The outer rubber cups are soft, not standard hard poly. It's more like a dust seal than a poly bushing. The ball is hard, and on a steel tube to take the compression loads. If you picture the whole thing as standard poly, you wouldn't gain anything. If you picture it with a poly (or steel if it helps the visualization) ball, and soft rubber end caps (dust seals), there could be more of an ability to rotate. I suspect that the limiting factor will be where the outer shell contacts the body (mount location). I've never calculated how much rotation our cars might need for one side to be on the bumpstops and the other side to be at the extended limit of shock travel. If we had that number, we could probably generate some numbers to work from.

But, as I said in the other thread, there are dozens of good quality parts from many vendors that will do the job. Pick a vendor you like and place an order.

 

yea i just ordered the umi lca phr combo from byunspeed and its been a week since i ordered... i emailed them thursday and they said "It will ship this week"..now its monday and it still says order processing...wtf? i wish i would have got them directly from umi or at ws6store... its really pissing me off i could have made them by hand by now..umi sounds like a good company that backs their products that thread sold me also...

 

I know that UMI has been swamped with their recent sale. Ryan and the guys are working to get things out ASAP.

 

Thanks Kevin... yes we are doing the best we can to ship as fast as possible. The sale has hit us pretty hard and my recent accident hasn't helped any, here is the link if you care to see about that- https://ls1tech.com/forums/suspension-brakes/615688-please-read-note-umi-performance.html But we are back on track and doing the best we can.

It is most likely a drop shipment from us for Byunspeed, if you would like PM me your full name and I will see where it is.

Thank you,
Ryan

 

I'm running all adjustable UMI stuff. LCA's, PHB, TA, Trans mount w/ta relocation bracket. Car is hard and mean and corners incredibly.
The rod ends made a big difference in the way it handles and feels under power in corners. The adj phb was a must with my 18x315 tires. They (rods ends)are not for everyone though. They are for the serious minded only. They will turn a soft riding car into a harder feel. I'm also running Poly mounts everywhere. Cruising at 45mph or less you dont really enjoy the firm feel. But from 55-150 it kicks ***.

 

[QUOTE=trackbird]The outer rubber cups are soft, not standard hard poly. It's more like a dust seal than a poly bushing. The ball is hard, and on a steel tube to take the compression loads. If you picture the whole thing as standard poly, you wouldn't gain anything. If you picture it with a poly (or steel if it helps the visualization) ball, and soft rubber end caps (dust seals), there could be more of an ability to rotate. I suspect that the limiting factor will be where the outer shell contacts the body (mount location). I've never calculated how much rotation our cars might need for one side to be on the bumpstops and the other side to be at the extended limit of shock travel. If we had that number, we could probably generate some numbers to work from.
QUOTE]

When you're still bound by the outer caps as well as the inner cups of the "soft" rubber bushings to move as with standard rubber bushings, I do not see what gain is implimented using this hard ball in the middle over a standard rubber bushing. If these rubber "seals" are TOO soft, it will be actually a poor setup as the whole rear-end will feel like it has marshmallows for suspension components. Who cares what how the actual control arm is made at that point...the whole rear would move not just up and down but left right...all over the place!!. It would be a setup that would not improve handling!

A rod end it to rotate freely and up and down with little friction involved. It also eliminates movement in directions that are detremental in handling. This setup does not react the same. Examining the center hard bushing out of that setup, remove it...and you'd have standard rubber bushings...seems overdundant to leave a component in the middle. The LCA is bound by the outer rubber bushings, not the center hard bushing.

I don't think I'm being closed minded on this one. I really don' t see benefits from this...actually more negative aspects if any.

 

My only thought is that it will be a bit more solid for acceleration (possibly reducing the tendency to wheel hop) while allowing a bit more rotation than a full poly bushing. It seems to basically be a poly "rod end" in design. I can't say how well it will work at this time, but I'll get back to you on that at a later date (I'm going to try them for the sake of science). And not to worry Steve, I'm not calling you closed minded. After handling one, I think it could work, but I won't know until I install a set and beat on them for a while. Research is the only way to find out how ideas work in the real world (not news to you I'm sure).

The rear can't move left/right, etc due to the PHB. The arms might "wiggle" in their locations, but I don't know that they will have the freedom of motion to make any appreciable change (if they were to wiggle). They can't move enough to change the effective length of the arm any appreciable amount, or that's my hunch at least.

 

Steve, from both your posts it seems clear you do not understand the forces acting on the arms during cornering. This is why your not understanding the basic design of these arms.

Hold out your arm at a 90* angle and think of your fist as a pivot point like the front of the LCA pivot. Your elbow will be the rear pivot of the LCA. Now hold your fist still and move your elbow up and down. This is how the LCA moves when going through a dip or speed bump. Both tires move up and down at the same time and any material in the joints will work, poly, rubber, rod end, etc...

Now under cornering one tire goes higher and the other tire goes lower. What happens to the LCA is like your wrist twisting 45*. This type of twisting puts the LCA in a bind. With rubber and poly bushings the pivot points bind up. Your elbow will not want to move up or down without a lot of extra force. On a perfectly smooth road this would be no big deal. Now if you hit a bump or hole the rear axle will need to move or pivot which means the LCA's need to pivot up and down and since they are in a bind they can't move easily. They don't want to move and this can cause a loss of grip.

I'm sure every can understand that a rod ended LCA can pivot and twist and not create any bind and are almost perfect for a LCA. It's just the pesky noise and vibration they transmit that makes folks not want to use them. What J&M Products made is actually a big rod end made of polyuerethane. The middle ball is very hard and the outer cups are very soft. This should allow for the twisting motion without the bushings getting tight and binding up.

Does that make sense? I can draw up a diagram which might be easier to visualize the forces, but I don't have time right now.

If you have an extra LCA laying around you can clamp one bushing end in a vise and put a long screwdriver through the other ends bushing. Now move the arm. It will move easily with poly. Rubber moves easily at first and then starts to get firmer. Now twist the long srewdriver to simulate cornering conditions. Now try and pivot the arm. You will feel that it's very difficult and the arm does not want to move. This extra force adds directly to the spring rate, as more force is needed to compress the axle. Any racer can tell you what happens to a car when you incresae the rear spring rate. On a well balanced car the extra rear rate will cause an oversteer condition and loss of grip.

 

Jason,

I understand what you are trying to explain. The problem with this is that the "can" of the LCA and bushings does not work as you are describing. The movement in that location is strictly due to compression of the rubber. With a rod-end, you do not have this problem.

I do understand what forces acting on the joint. The ball in the center does not function as a typical rod-end, remove the ball, the arm will function similar, it is a redundant component.

The pivot/rotation action is a result of a very soft bushing, not the center hard ball. These rubber bushings are constrained by the stock brackets as well as the bolt. Binding will still occur at the bracket location as well as the socket location.

If you applied a force axially to the LCA the whole rear-end will move forward and back due to the soft deflection of the rubber bushings. This is felt in an OEM setup as well. This is one reason when you change to a hard bushing or rod-ends, the car feels tighter. The mushy feeling is less, road noise is increased.

Plain and simple, if the rubber bushings are very soft to allow rotation (ball does not create this), the bushings will allow the rear to not only pivot/rotate but will move forward/aft. These are movements you do not want. You cannot constrain a soft bushing to move in one direction.

 

looks like a cheap atttemp to reproduce the effects of a rod end without actually getting one, i would say to just go for a straight up rod ended LCA if thats what you want, and steve i would say that you're right to take into consideration frictional coefficients that the outer bushing put on the inner ball as well as the force put on to the LCA as a whole by the bracket that holds the LCA to the car and axle when fully torqued

 

Yes, essentially the same problem that you have with the OEM components and converted poly setups.

I will say this again; I think it is a fresh approach to creating something new. It appears that this is something new. The typical consumer is not going to dissect it as we are here, they will read the testimonial and purchase it based on that...

...I think for the most part, many of the other sponsor typical designs work well for the masses. I’ll stress “sponsors”

…For the discriminating users, the rod-ended setups work best...you need to take the good with the bad...the bad being increased road noise transmission. We’ve only built rod-ended setups, I’ve looked into the typical rubber/poly setups but frankly, I haven’t had the time to do it…lol it appears I spent too much damn time posting replies in here...hehe

 

road noise ha! i cant hear **** over the exhaust

 

You say this yet your explanation of why it does or does not work makes no sense.

Like right here. By "can" do you mean the round tubes welded on the end?
What rubber are you refering to and what compression?

By looking at it and hearing that that the ball part is a hard polyurethane then it SHOULD function like a typical rod end. Why are you saying it won't?

If you remove the ball you would be left with the soft poly bushings which will easily compress. They will be softer than the stock rubber bushings and create more wheel hop and more of a general sloppy feeling. The key is the hard ball. It takes all the slack out of the bushing under acceleration as it won't compress. It is not at all redundant.

No, it is due to the suspension design.

You mean the soft poly outer bushings, right? They are not rubber. Yes they are constrained by the brackets, but they are not under pressure or squeezed if that is what your getting at. The hollow shaft the bolt goes through is slightly wider than the bushings. When you tighten the bolt, the bushings are not squeezed. They are there to keep the metal arm centered and to isolate the arm from the car. That way noise is not transfered.

No it won't. Where are you getting this info? If you applied a force axially to the LCA the LCA would rotate. The axle will not move. Get under the car and try it. You'll see.

Changing to a poly bushing or rod end gets rid of the play front to rear, like when accelerating and decelerating. If there is play the rod end length effectively gets longer and shorter. With the stock rubber bushing under acceleration the effective arm length will shrink due to the axle being pushed forward. The rubber will compress and then rebound slightly, this can break the tires loose. It can also create an oscillation in the bushing. As the car accelerates the bushing can flex back and forth making the arm shorter, then longer, then shorter, etc.... This doesn not feel good to the driver. A firmer material can fix this flex so the arm length stays fixed.

Correct, the ball does not create this, but it does ALLOW this to happen
Correct if you are only talking about the soft bushings, but since the hard ball is in there it will not move foreward/aft.

With you being a Mechanical Engineer and your company actually making LCA's I would think you would understand the forces involved and how these arms worked. If anything you should be telling me how they work, not the other way around.

Do you see a flaw in the design that maybe I don't see? If so, please point it out.

 

One last clarification.

The ball is hard rubber (poly), the outer cups are soft. They also have an "edge" that acts as a spacer between the edge of the housing and the mounting locations on the chassis/axle. The metal "tube" through the ball will support the loads without allowing you to compress the bushings too much. This should help prevent them from being torqued down and smashed solid in the mounts. I agree that there will still be some degre of bind present, the question is how much bind. If it falls somewhere between a standard poly bushing and the stock LCA's, it's a decent idea. The ball is quite hard and will limit fore and aft compression (it's a tight fit in the bore), but it may prevent the cold flow issues of a standard poly bushing. The LCA "should" be able to rotate around the ball (while compressing the rubber cups) until it either:

1. Binds the cups enough to limit travel.

2. The sides of the end (that houses the ball) contact the sides of the mounting locations on the axle and chassis.

As I said, I don't know how well they will work, but I plan to find out. It's not the kind of part I'd normally use (I won a regional SCCA autocross championship on stock LCA's with stock bushings....in a class where I could have run rod ends). I'm usually a rod ends or stock LCA's kind of guy. I generally avoid poly stuff like the plague. However, I'm going to try a set as I stated just because inquiring minds want to know. I might love them, I might not, but I may as well try them. Besides, I own a set of them now, so I guess I have to put them on and try them out.





Now, this is back to my question of how much rotation do we need for proper articulation of the rear suspension? I don't have the numbers on that, so I can't say if there is enough travel here. My hunch is that it's an improvement, but probably still a bit limited at the ends of the travel.

Anyway, my interest in this is more a case of inquiring minds want to know than anything. Since I did a bit of research on these, I'm just trying to answer the questions/provide proper information (food for thought/discussion?) for the discussion.

Edit: Jason's last reply wasn't there when I typed this. This post was just for clarification. I'm staying out of the "debate" and just trying to provide information for discussion.

And, at this point, all the info is pretty much here, so there is not much else for me to do in this discussion but sit back and let it continue with the rest of the info I've provided.

 

I was rereading what you said earlier and this is a qoute from that.
The friction coefficient between the ball and socket should NOT be high, nor should they be compressed from the bolts. The internal diameter of the outer soft poly bushings should not have any effect on whether the shaft can rotate freely.

One thing I'm not clear on is wheher the ball part is bonded to the shaft or is a slip fit. If a slip fit the shaft should rotate freely. If the shaft and ball are bonded together then the outer diameter of the ball will have to rotate in the metal tubing. I don't think the friction will be high due to the round shape never causing a bind. So it should rotate fairly freely. With lube in there it should rotate nicely.

How can you say that? The outer bushings aren't the main functioning part. I don't know why you keep focusing on them. The main part is the hard poly ball. That is what gets the slop out under acceleration. It should be much better than the stock rubber bushing.

 

You say you have a set Kevin?
Did you just order them or do you have them already?

I'd like to see a picture showing how easy it is to deform the 2 poly pieces.

For instance, is it like the pic below? This is a torque arm mount I bought. It was much softer than I thought it would be. Poly can be really soft or really hard with a lot in between.

 

Are the outer cups rubber or soft poly? I thought they said poly, but the web page says rubber. It looks like poly. I don't really know now.

 

You're probably saying to yourself "why can't he understand this" while I am strongly doing the same!

The can is the component that houses the rubber bushings. The can if not for the rubber bushing would be touching the LCA mounting flange. It is ~1/8 away due to the rubber bushing. The ONLY rotation or articulation that you'll see is when the thin bushing wall compresses between this as well as from the area between the shaft and outer surface of the bushing. This has nothing to do with the center. This is no different than an OEM rubber bushing reacts. The center hollow shaft of the OEM bushing acts just the same as you are describing regarding squeeze or excessive compression. The ball does NOT allow it to rotate; it has nothing to do with it.

The surface between the rod end LCA mount and the rubber IS the primary binding area. Ball or no ball will not solve this or magically allow it to rotate easier! The center ball will increase frictional surface areas now.

The ball has nothing do to with preventing the shaft to move forward/aft. THIS movement is due to the compression of the actual rubber bushing JUST as the stock component does. I’ll try to simplify this since you do not understand what I’m referring to. Take the rear-end and the LCA’s, suspend them from the ceiling, the rear-end will move up and down DUE to the rubber internal bushing of the LCA. This would also apply to the PHR as well! This is why the rear end feels like it is not firmly planted during maneuvering. If the rubber is softer then OEM, then it will move with less force. What I’ve described will NOT occur with a rod end, poly components will also lessen this effect but increase bind at the point between the LCA mount and “can”.

I see minimum to zero differences between this and an OEM rubber bushing with the exception of a hard rubber ball in the middle which does not allow anything to occur. You are confusing this design (can with rubber mounts) with how a rod-ends where the constraint of rotation AND friction is due to the rod-end itself.

If one compared them to stock, I don't see a person feeling a difference...only a self persception in their head to validate their purchase. The differences may be only measured on a jig...and at that point, sticking with the stock part, saving your money may work just as well. Trackbird showed that he indeed can perform very well with a stock component.

Trackbird, your results may be biased since you were probably given the component to play with...not exactly an independant study by any means. I highly doubt you'd state "I didn't feel any difference" stick with the stock part.

This is just another approach, doesn't mean it is bad/good, just another option I suppose. Once again, when discussing performance, the rod-end is best...for the guys who don't want road noise transferred as easily...anything else will probably work just fine as they are looking for comfort giving up max performance. When I hear someone state "what is the best..." this new approach wouldn't be the top of my list.

I really can’t take any more time on this. Good luck to you all.

 

It sure looks like the end cups are a soft poly as opposed to rubber. Poly can be very slippery, while rubber is not. I'm assuming they are poly and will allow the ball to slip easily.

The pic below shows why the fore and aft play is removed.

I guess I'm going to have to get a pair and see for myself.

 

This is where I have to mostly agree with Steve. The rubber "spacer" at the edge will likely be the primary point of bind. I think this bushing assembly will act mostly like a poly bushing ended LCA (more so than a rod end) but I suspect it will reduce or elminiate the cold flow problem that poly exhibits which will be the main advantage of this design. I expect that the ball will make it less likely to change length under acceleration or braking, but I'm not sure how much rotation you'll gain. As I said, I look at it as a poly bushing that shouldn't cold flow from the rotation of the axle and consider that to be the main advantage. I think it might bind less than a solid poly bushing by providing some degree of give, but again, without knowing the maximum angle that can be acheived by the axle end attaching bolts in relation to the chassis end, I can't say how much of an improvement it will provide and for how much of the travel. It looks like it should provide more fore and aft stiffness than the stock design, but it will probably not allow quite as much rotation as the stock rubber bushing. Everything is a compromise, remember?

Yes, I do have a set at home at this point. I got my hands on a set to try in the name of science. It just seemed like something I should play with for a while.

Steve, I appreciate your time and input on this. I'll provide more information after I get a chance to do some testing in actual use. The only way to really know how they feel is to put them on a car and drive it. That's what I intend to do. However winter driving isn't the best way to test such an item (and running on snow tires makes it worse).