IRS or Solid Axle?

[Desi]

Ok, so I have had some issues witht he IRS, most notably the bushings are (all) shot, I haven't priced them yet, and am really dreading it, so I was thinking about putting the factory rear end back under the car & selling the IRS for some cash for some other goodies, in fact the only reason it has an IRS is the prev. owner thought it would be cool, (and it is), but an occasional jaunt to the track (road racing or drag) doesn't seem to favor the IRS's much and the orig solid axle would be less hassle.
So.. since to replace the bushings, I have to drop the rear-end anyway, which would you do, orig solid axle, or keep the IRS & blow the cash on bushings?

[Ken Potter]

Do you already have a 7.5, or an 8.8, to put in it or would you need to buy the complete rear first?

[Desi]

Do you already have a 7.5, or an 8.8, to put in it or would you need to buy the complete rear first?

Have the full original 7.5, was in great shape when removed, it was just taken out to put in the IRS.

[Raven855]

Go for it Desi! Replace some bushings and enjoy the ride.

[Ken Potter]

Well if it's cheaper / easier and you really don't want to mess with the IRS I'd swap the 7.5 back in to it.

I don't know how much better the 7.5 would be at the drags?

[Philc]

I'm also contemplating pulling the IRS and going w/ a PHB. I'd like to keep it simple back there as all I seem to have done over the past few years was complicate matters w/ the car.

yes., the IRS does have its merits, but as I have too many projects, I need to KISS (Keep it simple stupid!)

[Henson]

Hmm... Is Ford using the IRS's in Mustangs now???? No? I wonder why...

What are they using? Oh 3- Link... Hmm...



If I were you... I'd go 8.8 with Torque Arm and Panhard. That maybe the real solution for a FOX Stang. No 8.8 then 7.5 will do.

[Philc]

I wouldn't bother w/ a 7.5 either. Go pull a 3.73 8.8 from a tbird and away you go!

[caroth]

Hmm... Is Ford using the IRS's in Mustangs now???? No? I wonder why...

Cost is the reason they stuck with the live axle. Plus all of the usual redneck mustang buyers want to go drag racing.

What are they using? Oh 3- Link... Hmm...

Yes and it sucks too, nice wheel hop with the new Shelby:

http://www.youtube.com/watch?v=_C9zanLcpXY&NR=1#t=0m50s

It is pretty well known that the rubber bushings in the IRS are what cause the wheel hop, so eliminate the rubber with a delrin bushing and the IRS becomes a pretty stout setup.

What car was second on the road course at this year's reunion? I think it was Gator's IRS equipped SVO. Put a real driver in the car (haha, sorry Gator) and it might have done better.

[caroth]

I'd like to keep it simple back there as all I seem to have done over the past few years was complicate matters w/ the car.

Can you elaborate on the issues you are having?

Thanks,
Chris

[caroth]

Desi:

http://fulltiltboogieracing.com/ for bushings.

Or, I will bring you my 3.55 8.8 rear in trade for that worn out IRS.

[Henson]

I always say...
Keep it simple stupid.

The Ford suspension guys I talked to stated the "stock" IRS geometry is incorrect but was edited to make it work at the time. I won’t go in to details due not stating it right but it is a combination of a few things like the spindle (upright) is not clocked right correctly. To do it right you need to build a new cage and not use that flimsy yet grossly heavy 3" tube structure thing. The final outcome when real HP is added is there is a lockup-bind situation and then breakage. Not including that the IRS needs and oil cooler.

I wonder how many folks are actually installing these IRS’s correctly. Meaning clocked correctly? From what I remember you have to do a lot of cutting and fabricating to get all the points correct. Yet I don’t see this happening? I’m not say just saying…

I’m all for get’r dun… but this is the drive suspension. I wonder how many are just F’n their sh!t up?

There is nothing wrong with the 3-link. All suspension components should be 2 force members. IRS is not. 4-link isn’t either. The best we have is the 3-link unless you build the IRS structure from scratch. Again the 3-link is best and cheapest solution for this Mustang Platform if you’re into racing. Especially for the FOX platform. End of story. Just $0.02. Food for thought. Now make up your mind and Get’r dun.




Just think of this... Anything is better than the stock 4-link.

[Desi]

Eh, a tie...well, I think I am gonna park it for the winter & think about it.. but I am leaning towards keeping the IRS, (thanks for the link Caroth)

[Raven855]

The IRS makes for one of the best riding mustangs you can get and the IRS in the hands of a good experienced driver on a road course is fantastic. Henson you are right in that the pick up points are wrong for an IRS, but it isn't too bad especially compared to the quadrabind unit in there now. And your panhard bar sucks compared to my watts

[caroth]

Henson, how do you explain Gator's car being faster at the reunion than your SS car? Just asking...