IRS vs. Live Solid Axle

[caffinecobra]

ok, I've seen a number of posts on this issue, but more on the "how-to" and "what" than "why". My understanding is that the solid axle will handle more power and eliminate wheel hop during hard launches. If I were to switch over to a live axle and coil-over suspension, would my car handle better or worse than it does stock with the IRS?

I guess I'd like to know the pros and cons of both rear ends...

 

[Tat98Cobra]

ok, I've seen a number of posts on this issue, but more on the "how-to" and "what" than "why". My understanding is that the solid axle will handle more power and eliminate wheel hop during hard launches. If I were to switch over to a live axle and coil-over suspension, would my car handle better or worse than it does stock with the IRS?

I guess I'd like to know the pros and cons of both rear ends...

My guess would be that the IRS cars would be better Autocross racing, will live axle would be better for 1/4 mile racing.
You may lose a little handling, but it can be made up easily with the other upgrades you can make to your suspension

peace

 

[99SVTAddict]

With the right aftermarket suspension pieces, you can make a solid axle out perform the pieced-together IRS that came with the Cobra.

Solid axle is better suited for drag duty than the IRS for sure.
When I put in my solid axle I opted for 31 spline mosier axles, eaton diff, 4.30 gears, SVO lower control arms, Mega byte Jr. upper control arms, upgraded springs, shocks, bushings.....it's ready for some serious drag duty. If I cared about auto cross I could have done some things differently to make it out handle the stock IRS.

As for your other questions, yes, the solid can handle sticky tires, more power, and high RPM launches. The IRS's break under these same conditions. The weak point is really the 1/2 shafts. Also, the IRS is famous for the dreaded wheel hop. On the way to the shop I spun the tires and got horrible wheel hop on a cold December day....on the way back after the swap I floored it and just got nice solid wheel spin (stock tires, cold day).

IRS is nice for a daily driver.
Solid is nice if you want a predictable car that sees street and track duty.

 

[caffinecobra]

It sounds like a live axle would work better for me then... I really hate that wheel hop, too!

99SVTAddict, your car sounds sweet! Did you make any internal mods to the engine to handle the power or to lower the stock compression? I've really wanted to put on a blower for a while but have been told not to unless I modified the pistons and rods, which I really don't want to do.

 

[99SVTAddict]

No internal mods yet....money is set aside for the most part. I'm hoping to get through the whole summer with no issues.

I was thinking of doing a bigbore forged block and doing a P&P job on the heads...maybe cams too. Now I'm thinking I may just forge the block and be done with it. I don't really need any more power. Once the block is forged I may just up the boost. Easy/cheap power compared to doing the heads and cams and such.

So far no issues with the stock block. But that's only 4,000 miles or so and 10 passes down the 1/4 mile.

I have a couple more "look good mods" I'd like to do, so I'm thinking of just doing the forged block approach. Then new seats and a custom paint job and I'm done.

 

[caffinecobra]

very cool. what's your best 1/4 et so far? Keep me posted if you would; I really want to supercharge.

 

[99SVTAddict]

I'll let you know....best quarter mile so far sucks as I just spun the tires....or wheel hopped through second gear Mid-high 12's believe it or not. On street tires though.

BTW, out in CA you will have to give up some power due to the low octane gas you are stuck with. Just an FYI. I'm running 94 octane mixed with 2 gallons of race gas.

 

[caffinecobra]

12s are excellent for street tires! I couldn't bite until 3rd on street tires and the wheel hop was horrible.

94 octane??? nice. Yeah we're stuck with 91!

 

[32vmonster]

i was thinking of swapping my 03' cobra rear for my 00' gt and vice versa. both rears are complete. i just want the cobra to have a solid axle. any suggestions if it would work??

 

[103]

It'll work fine, you just need to weld on cat-back hangers and the pinion snub on the solid axle car. Plus you need to swap around the rear ABS lines. Otherwise it's a direct bolt(SSSSS)... Have fun.