What rear suspension and why?

So, i need to start thinking about the ass end of the challenge car.

Only constraints are cheap, solid axle, rwd.

Currently has leafs that are junk, and rotted out attachment points that would have to be rebuilt regardless of rear suspension.

So, 300 horse, 300 ft lbs of torque, solid axle, 2600lb car.

Any answer can be right, just explain why you picked it.

Lots depends upon desired width...

but I would venture to say its hard to go wrong with an 8.8 out of a ford exploder. (disc brakes, lots in junkyards, narrower width than some others..)

Should be easy enough to adapt to either leafs, or if you want to be more adventurous, homebrew a 3 link with a panhard.

Truck arm and coilovers would be cheap and easy, but not awesome.

Explorer rear is almost a given. Im more focused on the bits that connect the axle housing to the car. There 3 links, 4 links, j bars, torque arms, de dion, truck arms, leaves, quarter elliptical.....

Think about a blank sheet of paper with an axle drawn on it. Connect it with whatever chassis and suspension you want, regardless of cost or difficulty, and defend why you think this is the best solution.

Kind of like the debate team meets smokey yunick....

This has me wondering again if there is a way to significantly lighten up the ubiquitous Explorer 8.8. Perhaps some careful removal of extra casting on the center pumpkin or stuff the guts into a lighter car based housing?

When I did the 8.8 swap on my falcon I was able to lift the old rear end out by myself, it took two people to lift the 8.8 back into the cradle. It feels like I am dragging a boat anchor. I am very aware of the extra weight in a way I didn't expect.

Technically a 4-link with Panhard/Watts/etc is overconstrained. From a technical perspective, I like the 'Satchell' configuration triangulated 4-link and 3-link with Watts or Mumford. For more of an off-the-shelf solution, an 05-14 Mustang 3-link 8.8 axle would be my easy button...Provided it can all be made to work with your chassis.

You mention DeDion, which is another I would favor, but that's not actually a live axle.

Why not an Explorer or a Cute-ute IRS?

They look pretty good, with lots of control arm length and decent geometry, etc.

It would certainly be different and if combined with a pushrod front suspension, could help with an engineering award and performance, of course.

In reply to Stefan:

Now i am thinking about this. What advantage ove a live axle, and what penalties?

so I went and looked for the parts I offered and said I had better go look at what he has,went to National Title Pawn And they had two stepside rangers one two wd the other 4 wd.I am going to post their For sale list later,back to you, Mustang front end fabbed on your truck. truck arms out back, I have the arms complete... I have the coil over shock assy. I cannot find the screwbolts or plates but do have the rears(spring cups for bottom) I mentioned if you want to try that, why truck arms, Nothing articulates better on a live axel. got the stuff but can't spend money to ship, Ya'll come on Down, Bring a truck.Got some other stuff you may want.

In reply to GTXVette:

I know you are in north Georgia or thereabouts. What town? Me and a teammate may be able to make it over one Sunday soon.

Dusterbd13 wrote: In reply to Stefan: Now i am thinking about this. What advantage ove a live axle, and what penalties?

Well, you get less unsprung weight and more consistent traction over uneven surfaces and no axle wrap or spring twisting that can cause inconsistent handling. There are more, I'm sure, those are just off the top of my head.

A solid axle is great for the drag portion since it can often provide better acceleration in a straight line.

However once you add all of the parts needed to build a solid axle that can handle corners and go in a straight line, you may find that your budget has taken one hell of a hit along with time lost fabricating the 3 or 5-link solution along with a Mumford or Watts link for the rear axle.

Just seems a sawzall with a couple of battery packs would take care of the subframe of whatever you chose to grab at the local salvage yard, especially on a 1/2 price day and you could be miles ahead.

In reply to Jumper K. Balls:

Replace the tubes with thinner ones? Are the Mustang 8.8 housings/tubes actually lighter? All the other metal is what gives it it's strength in terms of power holding so you can't really lighten it up much without making it weaker, might as well just go to a lighter duty axle (Mustang 7.5?) at that point.

Jumper K. Balls wrote: This has me wondering again if there is a way to significantly lighten up the ubiquitous Explorer 8.8. Perhaps some careful removal of extra casting on the center pumpkin or stuff the guts into a lighter car based housing? When I did the 8.8 swap on my falcon I was able to lift the old rear end out by myself, it took two people to lift the 8.8 back into the cradle. It feels like I am dragging a boat anchor. I am very aware of the extra weight in a way I didn't expect.

I've heard you say this before... I completely disagree. I put a ford 8.8 (with drum brakes at that!) into my 2300lb Celica. It's incredible. Best mod I've done yet. Weight difference was 50lbs compared to the old t code axle I had. I drift that car all the time. It didn't change the dynamics of handling at all. (Aside from the lack of a rear sway bar) I did my ford 8.8 swap for about 150$. That includes the axle (50$), the passenger short side axle(10$), and a full brake rebuild and fluids (the remainder$). I could not be any happier.

Also, that Irish e30 purpose built rally car has a solid axle. It has many benefits. One being the cheapness of performance and repair. Can't beat that.

8 rod ends are the most expensive/hard to get parts of doing a 3 link/panhard...

You can get them fairly inexpensively from QA1 (but I bet theres cheaper...), then you just have to make threaded inserts to weld into tubes (trimmed to length). Then you just fab brackets to weld to the chassis and axle.

If you make the panhard long enough, you wouldnt gain much out of a watts link (if both are properly set up), but would add a few more bearings, a few more threaded inserts, and more complicated fab. (more parts - more effort for the watts). Realistically, how much travel do you want? Panhard works fine for a lot of race cars.

So... get some beefy rod ends and go do some research. There are good online resources for 3 link calculations. Basically, try not to have roll steer, get the anti's in shape (3 arms and where they meet), verify pinion angle consistency, and set up a long panhard to determine roll center.

Not sure what we are building here, but the RX8 rear suspenson looks like a 6 bolt solution to the problem

If it were me, I would go 3-link or parallel 4-link with a panhard, and make all the arms as long as possible. Better control of axle movement than leaf springs, and not too complex. I've never understood why some folks going to all the trouble of fabbing up custom rear suspension do so with Mustang-style short angled upper links.

FWIW, there are two poplar solutions on the four-link-plus-panhard AE86 Corolla when concerned about bind. The simple/cheaper one is to use half rubber bushings and half heim joints.

The other is to replace the short (8" long or so) upper arms with two longer ones that are close to the 20" or so length of the lowers. The front mounting point is obviously moved forward a corresponding amount. A few extra mounting holes lower and higher will allow some tuning of anti-squat.

I know that 3-link setups have less potential bind, and that the location of the third link can be used to control anti-squat and minimize the torque reaction. I haven't looked into the specifics, but I think kevlarcorolla has played around with it.

PM sent

If you're worried about a live axle giving up performance to an IRS for autox...Don't. Consider that some of the most winning cars in D/E Mod have used live axles. As a frame of reference, Jeff Kiesel's multi-time National Championship winning (Every year for a decade now) E-Mod Sprite runs a 'Satchell' style triangulated 4-link, and Del Long's (currently Jeff Cashmore's) multi-time National Champtionship winning D-Mod Locost runs a 3-Link.

I wouldn't get too concerned about fancy. Fox body cars have a swanky 4 link, and they wheelhop all over the place. Leaf springs with some sort of traction bar thingy is the easy button, and there are a whole lot of truck arm cars turning left at a very high rate of speed almost every weekend.

If you want swanky, head for the super late model catalogue and buy whatever floats your boat.

gearheadmb wrote: Truck arm and coilovers would be cheap and easy, but not awesome.

Truck arms are the most awesome suspension ever. They work great for traction and handling and are simple. And they make sidepipes practical. How is any portion of that not awesome?

Trackmouse wrote: Also, that Irish e30 purpose built rally car has a solid axle. It has many benefits. One being the cheapness of performance and repair. Can't beat that.

Consistent handling over long suspension travel means you can run softer suspension, softer suspension always means more grip.

I am a firm, FIRM, proponent of solid axles. They allow you to incorporate more anti's in your handling than you can with an IRS. IRS allows you to play games with toe on bump/droop but that makes for inconsistent handling if you allow the suspension to move much. Camber is not to be considered because solid axles by definition keep the tires planted regardless of body position. Camber curve is a crutch independent suspension needs for chassis roll.

ae86andkp61 wrote: I know that 3-link setups have less potential bind, and that the location of the third link can be used to control anti-squat and minimize the torque reaction. I haven't looked into the specifics, but I think kevlarcorolla has played around with it.

Knurled has been on the 3-link train since 2006 or so.

Knurled's car has so much acceleration grip that it understeers like a front driver on acceleration. This is Good because it encourages driving too hard. You can get out of problems by adding more power. Any time you add more power to solve a problem, you go faster.

I vote truck arms