Solid rear axel or upgrade IRS?
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
One important difference between the design of the C4 rear compared with the C5 and C6 is that the halfshafts are a structural component of the suspension in the C4s which maintains the lateral positioning of the rear hub. This means that the ujoints and the halfshaft are not only being twisted but pulled or compressed at the same time which puts added stress on the halfshaft and ujoints. The rear spindle on the C5 and C6 models is fixed laterally and do not require the axles to maintain their geometry. This allows the use of CV joints and a solid axle which are stronger than the C4's aluminum halfshaft and ujoint. This does not make them immune to failure, though. Below are pictures of my C6Z06 halfshaft which failed during a launch at the strip.
Pro
Joined: Mar 2000
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From: Perth Amboy New Jersey
Safety Car
Joined: Feb 1999
Posts: 4,724
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From: Little Elm TX
In my experience, the Dana 44 is worthless once you get some power and you want to optimize your power. (Launch hard) That Turbo Vette earlier in this thread is leaving soft.... 164 mph and only 8.97.... a car properly optimizing its power can typically sneak into the 8's in the low 150's area and even in the high 140's if you're milking it. (But, I like that Turbo Vette.... its the schilmtzie !! 
)
Most of the racers in the past here have noted, that a properly built Dana 36 will run 1.7's without issues, once you go into the 1.6's and 1.5's, it becomes moment by moment thing. The Dana 44 can run 1.5's fairly reliabily with an auto. (I have somewhere around 1000 1.5's on mine with no issues), but once they go into the 1.4's and quicker, its a hit and miss thing. Any low 11 second car is capable of eeking into the 1.4's, hence it becomes a real issue with 10 second cars, which all are capable of running 1.4's and even into the 1.3's if you're launching appropriately.
But, I'll never say something can't be done, I guess with enough money and know how, somebody could make one last reliably for 9 and 10 second cars.... I just haven't seen it. I will add, for the rare occasion you do see somebody running fast with a Dana 44, what you don't know, is that they have broken it and rebuilt it 1/2 dozen times already...... I think its cheaper in the long term to just go Solid.
As a note, I do not think a Solid Rear takes away from a C4 in anyway at all.... if anything, it actually adds value to those in the know. Given the choice, with what I know today.... show me a high power vette with an IRS and one with a Solid and I'll buy the Solid, even if its more money.
)Most of the racers in the past here have noted, that a properly built Dana 36 will run 1.7's without issues, once you go into the 1.6's and 1.5's, it becomes moment by moment thing. The Dana 44 can run 1.5's fairly reliabily with an auto. (I have somewhere around 1000 1.5's on mine with no issues), but once they go into the 1.4's and quicker, its a hit and miss thing. Any low 11 second car is capable of eeking into the 1.4's, hence it becomes a real issue with 10 second cars, which all are capable of running 1.4's and even into the 1.3's if you're launching appropriately.
But, I'll never say something can't be done, I guess with enough money and know how, somebody could make one last reliably for 9 and 10 second cars.... I just haven't seen it. I will add, for the rare occasion you do see somebody running fast with a Dana 44, what you don't know, is that they have broken it and rebuilt it 1/2 dozen times already...... I think its cheaper in the long term to just go Solid.
As a note, I do not think a Solid Rear takes away from a C4 in anyway at all.... if anything, it actually adds value to those in the know. Given the choice, with what I know today.... show me a high power vette with an IRS and one with a Solid and I'll buy the Solid, even if its more money.
Safety Car
Joined: Feb 2000
Posts: 4,564
Likes: 110
From: Austin Texas
In my experience, the Dana 44 is worthless once you get some power and you want to optimize your power. (Launch hard) That Turbo Vette earlier in this thread is leaving soft.... 164 mph and only 8.97.... a car properly optimizing its power can typically sneak into the 8's in the low 150's area and even in the high 140's if you're milking it. (But, I like that Turbo Vette.... its the schilmtzie !! )
Most of the racers in the past here have noted, that a properly built Dana 36 will run 1.7's without issues, once you go into the 1.6's and 1.5's, it becomes moment by moment thing. The Dana 44 can run 1.5's fairly reliabily with an auto. (I have somewhere around 1000 1.5's on mine with no issues), but once they go into the 1.4's and quicker, its a hit and miss thing. Any low 11 second car is capable of eeking into the 1.4's, hence it becomes a real issue with 10 second cars, which all are capable of running 1.4's and even into the 1.3's if you're launching appropriately.
But, I'll never say something can't be done, I guess with enough money and know how, somebody could make one last reliably for 9 and 10 second cars.... I just haven't seen it. I will add, for the rare occasion you do see somebody running fast with a Dana 44, what you don't know, is that they have broken it and rebuilt it 1/2 dozen times already...... I think its cheaper in the long term to just go Solid.
As a note, I do not think a Solid Rear takes away from a C4 in anyway at all.... if anything, it actually adds value to those in the know. Given the choice, with what I know today.... show me a high power vette with an IRS and one with a Solid and I'll buy the Solid, even if its more money.
)Most of the racers in the past here have noted, that a properly built Dana 36 will run 1.7's without issues, once you go into the 1.6's and 1.5's, it becomes moment by moment thing. The Dana 44 can run 1.5's fairly reliabily with an auto. (I have somewhere around 1000 1.5's on mine with no issues), but once they go into the 1.4's and quicker, its a hit and miss thing. Any low 11 second car is capable of eeking into the 1.4's, hence it becomes a real issue with 10 second cars, which all are capable of running 1.4's and even into the 1.3's if you're launching appropriately.
But, I'll never say something can't be done, I guess with enough money and know how, somebody could make one last reliably for 9 and 10 second cars.... I just haven't seen it. I will add, for the rare occasion you do see somebody running fast with a Dana 44, what you don't know, is that they have broken it and rebuilt it 1/2 dozen times already...... I think its cheaper in the long term to just go Solid.
As a note, I do not think a Solid Rear takes away from a C4 in anyway at all.... if anything, it actually adds value to those in the know. Given the choice, with what I know today.... show me a high power vette with an IRS and one with a Solid and I'll buy the Solid, even if its more money.
If you drive it on the street/road race it?
Not worth the effort, as you rarely launch the car hard like in the 1/4.
Take it to the drags religiously? Yes...worth every penny to convert it to a reliable rear diff.
Like I said earlier...I've been looking at the Viper D44 for my ZR1 racer. There are TONS of the Vipers out there running fast times (some in the 8 second territory) running the STOCK D44 IRS.
The issue with the C4 IRS is the casting...not enough beef in the pinion area to keep it from flexing and breaking. I'm sure you know this intimately already
They don't have that issue with the Viper.
Beefy, stronger than King Kong...and so I intend to buy one and see how tough it would be to modify the C4 chassis to accept the carrier that the Viper D44 has.See...I road race (predominately) but like to do the occasional 1/4 mile drags so in MY case, the IRS is required and making it bullet proof is the goal.
It all comes down to your 85% use rule of thumb. Build it for what 85% of your intended use is...
If you want to drag race (mostly) = solid axle conversion
If you street drive it and occasionally drag race = IRS beef up
If you decide to drag it more after you beef it up, after the first major breaking of the D44 go directly to a solid rear, do not pass go, do not collect another $3500 to fix the D44.
Safety Car
Joined: Feb 1999
Posts: 4,724
Likes: 16
From: Little Elm TX
But, again, it's what the end use is going to be that determines the path...
If you drive it on the street/road race it?
Not worth the effort, as you rarely launch the car hard like in the 1/4.
Take it to the drags religiously? Yes...worth every penny to convert it to a reliable rear diff.
Like I said earlier...I've been looking at the Viper D44 for my ZR1 racer. There are TONS of the Vipers out there running fast times (some in the 8 second territory) running the STOCK D44 IRS.
The issue with the C4 IRS is the casting...not enough beef in the pinion area to keep it from flexing and breaking. I'm sure you know this intimately already
They don't have that issue with the Viper. Beefy, stronger than King Kong...and so I intend to buy one and see how tough it would be to modify the C4 chassis to accept the carrier that the Viper D44 has.
See...I road race (predominately) but like to do the occasional 1/4 mile drags so in MY case, the IRS is required and making it bullet proof is the goal.
It all comes down to your 85% use rule of thumb. Build it for what 85% of your intended use is...
If you want to drag race (mostly) = solid axle conversion
If you street drive it and occasionally drag race = IRS beef up
If you decide to drag it more after you beef it up, after the first major breaking of the D44 go directly to a solid rear, do not pass go, do not collect another $3500 to fix the D44.
If you drive it on the street/road race it?
Not worth the effort, as you rarely launch the car hard like in the 1/4.
Take it to the drags religiously? Yes...worth every penny to convert it to a reliable rear diff.
Like I said earlier...I've been looking at the Viper D44 for my ZR1 racer. There are TONS of the Vipers out there running fast times (some in the 8 second territory) running the STOCK D44 IRS.
The issue with the C4 IRS is the casting...not enough beef in the pinion area to keep it from flexing and breaking. I'm sure you know this intimately already
They don't have that issue with the Viper.
Beefy, stronger than King Kong...and so I intend to buy one and see how tough it would be to modify the C4 chassis to accept the carrier that the Viper D44 has.See...I road race (predominately) but like to do the occasional 1/4 mile drags so in MY case, the IRS is required and making it bullet proof is the goal.
It all comes down to your 85% use rule of thumb. Build it for what 85% of your intended use is...
If you want to drag race (mostly) = solid axle conversion
If you street drive it and occasionally drag race = IRS beef up
If you decide to drag it more after you beef it up, after the first major breaking of the D44 go directly to a solid rear, do not pass go, do not collect another $3500 to fix the D44.
Not sure, maybe you meant to quote somebody else's post.... I don't know.
Safety Car
Joined: Feb 2000
Posts: 4,564
Likes: 110
From: Austin Texas
I don't think anybody is recommending to go Solid if they are not high powered set-up that is Drag Racing...... this is common knowledge, if not drag racing, then no need to upgrade the rear-end. This thread seems to be more about drag racing a high powered set-up, hence why all of the talk around ET's and 60 ft times with linked videos in this particular thread
Not sure, maybe you meant to quote somebody else's post.... I don't know.
Not sure, maybe you meant to quote somebody else's post.... I don't know.
If the OP is going to HEAVILY drag race the car...then yes, a solid rear end is the way to go...as everyone has been suggesting.
If they only occasionally drag race, and like the performance the IRS gives on the street/track carving corners then a solid rear is NOT the best thing to do.
Ideally, something that could be easily swapped out would be the way to go but that isn't going to be an easy solution (or cheap).
One of the guys from Tiretown had his C4 set up that way...and he would come to NCCC convention with the IRS (and the 6-speed) installed in the car for autocross.
Then after that was done they would wrench all night, swapping out the rear AND the trans (to an automatic) and do drags.
Seemed like WAY too much work to me...I think I'd have just stopped at the rear end and been done with it.
It all comes down to what the OP WANTS to do with the car and where they think the money should be spent...
I don't particularly like how a C4 Corvette rides and handles curves with a solid rear. Been in a few of them now and can honestly say my Z07 will eat them for lunch on a track.
But then again I rarely take mine to the 1/4...and so that is where the value (for me) would be NOT to put in a solid rear.
Last edited by 1991Z07; May 1, 2012 at 06:12 PM.
Safety Car
Joined: Feb 1999
Posts: 4,724
Likes: 16
From: Little Elm TX
Nope...I meant to quote yours...
If the OP is going to HEAVILY drag race the car...then yes, a solid rear end is the way to go...as everyone has been suggesting.
If they only occasionally drag race, and like the performance the IRS gives on the street/track carving corners then a solid rear is NOT the best thing to do.
Ideally, something that could be easily swapped out would be the way to go but that isn't going to be an easy solution (or cheap).
One of the guys from Tiretown had his C4 set up that way...and he would come to NCCC convention with the IRS (and the 6-speed) installed in the car for autocross.
Then after that was done they would wrench all night, swapping out the rear AND the trans (to an automatic) and do drags.
Seemed like WAY too much work to me...I think I'd have just stopped at the rear end and been done with it.
It all comes down to what the OP WANTS to do with the car and where they think the money should be spent...
I don't particularly like how a C4 Corvette rides and handles curves with a solid rear. Been in a few of them now and can honestly say my Z07 will eat them for lunch on a track.
But then again I rarely take mine to the 1/4...and so that is where the value (for me) would be NOT to put in a solid rear.
If the OP is going to HEAVILY drag race the car...then yes, a solid rear end is the way to go...as everyone has been suggesting.
If they only occasionally drag race, and like the performance the IRS gives on the street/track carving corners then a solid rear is NOT the best thing to do.
Ideally, something that could be easily swapped out would be the way to go but that isn't going to be an easy solution (or cheap).
One of the guys from Tiretown had his C4 set up that way...and he would come to NCCC convention with the IRS (and the 6-speed) installed in the car for autocross.
Then after that was done they would wrench all night, swapping out the rear AND the trans (to an automatic) and do drags.
Seemed like WAY too much work to me...I think I'd have just stopped at the rear end and been done with it.
It all comes down to what the OP WANTS to do with the car and where they think the money should be spent...
I don't particularly like how a C4 Corvette rides and handles curves with a solid rear. Been in a few of them now and can honestly say my Z07 will eat them for lunch on a track.
But then again I rarely take mine to the 1/4...and so that is where the value (for me) would be NOT to put in a solid rear.
Bear in mind, he has a 800-900 HP motor.... he also stated he goes to the track only twice a year, because he knows the carnage is coming..... hinting, he would like to go much more often if he had a reliable rear-end.
For what its worth, I agree, if you're autocrossing, a solid rear isn't necessary. Just not sure what that has to do with my post.
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Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
In my experience, the Dana 44 is worthless once you get some power and you want to optimize your power. (Launch hard) That Turbo Vette earlier in this thread is leaving soft.... 164 mph and only 8.97.... a car properly optimizing its power can typically sneak into the 8's in the low 150's area and even in the high 140's if you're milking it. (But, I like that Turbo Vette.... its the schilmtzie !! )
Most of the racers in the past here have noted, that a properly built Dana 36 will run 1.7's without issues, once you go into the 1.6's and 1.5's, it becomes moment by moment thing. The Dana 44 can run 1.5's fairly reliabily with an auto. (I have somewhere around 1000 1.5's on mine with no issues), but once they go into the 1.4's and quicker, its a hit and miss thing. Any low 11 second car is capable of eeking into the 1.4's, hence it becomes a real issue with 10 second cars, which all are capable of running 1.4's and even into the 1.3's if you're launching appropriately.
But, I'll never say something can't be done, I guess with enough money and know how, somebody could make one last reliably for 9 and 10 second cars.... I just haven't seen it. I will add, for the rare occasion you do see somebody running fast with a Dana 44, what you don't know, is that they have broken it and rebuilt it 1/2 dozen times already...... I think its cheaper in the long term to just go Solid.
)Most of the racers in the past here have noted, that a properly built Dana 36 will run 1.7's without issues, once you go into the 1.6's and 1.5's, it becomes moment by moment thing. The Dana 44 can run 1.5's fairly reliabily with an auto. (I have somewhere around 1000 1.5's on mine with no issues), but once they go into the 1.4's and quicker, its a hit and miss thing. Any low 11 second car is capable of eeking into the 1.4's, hence it becomes a real issue with 10 second cars, which all are capable of running 1.4's and even into the 1.3's if you're launching appropriately.
But, I'll never say something can't be done, I guess with enough money and know how, somebody could make one last reliably for 9 and 10 second cars.... I just haven't seen it. I will add, for the rare occasion you do see somebody running fast with a Dana 44, what you don't know, is that they have broken it and rebuilt it 1/2 dozen times already...... I think its cheaper in the long term to just go Solid.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Then go out and get a 5.0 then if you think they are so better. Where did I say I'm looking to claim a title for the fastest street car?
Id rather have the c4 (w/ irs) running 8.97 then a solid axle 5.0 running 8.60
-or-
Id rather have aaron at aks racings car running low 9s w/ an irs vs. His car runnng low 8s w/ a solid rear.
Its clear we disagree and I'm sure we can agree at that.
The op needs to be aware that there are different ways of thinking.
Id rather have the c4 (w/ irs) running 8.97 then a solid axle 5.0 running 8.60
-or-
Id rather have aaron at aks racings car running low 9s w/ an irs vs. His car runnng low 8s w/ a solid rear.
Its clear we disagree and I'm sure we can agree at that.
The op needs to be aware that there are different ways of thinking.
Lots of aftermarket support for go fast parts.
But all the 5.0 guys like my 87 C4 A4 roadster.
Its something different to them.
Owned it 5 years now too.
Paid off & its all mine.
Sorry you disagree.
I have already destroyed several new Half shaft 1350 Spicer U-joints.
They don't last long with my right gas foot planted hard.
Solid axle & 4- link Competition Engineering Pro Magnum 4130 Chrome Moly construction.
Completed by myself.
Good luck with yourC4 IRS & drag racing hard.
P.S. All 1953 to 1962 Corvettes had a Live Hotchkiss Solid Rear Axle Differential.
I drove a 1958 a few years back.
Daul Quad 4-speed.
Top down in the sun.
Ran it hard.
Had plenty of character & personality only a Corvette could have.
Last edited by cv67; May 1, 2012 at 08:08 PM.
Safety Car
Joined: Feb 1999
Posts: 4,724
Likes: 16
From: Little Elm TX
I have to agree with Todd here. I raced for years with a Dana 44. When the 60's got into the low 1.5's, I averaged about 2 blowups per year; spiders, pinion, halfshaft, ujoints, spindles. This didn't account for the cost of the yearly freshenup. Keep in mind I make an average of 150 runs per year. A few years of this, and you can figure out the cost, not to mention the possible safety factor of possibly kissing the wall at speed with 1 wheel drive. Since my 12 bolt install 4 years ago, the last worry on my mind during a launch is rearend breakage. My 60's are now in the 1.39 range and hopefully will be lower. Willie
I'd consider purchasing that if one existed.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
Safety Car
Joined: Feb 2000
Posts: 4,564
Likes: 110
From: Austin Texas
You can imagine what the cost would have been...a solid block of billet aluminum the size of the pumpkin? The (many) days of machine work to whittle it down?
When I asked him about it last year he just laughed and said the price point was too high to even make it worth their while.
Le Mans Master
Joined: Oct 1999
Posts: 6,366
Likes: 34
The thought of dumping my C4 for a 5.0 Mustang has occurred in the past.
Lots of aftermarket support for go fast parts.
But all the 5.0 guys like my 87 C4 A4 roadster.
Its something different to them.
Owned it 5 years now too.
Paid off & its all mine.
Sorry you disagree.
I have already destroyed several new Half shaft 1350 Spicer U-joints.
They don't last long with my right gas foot planted hard.
Solid axle & 4- link Competition Engineering Pro Magnum 4130 Chrome Moly construction.
Completed by myself.
Good luck with yourC4 IRS & drag racing hard.
P.S. All 1953 to 1962 Corvettes had a Live Hotchkiss Solid Rear Axle Differential.
I drove a 1958 a few years back.
Daul Quad 4-speed.
Top down in the sun.
Ran it hard.
Had plenty of character & personality only a Corvette could have.
Lots of aftermarket support for go fast parts.
But all the 5.0 guys like my 87 C4 A4 roadster.
Its something different to them.
Owned it 5 years now too.
Paid off & its all mine.
Sorry you disagree.
I have already destroyed several new Half shaft 1350 Spicer U-joints.
They don't last long with my right gas foot planted hard.
Solid axle & 4- link Competition Engineering Pro Magnum 4130 Chrome Moly construction.
Completed by myself.
Good luck with yourC4 IRS & drag racing hard.
P.S. All 1953 to 1962 Corvettes had a Live Hotchkiss Solid Rear Axle Differential.
I drove a 1958 a few years back.
Daul Quad 4-speed.
Top down in the sun.
Ran it hard.
Had plenty of character & personality only a Corvette could have.
Le Mans Master
Joined: Oct 1999
Posts: 6,366
Likes: 34
Safety Car
Joined: Feb 2000
Posts: 4,564
Likes: 110
From: Austin Texas
Which is why I'm looking at a Viper D44 conversion for the race car.
You can find them on that auction site for about $1000 all the time...
I've been looking at the Viper boards for some time and rarely see complaints of "breakage" on them...even in those 1000+ HP turbo versions doing 8's & 9's in the 1/4.
Of course, the C-beam will have to either go or be modified to fit. Lots of things to think about and modify.
It won't be a cake-walk but it will be fun
Should keep me out of trouble for the next year
