Beefing up an '80 rear end
Thread Starter
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Beefing up an '80 rear end
Ok so I know what kind of power I am making and I want to get some real timeslips, that means drag radials and doing whatever to the rear of my Vette that needs to be done to launch the car properly. 14 secs @ 114 mph with a 3 sec 60ft gets old real fast. 
The aluminum Dana has held up quite well with street tires acting as a relief valve and spinning instead of sticking and destroying the rear end parts.
So I would like to know what you guys have done to '80-82's to make the rear end stronger for a good launch at the drag strip. I will be around 500 RWHP. Opinions are also welcome, I will be collecting parts to do this over this winter
The aluminum Dana has held up quite well with street tires acting as a relief valve and spinning instead of sticking and destroying the rear end parts.
So I would like to know what you guys have done to '80-82's to make the rear end stronger for a good launch at the drag strip. I will be around 500 RWHP. Opinions are also welcome, I will be collecting parts to do this over this winter
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
I quizzed Gary quite a bit about this a couple yrs ago. With $$ not a show stopper, a Tuned iron unit from an older vette would be the answer. There is not enough meat in the aluminum units and there is really no good way to blue print them. SOme can be done, but it didn't seem worth the effort to me.
Thread Starter
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Gary won't touch an aluminum punkin. I don't want to spend a fortune but I know me once I get into it, it's gonna hurt.
Just want to know my choices. Has to stay IRS no straight axle. Would love to here from someone who is running the same or less HP with a clutch and able to launch fairly hard to real hard. What parts they had to change / use. Automatic is fine too
Just want to know my choices. Has to stay IRS no straight axle. Would love to here from someone who is running the same or less HP with a clutch and able to launch fairly hard to real hard. What parts they had to change / use. Automatic is fine too
Safety Car
Joined: Nov 2005
Posts: 3,961
Likes: 573
From: Lompoc, CA. Santa Barbara County
I'm with you on this one Motorhead. I just bought an aluminum rear for my Vette. But I'm sticking with street tires and automatic transmission. You are my example that the aluminum rear end isn't all junk.
Bee Jay
Bee Jay
Melting Slicks
Joined: Jun 2002
Posts: 2,844
Likes: 99
From: Orrtanna Pa.
So far I have hit 7000 rpms on the 1/2 shift and haven't heard anything break in the rear. I have not yet tried a full on launch in first......Should be interesting. With my street tires, it would roast them from a 25 mph roll in first, and keep them boiling through third.
These MT's are sticky, which is what I needed....But now I have to work up the nerve to hit them hard off the line. I suspect my 3000 stall and almost 500 ft lbs is going to hit pretty hard. Mind you this car has not been on the track,...just playing around once in a while.
The rear is the stock aluminum one, but I put 3.70 gears in it about eight years ago, and all U-joints are solid.(No grease zerks)
Last edited by The Money Pit; Jun 22, 2010 at 09:01 AM.
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
If you get in touch with tracdogg2 (Mike) here on the forum, he can fit a billet steel cap to the aluminum rear end that should help.
I still doubt it would hold up to the power that you are making with sticky tires though.
I switched over to a iron differential in my 80, but I am sure its still not strong enough for serious drag duty.
You would probably have to get one done up 12 bolt style to be able to really beat on it without worrying.
I still doubt it would hold up to the power that you are making with sticky tires though.
I switched over to a iron differential in my 80, but I am sure its still not strong enough for serious drag duty.
You would probably have to get one done up 12 bolt style to be able to really beat on it without worrying.
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12bolt with upgraded half-shafts and outer/inner spindles.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
With 500rwhp and a stick shift on drag radials AND going to the strip, I would damn sure go with an iron diff and at a minimum, do the "Super 10 bolt" from Tracdogg or GTR1999.....but the full 12 bolt internals upgrade would be your best bet for sure.
I am having Tracdogg do a Super 10 bolt with the 30/31 spline axle setup in August, I drag race but my car is an Auto so I think it will live...especially since I am only going to run a 3.36.
Both Tracdogg and GTR1999 have excellent reps for building these things, lucky for me, Tracdogg is within driving distance for me.
You get your car to hook and you can shift, you "should" blow into the 10s...good luck....it's about time you start putting all that power to use...
I am having Tracdogg do a Super 10 bolt with the 30/31 spline axle setup in August, I drag race but my car is an Auto so I think it will live...especially since I am only going to run a 3.36.
Both Tracdogg and GTR1999 have excellent reps for building these things, lucky for me, Tracdogg is within driving distance for me.
You get your car to hook and you can shift, you "should" blow into the 10s...good luck....it's about time you start putting all that power to use...
Thread Starter
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I actually got tired of drag racing ( my own cars ) years ago but since last year the interest has come back.
I think I am going to be sinking some big money into the rear to handle the power and stick shift. If I am going to do I will do it all the way that mean best launch possible and shifting at 7000 RPM's
I was browsing the DragVette site, he has a interesting and cool looking 6 link setup it looks like he bolt right to the aluminum Dana rear, I still think the diff is going to blow if I did that, even an older iron case won't last.
Looks like a 12 bolt of some kind is in my future. Would like to see this thread go for while and get some guys who have converted the rear ends in there '80-'82's for big power. It could be used as a reference
I think I am going to be sinking some big money into the rear to handle the power and stick shift. If I am going to do I will do it all the way that mean best launch possible and shifting at 7000 RPM's
I was browsing the DragVette site, he has a interesting and cool looking 6 link setup it looks like he bolt right to the aluminum Dana rear, I still think the diff is going to blow if I did that, even an older iron case won't last.
Looks like a 12 bolt of some kind is in my future. Would like to see this thread go for while and get some guys who have converted the rear ends in there '80-'82's for big power. It could be used as a reference
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Do your research on the DV 6 link..... I had a thread running on it a few months ago and most that had it on a street car didn't like it. If you can limit the squat, you will limit some breakage...the DV 6 link basically just corrects geometry during a squat but...doesn't do anything to strengthen the rear end other then taking the load off of the half shafts by not using them as a stressed member in holding the wheel/suspension in place. They work well for that but it doesn't do crap for sheering posi units, ring gears, outer axles etc.
I think that $900 would be better spent on a severe duty rear spring, QA1 dbl adj shocks, all new bushings and ofcourse towards the mortgage of a 12bolt IRS, 30/31 spline axles, 3" thick walled half shafts or even 3.5".
Put good parts in the diff, stiffen the hell out of the rear to limit squat.
I am going through all of this crap myself deciding what all to do. I am pulling the trigger at the end of the summer...... About $4k down the tubes....and that's just for a super 10 bolt.
I think that $900 would be better spent on a severe duty rear spring, QA1 dbl adj shocks, all new bushings and ofcourse towards the mortgage of a 12bolt IRS, 30/31 spline axles, 3" thick walled half shafts or even 3.5".
Put good parts in the diff, stiffen the hell out of the rear to limit squat.
I am going through all of this crap myself deciding what all to do. I am pulling the trigger at the end of the summer...... About $4k down the tubes....and that's just for a super 10 bolt.
Thread Starter
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Yes I read some of that thread and do know what it does. I just never looked at it closely. What was interesting to me when I first looked at was the fact he was using the aluminum Dana 40. I personally know that diff is much stronger than anyone gives it credit for.
That said NFW is it gonna handle a wheels up launch on slicks, I was thinking about a cheap easy route but I don't think there is one. It looks like a 5 grand upgrade is what I'll be doing.
Now that said what exact parts are we looking at. 12 bolt diff to start now and add the rest of the parts, from who and which parts to use. Mines an '80 so it might require a bit more modifications than previous years ? .....
That said NFW is it gonna handle a wheels up launch on slicks, I was thinking about a cheap easy route but I don't think there is one. It looks like a 5 grand upgrade is what I'll be doing.
Now that said what exact parts are we looking at. 12 bolt diff to start now and add the rest of the parts, from who and which parts to use. Mines an '80 so it might require a bit more modifications than previous years ? .....
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Could you use this with your aluminum rear cover ?
http://www.vettemod.com/forum/showthread.php?t=5921
http://www.vettemod.com/forum/showthread.php?t=5921
Thread Starter
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Could you use this with your aluminum rear cover ?
http://www.vettemod.com/forum/showthread.php?t=5921
http://www.vettemod.com/forum/showthread.php?t=5921
Roger, at this moment I don't know what will fit or what I need. I would like to turn this thread into here's what you need for a bullet proof IRS for C3's.
I am obviously only interested in what an '80 needs. It would be nice to have a tidy list of all the parts, part numbers, approx. prices and where to get all of these parts. Maybe someone has them all in one place I don't know, or could put a package together
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
First you will need an iron diff. Not sure if any year case is better then the other...but either way you will need an iron case. Toms Differential is the only show in town. Other vendors just resale Toms stuff so....go to Tom direct and save the middle man mark up.
For the best of the best:
12 bolt internals kit...$1750
HD axle kit (30/31 spline inner/outers), 3.5" half shafts and flanges etc...$1988
HD cover.....$150
Ofcourse you need adj struts, a good spring, good shocks etc if you don't already
have these items.
Labor to rebuild the trailing arms(to install big bearings/31 spline axles) $500-700+
Labor to machine everything in the 10 bolt housing for clearance for the 12 bolt guts, machine all guts, install and correctly setup $500-700+,,,(rough estimate, probably more...)
It ain't cheap. A MINIMUM of $5k assuming you already all some of the suspension stuff. In reality, it's upwards of $6k
I was just quoted $4000 for Super 10 bolt which is basically the same except no 12 bolt ring/pinion and no 12 bolt posi carrier....and I already have the good half shafts.....but that was with a full trailing arm resto....
For the best of the best:
12 bolt internals kit...$1750
HD axle kit (30/31 spline inner/outers), 3.5" half shafts and flanges etc...$1988
HD cover.....$150
Ofcourse you need adj struts, a good spring, good shocks etc if you don't already
have these items.
Labor to rebuild the trailing arms(to install big bearings/31 spline axles) $500-700+
Labor to machine everything in the 10 bolt housing for clearance for the 12 bolt guts, machine all guts, install and correctly setup $500-700+,,,(rough estimate, probably more...)
It ain't cheap. A MINIMUM of $5k assuming you already all some of the suspension stuff. In reality, it's upwards of $6k
I was just quoted $4000 for Super 10 bolt which is basically the same except no 12 bolt ring/pinion and no 12 bolt posi carrier....and I already have the good half shafts.....but that was with a full trailing arm resto....
Last edited by ajrothm; Jun 22, 2010 at 05:17 PM.
Thread Starter
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
So far I have hit 7000 rpms on the 1/2 shift and haven't heard anything break in the rear. I have not yet tried a full on launch in first......Should be interesting. With my street tires, it would roast them from a 25 mph roll in first, and keep them boiling through third.
These MT's are sticky, which is what I needed....But now I have to work up the nerve to hit them hard off the line. I suspect my 3000 stall and almost 500 ft lbs is going to hit pretty hard. Mind you this car has not been on the track,...just playing around once in a while.
The rear is the stock aluminum one, but I put 3.70 gears in it about eight years ago, and all U-joints are solid.(No grease zerks)
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Thread Starter
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
First you will need an iron diff. Not sure if any year case is better then the other...but either way you will need an iron case. Toms Differential is the only show in town. Other vendors just resale Toms stuff so....go to Tom direct and save the middle man mark up.
For the best of the best:
12 bolt internals kit...$1750
HD axle kit (30/31 spline inner/outers), 3.5" half shafts and flanges etc...$1988
HD cover.....$150
Ofcourse you need adj struts, a good spring, good shocks etc if you don't already have these items.
Labor to rebuild the trailing arms(to install big bearings/31 spline axles) $500-700
Labor to machine everything in the 10 bolt housing for clearance for the 12 bolt guts, machine all guts, install and correctly setup $500-700....
It ain't cheap. A MINIMUM of $5k assuming you already all some of the suspension stuff. In reality, it's upwards of $6k
I was just quoted $4000 for Super 10 bolt which is basically the same except no 12 bolt ring/pinion and no 12 bolt posi carrier....and I already have the good half shafts.....but that was with a full trailing arm resto....
For the best of the best:
12 bolt internals kit...$1750
HD axle kit (30/31 spline inner/outers), 3.5" half shafts and flanges etc...$1988
HD cover.....$150
Ofcourse you need adj struts, a good spring, good shocks etc if you don't already have these items.
Labor to rebuild the trailing arms(to install big bearings/31 spline axles) $500-700
Labor to machine everything in the 10 bolt housing for clearance for the 12 bolt guts, machine all guts, install and correctly setup $500-700....
It ain't cheap. A MINIMUM of $5k assuming you already all some of the suspension stuff. In reality, it's upwards of $6k
I was just quoted $4000 for Super 10 bolt which is basically the same except no 12 bolt ring/pinion and no 12 bolt posi carrier....and I already have the good half shafts.....but that was with a full trailing arm resto....
But the way I do things I would imagine everything is going to be changed from the trailing arms to... well every part behind the end of the driveshaft.
