Complete MM IRS Fix It Kit or Built Live Axel???

[393Bird]

Another thing that hurts the IRS, is a conventional limit slip differential. When is does spin, it tries to equal the traction by transferring load back and forth as needed. This can happen very fast, especial if there is any hop at all. Once it starts, it loads and unloads all the suspension parts and bushings. Then you get serious wheel hop. A true locker type differential will drastically reduce this.

 

[sedanman]

How do the IRS cars ride after installing all new bushings?

 

[yoshis99_cobra]

I've been thinking about doing a solid axle or keeping my IRS but I hear both sides and they're both very convincing. I've read all these posts for the past 2 hours and I think I have a headache :xpl:
But I guess I'm going to stick with my IRS as well and see how it holds up. I don't have nearly the amount of power the 03 and 04's are running and probably won't for some time. I think what I'm going to have to do is start from the back end, being axle and suspension, and then work my way forward to the engine. That should probably take me about 2 years to get all the work done for both suspension and engine. I don't have traction as it is now anyway so why would I keep adding more HP. Traction is what I need and Traction is what I'm going to get.

Thank you all for your posts. They have been real informative.

 

[racebronco2]

i have replaced the dif and subframe bushings and still get a little wheel hop in the dry and more in the wet .... i bought the torsen tr2 and i have no wheel hop in the dry or wet no matter what i do to make it hop .... i heard they are not good for drag racing (due to the high rpm launches)but if you slip the clutch they should last a while

 

[silvercoffin]

...

For those of you with built up IRS cars a few Qs

1. Why is the shop recommending levels two axles to me? (I explained that I will be getting a whipple next and running some big numbers)

and the big Q

Once you have the Pinion snub, axles and an IRS Brace can you really launch the car differently? or is it just less likely to break?

I guess once you add some SLicks it will all be worth it.

Is there anything else I should be getting...aside from pinion snubber, axles and an IRS Brace...to beef up the IRS? oh I already have adjustable shocks and 1.78 60 fts with no wheel hop.

 

[Snake40]

great thread

 

[xstork]

I would avoid dealing with DSS on the level 5 halfshafts I made this modification and am having nothing but problems , I am on my second set of wheelbearings within 80 miles ,we sent my stock hubs and half shafts into DSS to have the level 5 upgrade done and within 50 miles the first set went . I inspected the hubs before they were sent back and Karl at Pauls high performance stated that the area where the wheel bearings are supported looked to be too thin on the outer edge and he felt that the wheelbearing was not being fully supported also we found that the washers provided by DSS were now bent , so they sent the first set of hubs back, I had to pay for the second set at a cost of 379.00 dollars, Pauls High Performance installed the second set and within 80 miles the same thing happened , and now no one at DSS will return any phone calls ,I have the level 5 halfshafts which were suppose to be rated at about 900 hp I am only putting out 480 and not even running slicks or drag radials so I am seriously considering a solid axle I have done all the bushings toe links and all the other things I have no problems with wheel hop the other mods were all done before I got the level 5s so I know that is not the issue so unless DSS lives up to there warrenty I might have to go with a solid axle , I am currently looking into legal action against DSS depending on the out come of what they find with the hubs we sent back, I know they have recieved them because they were signed for by someone from DSS ,once they decide to respond to the numurous calls that Pauls High Performance has made to them to try and sesolve this issue will determin my course of action I really want to keep the IRS but may not have a choice in the matter / just a side note I had no problems at all with the stock halfshafts just wanted to make the IRS stronger because I am planning on upgrading to a Kenny Bell

 

[mustarrosa]

This is not good news. I ahve the level 5's in my garage wating for the moment to install them..Now I read this..So am I hosing myself into thinking I am making a good choice? Help me out there..is this the only post about a DSS level 5 not going well?

 

[2JZFAN]

go live.

less weight. proven performance. can be made to out handle IRS. swap it and forget it. :beer:

 

[otto]

the mustang cobra irs rear is not a high performance piece it was designed as a high speed cruiser. look at the spring placement canted forward and the bottoms are inboard for lots of cushy leverage the angles of the arms are wrong for serious high performance too. the cobra is what it is a fast and capable cruiser. four link guys dont get smug because four links are garbage for ultra high performance too. four links have inherent bind and are more for luxury also. so if you are trying to make an ultra high performance stock body type car you need A THREE LINK and i DONT mean the 197s piece.the top link is too short (about two and a half to three times too short) to be effective. so we are talking about a custom 9inch three link set up if you are serious thats what you will do. if not people can argue over two stock parts designed for the street and passenger comfort. it seems every body is puting massive power in to inferior drive lines and then complaining.600+hp demands a serious suspension especialy for handling. by the way i dont see too many, in fact no serious mustangs running irs in high level road racing competition.they are all three links. Trans am stangs were running three links in the eighties and ever after. I realise t.a. cars are tube cars but if irs system were better dont you think they would have used them. i dont think those guys were very cheap.

 

[shamis935]

go live axle. if your worried about handling just look at American Iron cars.

 

[bigdog93lx]

Just get new tires, Sub frame connectors, and a BF brace.

After spending money on the bushings, H&R Springs, SFC, BF Brace and still having wheel hop (granted its still only 40-45 degrees out) 95% of the wheel hop problem comes from having the sh!ttiest possible tires on these cars. These F1's really suck balls.

 

[silvercoffin]

...

Think I already posted this...but

All I did was get QA1 adjustable shocks and run them real soft on the street and my hop is gone..

At the track with the QA1s set stiff, MT Drag radials and a pinion snubber I really have no hop at all ever..

I didnt spend money on all that other stuff...

 

[Cobra-R]

go live axle. if your worried about handling just look at American Iron cars.

More and more AI cars are switching over to IRS, don't be afraid of it on the race track and street.

Brian

 

[01cobravortech]

I can understand the serious drag racer going to a solid axle because he bought this car to race and hopefully make some money. But if the car is a daily driver/part time track visitor and a car that you will keep for some time then it really makes no sense to dump the IRS. Its a great ride witht he IRS. I personally don't like the ride of a solid axle. Its a night and day difference when I'm in my Cobra. MM did a great job addressing the IRS' shortcomings. Before rushing for the Level 5 axles, you may want to program yourself to not try and fight through wheel hop. I've read so many posts on SVTP of guys who broke a half shaft because when the car started to hop they still kept flooring it hoping the hop would stop.

 

[ac427cobra]

IMHO a factory IRS is somewhat inferior in performance to a factory live axle. But that's about the only time the SRA is better. By removing all of the rubber in the IRS it becomes better riding AND handling hands down, without a question.

If you are a hard core drag racer with tons of power, that would be the only scenario I could see replacing the IRS with a SRA.

FWIW, YMMV

:thumbsup: :coolman: :beer: