Needing Dragracing specific suspension guidance for my 81 Regal

Jdam

Apprentice
Mar 10, 2018
79
33
Heres what I would do, I would yank the motor, trans and rear out and put it in a fox body and go low 5s and be able to drive it with 1 finger on the wheel.

Merillat upper and lower torque boxes are a must in my opinion if you are going to throw some power at it. Afco big guns front and rear. Your converter sounds way to tight. My first converter stalled at 5200 and it was too tight. The new one stalls at 6100 and works good.
 
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64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
5,090
113
Upstate NY
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bracketchev1221

Royal Smart Person
Jan 18, 2018
1,239
113
Do you have any photos of the existing 10.0 legal cage? A 10.0 cage MIGHT be able to be upgraded to a 8.50 if the bars are in the right spot, but MRC makes the pre bent kit these days that's actually nice and an easy weld in.

The issue is a chassis shop (since you mention you aren't a welder) is going to probably charge more to upgrade a decent 10.0 cage rather then just buying a new good quality 8.50 kit and starting from scratch. If you are in the central, east, or south in the US there is likely a chassis shop that can put a pre bent cage in under week for ~$2500. I'd expect a pre bent kit to be $5000 installed and NHRA inspected. There are additional things like battery cutoffs, bellhousing/trans blankets, driveshaft hoops, harnesses, etc that aren't included in there.

Low 9's is a serious car. If the 10.0 cage is well done, you could likely look at just getting some instant center improvement bolt on or light weld on brackets and going from there. If the cage is OK possibly pull some timing out, try to get it to run 10.0's reliably. The jump from 10.10 to 9.70 is significant in terms of safety equipment so I'd get the car to be reliable 10.10 first, and then look at going into the low 9's.

I totally get the staged, budget build. The issue is when you jump into a car that already is a serious high HP setup it's tough to grow with the power as it's already there. You have a lot of deferred chassis/safety mainentence.
Its not worth upgrading a 10.0 roll bar. The issue is a 10.0 roll bar is 1 3/4" mild steel tubing where a 10 point roll cage is built out of 1 5/8" bar. As far as my car goes, I started with the stock 4 link bars and then went to SSM bars and went 1.47 in 60'. Swapped to ladder bars on the small tire and instantly went 1.42 in 60' going 10.30's'. At that point I blew up the motor and backhalved the car around the ladder bar and crossmember set up. I never changed a single thing with the ladder bar setup and it was in the car down into the 8.80's at 151 mph with a 1.21 60' time at 3200 lbs.
 

81cutlass

Comic Book Super Hero
Feb 16, 2009
4,362
113
Western MN
Its not worth upgrading a 10.0 roll bar. The issue is a 10.0 roll bar is 1 3/4" mild steel tubing where a 10 point roll cage is built out of 1 5/8" bar. As far as my car goes, I started with the stock 4 link bars and then went to SSM bars and went 1.47 in 60'. Swapped to ladder bars on the small tire and instantly went 1.42 in 60' going 10.30's'. At that point I blew up the motor and backhalved the car around the ladder bar and crossmember set up. I never changed a single thing with the ladder bar setup and it was in the car down into the 8.80's at 151 mph with a 1.21 60' time at 3200 lbs.

I was under the understanding 1 3/4" mild steel is good down to 8.50 (same as a 1 5/8" 4130 cage).

4130 moly steel lets you go down 1/8" in diameter due to the increase and strength, mostly for weight savings. If it's 4000 series it has to be TIG welded rather than mig.

Doesn't matter if it's mild carbon steel or 4000 series, an 8.50 cage has to have the same bars in the same place.
 

bracketchev1221

Royal Smart Person
Jan 18, 2018
1,239
113
I was under the understanding 1 3/4" mild steel is good down to 8.50 (same as a 1 5/8" 4130 cage).

4130 moly steel lets you go down 1/8" in diameter due to the increase and strength, mostly for weight savings. If it's 4000 series it has to be TIG welded rather than mig.

Doesn't matter if it's mild carbon steel or 4000 series, an 8.50 cage has to have the same bars in the same place.
Oh yes it is good to 8.50. The point I was trying to make is that if you do a cage, it is 1 5/8" mild steel for the entire cage. When you start with a 6 point roll bar, the roll bars are sold as 1 3/4" tube. So then the cage is heavier with a partial 1 3/4" roll bar and then hoping that it can be upgraded to a cage. My car was a 6 point roll bar car when I started, and by the time I was done with the cage the only part I saved was the main hoop and 2 door bars. And if you really want to push it, when the cage is certified to 8.50, there are only certain bars they check. So there are bars not needed to certify and these can be made out of Chromoly tubing if you choose. If you look at my cage, the X bar was the structural bars and were certified. the 2 smaller bars go through to the rear bumper and are basically there to support the back end of the frame to the cage. These do not need to be certifed so they were 1 1/4" chromoly tubing. But the X was tied to the frame rails at the upper shock mount.
DSC01450.jpg
 
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Birdoprey

Not-quite-so-new-guy
Thread starter
Sep 5, 2022
20
3
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Jdam

Apprentice
Mar 10, 2018
79
33
Welp, i ordered this one:

Added the swing out on drivers side and added the side bars clearing the OEM door handles. Gonna be removing the rear seat so i went with straight bars for the back.
Down the rabbit hole i go....:)
If you plan to notch the frame and mini tub the car do it before you do any cage work.
 
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Birdoprey

Not-quite-so-new-guy
Thread starter
Sep 5, 2022
20
3
Looks like the rear lower control arms have been relocated:
 

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