i think my coffee is not working today...
https://cimg9.ibsrv.net/gimg/www.rx7...0a24f2b563.png

My 83 GSL had front oil cartridges prior to my replacing them with Tokico blue. The rear were the Tokico black, FA01 28 700A but stamped with the "System of Dr. deCarbon" which the MazdaTrix OE ones do not seem to have.

https://cimg3.ibsrv.net/gimg/www.rx7...4a4f25748a.jpg

Dr DeCarbon? That would be a good username!

Again, I appreciate the insight. Is it necessary to replace the strut mount? thank you ...

Do it. All over ebay at $30-50 each. Never cheaper, never easier than now...


Stu A
80GS
AZ

Late to the party here but I wanted to offer a dissenting opinion on rear suspension modifications.

I don't buy into the fear around poly bushings in the rear causing "binding" based upon experiences with my vehicle and other local FBs. And even if you do, polyurethane bushings in the rear are massively superior and safer than wasted stock rubber bushings that could be 35-41 years old, if you cannot find adequate replacements. They will change how the car can drive at or close to the limit, however.

The fact of the matter is if you convert to polyurethane bushings instead of rubber you doing more to ensure that the axle stays located where it is supposed to be. This can reduce wheel hop and increase traction. At the same time, without the bushing flex you remove the car's ability to have any passive rear steering, which can allow the rear of the car to step out and over steer easier. This has never presented in a way that was unexpected to me.

"Binding" would indicate that the suspension wants to move (up or down) and that it cannot, causing the car to behave unpredictably, and that the poly bushings are to blame. They will of course resist movement more than the rubber bushings. One experiment that I have done previously was to note from fully compressed to fully decompressed how far the control arms can move. Bolt a poly bushing equipped control arm in place, greased and torqued to spec, and by hand with a bit of effort, see if that control arm can move through the range previously measured. It did for me, so I was satisfied that the bushings alone would not be the cause of any "binding."

Polyurethane bushings will make your suspension louder. If such bushings are installed only in one or two places, it is not really noticeable. If you install the entire energy suspension kit, the noise over big bumps will be considerably louder. Something people only tell you after you install all of your new energy suspension bushings is that the red ones are prone to squeak and the black ones are not. Mine are red and they squeak sometimes, but I cannot speak to the black ones. I assume the noisy ones displaced their grease upon installation and are now dry.

Typically the "binding" in the rear suspension comes from the watts link on a lowered car. The arms need to be shortened so that the watts link is not bound up with the weight on the wheels and to ensure the watts does not run out of room to move under suspension compression. As well, those watts bushings have to twist a LOT more than the control arm bushings throughout suspension movement. The watts link design is often discussed as being poor, which is why places like techno toy tuning offer a panhard bar to replace it. (I haven't found a reason to buy one myself)

I can only quantify these claims with my experience over the last 8 years spending way too much time messing with my rear suspension and the many miles of hard driving I've put on the car. YMMV, but with a fully poly rear in my car which is lowered at least 2 inches I have never experienced suspension binding or unpredictable movement from the rear of the car, either on the street like at the tail of the dragon or on an open lapping day. To me, the car felt a lot more solid after installing, and it is very apparent that it drives differently than cars with stock original bushings.

Rear wheel bearings aren't something I would bother messing with unless you are having a problem. They're pretty stout and not prone to the same type of wear and damage as the front bearings are.

Good luck with your restoration! I hope the car you build drives exactly the way you want it to.

Thank you for the comments!
I've asked a friend who owns a shop in Raleigh to provide a quote in terms of how much it will cost to do this work. I really appreciate the different views on the full poly kit for bushings, too. I live in NC and do hope to take the car to the Tail of the Dragon at some point. :)

Adding to Sommatt's full poly comments, and the others as well, I don't plan to lower the car, other than what new springs, shocks, and struts will give me. (Which may raise it, considering the age of the current components). Will full poly vs some poly make a difference in this case?

the next car in line is an FB, and since the car we're starting with is pretty rough its kind of a low budget beater. its going to get poly bushings, but the suspension is going to be stiff too, hopefully the stiffer suspension moving less will reduce any binding problems.

I agree with Summatt, I've had poly for 5 months or so and the car feels much more solid. I'm not racing it or for that matter pushing it beyond the cars limit.

Thanks. This is definitely a street only car. As much as I'd love to build it up; it is far too original. I really need a second one. :)

The more poly you add the noisier the suspension will be. Consider it in places where you want compliance vs where you want it to be solid. For example in the front end, I'd much rather poly than rubber in the tension struts so the suspension has a harder time moving forward and backward, but rubber in the lower control arms may improve ride quality and reduce suspension noise, meaning how loud the car is when you crash over bumps.

You might just be straight up unable to buy new rubber bushings for some places on the car.

I'm always stuck on the price of an energy suspension kit. The value is unbeatable.

On a sub-2000 mile per year car the noise is insignificant. On a 20K per year daily driver, its a totally different story. My Subie has rod-end sway bar links and zipping around the backroads where I live I dont notice. But on my 100mile daily round trip, stuck in city traffic, if I'm grumpy, I notice every click and clack. I dont really care about suspension noise on my RX as long as I know everything is tight and not working itself apart. I do care that the rear end bushings' softness is integral by design, by Mazda, and proven by countess racing teams.

Yes a more "solid" rear end is very noticeable and positive. But the geometry of the links' arcs makes the link end HAVE to move or flex, as they dont move in the same arcs/relations to each other.
I put T3 solid links all over my rear, and noticed (working on it in the garage) that it didn't articulate like it should. If I tried to jack up one wheel (lifting on the axle tube) it would barely come off the ground before the whole rear wanted to lift, like the suspension couldn't flex. I was very precise when I adjusted the links to proper length on the bench,, so I dont think that was the problem. The rear as a whole had some movement if I stood behind the car and pushed down on the tail. But trying to move just one tire it was noncompliant. I put it on stands and took off the springs/shocks and the axle didn't flex much. I put stock upper links back on and got much more articulation. That was all the proof I needed of what im talking about.

I know solid rod-end links are much more extreme than the uerethane bushings were discussing here but its the same principal, just taken farther. Jim Susko (G-Force racing) explains it very well in his 3-link book "Setup and Tuning of the early RX7 suspension, from A to Z". The rear link bushings (with the factory 4 link design) must have some give, or else they cannot move in their full natural arcs without "binding" to some degree. How significant that is to your driving style is up to you I guess, but as you hear all the tales of "snap oversteer", caused by this binding, I think its worth considering if you plan to modify the rear end.

Note - My first '85 FB was all stock and I drove it very hard and recklessly, and never experienced any snap-oversteer. The rear was easy to get out if I wanted. But it never did anything unexpected. But now that I'm rebuilding and modifying t he rear links on an FB, I want to be careful and not set myself up for trouble. That's why I care about this topic.

Maxwedge,

I want to challenge your conclusion about rod ends and articulation for a second, and maybe correct me if you feel I am wrong. I know you understand what I'm saying, but I'm spelling it out for anyone reading along.

T3 rear links are built with rod ends, which by definition have free movement everywhere as long as they don't crash into themselves and are completely unaffected by the angle that they are operating at. Meaning that if there was no car in the way, you would be able to turn a rod end control arm all of the way around with very little effort.

This is opposed to a bushing which will always try to be in its installed position and progressively add more resistance the further away you get from it, until the bushing tears or spins. Some refer to it as binding, when the vehicle cannot exert more force over the suspension to allow it to move more. On stock bushings you will be on your bump stops well before this point.

Knowing this a rod end link is significantly less likely to ever cause "binding" and would allow the suspension to fully articulate with considerably less force applied (without having the resistance of 8 control arm bushings fighting the articulation).

That just has me confused as to why you would have more articulation out of a bushed rear end. Do you suspect the T3 rod ends are so tight they allow no suspension movement? It is normal for these things to be very tight when they are brand new, but they should always allow movement. Enough that when your shocks are not installed and no watts link attached, the control arms would be almost vertical and the axle would have ripped the brake lines off of your car. I don't own T3 rear links so I won't speak to their construction or quality, I just have familiarity with aftermarket suspensions.

What rod ends cannot do is allow for any passive steer of the rear end. With no movement in the bushing in any direction, your rear wheels will always be in line with the chassis. A rubber bushing equipped rear end will flex naturally in the opposite direction if your steering wheels in a hard corner which helps to tighten your turning radius. And they make your car miserably uncomfortable and loud.

An example of large articulation out of rod end suspension can be seen on the front and rear suspensions of any kind of trophy truck or buggy. Their front suspension rod ends work an almost 90 degree range and they move freely when the shocks/springs are not attached.

https://cimg2.ibsrv.net/gimg/www.rx7...8681867569.jpg

So the the twisting of the bolt and sleeve inside the rubber bushing is one part of this discussion, in that it has to happen for the axle to articulate. And yes a rod-end serves the same purpose but with a smoother and wider range of motion. Agreed. There is no binding in a spherical rod end, at least not until the mounting bolt has reached its full rotation, but I'm not talking about that at all. I agree the rod ends themselves don't bind.

There is also little to no (noticeable) binding in the stock rubber bushings. That's not where the binding comes from.

The truck in your picture is using the rod-ended links in place of A arms and does not relate in any way to the geometry of our rear end. A better comparison to our cars would be a simple hot rod parallel 4-link like this....
https://cimg7.ibsrv.net/gimg/www.rx7...59eb37c388.jpg
This car has a much better trailing arm setup than our cars and still using rubber bushings. It needs a panhard (or watts) to locate it side-to-side but there's no binding or funny business to its articulation. The links are parallel to each other looking down from on top, and parallel (or close) to each other from the side. This can be used on front or back (like a 4x4 application) and is very effective. But its a packaging problem for a small, cheap full-bodied sports car.

Rock Crawlers often run full triangulated 4 links, where both the upper and lower links are drastically angled but in opposite directions of each other.
https://cimg1.ibsrv.net/gimg/www.rx7...7349c0488b.jpg
This allows drastic articulation and self centers the rear end without a panhard or watts. Hella tough with no binding, but again too big for a small car.

*But what do you get when you use lower links straight to the chassis, that swing up-n-down in a straight line with the chassis, and then use upper links that angle out away from the body? Well those upper links outer ends (rear ends) move outwards as they swing through their arc. The lower link seem to get longer towards the rear of the car as they arc, but the uppers "get longer" outwards as they arc. The steel mounting brackets on the axle aren't going to move, and the rods can't actually get longer or shorter, so something has to stretch, squish and twist. And that is the purpose of the rubber bushings. Not only are they twisting but they are pulling longways and pushing shorter as the trailing links are trying to swing in different directions, even though the mounting points cannot change their distance from each other. IE the upper and lower points on rear axle can't move, but the different length links swinging in different directions are trying to move those points away from each other.

This doesn't happen on any of the setups you or I pictured above. I have never broken any of these parts on my car. But I remember @Peejay talking about trying all rod ends and ripping the mounting points off the body of his car. The geometry Im talking about is the reason for that. I dont think the stock setup has anything to worry about. But start taking out the necessary twisty/squishy bits. And something else will break, or bind, or bind then break.

Rubber has a limited range of movement, and it does have a spring rate, but it has zero friction. it also absorbs shocks, by deflecting
Poly has an unlimited range of movement, no spring rate, but high friction. it absorbs shocks, deflects less than rubber
Rod Ends. unlimited movement range, no spring rate, no friction (unless assembled wrong), transmits shocks

the rear suspension has a lot going on in it at once, and we say binding because as you articulate it, the spring rate goes up to the point where the thing doesn't move anymore, binding. there are 13 bushings in the suspension, and they are all rubber and all have a small spring rate. you have to add to that, the pinion angle changes as the suspension goes through its travel, so the Watts links have to twist as well as go up and down. the two upper links are short and not parallel so in roll not only do the bushings need to twist, but the axle housing is actually having to change toe, so the upper link bushings need to pivot, twist and get shorter and longer, the rod end cannot do this, even rubber has a hard time.

Mazda's rubber is soft when its new and hardens with age, so the best alternative for the upper links is just to buy new. the rest of the suspension is less picky

^^^That^^^. About 10 years ago the trend on this forum/community was to drill holes all over the rubber link bushings to try and restore the softness, because those bushings get hard with age ( as J9 said ). As they get hard the "binding" effect gets more pronounced. Which is not good. I guess the economy has just gotten better because now we can afford to replace the upper links with new, instead of ghetto-rigging them.

So I dont understand why you would go through the trouble of replacing them with a component (eurethane) that will increase the negative traits of our already compromised rear end geometry. I completely understand the general benefits of eurethane and have used it on past vehicles. I think if used in the lower links it would do what you expect,, and Im positive it would do wonders in the front of our cars. Because in those places its reducing deflection,, which is the goal.. it makes things less squishy and gives a more direct and positive movement of the joints (steering feel and suspension movement).

But our rear upper links are doing multiple things (as said above) and MUST deflect, and twist, and stretch, and compress, for the rear to move as Mazda designed it. That infamous "bind" happens when the rubber gets to the limit of its squish, as J9 notes, and just stops moving in that/those directions. !BIND! Most street cars will never feel it, especially on OE links. But the harder that bushing gets, the sooner in the travel it will occur. So why make it happen? Urethane bushings are good. Just not in the upper links.

By replacing the upper links with solid rod ends I accidentally removed about 70% of my rear suspension's travel. If they were parallel to the lower links that wouldn't have happened,, and less than a month after I complained to T3 about it,, they started offering a spacer kit to move the front end of link outboard, towards the tire to make it parallel to the lower.

Putting new stock upper links back in gave me the movement back, and still allows easy breezy movement and adjustable pinion angle. I also have rod-end watts links. These have the full swing of, and better twist than the stockers without the (minimal) deflection of stock. Win win.

There are 10 ways to skin a cat, but gluing a wig to its head is moving in the wrong direction.

So, $150 for stock or $230 for T3 (links and relocatation). With that in mind it'd seem like stock would be the best route, less expensive and should last basically the remainder of the life of the car, lets say 30 more years. This'll probably be the route I go just because the new rubber should last "forever" especially if well looked after and the severely reduced yearly mileage.

$150 : https://www.tascaparts.com/oem-parts...link-887128200
$230 : https://technotoytuning.com/mazda/sa...-sa-and-fb-rx7

But let's say the T3 option was the same price or less. Will relocating the link to the outside solve all the problems? If it's articulating correctly there shouldn't be any added stress added to the mounting point, right? I know moving from center to outside should cause some stress but if before the slanted link was pulling, pushing, twisting. Is it still doing that?

I'm largely ignorant to suspension. I understand the issue but I don't have the experience and forethought to realize all the scenarios.

Yeti, that's an excellent question about the t3 spacers.

I wonder and worry about it too. When I complained about the "binding" I found with their upper and lower links installed they told me nobody ever complained before, but that all their shop guys and cars used the spacers.

:dunno: Spacers? What spacers??

They told me about what they did, and I asked if it put stress on that mounting bolt since the rod end would only be braced on one side, and might act like a lever against the thin sheetmetal. I believe that makes it a "single sheer" vs the less likely double sheet forces the mounting bolt would face under hard, "peejay" type usage. Would the hole get ovalled out after a while?
They said all their cars were rust free Cali cars and hadnt shown any issues yet. As I mentioned earlier, they started selling those spacers very shortly after my call.

My mounting plates show some rust where they join the body (easier seen once I pulled out the cargo bins). I was afraid of the metal being too weak here, so I went back to new OE uppers. I figure it can't be any weaker than when I bought it, and like I said, it gave me more flex than stock (since my lowers and watts are T3 rod ends). Someday I'll have a body guy reinforce this area and I'll try the t3 spacer kit.

New question! Hopefully a good one! How can I tell if the bushing is bad? I understand if it's ripped, non-existent, so on. I'm going to get the parts anyway as they'll soon be NLA. But maybe I'll put them away instead of use them if what is there is completely fine.

If cracks are bad are there an acceptable amount of cracks or an acceptable location?

If I'm being stupid asking these questions let me know.

that is actually a perfectly valid question. some bushings like the front control arms, are so easy to change its almost not worth doing the autopsy.

i changed bushings on an FC recently, and the old control arm bushings were old, and they had some external cracks, but cutting them in half revealed that the cracks were skin deep, inside of the bushing was totally fine. we're changing them because car needs to feel razor sharp (its getting comp bushings)

This is a great thread.

Yep. Thank you all for the responses and the education! :)

Looks like control arm assemblies are on the list of replacement items. Any recommendations?
This is a street car; not a track car. I'd like to keep the overall appearance as stock as possible - but I figure things underneath aren't generally seen and have not real impact on the car's appearance (other than maybe ride height).
I've ordered Racing Beat springs, KYB shocks/struts and I was able to get my hands on a Moog idler arm.
For the control arms - is there a factory option still available? OR do I want the $$$ techno toy options - and if so, what all would I need?

thanks - as mentioned - total noob when it comes to suspension.

Ebay is listing NOS arms for $130-200 each now. Mazdatrix? and dealer of course. Others have dropped the original arms, cleaned them up and pressed in new joints, but this seems to be hit and miss, since the arms were not designed to have all components replaced (...?).
Nice catch with the Moog.
Stu A
80GS
AZ