Straight axle conversion
Thread Starter
Melting Slicks
Joined: May 2002
Posts: 2,715
Likes: 120
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
Re: Straight axle conversion (chevymans 77)
My whole intention when I bought this car was to install a BBC. I do respect the thoughts of all the members on this forum but the reason I bought a 77 vette is because it is not the most sought after year so moding it will not hurt its value as it would a 70 model chrome bumper vette.
That being said I am trying to get a comparison on which will be a better upgrade for the rear of my car, a beefed up IRS or a straight axle.
Neal
:)
That being said I am trying to get a comparison on which will be a better upgrade for the rear of my car, a beefed up IRS or a straight axle.
Neal
:)
Le Mans Master
Joined: May 2000
Posts: 6,493
Likes: 6
From: Bloomington MN
Cruise-In II Veteran
Re: Straight axle conversion (chevymans 77)
There are lots of C3's, C4's, and C5's running under 12 seconds with an IRS. Tom's differentials and Denny's driveshafts both make some really nice stuff for the IRS. I think it's more unique to build up an IRS than to just throw a straight axle into a car that didn't come with one.
If this is going to be a full-on drag car then by all means go with the straight axle. It's cheaper and more developed for drag racing.
If this is going to be a full-on drag car then by all means go with the straight axle. It's cheaper and more developed for drag racing.
Race Director
Joined: Jan 2000
Posts: 13,003
Likes: 2,240
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
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Re: Straight axle conversion (A C)
I just finished installing a custom Dana 60 IRS set up in my '67. It's all a custom deal, but once the diff is built, the rest is relatively straightforward. I built it so everything could unbolt and revert to stock easily. It takes lots of work, but it can be done.
In addition to the center section, I used Tom's outer axles, custom built 3.5"x .134 halfshafts, 1480 series u-joints.
I researched lots of stuff too, and decided to do this mainly because I wanted to keep IRS for conversation purposes. The Tom's stuff is proven into the 8's, but I also wanted to run less gear than his 12 bolt conversions allow. There are Heidts 9" IRS setups and I'm sure others.
I did see one C-3 at the races one time that had installed a solid 12 bolt under it. He used the stock trailing arms and it looked like he had just shortened/notched them and welded them to 12 bolt housing. That located rear under car fine. The only issue would be *if* the attachement point geometry was correct for optimum traction, but I saw it pull wheelies, so it wasn't too bad! The stock transverse spring was attached to the housing and on initial first look, you'd never pick up on the fact it wasn't an IRS.
JIM
In addition to the center section, I used Tom's outer axles, custom built 3.5"x .134 halfshafts, 1480 series u-joints.
I researched lots of stuff too, and decided to do this mainly because I wanted to keep IRS for conversation purposes. The Tom's stuff is proven into the 8's, but I also wanted to run less gear than his 12 bolt conversions allow. There are Heidts 9" IRS setups and I'm sure others.
I did see one C-3 at the races one time that had installed a solid 12 bolt under it. He used the stock trailing arms and it looked like he had just shortened/notched them and welded them to 12 bolt housing. That located rear under car fine. The only issue would be *if* the attachement point geometry was correct for optimum traction, but I saw it pull wheelies, so it wasn't too bad! The stock transverse spring was attached to the housing and on initial first look, you'd never pick up on the fact it wasn't an IRS.
JIM
Melting Slicks
Joined: May 2002
Posts: 2,508
Likes: 0
From: Wisconsin
Re: Straight axle conversion (chevymans 77)
I don't see how you people say it'd be costly, you have the same cost in doing it to a Corvette as you would a car that is already a straight axle. The same frame modifcations, the same floor modifcations. You end up back halfing it anyway. I've seen two straight axle Corvettes. My dad's '64 and his friend's '77. If you aren't going to run 10s, don't bother. And if you are going to run 10s, find a POS on Ebay and put your own chassis in and just use the body, because that is all that is left of the drag car anyway.
Racer
Joined: Jul 2003
Posts: 287
Likes: 0
From: Dayton Area Ohio
Re: Straight axle conversion (shawn_cake)
Quote "They make a "bulletproof" (hopefully) 12 bolt conversion kit that retains IRS.
It is certified to 7.00 seconds by most snactioning organizations. Now you won't have to "chop up" your Vette! "
:bs
I have to totally disagree with you... Have you ever ran 7sec? The IRS couldn't post those numbers reguardless of your hp, because you'd NEVER get that power to the ground! I ran my brothers alcohol funny car, part of the Ohio Outlaws, for a best of 7.07.. and we were running over 1800hp with a blown 572BBC....
The IRS setup will translate into wheel hop, or tire spinning... there is just no function in the vette suspension to transfer weight, and 'plant' the tires. I also know of no one who would try to use a 12bolt for a 7-sec street/drag car. 12bolts suck, and break all the time..even the supposed HD models. You want a strong rearend, ....9" ford and Dana 60 is about it.. or go aftermarket.. but oh yeah.... they use 9" ford carriers~! :reddevil
I'd recommend anyone wanting to weigh in on this, first go to hotrod.com, and look up the article on drag racing suspension physics... you might learn something.
It is certified to 7.00 seconds by most snactioning organizations. Now you won't have to "chop up" your Vette! "
:bs
I have to totally disagree with you... Have you ever ran 7sec? The IRS couldn't post those numbers reguardless of your hp, because you'd NEVER get that power to the ground! I ran my brothers alcohol funny car, part of the Ohio Outlaws, for a best of 7.07.. and we were running over 1800hp with a blown 572BBC....
The IRS setup will translate into wheel hop, or tire spinning... there is just no function in the vette suspension to transfer weight, and 'plant' the tires. I also know of no one who would try to use a 12bolt for a 7-sec street/drag car. 12bolts suck, and break all the time..even the supposed HD models. You want a strong rearend, ....9" ford and Dana 60 is about it.. or go aftermarket.. but oh yeah.... they use 9" ford carriers~! :reddevil
I'd recommend anyone wanting to weigh in on this, first go to hotrod.com, and look up the article on drag racing suspension physics... you might learn something.
Le Mans Master
Joined: Oct 2000
Posts: 6,563
Likes: 2
Re: Straight axle conversion (chevymans 77)
There's a beautiful, immaculate Nassau Blue 66 BB roadster around here with a Camaro 12 bolt under it. And it's been that way for over 30 years! The guy used to run at the drags a lot- got sick of blowing driveshafts, half shafts and rear ends. The car looks stock, and you really have to look to see that its different.
Personally, I think the 6 link setup is better for the street, with Some Tom's differential mods. The Corvette IS supposed to be a performance sports car, and most roads have stop signs and curves. So, unless you are running VERY serious, extreme H.P., consistent straight-line racing, IMHO stick with the IRS.
:yesnod: :chevy :chevy :yesnod:
[Modified by MassVette, 10:07 AM 8/1/2003]
Personally, I think the 6 link setup is better for the street, with Some Tom's differential mods. The Corvette IS supposed to be a performance sports car, and most roads have stop signs and curves. So, unless you are running VERY serious, extreme H.P., consistent straight-line racing, IMHO stick with the IRS.
:yesnod: :chevy :chevy :yesnod:
[Modified by MassVette, 10:07 AM 8/1/2003]
Melting Slicks
Joined: Dec 2000
Posts: 2,198
Likes: 2
From: Eastern Connecticut
Re: Straight axle conversion (chevymans 77)
My whole intention when I bought this car was to install a BBC. ...
That being said I am trying to get a comparison on which will be a better upgrade for the rear of my car, a beefed up IRS or a straight axle.
:)
That being said I am trying to get a comparison on which will be a better upgrade for the rear of my car, a beefed up IRS or a straight axle.
:)
Safety Car
Joined: Jan 2001
Posts: 4,660
Likes: 3
From: South Central Louisiana
St. Jude Contributor
Re: Straight axle conversion (joe73vette)
Or you can take a less perfect car and mod the heck out of it..... I have an 80 frame and body for sale, cheap!!!
http://forums.corvetteforum.com/zerothread?id=616807
[Modified by LAvetteman, 12:39 PM 8/1/2003]
http://forums.corvetteforum.com/zerothread?id=616807
[Modified by LAvetteman, 12:39 PM 8/1/2003]
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Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Straight axle conversion (LAvetteman)
I advised a guy the other day that it's much cheaper to install a narrowed 9 inch 4 link than to try and beef up an IRS. You see very few c-3 late model drag cars. So he bought a gutted 81. Perfect race car material!:)
Safety Car
Joined: Feb 2002
Posts: 3,556
Likes: 0
From: Seattle WA
Re: Straight axle conversion (Pacin'California)
Instead, you can have a great drag race car, which everyone on the forum seems to cream over.
Seeing posts about autocrossing or road-racing is very rare here... I'm surprised I didn't get creamed on more for canning the straight-ahead only idea. The IRS is what makes the 'vette a 'vette. It's why the car exists. To be America's best SPORTS car.
Maybe I should use my knife to drink soup and my spoon to cut french bread...
Still, for the price of a solid-axle conversion, you could probably buy a motorless car and build up an 11 second car without a hitch.
BTW- the modded ZL-1 that ran 10.9 for motor trend, was it using the stock IRS or did it have a straight-axle too?
-Steve(who's related to Adam Von Trott Zu Solz... look him up sometime.)
Seeing posts about autocrossing or road-racing is very rare here... I'm surprised I didn't get creamed on more for canning the straight-ahead only idea. The IRS is what makes the 'vette a 'vette. It's why the car exists. To be America's best SPORTS car.
Maybe I should use my knife to drink soup and my spoon to cut french bread...
Still, for the price of a solid-axle conversion, you could probably buy a motorless car and build up an 11 second car without a hitch.
BTW- the modded ZL-1 that ran 10.9 for motor trend, was it using the stock IRS or did it have a straight-axle too?
-Steve(who's related to Adam Von Trott Zu Solz... look him up sometime.)
i plan on swapping to a 9" also, but im going to do coil overs and a bunch of goodies, so it will handle better than the stock IRS. proof? new f-bodies eat me alive in it twisties. and they are crappy 10-bolt solid axles. a 9" 4-link with coil overs should do great in the turns.
i understand what your saying Steve, but to me, a vette is something that should drop jaws at the drag strip. so thats what i plan on doing. ;)
and the comment on "Why not just get a camaro?" because youd have to swap the rear suspension anyway, and vettes look cooler :cool: :D
Intermediate
Joined: Jul 2003
Posts: 31
Likes: 0
From: Winnipeg MB
Re: Straight axle conversion ('79ProwlerOrange)
Just last Spring there was a solid axle 74 or 75 vette for sale in the Toronto area I think the owner said he had a 600hp engine it was a drag vette at one point in its life. I do not think there were any takers. Asking price was $35,000.
Le Mans Master
Joined: May 2000
Posts: 6,493
Likes: 6
From: Bloomington MN
Cruise-In II Veteran
Re: Straight axle conversion ('79ProwlerOrange)
i plan on swapping to a 9" also, but im going to do coil overs and a bunch of goodies, so it will handle better than the stock IRS. proof? new f-bodies eat me alive in it twisties. and they are crappy 10-bolt solid axles. a 9" 4-link with coil overs should do great in the turns.
Le Mans Master
Joined: May 2003
Posts: 5,642
Likes: 1
Re: Straight axle conversion (A C)
You are all wrong, okay here is what you do, make it a three wheller with only one wheel in the back and two up front with a turbine engine and spoilers like knight rider.
step two: race it and record it
step three: pull a knight rider and play at 5x speed to look even faster..
oh yeah and us a harley motorcycle chain and sproket set to relocate the steering whel to the right hand side so that you can be closer to the ladies on the sidewalk.
:steering: :rant: :withstupid: :rofl: :grouphug: :auto: :party:
step two: race it and record it
step three: pull a knight rider and play at 5x speed to look even faster..
oh yeah and us a harley motorcycle chain and sproket set to relocate the steering whel to the right hand side so that you can be closer to the ladies on the sidewalk.
:steering: :rant: :withstupid: :rofl: :grouphug: :auto: :party:
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Re: Straight axle conversion ('79ProwlerOrange)
Im pretty sure that ZL-1 did have an IRS. but how many runs did it do on it? and i bet it was gone through before every run.
i plan on swapping to a 9" also, but im going to do coil overs and a bunch of goodies, so it will handle better than the stock IRS. proof? new f-bodies eat me alive in it twisties. and they are crappy 10-bolt solid axles. a 9" 4-link with coil overs should do great in the turns.
i plan on swapping to a 9" also, but im going to do coil overs and a bunch of goodies, so it will handle better than the stock IRS. proof? new f-bodies eat me alive in it twisties. and they are crappy 10-bolt solid axles. a 9" 4-link with coil overs should do great in the turns.
But you really blinded me with science on that second paragraph. Apparently, my friend's 1988 BMW 325i has even better suspension, because he blew a 97 'maro Z/28 away in the twisties. Bone stock with bad tires. I think we should use his rear suspension for our cars instead.
-Steve
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Re: Straight axle conversion (Metal Wulf)
hope you have deep pockets... for the cost of the conversion you could buy a nice solid axle car.
Safety Car
Joined: Feb 2002
Posts: 3,556
Likes: 0
From: Seattle WA
Re: Straight axle conversion (Pacin'California)
wow i wasnt getting personal. damn steve take it easy. i was stating an example. i could list at least 10 stock cars with straight axles that handle better than my 79 vette. IRS will handle better with more money in it, but why would i want to blow 2K on a setup that couldnt handle the power my engine will be producing. thats plain vanilla stupid. no one converts to solid because it rides so good, and handles so well. they do it because thier engines rip apart IRS.
sound like this topic really ruffles your feathers. i dont know why, its not like were sneeking in your garage and converting your car. :rolleyes:
[Modified by '79ProwlerOrange, 1:12 AM 8/2/2003]
sound like this topic really ruffles your feathers. i dont know why, its not like were sneeking in your garage and converting your car. :rolleyes:
Im pretty sure that ZL-1 did have an IRS. but how many runs did it do on it? and i bet it was gone through before every run.
i plan on swapping to a 9" also, but im going to do coil overs and a bunch of goodies, so it will handle better than the stock IRS. proof? new f-bodies eat me alive in it twisties. and they are crappy 10-bolt solid axles. a 9" 4-link with coil overs should do great in the turns.
Ran all day for the press. I think they made at least 20 or 30 10 second passes, it was dead by the end of the day.
But you really blinded me with science on that second paragraph. Apparently, my friend's 1988 BMW 325i has even better suspension, because he blew a 97 'maro Z/28 away in the twisties. Bone stock with bad tires. I think we should use his rear suspension for our cars instead.
-Steve
i plan on swapping to a 9" also, but im going to do coil overs and a bunch of goodies, so it will handle better than the stock IRS. proof? new f-bodies eat me alive in it twisties. and they are crappy 10-bolt solid axles. a 9" 4-link with coil overs should do great in the turns.
Ran all day for the press. I think they made at least 20 or 30 10 second passes, it was dead by the end of the day.
But you really blinded me with science on that second paragraph. Apparently, my friend's 1988 BMW 325i has even better suspension, because he blew a 97 'maro Z/28 away in the twisties. Bone stock with bad tires. I think we should use his rear suspension for our cars instead.
-Steve
[Modified by '79ProwlerOrange, 1:12 AM 8/2/2003]
Safety Car
Joined: Feb 2002
Posts: 3,556
Likes: 0
From: Seattle WA
Re: Straight axle conversion (GrandSportC3)
not if you know the right people ;) i should have a complete 9" conversion for less than a VB&P kit. assuming i can get a junkyard 9" with gears i like. if i have to buy it new it may be arround 2,500 total.
[Modified by '79ProwlerOrange, 1:14 AM 8/2/2003]
hope you have deep pockets... for the cost of the conversion you could buy a nice solid axle car. :iagree: ... Converting a C3 to solid axle is very expensive...
[Modified by '79ProwlerOrange, 1:14 AM 8/2/2003]
Intermediate
Joined: Jul 2003
Posts: 31
Likes: 0
From: Winnipeg MB
Re: Straight axle conversion (GrandSportC3)
If any one is seriously considering a solid axel C3 let me know I will try and find the advert. For a C3 in the Toronto area. There was one for sale; it was a former drag vette now converted back to street use. Just trying to contribute to the forum members.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Re: Straight axle conversion ('79ProwlerOrange)
Just poking fun of your logic, Benny. :p
If I were really "ruffled", I probably would have tripped the forum censors off something fierce. :)
-Steve
If I were really "ruffled", I probably would have tripped the forum censors off something fierce. :)
-Steve
