Bush Timing -- Information and Nothing but Information

[Dznts]

Sounds good. I'll double check with her tomorrow.

[HumanWiki]

Pete.. Sent you a quick PM.. I'm having a bit of an issue that I need to speak with someone about.. I can explain in more detail later.

[JusticePete]

Originally Posted by HumanWiki

Pete.. Sent you a quick PM.. I'm having a bit of an issue that I need to speak with someone about.. I can explain in more detail later.

We are on it.

[HumanWiki]

Originally Posted by JusticePete

We are on it.

As usual, much appreciated sir!

[JusticePete]

Gixxer 1000

[Info@PeddersUSA.com]

for cid067

[Rob@WretchedMS]

bump for a couple people

[Norm Peterson]

Since this thread got recently bumped (sorry, SSE 4 2SS, just that I get a bit inquisitive and somewhat opinionated about this stuff)

Originally Posted by mhog
Do you have to bother loosening if it’s a poly bushing?

Originally Posted by JusticePete

No sir, the ferule in a urethane bush spins freely so timing is not required.

If the ferrules (aka "inner sleeves") in urethane replacement bushes are shorter than the urethane pucks in the as-installed condition, what will make the ferrules spin independently of the urethane? I realize that in this situation the poly will spin freely inside the brackets whether the ferrules spin with the poly or remain fixed with respect to the brackets.

At the dragstrip it probably doesn't matter whether the sleeves spin inside the poly or not, but for daily driving, autocross, and road course work it might.


Norm

[Rob@WretchedMS]

Rubber bushings tend to have bonded ferrules that are not allowed to rotate in the bushing, thus if the ferrule is twisted off center, it will retain a given amoutn of spring in it.

With the Urethane bushings the ferrules are not bonded to the bushing, but rotate freely inside of the bushing.

when you tighten a bushing, you are tightening the ferrule, not the bushing.

so in a case where the bushing is longer than the ferrule it would either be an incorrect ferrule, or a design element (typically the bushing would not be trapped on the outside of that area by the jacket.

i'm not sure if i'm answering your question or not,
is there a specific part that you are talking about?

[Norm Peterson]

Originally Posted by Rob@WretchedMS

Rubber bushings tend to have bonded ferrules that are not allowed to rotate in the bushing, thus if the ferrule is twisted off center, it will retain a given amoutn of spring in it.

With the Urethane bushings the ferrules are not bonded to the bushing, but rotate freely inside of the bushing.

when you tighten a bushing, you are tightening the ferrule, not the bushing.

Completely understood. If you're simulating the behavior of the OE bushing except for providing a slip surface instead of working the bush in shear, that's exactly how you'd do it. Most OE ferrules are detailed at the ends so that they CAN'T turn.

Mostly, I was asking in reference to mhog's question, which did not refer to any specific bushing, supplier, or part number.

However, nearly all of the polyurethane-bushed suspension links and polyurethane replacement bushing kits I've either seen or heard complaints of clunking about have involved ferrules shorter than the poly.

so in a case where the bushing is longer than the ferrule it would either be an incorrect ferrule, or a design element (typically the bushing would not be trapped on the outside of that area by the jacket.

I get what you're saying about the poly not being trapped in the shell, and that the relative rotation could occur at that surface instead. As long as the link or arm is not undergoing multi-axis rotation or the poly needs to distort to suit pivots on the same arm not being concentric, this is a perfectly acceptable solution. In such cases, the ferrule mostly serves to prevent the poly from collapsing or cold-flowing into the hole over time.

As I mentioned above, this isn't of much concern to a drag racer (which being the bigger part of the performance aftermarket is probably explanation enough).

But trailing links experience multi-axis rotation and components of multi-link rear suspensions don't always feature concentric pivot axes. Hence a too-short ferrule design in those applications tends to produce mostly minor ride quality consequences in a daily-driver and there can be enough extra roll stiffness introduced for the corner-carvers among us to not appreciate.


Norm

[Rob@WretchedMS]

Originally Posted by Norm Peterson

Completely understood. If you're simulating the behavior of the OE bushing except for providing a slip surface instead of working the bush in shear, that's exactly how you'd do it. Most OE ferrules are detailed at the ends so that they CAN'T turn.

Mostly, I was asking in reference to mhog's question, which did not refer to any specific bushing, supplier, or part number.

However, nearly all of the polyurethane-bushed suspension links and polyurethane replacement bushing kits I've either seen or heard complaints of clunking about have involved ferrules shorter than the poly.

I can only comment on Pedders, and i've never ran in to an issue like that with Pedders. The Ferrules do not turn, rotate or move, the ferrules are locked in tight by the bolts and nuts

The bushing rotates around the ferrule, and they are typically the same length as to stop end play.

Originally Posted by Norm Peterson

I get what you're saying about the poly not being trapped in the shell, and that the relative rotation could occur at that surface instead. As long as the link or arm is not undergoing multi-axis rotation or the poly needs to distort to suit pivots on the same arm not being concentric, this is a perfectly acceptable solution. In such cases, the ferrule mostly serves to prevent the poly from collapsing or cold-flowing into the hole over time.

As I mentioned above, this isn't of much concern to a drag racer (which being the bigger part of the performance aftermarket is probably explanation enough).

But trailing links experience multi-axis rotation and components of multi-link rear suspensions don't always feature concentric pivot axes. Hence a too-short ferrule design in those applications tends to produce mostly minor ride quality consequences in a daily-driver and there can be enough extra roll stiffness introduced for the corner-carvers among us to not appreciate.


Norm

I think the corner carvers are more numerous than you think, look at this years fest, we had a lot more cars at the autocross than we did at the drag strip, i think the masses are learning about the fun of turning that steering wheel.

[Norm Peterson]

You and I (and the OEs) are on the same page about how ferrules are supposed to work.

The problem seems to be that most of the other products I've seen aren't. As it so happens, I just this past week finished up modifying the poly-bushed ends of a pair of trailing arms - and these had even been produced by a mfr who has been deep into understanding the importance of suspension articulation for many years (based on off-road and rock-climbing experience). Over 1 mm had to come off the ends of each pair of pucks, and that was just the beginning. Fresh in my mind, as it were.


Yes, there are more corner-carvers now than 20, 10, or even 5 years ago, but there are still many more drag racers and drag-race wanna-be street guys than autocrossers, open-track, and canyon-running guys. So I don't really blame the aftermarket too much for supplying what works better for the apparent majority.


BTW, I'll be keeping Pedders in mind.


Norm

[Rob@WretchedMS]

i'm going to assume that the bushings you have a problem with are not Pedders.
I have 70-75k on the suspension on my GTO, and the bushings are just as good as the day they were installed, the ferrules are free just like day 1. Had the lower arm out about 4-5 months ago, no problems.

When you talk about inexpensive urethane used by most of the other bigger names, they tend to distort over time, and the ferrules tend to seize, squeak.

We offer a full line for your Mustang, Braces, Bushings, Sways, the whole shebang.

[Norm Peterson]

Originally Posted by Rob@WretchedMS

i'm going to assume that the bushings you have a problem with are not Pedders.

No, not Pedders.

This mild thread-jack has been partly because I've found it rare for the need to re-time OE bushings to be mentioned online and partly because I hadn't in over 20 years seen anybody's polyurethane bushings where the ferrules weren't shorter.

I hope you weren't getting the idea that I was questioning the bushing details to be mean-spirited or anything like that. Lack of knowledge, probably, and it seems that this tangential discussion has at least put some tech out there for those who stumble across this thread and read through it all.

One other thing I am a little curious about is whether the ratio of corner-carvers to drag racers is any different over in Australia than it is here in the USA and if that had any influence in establishing the details of the Pedders bushings.

We offer a full line for your Mustang, Braces, Bushings, Sways, the whole shebang.

I really don't want to clutter up a Camaro5 suspension thread with Ford details beyond mentioning that while I'm already part of the way to where I want that car to end up suspension-wise, there are some Pedders pieces that will very likely find their way onto it. Anything else will be privately.

Guess I should thank in absence whatever brought this site to my attention in the first place for that.


Norm