I am trying to understand this?
 

I am well aware that using aftermarket trailing arms reduces wheel hop. And I know that changing that rubber bushing to the round spherical heim joint style will eliminate flex, that's why I bought them. But, the other end of the trailing arm that bolts into the lower control arm is another rubber bushing... ?? Doesn't make any sense to replace just one.
I understand that under load that forward bushing takes the hit from the launch, but isn't there just a tiny amount of deflection backwards that puts stress on that back bushing?
I haven't found anyone discussing this so I'm guessing it plays a very minimal part.
Also, don't they make a spherical end that REPLACES the one in the control are? By replaces I mean aftermarket, not stock Mazda.

Re: I am trying to understand this?
 

No, they're not. They're pillow bushings, or in other words, a spherical metal bushing of a slightly different design. I suspect that the reason you thought they were rubber bushings is because they have rubber dust caps.

In the first picture below, you can see the pillow bushings and rubber dust caps at lower left, next to their positions in the lower control arms. In the second picture, you can see a close up of one of the pillow bushings packed with grease prior to installing the dust cap, and one already installed.

https://www.rx7club.com/forum/attach...postid=2141226

https://www.rx7club.com/forum/attach...postid=2141272

No, the only replacements are Mazda OEM, and as I mentioned above, they're already spherical metal bushings.

Thanks Jim, ya I saw the dust caps and thought it was all rubber. But How do I determine how much play, is too much play, and how often do those bushings themselves get worn out?

For the pillowball bushings if you can detect any play at all then they need to be replaced. As for how often they go I'm on my second set in about 60,000 miles but I spend a lot of time at the track on race rubber and so would expect to wear them out much more quickly.

Of special note in the photos above are the Mazdaspeed rubber bushings vice nylon ones :D

Huh?

Not understand you say what, I.

-Max

There are no Mazdaspeed bushings in the pictures. All of the bushings to the right of the trailing arms are custom pillow bushings with the exception of the Mazda OEM pillow bushings for the rear upper control arms (shown with separate dust caps and C-clips). Everything to the left of the trailing arms is Mazda OEM.

https://www.rx7club.com/forum/attach...postid=2141226

More pics of the OEM pillow bushings...

http://home.gci.net/~jimlab/images/B...Bushing003.jpg

http://home.gci.net/~jimlab/images/B...Bushing007.jpg

OEM rear upper control arm bushing on the left, Nylon on the right, custom pillow ball (note articulation) in the center.

https://www.rx7club.com/forum/attach...postid=2048116

All this and more available here... :D
https://www.rx7club.com/showthread.p...5&pagenumber=1

You know what though, these little pillow ball bushing designs seem so wimpy, since most people change them often anyway. The actual spherical rod end design,(especially with a large one) is a much stronger setup to take beatings.
What Mazda should have done if they were going to keep this design is gone with much larger pillow ball bushings to take the abuse, or offer an upgraded stronger one in it's place.
It's not rocket science that these little ends and the rubber bushing design will wear out fast, it seems like another chance for Mazda to make a killing on replacement parts.....that still have the oem strength.
Anyone with me on this?

What's often? Most people get 60k or more miles out of them before they need replacing.

Maybe you should ask people how many miles they get out of the rod ends in their aftermarket toe links and trailing arms before you make a decision.

I'm concerned about this.

Jimlab and DamonB - what trailing arms and toe links do you use?

Well it's to late, I already have the aftermarket toe links and trailing arms on the car. And when I took the stock trailing arms off, they had a slight bend to them, aftermarket is much stronger.
I thought that the rod ends lasted as long as no dirt got in there?

Stock trailing arms with jim's solid bushings at the front of them. Stock toe links with stock toe link bushings. Try as I might I could never make a rod end type toe link live anywhere near as long as the stock ones. Aftermarket trailing arms with rod ends in them have the same problem IMO. Rod ends just can't handle the grime and grit that a daily driven car sees. Adding dust seals helped tremendously but life was still not even close to stock parts. If you go with rodends a good 3 piece teflon lined part is a must for longevity and those are not cheap.

It's no more expensive to replace the stock toe link bushings than to "upgrade" to aftermarket toe links. When you go aftermarket you'll have to pay for a new alignment too. If you stay stock and label the left and right sides you have no need to realign the car afterwards.

Most of the wheel hop problem comes from the trailing arm bushing. Adding jim's bushings here will cure the majority of it and diff mounts will take car of the rest. I have spent a lot of track time on both aftermarket and stock toe links and I can tell no difference between them at all except that the stock ones don't wear out near as fast.

That's the key and it's tough to do. Rod ends are metal on metal and their tolerances will open up very quickly with even the least amount of contamination as the bearing surface is actually quite small. Make no mistake, a rodend is a very strong and tough part. They are not designed for daily use though as they are just too easy to wear out.

Once again, I think you're mistaken. The stock trailing arms are forged pieces which are extremely strong. If they're bent, it's most likely because the car has been wrecked or abused.

As Damon stated, the bearing surface is fairly small. Even without contamination, load is placed on a very small area, especially with the trailing arms which only move through a very narrow angle as the suspension cycles. The best solution for aftermarket pieces is to get them with or install dust seals and pay extra for 3-piece rod ends, as Damon mentioned. I paid a little extra for the Rotary Extreme pieces which include both features, but I don't expect my car to see a lot of mileage and very little wet weather, if any.

I also have a set of custom pillow bushings installed in stock trailing arms, and I have a pair of my Nylon trailing arm bushings being made as part of the most recent group buy, so let's just say that my mind hasn't been totally made up yet where the trailing arms are concerned. :D