteners, could you purchase grade 8 bolt and nuts from your local hardware store ?
Is there something special about the Ford fasteners? On my 72 Chevy PU with trailing arms, I just replaced all the bolts and nuts with grade 8 hardware when I rebuilt the suspension.
F1Fan,
Instead of the Ford fasteners, could you purchase grade 8 bolt and nuts from your local hardware store ?
Is there something special about the Ford fasteners? On my 72 Chevy PU with trailing arms, I just replaced all the bolts and nuts with grade 8 hardware when I rebuilt the suspension.
If you could actually buya grade 8 bolt that was actually an authtenticgrade 8 spec bolt I would imagine it would be fine. But I wonder if the engineers at Ford wanted as hard a bolt as a grade 8 or they intended to usethe softer more elasticbolts they supplyin these locations. The problem is that most grade 8 bolts out in the hardware stores are not real grade 8 bolts.Even if you know what to look for it is hard to know if a bolt marked with all the right marks are really grade 8 or not. But I suppose that even a suspisious grade 8 bolt is better than a "super bolt" or "grade 10" bolt which as far as I can tell are all garbage. I'm in L.A. so there areseveral reliable speed and machine shops selling aircraftgrade bolts. There are also a fe surplus stores dealing in aircraft fasteners around whee you can find incredible deals but if you only need a few this is not as big a deal. You generally have to bring in or measureyour bolts and then they will find an aircraft bolt that is approriate and then cut it down to size and refinish theendsso theystart properly.
HTH!
09-25-2007, 06:43 PM
#12
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
RE: LCA trouble
Are the Lakewood bushings poly? And if so, is the poly longer thanthe inner sleeve? If that's the case, some of your bolt torque is "wasted" in compressing the poly. That leaves less for compressing the metal stack (bracket side, inner sleeve, other bracket side), so the friction developed in the joint will be nowhere near what the torque setting is supposed to indicate is there. As the poly cold-flows, sleeves do pick up a little more load and consequently develop a little more friction, but not enough more to matter.
The important thing to recognize is that these bolts are not supposed to locate the LCAs by shear, either in the OE configuration or in Lakewood's. It's friction developed by the bolt tension that does the locating (or the 'teeth' in most OE LCA sleeves, which alsorequire bolt tension to set). And that's indirectly indicated by bolt tension, which itself is being indirectly measured via installation torque.
There's a cheap enough fix assuming that the poly isn't permanently distorted. Sand or grind the ends of the poly pieces until they are justa tiny bit shorter than the inner sleeves. Perfectly flat does not matter, but try to keep it close. That will allow all of the bolt torque to develop metal-against-metal friction. A side benefit is that the poly will be less likely to squeak, as the rotation between the bushing and the bracket sides will not be occurring with pressure between those faces.
Norm
The important thing to recognize is that these bolts are not supposed to locate the LCAs by shear, either in the OE configuration or in Lakewood's. It's friction developed by the bolt tension that does the locating (or the 'teeth' in most OE LCA sleeves, which alsorequire bolt tension to set). And that's indirectly indicated by bolt tension, which itself is being indirectly measured via installation torque.
There's a cheap enough fix assuming that the poly isn't permanently distorted. Sand or grind the ends of the poly pieces until they are justa tiny bit shorter than the inner sleeves. Perfectly flat does not matter, but try to keep it close. That will allow all of the bolt torque to develop metal-against-metal friction. A side benefit is that the poly will be less likely to squeak, as the rotation between the bushing and the bracket sides will not be occurring with pressure between those faces.
Norm
09-26-2007, 12:59 AM
#13
4th Gear Member
Join Date: Mar 2005
Location: California
Posts: 1,471
RE: LCA trouble
ORIGINAL: Norm Peterson
Are the Lakewood bushings poly? And if so, is the poly longer thanthe inner sleeve? If that's the case, some of your bolt torque is "wasted" in compressing the poly. That leaves less for compressing the metal stack (bracket side, inner sleeve, other bracket side), so the friction developed in the joint will be nowhere near what the torque setting is supposed to indicate is there. As the poly cold-flows, sleeves do pick up a little more load and consequently develop a little more friction, but not enough more to matter.
The important thing to recognize is that these bolts are not supposed to locate the LCAs by shear, either in the OE configuration or in Lakewood's. It's friction developed by the bolt tension that does the locating (or the 'teeth' in most OE LCA sleeves, which alsorequire bolt tension to set). And that's indirectly indicated by bolt tension, which itself is being indirectly measured via installation torque.
There's a cheap enough fix assuming that the poly isn't permanently distorted. Sand or grind the ends of the poly pieces until they are justa tiny bit shorter than the inner sleeves. Perfectly flat does not matter, but try to keep it close. That will allow all of the bolt torque to develop metal-against-metal friction. A side benefit is that the poly will be less likely to squeak, as the rotation between the bushing and the bracket sides will not be occurring with pressure between those faces.
Norm
Are the Lakewood bushings poly? And if so, is the poly longer thanthe inner sleeve? If that's the case, some of your bolt torque is "wasted" in compressing the poly. That leaves less for compressing the metal stack (bracket side, inner sleeve, other bracket side), so the friction developed in the joint will be nowhere near what the torque setting is supposed to indicate is there. As the poly cold-flows, sleeves do pick up a little more load and consequently develop a little more friction, but not enough more to matter.
The important thing to recognize is that these bolts are not supposed to locate the LCAs by shear, either in the OE configuration or in Lakewood's. It's friction developed by the bolt tension that does the locating (or the 'teeth' in most OE LCA sleeves, which alsorequire bolt tension to set). And that's indirectly indicated by bolt tension, which itself is being indirectly measured via installation torque.
There's a cheap enough fix assuming that the poly isn't permanently distorted. Sand or grind the ends of the poly pieces until they are justa tiny bit shorter than the inner sleeves. Perfectly flat does not matter, but try to keep it close. That will allow all of the bolt torque to develop metal-against-metal friction. A side benefit is that the poly will be less likely to squeak, as the rotation between the bushing and the bracket sides will not be occurring with pressure between those faces.
Norm
Warning this post is sort of off topic but sort of related. Maybe you can help me with your opinion on an issue that came up recently about bushings used in LCA's from J&M. These guys are selling a three piece bushing that they alledge eliminates all binding in their bushing. The bushings use the usual polyurethane bushing with a twist, the center bushing is a round ball and the outer bushings are cupped to acommodate the central poly ball.The outer bushing faces are just like any other poly bushings and thewhole thing is containedby the usualsteel shellwith a thinwall steel tube through the middle for the bolt to pass through and fasten the bushing to the mount. The outer faces of the bushings are as usual constrained by the LCA brackets.Picture this -[][o][]- So my question to you is does this "new" bushing work as advertised or is itmarketing fiction.
Cheers!
09-26-2007, 07:26 AM
#14
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
RE: LCA trouble
That would be the so-called "poly-ball" bushing, which have apparently been around for a while.
Depending on the stiffness of the 'flanges" of the outer cups, it should work pretty much as advertised, as it is similar to the Johnny-joints (a Currie piece IIRC), which in turn is not much different from a rod end in terms of the mechanism by which multi-axis motion is accommodated. The radius of the ball is pretty small, so the effects of friction/stiction cannot generate much moment, which is what the big downside of a plain, cylindrical, out-of-the-box poly bushing is with its high stiffness against all loads except one(and you really do want low stiffness against a couple of the others).Even unlubricated, I doubt that the ball by itself can develop moments appreciably greater than what you get with OE rubber via its compliance. Nowhere near the ~order of magnitude higher moments as with plain poly.
My only question involves compliance of the cup flanges if they extend to or beyond the length of the inner sleeve that passes through the ball. Their compliance (or lack thereof) would then determine how easily torsion and lateral bending in the LCA can be accommodated at the ends, and consequently the total moment that is developed. If the flanges are relatively rigid and there is no clearance, there's a pretty simple mod you can do to relieve this situation (think belt sander, flattish cone shapes, and probably a need for somewhat more frequent inspection).
Might as well add here something that occurred to me after I shut the computer down last night. If you have plain poly bushings and do not get them compressed such that metal to metal contact between the sleeve and the bracket sides occurs, the combination of wear and relaxation of the poly which will occur over time and under load could eventually render the joint completely loose. Even a partial relaxation will likely allow the joint to move enough to either hear or feel, since the rotational sliding motion at the bushing faces that goes withvertical suspension motion will easily pick up a fore/aft sliding component once the suspension motion gets going. It's easily possible for this to be a one-side condition, which would introduce a slight axle steer effect.
Norm
Depending on the stiffness of the 'flanges" of the outer cups, it should work pretty much as advertised, as it is similar to the Johnny-joints (a Currie piece IIRC), which in turn is not much different from a rod end in terms of the mechanism by which multi-axis motion is accommodated. The radius of the ball is pretty small, so the effects of friction/stiction cannot generate much moment, which is what the big downside of a plain, cylindrical, out-of-the-box poly bushing is with its high stiffness against all loads except one(and you really do want low stiffness against a couple of the others).Even unlubricated, I doubt that the ball by itself can develop moments appreciably greater than what you get with OE rubber via its compliance. Nowhere near the ~order of magnitude higher moments as with plain poly.
My only question involves compliance of the cup flanges if they extend to or beyond the length of the inner sleeve that passes through the ball. Their compliance (or lack thereof) would then determine how easily torsion and lateral bending in the LCA can be accommodated at the ends, and consequently the total moment that is developed. If the flanges are relatively rigid and there is no clearance, there's a pretty simple mod you can do to relieve this situation (think belt sander, flattish cone shapes, and probably a need for somewhat more frequent inspection).
Might as well add here something that occurred to me after I shut the computer down last night. If you have plain poly bushings and do not get them compressed such that metal to metal contact between the sleeve and the bracket sides occurs, the combination of wear and relaxation of the poly which will occur over time and under load could eventually render the joint completely loose. Even a partial relaxation will likely allow the joint to move enough to either hear or feel, since the rotational sliding motion at the bushing faces that goes withvertical suspension motion will easily pick up a fore/aft sliding component once the suspension motion gets going. It's easily possible for this to be a one-side condition, which would introduce a slight axle steer effect.
Norm
10-18-2007, 10:32 PM
#15
4th Gear Member
Thread Starter
Join Date: May 2005
Location: FL
Posts: 1,138
RE: LCA trouble
After like 3 weeks, I just finally was able to order some replacement bushings. I talked to a custome service rep from Lakewood and he said the older bushings had some failure problems so they are sending me new replacements for free.
Plus 1 to Mr. Gasket customer service
Plus 1 to Mr. Gasket customer service
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