kevinbtz

iTrader: (4)

I have searched for any information on them and was not able to find a place that I could source the parts from to make replacements for the upper control arm links with units that would have spherical bearings instead of the rubber mounting points.

Thanks for any help,
kevin

aussiesmg

iTrader: (1)

There are no replacements as the part is flawed research under tri link, this is the usual upgrade done to eliminate the inherent binding issues.

aussiesmg

iTrader: (1)

link to an example

https://www.rx7club.com/race-car-tech-103/making-fb-panhard-bar-3rd-link-plans-489343/

kevinbtz

iTrader: (4)

well, isnt it flawed because the rubber bushings actually bind when ever the suspension rases on one side and lowers on the other like durring hard turning. From what I understand you could replace the stock links with ones with spherical bearings so that it would not bind, it would let the suspension move freely. The tri link is a good set up, but I dont like the fact that it has "foam inserts" that are instaled in the upper links. It seems that there would be a cernten degree of movement.

Hyper4mance2k

iTrader: (40)

Do not replace the factory bar with sphereical bearing bars. Mazda them selves in the handbook say not too because it will increase binding. Shperical lower arms are great. I have spherical lowers. They're awesome the car handled noticably better, but they are loud as hell you will hear every little bump! It's loud and harsh, but handles good!

aussiesmg

iTrader: (1)

The binding caused by the length of the upper arm, it is way too short, this combined with the longer lower arm and the watts linkage set up. The difference in the arc of these rotating arms is the issue.

For example take a 12 inch ruler and move one end up 1 inch, note the angle difference, then take a pen and move one end an inch and note the difference again, this angle variation is the major issue.

kevinbtz

iTrader: (4)

yea, I get what you are saying. I was thinking that there would be less binding verses stock if the spherical bearings where used instead of poly bushings that do not give very easely which causes snap over steer in some situations. I am not going for a perfect suspension, rather just a little better than stock.

kevinbtz

iTrader: (4)

oh yea, aussiemg have you heard anything on the carbon fiber sun roofs?
and thanks for the input on the suspension.

aussiesmg

iTrader: (1)

Still waiting my guy is letting me down, I'll be on his butt after the new year.

Is your car for street, if so you wont need to worry too much about the upper link, just replace new rubber in it (not poly re binding) and poly in the lowers, there is a great thread on the watts linkage in FAQ also. bwaits is working on a replacement lower arm with bearings, I am waiting on these or I may build my own.

If its for race you will need to consider how far and at what price you can go.

kevinbtz

iTrader: (4)

cool, let me know when it can happen... I have money burning a hole in my pocket for something to replace my glass sunroof for when ever I race.

Mostly street/drag, but I do plan on doing some autox this upcoming year.

Yea, I might just wait for my rearend to handgernade and do some thing crazy when I put a better rearend in it.

And thanks again.

Hyper4mance2k

iTrader: (40)

Correct, but it works under the same principal as the rear sway bar. Keeping the top arms with the rubber bushings it slows the rotation of the arm keeping it from binding as quickly. with spherical ends on the top arms will rotate freely and get to the binding point quicker...

kevinbtz

iTrader: (4)

ok, that makes sence. but why do they say not to use poly in the upper? It would delay the point where the binding takes place.... I guess it is just too stiff and would inhibit the suspension pivoting?

and thanks for the input.

trochoid

iTrader: (6)

The rubber can twist more than the polys, which helps reduce the binding. The rubbers also compress easier.

RE-TurboFB

Try www.iscracing.net they might have what ya need..

peejay

Of COURSE there is a certain degree of movement.

The way the four links are laid out, if they were all of solid pivots, the suspension could not move in any way other than a straight line up and down. This is why the upper links NEED to have plenty of give in them, otherwise the suspension would lock up solid on any one-wheel bump... or when going around a corner!

The only reason you replace the bushings with foam when you do the tri-link setup is for racing classes that let you add traction bars but won't let you remove any existing suspension members. When you have a 3 link, the two stock links can otherwise be safely removed and used to hold down shelving in your garage. They serve no better purpose.

The 4 link geometry issue is the reason why the upper pivots like to tear off of the body. They are under a lot of stress when the axle "articulates" (one wheel up, the other down, to whatever degree) and, despite being attached to metal on 3 sides and with an extra beef plate on top, the slightest additional weakness (rust) causes them to rip right off of the body, the pushing and pulling loads are so great.

It's the #1 natural cause of death for a 1st-gen bodyshell, and it is ENTIRELY due to the awful geometry in the 4 link suspension.

This is an ENTIRELY SEPARATE ISSUE from the Watts link BTW... the Watts problem is relatively simple: The roll center is just too damned high...

IanS

iTrader: (4)

Is there some sort of cost effective way to reduce the roll center?

Re-Speed.com

iTrader: (3)

I would think a pan hard would be the cheapest way to lower the roll center.

-billy

cpa7man

iTrader: (2)

Correct, good points made in the entire post.

I was told by Susko of G-Force Engineering not to run my lower spherical arm bushing controll arms without the 3rd link. Here is an old email from him. I have since installed all of his pieces. There are some other interesting tidbits in his email I left in that aren't exactly on topic here. I think he's also beating me up a little for buying my Tri-Link used from another racer here in Texas:

"Hi Paul,

The rigid lower control arm bushings will hurt you until you get the third link installed. Be sure that the Tri-Link link you purchased has a 1 1/16 OD. If it is only 1 inch, that was an earlier model made for IT and it is possible for it to weaken over time due to stress. The larger diameter bar gives more rigidity plus I increased the wall thickness considerably. I also used a mandrel bend which further strengthens it.

The reason the rigid bushings will hurt you is that on a four link suspension the rear end is what is called "over constrained." That means that if all of the bushings were replaced with rigid bushings then the suspension actually could not move at all without warping the chassis. This is a common design feature of production cars, and they rely on the bushings to allow some suspension movements. When you begin replacing these with rigid bushings, the suspension begins to "lock up" and you will experience oversteer. Furthermore, the car will be difficult to recover. On some extreme cases where all of the bushings are made rigid, the body mounts have torn from the body. So it is important you go to the Tri-Link as soon as possible. If you bought it used, then make sure you also bought the instructions. IT IS EXTREMELY CRITICAL YOU INSTALL IT CORRECTLY, E! ! SPECIALLY IN GETTING THE DRIVESHAFT ALIGNMENT CORRECT, OR IT MAY STRIKE THE BODY AND BREAK, LEADING TO LOSS OF CONTROL AND LOTS OF DAMAGE. IT IS ALSO CRITICAL YOU REPLACE THE UPPER CONTROL ARM BUSHINGS WITH SOFT FOAM WHICH I SUPPLY SO THE REAR END IS NOT LOCKED UP. THE TRI-LINK SUBSTITUTES FOR THE UPPER ARMS AND THEIR FUNCTION MUST BE DEFEATED THIS WAY. There are other cautions and instructions as well that are key to getting it right. I cannot emphasize this enough.

Just be sure you don't succumb to the urge to use synthetic oil in your transmission or your synchros will not work and you will eventually destroy it. Use straight 80-90WT gear oil only.

I don't recommend using the Ground Control Panhard, it tends to flex and the mounting points are fixed, meaning the bar generally is not parallel to the ground which it must be in order to avoid jacking forces in turns. It will tend to make the car oversteer or understeer more in one direction. It is also not adjustable. My panhard is very rigid and can adjust for level and height. The height adjustment allows oversteer/understeer tuning just like an adjustable swaybar.

Jim"

Just like peejay said.

Re-Speed.com

iTrader: (3)

As aussiesmg mentioned, we do have solutions for the rear arms on FB's. Production parts will be done in the next few weeks. The new website will be up around the 10th.

Item 1:

Complete Replacement Arm. This is for the guys that do not have to be "IT" legal. The kit comes with:
Left hand / Right hand threaded arm, 2 high quality lined rod ends, 4 Spacers and Rod end Dust Shields (Condoms) to keep the dust and grime out of the rod ends. We are thinking $129.99 retail.

Item 2:

"IT" Legal spherical bushing kit. This kit is per joint and used to replace the stock rubber bushing without modification to the stock steel arm. You just press the rubber bushing out and insert the billet aluminum part.
The kit comes with:
Machined Bushing Insert, high quality lined spherical bearing, 2 spacers, 4 c-clips and 2 spherical Dust Shields (Condoms) to keep the dust and grime out of the spherical ends.
We are thinking $73.99 retail.

Item 3:

" IT Legal Front control arm kit. Same design as the rear arm kit but for the front, inner control arm pivot points. Kit comes with everything needed to do 2 control arms.
We are thinking $129.99 retail.


We do not recommend using the spherical ends on the upper arms. We suggest using a upper link to eliminate the watts and remove the upper arms. Upper link to be done in Feb. with our pan hard solution.


Pictures are of the front and rear IT legal parts. We do not have a picture of the complete replacement arms yet.

cpa7man

iTrader: (2)

Very nice billy, your stuff seems to be first class. I'll be looking at your parts closely as I build another EP car.

peejay

That's the biggest change I noticed after doing away with the upper links. The car doesn't snap sideways and become a handful to get back in line, when you do things like hit mid corner bumps or transitions in pavement... instead it just smmmeeears smoothly around the road, and you can drive on the edge of best grip (but still pretty far away from "drifting") and when things try to unsettle the rear it's not anywhere near as drastic.

It's, say, the difference between what a big wave does to a big boat versus a smaller boat. Small boat gets a wild ride, big boat goes "eh.".

kevinbtz

iTrader: (4)

Thanks for all the info, I guess I have a winter project for next year.