'68maro

I was told that the rear-ends in the C3 vettes are extremely strong, even for being IRS. I have a 74 Vette that I am going to be doing a fairly radical 408 build with about 525-540whp through a Viper spec T-56 transmission. I was also planning on running either a plate system or possibly direct port system for track use only. Maybe a 200 shot or so. I am focusing more on NA though, because I cruise on the streets a lot. The car won't be a daily driver, but I don't want it to be too radical that I can't take it out and cruise with a few friends without risking breaking something.

Now, how much hp can this rear-end really take? I used the search function, and browsed through over 5 pages, and found nothing. Also, how do you strengthen it, what is good? I want this thing to take quite a bit of abuse. Is it possible at all to go to a solid axle without much work, or is it just easier to build up the IRS? I am not super fabby, so I won't be putting in a 9" if I have to customize everything myself...

Hotrod406

iTrader: (6)

Do a search on the Corvetteforum.com. The center section is pretty good; the axles and u joints are the weak points.

Scooter70

iTrader: (1)

I agree. I think most people who want to launch the car hard and run big power (like you seem to be planning) do a 9-inch swap. If you search on CorvetteForum for a guy who goes by GrandsportC3 you can see his progression. He runs a big inch smallblock and made the switch to a solid axle after breaking too many driveline parts in his quest for lower times. I think he's running mid-9s right now.

That's not to say that you can't make the IRS work. There are others running 10s with a few key upgrades. I guess it just depends on your goals.

-Matt

Nitrus rush

GrandsportC3 is still sticking with an IRS unit, but it's far from stock. He's using a modified unit from Tom's Differentials that has an IRS case stuffed with a 12 bolt ring, pinion, and posi unit. He's run a best of 10.078 @ 131.82 mph with this setup and plans to go even faster. I guess if you want to hit the IRS rear with a 200 shot AND a T56, Tom's will be your best bet.

Scooter70

iTrader: (1)

You're right. I seem to remember Oliver talking about a 9" swap a while back but I guess he never did it. I haven't been paying attention lately.

So the answer is... it is possible to run low 10s or even 9.90s on a built IRS setup.

93Polo

iTrader: (5)

Oliver is a nice guy and a CFOT regular. I have met up with him at a few Corvetteforum events.

You may want to search ML67, 632C2, and 540hotrod's posts. 540Hotrod drove his C2 from Texas to Cruise In in Bowling ran a 10 sec pass and drove it home. IIRC 632C2 has a Dana 60 center section and IRS.