Best performing rear suspension-if packaging was not an issue

I know there have been a ton of threads discussing various suspension designs, but my situation is a little different from most. Most deal with what fits what car.

My question is what would work best for all around performance suspension (street, cornering maybe a little drag strip), if you could build what you neded, without existing car parts getting in the way?

I am building a 30's Indy/grand prix inspired boat-tail speedster from scratch. The body and frame are not based on an actual car. I am designing/building it as I go.

http://www.jalopyjournal.com/forum/showthread.php?t=339315&highlight=roofus

Right now the rear suspension/frame layout is a blank canvas from the seats back. Other than the basic shape of the body, everything os open for discussion. The frame and floor of the car will be built around the suspension.





The rear diff will be inside the boat-tail (frame and sheetmetal below the axle) with just a slot for the axle to move. Some ugly stuff could be hidden.

I have thought about a triangulated 4 link with the bottom bars on the outside of the body (attaching at the node just ahead of the quarter panel skin). The uppers would be inside the body.

I have though about parallel 4 link with links on the outside of the body. If the parts were painted, it might not look street-roddy.

I have also considered hairpins attaching at the same general location.

Is there something else out here other than these that might work better?

What about springs?

Oh yeah, wheelbase will be 100" and the ride height is about 5 inches. Weight should be under 2000 lbs.

 

A lot of those cars from the 50's era used cross torsion bars front and rear... at least the pavement Indy roadsters. Earlier cars had buggy springs front and rear.

I think the early F-1 cars had coilovers... I'm sure there will be more knowledgeable guys chiming in... good luck.

 

Anything other than the four link will of course move in an arc so you'd have to arc the body holes for the axle if you go that way, which would look cool.

The cars you spoke of where rather advanced compared to most of our hotrods, I'd consider a cantilever set up with in board coilovers keeping the ugly inside the body and allowing adjustment. With that how about an independent rear with thin external A frames ?

 

Oh yeah, I forgot to say the rear is a live axle from a 1960 Jaguar MK2. It looks like a slightly smaller Dana 44.

 

as far as lateral placement is concerned, a WATTS link is far superior to a panhard bar. serious corner carver usually stick to them.

 

Well, for all-around handling, drag-strip blasts and decent street manners...I think the "Third Gen" F-body design is really tough to beat, although it may not be suitable for your application. It uses coil springs with lower trailing arms and a long central arm that runs along the driveshaft to the tailhousing on the transmission, and incorporates a panhard bar as well. (1977 Vega GT cars used a very similar design as well, improved over earlier Vegas). That design offers excellent handling, all but kills wheel hop and rides okay on the street, too.

 

I've got a truck with the suspension that is based on the 3rd gen camaro but use a transverse leaf on it. It ewas built by Elpolacko at his shop, Industrial chassis. It has a very good all around ride, handles like a champ, no axle wind up. I've out run lte a latemodel mustang around Mesa Verde in the San Diego area. Pissed the moron off getting beat by an old truck!

It would give the car an old timey look with all tha handling and ride quality that you could want.


jerry

 

Best handling and overall performance regardless of packaging? Jag.

For your neat little boat tail? Perhaps quarter elliptics?

 

Are tall skinney tires gonna negate any gains from suspension improvements?

Is the idea of sportscar handling just a dream?

 

a car like that needs one of those old time fancy Mopar frames with parrallell leaves front and rear.

 

I was just discussing great rear suspensions last week with Zorba's Ghost and we both agree about the 82-92 Camaros/Firebirds. Two lower control arms and a long centrally-located torque arm. Works very well in drag strip applications and road racing. If you wanna see a neat rear suspension, do some research on the 1987 Buick GNX. They used the two lower stock control arms and a center cast aluminum torque arm that attached to a bitchin' cast aluminum rear end end cover with integral mounting ears. Click my link and see the photos and diagrams. I'm pretty sure this set-up is reproduced and would be neat to put into an old car! http://home.att.net/~buickGNX/GNX/susp.htm

 

Fbody for sure,,, My buddy specializes in them and they can be made to hook hard, and that doesnt detract from the cornering either.

http://www.burkhartchassis.com/

 

quarter elliptic springs mounted out side body lines is the way to go&parts are cheap easy to home make

 

Sounds neat.

Can you post up some pictures of your suspension?

Does anybody know how much effect changing the length of the outer arms would have on function of the suspension? Longer arms would probably look "racier".


I guess I need to go look at a Camaro.

 

I have done some more searches about tourqe arm suspensions. It looks like it is the way to go.

Does anybody know if there is a benifit to raising the torque arm in the chassis? or should it be close to the driveshaft?

 

offset three link, watts link, inboard coil overs.

http://home.earthlink.net/~whshope

 

Technically speaking the torque arm mount should be pretty close to the front u joint, this acts like the instant center of a 4 link which gives you good bite and decent manners on the street. In the grand scheme of things on a driver type street car raising the instant center a bit would have litttle or no effect on drivablity.

On the racecar stuff Chuckie builds they shorten the torque arm a lot to hit the tires much harder on launch.

Running longer lower bars should have little or no effect on how the suspension works, although they should be kept in the proper plane.

 

You said "Best performing". If that is what you really mean, you might look at what the higest-performing cars in the world are using; Formula One, Indy, LMP, Various so-called 'Super Cars, (Ferrari Enzo, McLaren F1, Corvette) etc. Here, I think you'll find that independent rear suspensions are the rule.

If by "best performing" you mean drag racing, look at Top Fuel. Here, I think you will find solid axles with 4-link are the rule.

Everything else is a compromise.

JG

 

The problem with a torque arm on a road race type suspension is they induce wheel hop under hard braking. they have a fairly short effective length, essentially wherever you place the front mount, usually at the front U Joint. You would be much better off with a simple 3 link. The lower arms should be as close to parallel with the ground as possible and the upper can be kept short with somewhere between 10-12 degrees downward. The effective length in this design moves forward out near the front bumper greatly enhancing traction and improving braking wheel hop. This will give you good adjust-ability, a good instant center and easy to package in your confined area.
For Drag Racing or a simple street car the torque arms are OK but from road racing type applications, not so much.

 

Any diagrams or measurements for where mounting points should be?

 

IMHO, your overthinking it.
You should be looking "back" to find your rear suspension design.
I'd look at just a basic 1/2 elliptic leaf setup or even quad 1/4 Elliptics....maybe even so far as a dual cantilever system like on Cobbs "Napier-Railton" just to be different...
No need to hide the bouncy stuff if its interesting to look at!
You have a lot of stuff like fuel tank, battery etc that are already gonna compete for the room inside that small body.

 

link for a vega torque tube...http://66.154.44.164/forum/album.php?albumid=1341&pictureid=23502

or just go to my albums and look under vega,,been playing with them for years..and in spite of what ya hear, they work very well for road race too....many friends run road course with them...

 

Herb Adams 'Chassis Engineering' book has diagrams and explainations of the 3 link and torque arm suspensions and also of the "de-coupled" torque arm suspension which, when properly designed, eliminates the brake hop issues with a standard torque arm set-up.

-Bigchief.

 

That is easy. Fully independent rear suspension with wide based linkages, aluminium hub carriers and disc brakes. You will never find a Ferrari owner ripping out his rear suspension and replacing it with a drum brake live axle out of a truck to make his Ferrari perform better. Only place you will find live axles winning races is where the RULES demand live axles be maintained. So arguing about how best to locate a huge and heavy live axle is missing the point entirely. They certainly have a place in traditional hot rodding, but then that is all about looks and tradition, not handling or traction on the street. Corvette have known this for quite some time. Foreign high performance cars for a good deal longer. Where space is limited, the Jaguar rear suspension is hard to beat.

 

Find an older F1 car, say last years Mclaren.......

 

Except that he already stated that he had a live axle that he wished to use.

 

This is what I did on my first project,the current owner said it handles like a go cart.

 

This is the current one.

 

And I agree that using parts you have should be weighed against better results by selling them. A small short wheelbase 2,000 lb. car is a no-brainer: IRS with coils, wishbones and inboard discs.

 

Yes, but he also made performance, handling and traction his first goal. Something I can really identify with myself.
A well thought out IRS will give him all that.