Scott can we get pics of where the upper links in the 4 link mount on the axle?

*cough*
Recently did the PB&J mod to my suspension again. It works well, but it's clickity clank annoys me considering my car sees on average 100 miles a day...

oops! Sorry - not been paying attention

They are using the stock upper control arm mounts that are on the axle.

my friend bought an AE86 that had had a bunch of things done to it

basically the AE86 is a 4 link with panhard, looks a lot like a 1st gen

anyways the people who built it moved the brackets for the upper control links, so that it now runs stock lower links in all 4 spots.

the other mod is pretty standard in that crowd, the traction bracket, they move the lower link attachment on the axle down

Torque Arm Suspension
 

It was mentioned earlier that there were some successful torque arm suspension setups used in road racing.

Any more details on those setups?

Has anybody used a Granny's SpeedShop setup on a track with turns?

i was looking at the GTU SA at seven stock, and those bar/channels behind the drivers seat are NOT chassis reinforcement like i had thought, they are actually relocated upper control arm pivot points.

it looks like they tried a couple different things, as both of those had been used.

the current one as of 9/2010 was (and you can see it) on the diagonal channel

Has anyone considered a "Lotus Link" for the 1st gen?

A what?

Yes I have seen them. I know there was one member on here who posted pics of his setup. Can't remember who it was. It usually doesn't happen as with most rearend setups it bumps us into "anything goes" go cart classes.

I see. I had considered a lotus link setup when I was deciding on going FB, or FC for a track car. the design is so clean and lightweight, lowers CofG the most out of all designs, and seems relatively easy to fabricate.

Sorry BlackWorks-I cannot find any pics of the design...

~M

lotus in a FB

Is there an actual term for it? I can always look it up. Lotus link brings up a lot of weird things in google.

Hyper, thanks for the pictures! I was looking for those exact pictures but couldn't seem to find them. Blackwork, the only pics I know of are the ones supplied by Hyper and I only know of the suspension design as a Lotus Link.

The upper bar to bushing looks MIG welded. And you can MIG 4130 with no issues.

GD

When this shows up in the mail, you just gotta put it on.
https://www.rx7club.com/attachment.p...1&d=1290825928

lol, I don't know Hyper. Mine's been sitting on the shelf for three years now. :)

I'm telling you throw it on. They're life changing.

Holy christ!! Wow that's amazing! I'm still running the stock uppers and lowers, but I traded the Watts for the old school GForce bolt in Panhard bar. Wow what a difference. I just got back from a quick jaunt around the block. Mind blowing how different it is. I can't wait until I can do the 4 link like posted above.

P.s. I had to remove the rear swaybar. It desktop for with the kit. Oh well. Crazy how well the car drives right now. I was doing 70 MPH slaloms without anytype of slide.

So the lotus link is just a 4 link ?
How is the axle located laterally ?
Kinda hard to see with the closeup photos.

Huh, so you're running the panhard without the tri-link? I hadn't considered trying that. I had assumed that they had to be used together.

I didn't quite understand what you were saying about the swaybar, other than the fact that you had to remove it. Just remember that just by removing the bar you would've "stabilized" the rear end (less sliding). How bad is the body roll at the back end now? Any issues with understeer?

Thanks for the update! :)

Its actually flatter in the rear now with less roll becasue of the greatly reduced roll center. The mount for the panhard bar bolts to the axle right where the sway bar mounts and makes it near impossible to get the sway bar back on with the mount there. I might try and replace it later. I've driven the car with and wothout the rear bar hundreds of times and with the stock watts and upper links I feel the car is much much faster with a rear bar. I put the panhard on with the watts still attacked and you can actually see how easily the watts in conjunction with the upper links binds and causes the snap oversteer horror we all know. Huge upgrade and I recomend it to anyone. The car now has a slight natural understeer which is easily corrected with the application of throttle. It doesn't even feel like my 7 anymore. so much better... Better improvement than the springs, RB front sway bar. Biggest improvement to my car's handling since I added the roll bar.

I have heard they can be noisy. Is it louder ( road noise wise ) or significantly harsher than the watts linkage?

Are you running it on a street driven car?

Mine has teflon heim joints in it. It's honestly quieter than the stock rear setup with the PB&J mod. Secondly this is not a BMW. If I wanted one I would've bought one. You're not going to make a crazy fast FB that's BMW quiet. Like any built car you sacrifice some noise for performance.
https://www.rx7club.com/attachment.p...1&d=1290906950
https://www.rx7club.com/attachment.p...1&d=1290906950
https://www.rx7club.com/attachment.p...1&d=1290906950
Since noone else has ever put up Gforce engineering panhard pix installed I thought I might.

this thread rocks.

This car has a Lotus link rear suspension:

http://www.maierracing.com/images/5frankstgnaro.jpg

This style of rear suspension was used in Roush Trans AM cars in the 90's. So it has a high HP potential. The beauty of the design is that is has only 4 links, a very low roll center and no roll steer. All of the advantages of a watts link in a much less complex and light weight design plus a roll center height that a watts can't really match.

There are negatives with this design, however. On an RX7 the lower links cut into exhaust clearance. The V8 cars get away with it because they can meet sound with a shorter exhaust. Also, roll center is not easily adjusted because the mount is in the bottom of the rear end housing.

Here is a diagram of a Lotus Link - Classic 3 Link rear suspension. The view is from below.

http://inlinethumb04.webshots.com/57...500x500Q85.jpg

If you look under a stock FOX or SN95 Mustang (79-04 Non IRS Cobra) you can see an example of Lotus Link turned upside down. The lateral controling links are mounted on top of the rear end and the parallel links are mounted below the axle housing. GM also used this system on a number of mid size RWD cars from the 60's to the 80's. Among other things this design puts the rear roll center higher in the car. Not really very good at all.

Hey Hyper - my IT car had one of those panhard bars on it for years. Worked really well.

put em on! its like night and day.

Scott, thanks for posting the drawing of the Lotus link. I found a couple drawings after some diligent searching. I found a few photos, but they were from the side and difficult to learn anything from.

http://i52.tinypic.com/2qx93sn.jpg

http://i54.tinypic.com/vr658y.jpg

Sure thing. Actually your images are very good. In the racing applications I am familar with the center piviot on the bottom rear axle housing were just rod ends on a common mount or on separate mounts that are very close together. Also the lower link consisted of two separate control arms that were not typically connected to each other.

Very cool stuff - these old school suspension designs work really well - especially the Lotus stuff, Had an "old timer" tell me that I ever found myself in a Solo class with a Lotus to pick a new class!

would it be feasible to do a lotus link on a streeted first gen... oh well maybe i'll just go with the trilink panhard setup

k. So who's going to start the FB Front Suspension Geometry Problems/Options/Solutions thread?

Some may disagree, but IMHO Billy Waits solved all of em!!!!!!

How? He's not the first to do coilovers, or a sway bar, or a strut tower brace, or a rack and pinnion. Jim Susko PWNS all on front suspension setup. His are the only "turn in spacers" that actually add ackerman. His are offset to correct the geometry, noone else does that, just spacers like the ISC ones in my car. Jim is the only person who offers a real bolt in double adjustable solution and the only person who sells shocks able to deal with spring rates above 300lbs. Mind you Jim probably has 30 years on Billy.

Mind you I do love RE-Speed and I run their coilovers on my car. They make fantastic parts, some of the best, but they have hardly solved the front end's problems.

the front is really simple compared to the rear! mazda had a solution for it before the car came out

Do you know what is different about Jim's "turn in spacers" vs others? It seems like they would all do the same job, raise the roll center and add ackerman.

I've been thinking about getting his front trailing arm spherical bushings.

7's only sell ackerman arms which will increase ackerman over stock, especially when combined with turn in spacers. I run 2" turn in spacers from sevensonly. I also run their large diameter upright with big bearing spindles and big brakes.

The geometry problem I'm working on now is bump steer. We're getting 1/8-1/4" toe in for every inch of up suspension travel. We have adapted a kit that raises the steering nuckle 1/2" onto the ackerman arm. Seems to have almost eliminated bump steer.

Most people with first gens probably don't realize they have bump steer, mainly because it is toe in bump steer, it feels stable but it still causes a certain amount of unwanted scrub. It's probably the least important 1st gen suspension geometry problem.

The gforce bolt in at the strut and at the arm at different angles. If you just use a big spacer it adds toe that you have to align out. Gforce actually add ackerman the more steering angle.

Just reading the info so far. Great stuff! So which is better on the rear: Panhard rod convesion or Watts?

On the front: More Ackerman and work the bump steer. Right?

GD

http://www.usa7s.com/forum/uploads/s...t/DSCF1322.jpg


what would this be called, its kinda a watts link ? an under-the-axle watts link. are there advantages to doing it this way?

Emerxfudd,

Yeah that is a watts link. I had a friend with a SCCA GT-Light (GTL) Nissan Sentra with one of those. That design also has a low roll center - lower than the ones that attach to the back of the rear end. They work well.

I thought about design for my STU project but decided to do a pan hard bar to save weight and complexity.

Good question!

Actually I'm pretty pleased with the front end on the RX7. It can be lowered and with strut spacers it is possible to maintain geometry. As strut front ends go I think this one works pretty good. There are improvements that can be made, however.

On my racecar, every pickup point has a spherical bearing - including the strut rods. As far as spacers are concerned I have used both the Susko ackerman spacers and the straight - non ackerrman spacers. I like the ackerman spacers for Solo/Autocross use because they make the car turn in better and work better in transition. For clubracing I perfer the npn-ackerman spacers because I don't like twitchy cars on a race track.

The big strut tube conversion is important if heavy rate springs are going to be used. We made the ones on my car.

For my STU project I will be lowering the car another inch. To compensate I will add a 2" spacer to the strut and raise the top of the strut tower. I'm also going change the sway bar to an adjustable Speedway design.

Here are some shots of the strut tower mods. I'll shoot some shots of the struts, sway bar design over the next week of so.

http://inlinethumb10.webshots.com/14...600x600Q85.jpg

http://inlinethumb36.webshots.com/21...600x600Q85.jpg

http://inlinethumb63.webshots.com/21...600x600Q85.jpg

http://inlinethumb35.webshots.com/45...600x600Q85.jpg

I wish the Racing Beat ones were still available.

Cool! Thanks for the information regarding the front end. I am pretty well versed on suspension dynamics, and I am failing to see where the spacers change the Ackerman, as they do not change the angle of the steering arm, or the tangent of the strut mount and the lower ball joint. Or the intersection to the rear axle centerline.

I see that it does do the roll center mod to the good side, but that's about it.

Can someone illuminate this relationship?

GD

In my view the issues with the 1st gen front suspension are:

1. camber adjustment

2. Roll center adjustment

3. Ride height adjustment

4. Better steering than the antiquated recirculating ball setup

5. Maintaining desirable ackerman geometry

Maybe there are others I am not considering????

For me the ReSpeed setup accomplishes all the above except #5 and since I have the Racing Beat Strut tops I can use turn in spacers that give the ability to adjust/change Ackerman. It is the perfect solution as far as I am concerned. It also gives the option to adjust the steering ratio. ( I have tried both 20-1 and 15-1)

I guess I should have said that Billy had the best solution for me, IDK about everyone else.....I have no experience with the Gforce products so I cannot comment on them except to say that you do have a point about the turn in spacers, with Billys setup you do need to address the Ackerman issue somehow.

Maybe he has not been around as long as some others but I am happy with my setup. As far as I can see there are no shortcomings to it other than price.

dear sir,

we here at BMW would like to inform you that you are misinformed. the recirculating ball steering system is used in our flagship models. as BMW is the ultimate driving machine, this makes the recirculating ball steering system cool and high tech.

sincerely
BMW

Well darn, so now I guess I will have to pull out this piece of crap rack and go back to the old setup.

Just when I thought I had it right! Dagnabit!!!!

its just funny how everyone complained about the rx7 steering from day one, but it was fine on a BMW until 2001, double standard?

The problem with the stock steering is that there are no parts to service worn out boxes. The RE Speed kit addresses this, unfortunately it isn't even remotely legal for the SCCA class I am building a car for. Not Billy's fault, just the way it is.

That makes sense, I might have to try Jim's after I try the car with bump steer corrected. I'm worried about having to much ackerman since I already have "sevensonly" ackerman arms.

Looks like I need to ditch my panhard bar and make a custom watts linkage. It's funny, I've been complaining about picking up my right (passenger side) rear tire since I've had the panhard bar. It just so happens that my panhard connects to my rear end on the passenger side. It has been costing me almost a second a lap at some tracks.

I though with the rack you lost turning radius and steering angle... both thing's I'm not willing to compromise on especially considering two of the FB's drawbacks you forgot to mention was its already poor turning circle and lack of steering angle.
There was a place in Seattle that told me they could rebuild my box. I wish I remembered the name of the place. All they did was rebuild RB boxes.

p.s. found it. i never researched price or exactly what they'd do, but the guy told be he could rebuild them right before I moved to Cali.
http://www.redheadsteeringgears.com/