Johnny Joint rear control arms vs non?

[The_Humbler]

Anyone have any measureable data that proves that the rear control arms with Johnny type joints are "better" in some way than the non-joint arms?

Just wondering if they're worth the $. They're pretty, but I'm not made o' money.

[parsonsj]

We're using Spohn's Del-Spheres on Unfair:

http://iimuchfabrication.wordpress.c...s-del-spheres/

[The_Humbler]

Thanks.

Prices sure are better, seems like they'd (arms themselves) would flex more. Anyone have any data on these? Anyone using them (driving already).

[parsonsj]

I used them for a year or so on II Much before I sold the car. They worked exactly as advertised. Low NVH, plenty of articulation. Highly recommended.

jp

[wmhjr]

I think you're going to find it very difficult to come up with meaningful data suggesting that Johnny joints are or are not better. To me it's obvious that they're better than an oem type. The question is how much and will you notice it. I think the answer to that will be based on a subjective and not an objective opinion.

Btw - I'm using the currie rears with Johnny joints and they work great. However the car was built that way and I have no idea of what the difference is. I really like the spherical joints above. Anything to me is better than oem.

[The_Humbler]

I would agree. Just hoping maybe someone did a "back to back" test of some sort. Probably not much in the way of differences. I know I don't want poly bushings, as you can hear them miles before the car gets there.

Looks like I'll look at the Spohn stuff closer.

[ErikLS2]

Prior to John's comment I was concerned about NVH on the Del-Sheres but they seem like a no brainer to me now. However, a friend has used these poly versions from Pete & Jakes with good success.


http://www.peteandjakes.com/parts/pa...bleBarEnds.htm

[wmhjr]

I can tell you that the currie stuff I'm running with Johnny joints combined with solid motor mounts and poly body bushings result in excellent nvh IMHO. I used a good deal of second skin damp pro, and the actual exhaust isn't real quiet, but the noisiest thing in the car other than that is probably the tremec.

[TBART70]

I'm not sure but the thru-bolt size is alot smaller in comparison to the spohn's.

[CRead01]

Personally I have the johnny joints but I was also looking at the spohn setup. The reason I went with the johnny joints is because they have a narrow version that fit perfectly into my mounts. If you havn't built your mounts yet then it probably wouldn't matter. I dont have any idea which one is better between all of the different ones but I do believe that the johnny joints will wear longer.
just because of there reputation on rock crawling and offroading.

[The_Humbler]

My mounts are all stock GM A-body, so that won't really matter.

I guess if no one's done a back to back then we're done here!

[wmhjr]

My mounts are all stock GM A-body, so that won't really matter.

I guess if no one's done a back to back then we're done here!

Let's face it. It's pretty much impossible to find the info you're asking for. Most of the people installing rear arms with either Johnny joints or Spherical joints do so while making many other changes. Mine went from completely stock (which frankly I never drove on this particular car) to all new front and rear, sway bars, springs, etc. You need to look at the cost, at least assume you're trying to build it once rather than several times, and determine whether the increase in cost makes sense. Didn't seem like much of a premium to pay from my perspective, considering the other advantages of the Currie system but we all have to make our own decisions.

[The_Humbler]

Ya don't know till ya ask..

I would imagine someone trying to sell one product over another would have that data if there truely was a difference. Seems to me it would be quite easy for anyone carrying those control arms and another brand, or even stockers on a customers' car to do some testing and get the answers.

[monteboy84]

I guess if no one's done a back to back then we're done here!

Well, plenty of guys have made the switch from one to another with good results, it's just that there really is no good way to quantify the difference. It's plain to me what makes them better, with freed up movement, better articulation, and more positive axle locating in a triangulated 4-link.

-matt

[The_Humbler]

Can't claim "good results" without measuring each type of control arm against each other.

I'm glad they're quiet, and that does make a difference, but I didn't ask about that...


I'm not sure any of the rest of what "makes them better" has been measured either. In fact, more movement and more positive axle locating would seem to run contrary to each other. And, if they do indeed provide such benefits, is it enough to warrant the added cost?

Not sure any of that has been answered on this post.

[parsonsj]

In fact, more movement and more positive axle locating would seem to run contrary to each other.

Not so. Axle location is due to linkage arrangement. It has very little to do with bind in the connection points.

jp

[The_Humbler]

But wouldn't more articulation lead to less of that? I understand that the ends don't move forward or back, but if there's more movement....

[parsonsj]

Nope. Live axle rear ends must have a linkage arrangement to fix the rear end in place independently of the articulation ability of the connection points. The design must allow for body roll -- that's why you need articulation. But the ends of the linkage arms do not provide any part of what keeps the rear in place as you drive down the road.

In fact, the popular GM A-body rear end (triangulated 4 link with the upper arms pointing outward from the housing to the chassis) is actually inherently bound. If you were to put steel rod ends on the ends of all 4 linkage arms, the rear end couldn't roll at all. It's the rubber interfaces on the ends of the linkage arms (plus some flex in the stamped steel arms themselves) that allow for movement. That's exactly opposite your statement above. The more articulating ends allow less movement.

jp

[The WidowMaker]

mark at scandc has done some seat of the pants testing. id call him for the actual story, but my memory recalls something like; swapping out one end of the lowers and taking the car out on a known high speed turn. with the rear of the lcas changed to jj's the snap oversteer caused by the stock binding was limited and allowed the turn to be taken faster. when both ends were swapped the speed again increased. again, subjective testing, but hes a very good resource to call.

[wmhjr]

Ya don't know till ya ask..

I would imagine someone trying to sell one product over another would have that data if there truely was a difference. Seems to me it would be quite easy for anyone carrying those control arms and another brand, or even stockers on a customers' car to do some testing and get the answers.

What exactly would you be looking for? Proof of free articulation increases? Well if you want proof or comparisons, that I can attest to. But proof as to the impact it has? How would you quantify it? Do you require objective proof for every part? Tires? Lighter components? Oil? Sometimes you have to look at the design, the physics, and listen to the guys who are very successful.

I think it's perfectly ok to say that there just isn't enough demonstrated proof to warrant you buying them. Not so much to say that since there isn't objective measurable data that they're not better.