F1Fan

If you want to help improve your 3-link suspension while keeping your strret ride nice and quiet I cannot recomment this setup or ANY other conventional poly bushing control arms. For a real world street car the huge NVH trade offs of using the simple poly bushings are additive. By additive I mean that as more and more poly bushings replace your OEM rubber bushings the worse and worse the levels of tire, road, drivetrain, engine and exhaust noises, vibrations and harshness invade your car's cabin.

If you want to maintain as much of your factory interior quiet and improve rear axle location at the same time for a DD real world S197 chassis you need to retain as much isolation and control arm freedom of movement as possible. Poly bushings are only good for VERY limited uses. ALL other uses of poly bushing material compromises the durability of the poly bushing material and causes them to fail MUCH sooner than almost ANYBODY expects.

The factory O.E. rubber on the other hand is designed to be used in locations that would destroy poly bushings very quickly. The O.E rubber bushings can easily go 100K miles in an application like the S197's 3-link control arms. Poly bushings used on the S197's 3-link control arms can start to degrade in less than 10K miles! The more a poly bushing is asked to flex and deform the more pronounced the problem will be.

For the doubter out ther with all poly LCAs order a new set of LCA bushings complete with new bushing sleeves. When you get the new bushings and sleeves, confirm they are the correct parts and go disassemble your poly bushing control arms with 10K+ miles. You will need to take the bushings and bushing sleeves out of the control arm shells and compare them with the new bushings and bushing sleeves for your control arms. Chances are good you will need to use those new bushings and if you use a torque wrench to torque your LCA and UCA fasteners there is a good change you will need to replace the bushing sleeves as well due to distortion of the sleeves.

For a real world street car where you would like to keep some ride and avoid as much NVH as possible I would suggest a pair of FRPP sourced GT500 LCAs and an adjustable UCA with the addition of a Currie Johnny Joint on the chassis side. You can buy the UCA from anybody and just order the Johnny Joint to fit or just order a UCA from Currie for an S197 Mustang. This setup is going to cost you $100 more but it will be much quieter, ride better and handle better due to the much reduced artifical spring rate due to the lower forces these bushing create when the axle is twisted in the chassis.

HTH!

Sam Strano

There is no reason to go through that trouble.

There are number of non-binding options. There are the UMI arms poly/roto-joint combinations (which are basically spherical bearings that are rebuildable like a "johnny joint" just with a different name). And there are the Steeda Billet arms that use a poly/spherical bearing combination (that that bearing is not rebuildable like the UMI one is). Both get rid of the bind that all poly bushings give.

What's more you save yourself a lot of hassle by buying this arm, buying a johnny-joint, changing it out.

F1Fan

Sam,

What trouble? If you would bother to take the time required to carefully read what I wrote you would see that I suggested combining a good UCA with O.K. isolation and excellent rotational freedom with FRPP GT500 LCAs to minimize tire and road noises, vibrations and harshness issues while providing enough rear axle location to eliminate axle hop. I even explained why and how it works. If you need more explanation keep reading.

There is no way around it, poly is not an ideal bushing material for a bushing where the bushing is asked to flex and/or compress repeatedly due to the fact that poly bushing materials do not recover well in this sort of use. Poly will cold flow and permanently distort like Delrin does in a surprisingly short time period when left under load or stressed.

Aside from the flow and distortion problems (and the need to inspect and replace poly bushings frequently to keep your suspension working right) poly bushings only provide modest isolation compared with OEM rubber bushings. In other words poly bushings make your car noisier inside the car by transmitting more NVH through the bushing joints. Delrin is an even worse isolator than poly is when used as a bushing.

So why would you suggest using an even worse isolation material (Delrin) control arm material when the Johnny Joints use the quieter poly material? In the poly bushed spherical rod-end design which Currie actually invented, there will be no difference in axle location. But you will find a decrease in NVH inside the car over using the Delrin spherical joint bushing material like UMI and other Delrin spherical joint bushing copies of the Currie Johnny Joint.

For many street cars people keep adding "stuff" to their suspension and eventually they find that their cars have become too loud and too harsh. My suggestion was for a realistic easily daily driven car that the wife or girl friend won't complain about if they have to ride in it or drive it. I say why not be realistic about suspension needs based on actual car use?

For modest horse power cars like N/A GTs the FRPP GT500 LCAs work very well in conjunction with a good UCA to locate the rear axle. This is because the UCA actually takes the most load from the rear axle when accelerating or braking due to the geometry of the control arms. This is why folks who only replace their UCA almost always eliminate or significantly reduce wheel hop to the point that they do not have a need to replace their LCAs. The trick is to use the combination of a good poly UCA bushing like the Currie UCA and moderately firm rubber LCA bushing to control the rear axle. This keeps the car under control and at stock NVH levels in the cabin.

This is why in my previous post I recommended that the OP just buy the UCA of his choice and add a Johnny Joint OR just buy a Currie UCA that comes with a Johnny Joint already installed. Nothing complicated here if they don't want to have more options for their UCA design. You know like using a longer UCA and changing the upper control arm pickup point to reduce wheel hop under braking and improve IC under power at the same time on a lowered car with good tires.

Cheers/Chip

Sam Strano

Poly is sticky, delrin is self lubricating. Noise from rod-ends and spherical bearings comes from play in the joint itself, not from the material being used as a race. The clunking noise that can be associated with such parts is very similar to the clunking you get from a loose wheel bearing. Snug it up, get rid of the play and the noise abates. Roto-joints allow you to tension the ball, rod-ends don't.

In fact I submit the the UMI Roto-joint is superior to the Currie Johnny-joint for the very simple reason that the races are NOT urethane. If you want ride isolation, then stick with the soft, compliant rubber bushings. If you want to get rid of bind, then having your bearing (the ball) ride in a sandwich of urethane isn't the best method. Better than a regular poly bushing? You bet. But anytime you have urethane and metal that have to touch and want the ability to rotate, you need to lube the urethane (because even hard urethane will want to "grab" the metal). Delrin is harder, and slicker, and in fact self-lubricating.

And the J&M type arms with urethane on urethane are even worse (that really wants to stick). The idea is fine, the execution of it is IMHO hampered by the materials used.

Also, I want to point out that UMI looked at Johnny-joints for use in their parts. And ordered more than a few at various times--before they decided to make their own... and let's be honest here F1Fan. Look at the two items. The differences are two: The race material is different, and the UMI versions are tension-able, the Currie's are not.

F1Fan

Poly is no more sticky than Delrin is when you lube them up with the right grease as is required even with the UMI spherical joints. Grease is used to protect the bushing materials from contamination not really to lubricate them. Mechanical noise can come from loose metallic joints but the noise I am speaking about is worse. It is the continuous transmission of tire and road roar through the bushing material itself that is the problem with both poly and Delrin. Poly transmits much less vibration through the bushing than Delrin does. If Delrin is such a great bushing material all the OEM's would be using it. Delrin is a good material for certain uses just as poly is but for the most part Delrin bushing went out in the '80's as suspension design got more sophisticated and required multi-axis movement from chassis pickup points. A well maintained bushing should not need to be "snugged up" to get rid of play if the materials are suitable for the job at hand.

Did you bother to read the OP's posts? This is for a street car not track car. Street cars need to retain as much isolation as possible to remain streetable and livable day in day out. Delrin has almost zero isolation of transmitted NVH when compared to poly material.

You have it wrong. The major advantage of the Currie Johnny Joint is the fact that it is bushed with a poly material for better isolation than Delrin could ever provide. It is the only spherical joint designed for isolation and has 30 degrees of free movement. If you think absolute location is required for the OP's street car application then recommend the right stuff and recommend Aurora lined rod-ends or whatever you have to sell and be done with it.

No disagreement here. J&M's so called polyballs are a joke as I have posted many times in the past. The problem is not so much the fact that they used poly on poly (this is an easy to solve problem) as much as the fact that the designer somehow managed to eliminate any advantage they had using a spherical ball by restricting the movement of the bushing sleeve in exactly the same way as a conventional solid poly bushing does. Polyballs have more B.S. marketing dollars spent on them than engineering dollars. If this is an incorrect assertion then they have pretty poor engineers working for them.

So UMI just like Hot Parts/J&M ordered some Currie Johnny Joints before trying to copy them, what is your point? You believe that UMI's copy of the Currie Johnny Joint is better isolated and can articulate farther? Go read up on isolation characteristics of poly vs. Delrin. Then go read the specs for the various spherical joints in question. As far as the force needed to rotate the joints in the real world once they are broken in there will be zero difference in the force required to move these joints. They are both going to have low enough friction as to make zero difference in operation on the end of a control arm.

As far as the differences between the Currie Johnny Joint and the third party copies goes the differences are more than simply the bushing material and having an adjustment for preload pressure on the spherical joint of the Delrin bushings. Why do you think the Delrin joints NEED to have a preload adjustment and the Johnny Joints do not? If durability and ease of maintenance is not important then go ahead and overlook the forged body of the Currie Johnny Joint and the precision CNC'd inner body and the use of a single inside clip to retain the spherical assembly. If you keep them greased the Johnny Joints do not require any adjustments.

Cheers/Chip

908ssp

[QUOTE=F1Fan;7056769.....

No disagreement here. J&M's so called polyballs are a joke as I have posted many times in the past. The problem is not so much the fact that they used poly on poly (this is an easy to solve problem) as much as the fact that the designer somehow managed to eliminate any advantage they had using a spherical ball by restricting the movement of the bushing sleeve in exactly the same way as a conventional solid poly bushing does. Polyballs have more B.S. marketing dollars spent on them than engineering dollars. If this is an incorrect assertion then they have pretty poor engineers working for them. .....[/QUOTE]

The J&M Polyball joints are not made from Poly and Poly. Sorry that is simply wrong. They are poly ***** with rubber, soft black rubber about the same durometer as the original Ford bushings. The rubber easily gives when torsion loads are applied but the ball in the center prevents for and aft movement of the axle.

Sam Strano

Yet again, we have to disagree on the level of "stick" that most urethane has vs. delrin. There is a reason that urethane bushings are always supplied with some sort of lubricant. You can use it with Delrin if you want, but it is not required.

Riptide

Is the following correct:

The UMI roto-joint is very similar to the Johnny Joint minus the race material. The UMI requires adjustment ("snugging up") and the JJ does not. Both are supposed to be greased although in the case of the UMI you might be able to get away without doing that. The UMI joint will be noisier than the JJ.

So if that is all correct. Is there any reason to choose the roto-joint over the JJ? Which one would tend to arrest wheel hop better or are they pretty much equal in that regard?

Sam Strano

The Roto-joint doesn't require adjustment all the time or anything, it's an option.

What gets rid of things like wheel-hop is getting ride of play. The stock bushings are soft and allow movement--too much movement. They do that for NVH purposes. If you have a metal bearing/ball in housed in a softer material, like rubber that center section will move more than it will if it's housed in a stiffer material like urethane, which will in turn move more than if it's housed in a stiffer material like delrin.

When you have softer urethane around the ball it takes up noise, so a few thousandths of play that would cause a clunk in a rod-end, or in a delrin raced joint likely won't make that noise to the same degree when the softer urethane is damping the movement. It's like hitting a wall with a dead blow hammer vs. a steel hammer. The dead blow will be more quiet---because there is more give in the system. Also, remember delrin is a plastic, not steel. It's harder and slicker than urethane, but not metal.