RotaryAXer

iTrader: (4)

Hyper,

That Watts link looks like a well developed and thought out application for the early Mustangs.

I'll bet if you can develop a similar product for the 1st gen RX-7 that is well proven and engineered there would be a market for it.

Would you also use a tri-link?

I do have my doubts that it would be any advantage over a well designed panhard rod though. To get a significant structure to mount the center pivot it will be heavier than a panhard. It will also be pretty tough to package it in there with the way the gas tank and axle and exhaust fit on the 1st gen. All those bent tubes, spherical ball joints and bearings will be pretty expensive also.

One would really have to be sure that the product would offer a significant improvement to make it worth it. I personally can't see how it will improve the driving feel, vehicle balance or ultimately lap times to make it worth it. Keeping the axle centered perfectly compared to keeping it located within an ~1/16" of center would be pretty tough argument. There is enough movement in the lower rubber bushings to move it that much.

It would be cool if we could get a intelligent discussion going here to think out loud about any potential advantages that there might be.

And please tell me that you aren't trying to say that the Sport Compact magazine is a better source for suspension design info than Puhn, Milliken(s), Smith or any of the others.

What books have you read? What computer modelling have you done? What stress analyses have you done? What racing have you done? What car have you prepared and run successfully?

DamonB

Do they pay you in candy, or do they do your homework for you?

We have to pay him in advance in order for it to be worth his time to grace us with a response What a Putz.

He's so dang smart he doesn't really need an answer to his original question, he just wants to test us. Apparently we all failed. I just read a bunch of his posts and he's a real hot bed of knowledge. We better get in line now before he wises up and raises his prices

Hyper4mance2k

iTrader: (40)

Wow you're an ***. I'm not trying to market anything. I'm simply testing the waters for opinions other than my own on rear suspension setup. I'm not going to just by a panard because everyone here says it's the best. Just like every one says RB exhausts are the best, and they are far from that. For every piece of exhaust they make there is something better out there. No need for you to personally attack me in my thread. If I would have never questioned the legitimacy of RB perfection I would've never learned about the much better options out there. And sorry I don't spend my entire life on the internet trying to be tough. I'm not some High school kid, I'm a territory manager for a Fortune 500 company. As far as my knowledge goes; I was the Seattle open AutoCAD champion in 1999 and 2000. I also took between 4th and5th in Vocational Industrial Club of Americas state AutoCAD championship in 1998, 1999 and 2000. Hobbies include MMA, and I have not lost a match in 4 years. I was the undefeated hand to hand combat champ in every company at every post that I was at when I was in the Army. Basically, please stop being an Internet tough guy because one day you might meet a real tough guy and get your *** kicked.

Hyper4mance2k

iTrader: (40)

So back on topic. I figure I'm going to rule out a Mumford link. Mostly because of the weight thing. Plus I think I could get the results I want from a watts link. Oh and I crewed with and was a huge part of building a 85 GT3 CRX project. We used the stock engine with some dual 45dcoe's made it RWD with a rx7 axle and a Munford link for rear location. I have plenty of experiace with racing. Sorry for wanting to hear what others have done besides the norm. I'm not sure if you know but it's thinking outside the box that brings innovation.

DamonB

I'd give you an answer but you have to pay me first

You want 1g in an FB? Ditch your $47 tires and put some decent rubber on there. 1g; no problem.

I think you lost everyone's respect when you insisted nobody is worth your time without payment.

Hyper4mance2k

iTrader: (40)

Hey this was a great thread until you came into it with your sarcasim questioning my experiance and knowlege. You assumed I was some high school kid and only made an *** out of your self. You were sarcastic with me I gave it back with the money comment. Since you're the mod why don't you just deleate this thread since you went through so much trouble to ruin it.

cpa7man

iTrader: (2)

Now lets all play nice. Damon I have found Hyper's posts in regard to the first gen to be both knowledgeable and informative. I also agree with Damon that if you have knowledge on how to improve the rear suspension then when you ask others for their opionions on such you should share your insight's.

Enough of that. The first gen's suspension has been improved as far as possible under the SCCA rule book, as earlier posts said. Get Susko's book and order his parts. Now if you could change the stock pickup points that a new ballgame. Go Sox!

Hyper4mance2k

iTrader: (40)

I've been doing alot of reading in the mustang world. And it seems that the PHB is the first step in improving handeling, but when people get serious they move to the Watts link. Tell me this is not hot! I'd love showing this off under my car!

Hyper4mance2k

iTrader: (40)

speedturn

iTrader: (1)

I can't tell about the last one you posted (since it is not mounted on a vehicle,) but all the other photos you have posted still have the rear roll center too high.

DamonB

Rear suspensions work in step with front suspensions. The FB has a pretty good front end compared to the miserable steering of a Mustang. The solutions posted may work well for Mustangs but that doesn't mean they translate to any car you wish to bolt them onto.

Building parts and sticking them on the car can be done by any idiot with the right tools. Making those parts actually work on the car requires sound engineering work far in advance of building the parts. Drawing parts (CAD users) and designing parts (engineers) are two completely different things. I tutored many CAD users in college and they were good behind a computer drawing parts, but that doesn't mean they had any grasp whatsoever on how those parts really function.

Just because parts can be built doesn't mean they suit the application.

Kenku

Watts link vs. panhard just falls to one of those "theory/practice" things. In theory, a chassis-mounted watts link works a little bit better; roll center remains where you want it relative to the chassis, no sideways movement, yadda yadda yadda.

In practice... well, first, I challenge you to demonstrate that it matters very much. And then, demonstrate how you're going to have a chassis mounted watts link without a signifigant weight penalty compared to a panhard bar.

It's not a new idea. People in EProd have tried it. There was very little (if any) gain, in exchange for more weight.

RotaryAXer

iTrader: (4)

Hyper,

I think that Damon and Kenku have made some valid points.

I think that you have shown some good examples of watts link setups. These are obviously designed for something other than the FB. This isn't to say that something like this couldn't be built and designed for the FB.

I think that you may be a bit ahead of yourself on asking for suggestions from the general public on this. It appears that you are just at the very beginning stages of coming up with a custom rear suspension design. I think that because you aren't showing any tangible products for the FB or any actual proven facts of the advantages people aren't taking you seriously.

I will also add that I don't think you have a real appreciation for what it really would take to reap any benefits from the work you would put into this. Have you done any sort of analysis of a suspension in the past? Do you have a good working knowledge of how the roll center location will affect the handling of the car?

It would be counter productive to just start designing parts that fit without first finding what location you would need that roll center to be at first.

If you are serious about this there are plenty of resources that can help you get the answers.

Off the top of my head I would think that the roll center should be just slightly above the bottom of the pumpkin....and I didn't even charge you anything.

Hyper4mance2k

iTrader: (40)

Ha ha ha, awesome! thanks for the free info! Yea I've been spending a lot of time modeling the car and where I need the rear roll center. The pics are just for ideas for others who might be contemplating a rear Watts link. I do not plan to bolt in something designed for another car. As I said before I am planning my own system the shots are just Ideas for mounting. As you can see some have the pivot point mounted on the axle, and some have put it on the support structure. I’m just currently unsure of how much a total lateral movement will cause toe steer with a PHB that only has of an 1/8” of an inch of lateral movement throughout the entire range of motion. My rough estimates are that it’ll only cause another .125* of toe out in a turn, which is not much of an difference over a system with 0” of lateral movement. And that’s in a perfect world where all forces apply perfectly linier. I guess bending the axle to get 1* of toe in that some of the pro7 guys do would make up for the difference and then some. huuuuummmm i need some coffee I'm going to work now..

DamonB

How can you spend a lot of time modeling the rear suspension when you don't know what the rear suspension is yet? You modeling everything you've mentioned? Can I see the Mumford stuff? Never seen it done on an FB.

Additional unsprung weight. Additional weight. Some use lower arms which locate the axle, some have multi-link designs.

If a panhard bar on an FB is lighter, simpler, cheaper and just as effective (how many FB's out there run these things???) why reinvent the wheel?

jgrewe

iTrader: (1)

Since we're all throwing smart-*** comments to make points now... I just wanted to clarify that Susko worked for Cooper Tire not GM. As you were.
Also, Jim uses the computer modeling system that Reynard and I think GM uses(or used).
AND, with the number of compromises in the rest of the car to make it a streetable vehicle why waste your time on the rearend when a simple panhard bar works.
I would just build a tube frame and do it all the right way from the start, but then, which right way?
When you take a street car and try to make it a race car something on that car is going to make you feel like you have a foot in a bucket to run a marathon. The thing to do is put your other foot in a bucket so you feel balanced running. That is what suspension on an FB was before Jim offered this set-up for sale. He didn't invent the set-up he sells for this rear end he just perfected it within the rules and made it available for everybody. Along the way he has probably spent thousands of hours thinking about the problems. So you're a few years of your life behind on this car. But good luck, please report back with what you find, people told a couple guys from Ohio they couldn't build a flying machine!

Hyper4mance2k

iTrader: (40)

Well thank you for all the honest opinions, at least those that were insightful. I'm pretty sure I know what I'm going with now. I'll let you all know how it goes in the end. Damon if you're ever in the Seattle area let me know so I can show you in person how it looks. Better yet, a few Army buddies are getting back from Iraq in a few months, and I'll be heading down to Austin to party with them. I'd like to come and say to you. internet tough guy...

DamonB

I'll buy your buddys who are getting home their first round at Touche's.

DriveFast7

iTrader: (1)

Can't we all just get along?

Those mustang torque arms are damn heavy.

I could have added another 50lbs of tubing to my rollcage and stiffen it up to no end, but we wanted it to be as strong yet light as possible. Going overboard is still overboard.

Questioning the marketability for a watts on street cars, and most racers build it themselves, or have a 'race shop' build it for them.

Hyper, I do wish you the best of luck with whichever design you go with. And am glad to see someone trying something fresh and new. I hope the reward is worth the time and dough.

KompressorLOgic

iTrader: (6)

your ALL WRONG!!! my dad drives a monster truck!!

rmriggin

I love random posts. They help "spice" up the thread a little bit and make it interesting... You know, make you forget what you were reading the thread for in the first place...

Smilodon

I agree that the fastest, cheapest way is a set of gooey tires.

smnc

Boy, I can't leave you alone can I? Lol...
I don't come in here for a week, and you manage to start a fight...


J/K...


But seriously, the Watts link idea has a lot of merit, and looks like an interesting project.

Personally I agree with some of the others that there really doesn't seem to be much of an upside past what the Panhard already offers...


Except one, and I think it's your main motivation:
You don't want to follow the crowd. You want somthing different. Even is it's more work, costs more, and does the same job... right?

I say go for it. That's one of the greatest things about these cars. The fact that you can build yours EXECTLY the way you want it.

I have quite a few unique plans in the works for my -SE in the spring.
At least some of them will probably be ridiculed by others, but if I like them, I'll make them happen

Hyper4mance2k

iTrader: (40)

you guys are halarious! gawd!!! LOL

Smilodon

I agree wholeheartedly. They are inexpensive, compared to performance to cost ratio of new rice daddysmoneymobiles, light, plentiful, EASY TO WORK ON, unlike most offerings these days, and they are such a nice place to start to begin with. How many cars from the early eighties OTHER than RX7s are anywhere near as desirable?