Have you considered building a panhard bar and tri link upper, I have been thinking of getting a G force set up but like the look of your work.

 

I think you should make a 3rd linkthat goes through the floor and mounts to the cross brace on the inside. Yesssss.

 

from my understanding of how the rearend "winds" up while cornering, i thought you couldn't use solid uppers on both ends of the rear axle without creating the snap oversteer. hence why you just run the one third link. i could be wrong though. i'd like to here how these solid upper and lower links perform, i wouldn't mind trying them on another car to compare if they seem to work well.

 

i see what bwaits is tryin to say, hes not off his rocker, i read a thread all about this once,
looks really good, though, but because it seems that this car is mainly for drag i dont think it will be a big deal, because mazda made the top/upper liks shorter than the bottom ones, when you try and take corners, one side of the axle will want to lift and the other lower, when the mounts are solid the suspension geometry doesnt allow this type of movement, mazda cheaped out and bypassed this problem by putting soft rubber bushings all around allowing the top arms to move the extra amount needed for a cornering action, still a very bad system thats why allot of people have converted to a three link system allowing the top link to be the same length as the bottom eliminating this problem completely,
one question, what type of rear end is that,? ford? cool lookin must be strong to take 680 hp,
again awsome job on that "680rwhp" a truly professional look, again i dont think this binding issue will be a problem, because it seems that you do mainly drag not autox

 

thanks but the pics are of my all motor car im building ...its a ford ranger 8.8 rear end, with 33 spline axles, lightened spool, disk brakes, with custom lines..

here is a pic of the rear end in the 680 car...
http://www.imagestation.com/picture/...a/f3373906.jpg

 

shouldn't you be more honest rob? isn't it a 720 car now?

 

i just wanna see his latest and greatest setup..... do i smell an automatic?

 

Nice Rear end - What brakes do you have front and rear?

 

here is the front brake kit ive been making.. its a nice looking low budget upgrade that removes over 10 pounds of unsprung weight.....


http://www.imagestation.com/picture/...f/f3351608.jpg

in this pic you can see not all of the brake pad gets used, im not sure if that will be a problem...

http://www.imagestation.com/picture/...4/f335160b.jpg


its a simple bracket, a wilwood 4 piston caliper, and a custom brake line... it utilizes the stock brake rotor so you dont have to convert to 5 lug or spend tons of money on aftermarket rotors // and hubs// and hats

http://www.imagestation.com/picture/...0/f335160e.jpg


and the brakes look nice too

http://www.imagestation.com/picture/...0/f335160a.jpg

the rear is a standard strange drag race disk brake kit

 

Posted by 680RWHP12A

***here are some pics of the solid upper arms .. chrome moly construction with cnc machined aluminum busings eliminate any deflection greatly improving handling (for the road race guys) ***

I am going to be very straight forward with my posted statement. THIS INFO & THESE UPPER & PROPOSED LOWER LINKS WITH SOLID BEARINGS ARE A CROCK OF **** FOR ROAD RACE CARS. If 680RWHP12A would understand the workings of the rear suspension of a 1st gen RX-7 he would not suggest that solid bushing would "greatly improving handling". The friiking links/bars/solid bushings will break under road racing conditions & also under any conditions where the body has roll. I will not go through the explanation of how the rear suspension works because anyone who thinks these solid bearings would work will not understand. Mr. Billy Waits & someone else who posted have a handle on how the rear suspension works.

Please quit posting B.S. folks. It's not fair to those who are trying to learn on this site.

David Dewhurst
1st gen RX-7 ITA #14

 

from what I remember about the rx7 deals with the rear suspension binding when under load and hence lots of people removed the rear sway bar because as the rear suspension loads up, it will start to bind, hence there is tri-link type suspension for these cars.

I think Robert has good intentions and is not BS imo..

 

i think these are a great idea.

i'll probably have some questions about it later, but i don't have time right now. i have a test in about 10 minutes.

 

Why dont you bring some to sell at SS8 I'll buy the whole set for a good deal.

 

my understanding of the rear stock suspension is softer bushings in the upper and lower arms are better. Ive seen them drilled so they flex better and I know some road racers use a type of foam bushing so that it can even futher reduce binding problems.

i think you would end up damageing your car or just breaking the links under road race or maybe even at an auto x.

they do look nice and are probably great for drag racing.

 

okay, i just read the whole thread now. while i don't share the inflammatory tone and colorful verbage utilized by #14, i do think his concerns are valid.

so, Robert, could you explain in lay-man's terms why these work in your experience? i'll speak for myself ... i'm confused now.

the mere fact that Rx7Carl posted that it would be of interest (page 1), is enough to make me all ears on this part's prospects. i respect Carl and his knowledge on setting up an Rx-7 race car, so aside from #14 (and by the way, i'm not being facetious by referring to you as #14, it's just easier that typing your screen name or real name) stating his credentials and concerns, i think i'll give you (Robert) a chance to explain this for those of us that are not quite there with suspension geometry knowledge.

so my first question is why does it work?

 

First, beautiful work. Second, while I didn't go through and look at all the pictures if the upper links are a direct bolt in for the stock arms they will cause the rear to bind in roll. They are probably OK for drag racing (I don't know, I don't do it) but I would be concerned with the rearend housing twisting forward(on top) as the rear travels up in relation to the chassis. That can cause driveshaft problems. Its not the bushings(stock) that cause the bind its the geometry of the suspension. Stiffer bushings only make the problem worse so spherical bearings create the worst case scenario--- no flex to allow any movement when in roll and squat at the same time.

 

just so you all know according to "Mazda RX7 Competition Preparation And Service Manual 1980" their recomendation is modifying the rear arms (and diff mounting) accordingly:

Upper arm - 413mm Long
Lower arm - 495mm long

However they suggest only to use spherical joints on the bottom and rubber on the top. This is what was run in the IMSA cars...

 

if you dont think the bushings twisting motion in the control arms causes a problem jack the rear of the car up...leave the rear axels unsupported. loosen the upper and lower control arm bolts all up then retighten them.

your car will be scary to drive afterwards.
the control arm bushings have to twist in order to function properly.

Carl knows this, not sure why he posted what he did about solid bushings on the control arms...
He wrote an article on how to make these bushings twist easier in order to improve how the rear suspension functions.