Solid axle vs. IRS

[slow4dr]

the im almost sure that you will need to shorten it to fit under the nova, unless you stumble upon one from an e-type.. ill measure the unshortened one i have for spares tomorrow and post specs, but im sure the info is on the internet somwhere... but the jag unit is prety much what kugel has copied... take a look at http://www.cwiinc.com/ in the mean time...

Interesting, thanks for the info. Weight is a concern as well which is why I have leaned away from using the Cobra IRS. It would be interesting to see actual weight #'s to compare all of them(both sprung & unsprung).

[RobM]

im pretty sure its dificult to get any sort of anit squat with irs.... corect me if im wrong irs isnt my game

[deuce_454]

well actually it isnt thar hard... but it requires that you think "4 link" when you decide where to attach the longitudinal controll arms, the IRS will (just like a rigid rear) react when you transfer torque to the wheels, where this reactant force, and in what direction relative to the C of G ot the chassis will determine if it squats or raises the rars, and also the amount of weigth transfer... but like designing a solid axle suspension, it requires knowledge of the forces in question and desicions on how tou want the car to react..

[RobM]

makes sence thanks, I dont see how you could get as much anti squat as a solid axle with links, but then again how much is really needed?

[Norm Peterson]

I don't think it's realistic to expect as much A/S with IRS as with a solid axle, at least not before you compromise other aspects of the IRS arrangement to the point of losing more somewhere else than is marginally gained with the last increment of A/S increase (rear toe change with suspension travel comes to mind).

Norm

[Mean 69]

The physics behind the IRS versus the stick axle regarding A/S are completely different, as are the equations that are used to calculate them. Literature suggests that about 25% A/S for an IRS is the practical limit, going beyond this is going to start really compromising the rest of the suspension attributes. IRS systems are obviously really great systems, but because of their relative complexity and various interactions of all of the suspension considerations, you can get lost REALLY fast with them.

A/S for a stick axle can easily be far hgiher, which means there is "potential" to plant the tires harder as a result of reactive forces, but here again one needs to really understand what the primary goal of the setup is before going too far (for instance, the biggest enemy of very high anti-squat and the corresponding short SVSA's is brake hop, not a good thing).

Nothing's free.
Mark

[hssss]

I am building a 351/392 powered Lotus 7 and am currently debating the relative worth of IRS vs a 3 link similar to the 05+ mustang. My problem is that unspring weight with the solid axle will be a large part of the overall weight. I can fairly simply fab either setup and using only selected Cobra parts, hubs for 5 on 4.5 and dif drive flanges for 31 spline (already have a Torsen T2 31 spline) the rest from a MK VIII. The more I look the overall weight probably would be about the same but the setup will be more complicated. The primary problem I have heard about the Cobra setup is that it is geometry challenged. For the Nova I would think the C4 setup would be the least complicated to install.

[deuce_454]

the jag rear suspension is in it self not geometrically challanged, but ive seen a couple of companies who sure screwed up in designing the mounting... the challenge you are refering to is that the LCA in th ejag suspension also transfers torstonal forces, where as that is dealt with in the longitudinal CA in a corvette setup.. that means that if the jag carrier is rigidly mounted the longitudinal CA will break off the bolts holding the LCA bracket to the carrier unless the forward mounts of the longitudinal CA are mounted on a line that intersects with the LCA inner bearings. and if thsi is not the case then the carrier must be mounted so as to allow it to swing... (which is also how you enable antisquat)

[hssss]

...The primary problem I have heard about the Cobra setup is that it is geometry challenged...

Note

[Protour_Pinto]

And if the rearend dosnt work out you can always make furniture out of it!



I went with a Jag rear in my car due to cost and my cars driveshaft was only 20 inches long. The pinion had to be stationary.

If you go to Pick A Part you can pull a whole rear assy for $250.00

[hssss]

Protour_Pinto I like your furniture but you must not be married. I have decided to go with a Roarty http://locost7.info/files/suspension...RSAssembly.pdf based Irs using late Explorer dif and MK VIII spindles, they are infact inroute as we speak. I like that the 8.8 is a bit stouter than the D44 and this design gives me a bit more wiggle room in the fabrication.

[daveheld]

I like the IRS TV stand... I have a table that would go well with it...




dave
Cocoa Beach FL

[Twin_Turbo]

I built a custom double a arm IRS using a C4 corvette super dana 44

[Samckitt]

Twin Turbo, Any chance you would share the CAD file of the factory Vette rear that you have modeled?

[Samckitt]

Daveheld - I love that table, I'm gonna have to make one of those.

[Twin_Turbo]

Twin Turbo, Any chance you would share the CAD file of the factory Vette rear that you have modeled?

Which one do you need? early cast iron w/ lid or w/ 80-82 batwing ?

Shoot me an email, I will send you the file later this week, have it on another system

[telite]

i like the twin turbo^ setup.
and the old pantera setup. real nice fully adjustable.

[Twin_Turbo]

Scot, did you ever get those models I sent you??

[Samckitt]

Yeah I got them, thanks. I have them imported into UG & have made the assy. I'll have the model the half shafts, hubs & the upper & lower arms.

I have to find a new batwing cover for the one I have. One of the "wings" is bent on the one I have. Paul Newman's Car Creatins sells a new redesigned casting that is heavier & has some supports inside for the bearings. $800! Ouch.

Thanks

[Twin_Turbo]

Why not just cut off the batwing all together and put togethre some kind of subframe to mount it, there are plenty of oints on the diff where you can mount it, like the stock camber rod moutns, the front c beam pad... just like mounting a quick change. This could easily be made stronger than the batwing.

Do you have a model of the halfshafts? I have it, the length is easily changed...if you want it, let me know.